/* Optimize by combining instructions for GNU compiler. Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003 Free Software Foundation, Inc. This file is part of GCC. GCC is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. GCC is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GCC; see the file COPYING. If not, write to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ /* This module is essentially the "combiner" phase of the U. of Arizona Portable Optimizer, but redone to work on our list-structured representation for RTL instead of their string representation. The LOG_LINKS of each insn identify the most recent assignment to each REG used in the insn. It is a list of previous insns, each of which contains a SET for a REG that is used in this insn and not used or set in between. LOG_LINKs never cross basic blocks. They were set up by the preceding pass (lifetime analysis). We try to combine each pair of insns joined by a logical link. We also try to combine triples of insns A, B and C when C has a link back to B and B has a link back to A. LOG_LINKS does not have links for use of the CC0. They don't need to, because the insn that sets the CC0 is always immediately before the insn that tests it. So we always regard a branch insn as having a logical link to the preceding insn. The same is true for an insn explicitly using CC0. We check (with use_crosses_set_p) to avoid combining in such a way as to move a computation to a place where its value would be different. Combination is done by mathematically substituting the previous insn(s) values for the regs they set into the expressions in the later insns that refer to these regs. If the result is a valid insn for our target machine, according to the machine description, we install it, delete the earlier insns, and update the data flow information (LOG_LINKS and REG_NOTES) for what we did. There are a few exceptions where the dataflow information created by flow.c aren't completely updated: - reg_live_length is not updated - a LOG_LINKS entry that refers to an insn with multiple SETs may be removed because there is no way to know which register it was linking To simplify substitution, we combine only when the earlier insn(s) consist of only a single assignment. To simplify updating afterward, we never combine when a subroutine call appears in the middle. Since we do not represent assignments to CC0 explicitly except when that is all an insn does, there is no LOG_LINKS entry in an insn that uses the condition code for the insn that set the condition code. Fortunately, these two insns must be consecutive. Therefore, every JUMP_INSN is taken to have an implicit logical link to the preceding insn. This is not quite right, since non-jumps can also use the condition code; but in practice such insns would not combine anyway. */ #include "config.h" #include "system.h" #include "coretypes.h" #include "tm.h" #include "rtl.h" #include "tm_p.h" #include "flags.h" #include "regs.h" #include "hard-reg-set.h" #include "basic-block.h" #include "insn-config.h" #include "function.h" /* Include expr.h after insn-config.h so we get HAVE_conditional_move. */ #include "expr.h" #include "insn-attr.h" #include "recog.h" #include "real.h" #include "toplev.h" /* It is not safe to use ordinary gen_lowpart in combine. Use gen_lowpart_for_combine instead. See comments there. */ #define gen_lowpart dont_use_gen_lowpart_you_dummy /* Number of attempts to combine instructions in this function. */ static int combine_attempts; /* Number of attempts that got as far as substitution in this function. */ static int combine_merges; /* Number of instructions combined with added SETs in this function. */ static int combine_extras; /* Number of instructions combined in this function. */ static int combine_successes; /* Totals over entire compilation. */ static int total_attempts, total_merges, total_extras, total_successes; /* Vector mapping INSN_UIDs to cuids. The cuids are like uids but increase monotonically always. Combine always uses cuids so that it can compare them. But actually renumbering the uids, which we used to do, proves to be a bad idea because it makes it hard to compare the dumps produced by earlier passes with those from later passes. */ static int *uid_cuid; static int max_uid_cuid; /* Get the cuid of an insn. */ #define INSN_CUID(INSN) \ (INSN_UID (INSN) > max_uid_cuid ? insn_cuid (INSN) : uid_cuid[INSN_UID (INSN)]) /* In case BITS_PER_WORD == HOST_BITS_PER_WIDE_INT, shifting by BITS_PER_WORD would invoke undefined behavior. Work around it. */ #define UWIDE_SHIFT_LEFT_BY_BITS_PER_WORD(val) \ (((unsigned HOST_WIDE_INT) (val) << (BITS_PER_WORD - 1)) << 1) #define nonzero_bits(X, M) \ cached_nonzero_bits (X, M, NULL_RTX, VOIDmode, 0) #define num_sign_bit_copies(X, M) \ cached_num_sign_bit_copies (X, M, NULL_RTX, VOIDmode, 0) /* Maximum register number, which is the size of the tables below. */ static unsigned int combine_max_regno; /* Record last point of death of (hard or pseudo) register n. */ static rtx *reg_last_death; /* Record last point of modification of (hard or pseudo) register n. */ static rtx *reg_last_set; /* Record the cuid of the last insn that invalidated memory (anything that writes memory, and subroutine calls, but not pushes). */ static int mem_last_set; /* Record the cuid of the last CALL_INSN so we can tell whether a potential combination crosses any calls. */ static int last_call_cuid; /* When `subst' is called, this is the insn that is being modified (by combining in a previous insn). The PATTERN of this insn is still the old pattern partially modified and it should not be looked at, but this may be used to examine the successors of the insn to judge whether a simplification is valid. */ static rtx subst_insn; /* This is the lowest CUID that `subst' is currently dealing with. get_last_value will not return a value if the register was set at or after this CUID. If not for this mechanism, we could get confused if I2 or I1 in try_combine were an insn that used the old value of a register to obtain a new value. In that case, we might erroneously get the new value of the register when we wanted the old one. */ static int subst_low_cuid; /* This contains any hard registers that are used in newpat; reg_dead_at_p must consider all these registers to be always live. */ static HARD_REG_SET newpat_used_regs; /* This is an insn to which a LOG_LINKS entry has been added. If this insn is the earlier than I2 or I3, combine should rescan starting at that location. */ static rtx added_links_insn; /* Basic block in which we are performing combines. */ static basic_block this_basic_block; /* A bitmap indicating which blocks had registers go dead at entry. After combine, we'll need to re-do global life analysis with those blocks as starting points. */ static sbitmap refresh_blocks; /* The next group of arrays allows the recording of the last value assigned to (hard or pseudo) register n. We use this information to see if an operation being processed is redundant given a prior operation performed on the register. For example, an `and' with a constant is redundant if all the zero bits are already known to be turned off. We use an approach similar to that used by cse, but change it in the following ways: (1) We do not want to reinitialize at each label. (2) It is useful, but not critical, to know the actual value assigned to a register. Often just its form is helpful. Therefore, we maintain the following arrays: reg_last_set_value the last value assigned reg_last_set_label records the value of label_tick when the register was assigned reg_last_set_table_tick records the value of label_tick when a value using the register is assigned reg_last_set_invalid set to nonzero when it is not valid to use the value of this register in some register's value To understand the usage of these tables, it is important to understand the distinction between the value in reg_last_set_value being valid and the register being validly contained in some other expression in the table. Entry I in reg_last_set_value is valid if it is nonzero, and either reg_n_sets[i] is 1 or reg_last_set_label[i] == label_tick. Register I may validly appear in any expression returned for the value of another register if reg_n_sets[i] is 1. It may also appear in the value for register J if reg_last_set_label[i] < reg_last_set_label[j] or reg_last_set_invalid[j] is zero. If an expression is found in the table containing a register which may not validly appear in an expression, the register is replaced by something that won't match, (clobber (const_int 0)). reg_last_set_invalid[i] is set nonzero when register I is being assigned to and reg_last_set_table_tick[i] == label_tick. */ /* Record last value assigned to (hard or pseudo) register n. */ static rtx *reg_last_set_value; /* Record the value of label_tick when the value for register n is placed in reg_last_set_value[n]. */ static int *reg_last_set_label; /* Record the value of label_tick when an expression involving register n is placed in reg_last_set_value. */ static int *reg_last_set_table_tick; /* Set nonzero if references to register n in expressions should not be used. */ static char *reg_last_set_invalid; /* Incremented for each label. */ static int label_tick; /* Some registers that are set more than once and used in more than one basic block are nevertheless always set in similar ways. For example, a QImode register may be loaded from memory in two places on a machine where byte loads zero extend. We record in the following array what we know about the nonzero bits of a register, specifically which bits are known to be zero. If an entry is zero, it means that we don't know anything special. */ static unsigned HOST_WIDE_INT *reg_nonzero_bits; /* Mode used to compute significance in reg_nonzero_bits. It is the largest integer mode that can fit in HOST_BITS_PER_WIDE_INT. */ static enum machine_mode nonzero_bits_mode; /* Nonzero if we know that a register has some leading bits that are always equal to the sign bit. */ static unsigned char *reg_sign_bit_copies; /* Nonzero when reg_nonzero_bits and reg_sign_bit_copies can be safely used. It is zero while computing them and after combine has completed. This former test prevents propagating values based on previously set values, which can be incorrect if a variable is modified in a loop. */ static int nonzero_sign_valid; /* These arrays are maintained in parallel with reg_last_set_value and are used to store the mode in which the register was last set, the bits that were known to be zero when it was last set, and the number of sign bits copies it was known to have when it was last set. */ static enum machine_mode *reg_last_set_mode; static unsigned HOST_WIDE_INT *reg_last_set_nonzero_bits; static char *reg_last_set_sign_bit_copies; /* Record one modification to rtl structure to be undone by storing old_contents into *where. is_int is 1 if the contents are an int. */ struct undo { struct undo *next; int is_int; union {rtx r; int i;} old_contents; union {rtx *r; int *i;} where; }; /* Record a bunch of changes to be undone, up to MAX_UNDO of them. num_undo says how many are currently recorded. other_insn is nonzero if we have modified some other insn in the process of working on subst_insn. It must be verified too. */ struct undobuf { struct undo *undos; struct undo *frees; rtx other_insn; }; static struct undobuf undobuf; /* Number of times the pseudo being substituted for was found and replaced. */ static int n_occurrences; static void do_SUBST PARAMS ((rtx *, rtx)); static void do_SUBST_INT PARAMS ((int *, int)); static void init_reg_last_arrays PARAMS ((void)); static void setup_incoming_promotions PARAMS ((void)); static void set_nonzero_bits_and_sign_copies PARAMS ((rtx, rtx, void *)); static int cant_combine_insn_p PARAMS ((rtx)); static int can_combine_p PARAMS ((rtx, rtx, rtx, rtx, rtx *, rtx *)); static int sets_function_arg_p PARAMS ((rtx)); static int combinable_i3pat PARAMS ((rtx, rtx *, rtx, rtx, int, rtx *)); static int contains_muldiv PARAMS ((rtx)); static rtx try_combine PARAMS ((rtx, rtx, rtx, int *)); static void undo_all PARAMS ((void)); static void undo_commit PARAMS ((void)); static rtx *find_split_point PARAMS ((rtx *, rtx)); static rtx subst PARAMS ((rtx, rtx, rtx, int, int)); static rtx combine_simplify_rtx PARAMS ((rtx, enum machine_mode, int, int)); static rtx simplify_if_then_else PARAMS ((rtx)); static rtx simplify_set PARAMS ((rtx)); static rtx simplify_logical PARAMS ((rtx, int)); static rtx expand_compound_operation PARAMS ((rtx)); static rtx expand_field_assignment PARAMS ((rtx)); static rtx make_extraction PARAMS ((enum machine_mode, rtx, HOST_WIDE_INT, rtx, unsigned HOST_WIDE_INT, int, int, int)); static rtx extract_left_shift PARAMS ((rtx, int)); static rtx make_compound_operation PARAMS ((rtx, enum rtx_code)); static int get_pos_from_mask PARAMS ((unsigned HOST_WIDE_INT, unsigned HOST_WIDE_INT *)); static rtx force_to_mode PARAMS ((rtx, enum machine_mode, unsigned HOST_WIDE_INT, rtx, int)); static rtx if_then_else_cond PARAMS ((rtx, rtx *, rtx *)); static rtx known_cond PARAMS ((rtx, enum rtx_code, rtx, rtx)); static int rtx_equal_for_field_assignment_p PARAMS ((rtx, rtx)); static rtx make_field_assignment PARAMS ((rtx)); static rtx apply_distributive_law PARAMS ((rtx)); static rtx simplify_and_const_int PARAMS ((rtx, enum machine_mode, rtx, unsigned HOST_WIDE_INT)); static unsigned HOST_WIDE_INT cached_nonzero_bits PARAMS ((rtx, enum machine_mode, rtx, enum machine_mode, unsigned HOST_WIDE_INT)); static unsigned HOST_WIDE_INT nonzero_bits1 PARAMS ((rtx, enum machine_mode, rtx, enum machine_mode, unsigned HOST_WIDE_INT)); static unsigned int cached_num_sign_bit_copies PARAMS ((rtx, enum machine_mode, rtx, enum machine_mode, unsigned int)); static unsigned int num_sign_bit_copies1 PARAMS ((rtx, enum machine_mode, rtx, enum machine_mode, unsigned int)); static int merge_outer_ops PARAMS ((enum rtx_code *, HOST_WIDE_INT *, enum rtx_code, HOST_WIDE_INT, enum machine_mode, int *)); static rtx simplify_shift_const PARAMS ((rtx, enum rtx_code, enum machine_mode, rtx, int)); static int recog_for_combine PARAMS ((rtx *, rtx, rtx *)); static rtx gen_lowpart_for_combine PARAMS ((enum machine_mode, rtx)); static rtx gen_binary PARAMS ((enum rtx_code, enum machine_mode, rtx, rtx)); static enum rtx_code simplify_comparison PARAMS ((enum rtx_code, rtx *, rtx *)); static void update_table_tick PARAMS ((rtx)); static void record_value_for_reg PARAMS ((rtx, rtx, rtx)); static void check_promoted_subreg PARAMS ((rtx, rtx)); static void record_dead_and_set_regs_1 PARAMS ((rtx, rtx, void *)); static void record_dead_and_set_regs PARAMS ((rtx)); static int get_last_value_validate PARAMS ((rtx *, rtx, int, int)); static rtx get_last_value PARAMS ((rtx)); static int use_crosses_set_p PARAMS ((rtx, int)); static void reg_dead_at_p_1 PARAMS ((rtx, rtx, void *)); static int reg_dead_at_p PARAMS ((rtx, rtx)); static void move_deaths PARAMS ((rtx, rtx, int, rtx, rtx *)); static int reg_bitfield_target_p PARAMS ((rtx, rtx)); static void distribute_notes PARAMS ((rtx, rtx, rtx, rtx)); static void distribute_links PARAMS ((rtx)); static void mark_used_regs_combine PARAMS ((rtx)); static int insn_cuid PARAMS ((rtx)); static void record_promoted_value PARAMS ((rtx, rtx)); static rtx reversed_comparison PARAMS ((rtx, enum machine_mode, rtx, rtx)); static enum rtx_code combine_reversed_comparison_code PARAMS ((rtx)); /* Substitute NEWVAL, an rtx expression, into INTO, a place in some insn. The substitution can be undone by undo_all. If INTO is already set to NEWVAL, do not record this change. Because computing NEWVAL might also call SUBST, we have to compute it before we put anything into the undo table. */ static void do_SUBST (into, newval) rtx *into, newval; { struct undo *buf; rtx oldval = *into; if (oldval == newval) return; /* We'd like to catch as many invalid transformations here as possible. Unfortunately, there are way too many mode changes that are perfectly valid, so we'd waste too much effort for little gain doing the checks here. Focus on catching invalid transformations involving integer constants. */ if (GET_MODE_CLASS (GET_MODE (oldval)) == MODE_INT && GET_CODE (newval) == CONST_INT) { /* Sanity check that we're replacing oldval with a CONST_INT that is a valid sign-extension for the original mode. */ if (INTVAL (newval) != trunc_int_for_mode (INTVAL (newval), GET_MODE (oldval))) abort (); /* Replacing the operand of a SUBREG or a ZERO_EXTEND with a CONST_INT is not valid, because after the replacement, the original mode would be gone. Unfortunately, we can't tell when do_SUBST is called to replace the operand thereof, so we perform this test on oldval instead, checking whether an invalid replacement took place before we got here. */ if ((GET_CODE (oldval) == SUBREG && GET_CODE (SUBREG_REG (oldval)) == CONST_INT) || (GET_CODE (oldval) == ZERO_EXTEND && GET_CODE (XEXP (oldval, 0)) == CONST_INT)) abort (); } if (undobuf.frees) buf = undobuf.frees, undobuf.frees = buf->next; else buf = (struct undo *) xmalloc (sizeof (struct undo)); buf->is_int = 0; buf->where.r = into; buf->old_contents.r = oldval; *into = newval; buf->next = undobuf.undos, undobuf.undos = buf; } #define SUBST(INTO, NEWVAL) do_SUBST(&(INTO), (NEWVAL)) /* Similar to SUBST, but NEWVAL is an int expression. Note that substitution for the value of a HOST_WIDE_INT value (including CONST_INT) is not safe. */ static void do_SUBST_INT (into, newval) int *into, newval; { struct undo *buf; int oldval = *into; if (oldval == newval) return; if (undobuf.frees) buf = undobuf.frees, undobuf.frees = buf->next; else buf = (struct undo *) xmalloc (sizeof (struct undo)); buf->is_int = 1; buf->where.i = into; buf->old_contents.i = oldval; *into = newval; buf->next = undobuf.undos, undobuf.undos = buf; } #define SUBST_INT(INTO, NEWVAL) do_SUBST_INT(&(INTO), (NEWVAL)) /* Main entry point for combiner. F is the first insn of the function. NREGS is the first unused pseudo-reg number. Return nonzero if the combiner has turned an indirect jump instruction into a direct jump. */ int combine_instructions (f, nregs) rtx f; unsigned int nregs; { rtx insn, next; #ifdef HAVE_cc0 rtx prev; #endif int i; rtx links, nextlinks; int new_direct_jump_p = 0; combine_attempts = 0; combine_merges = 0; combine_extras = 0; combine_successes = 0; combine_max_regno = nregs; reg_nonzero_bits = ((unsigned HOST_WIDE_INT *) xcalloc (nregs, sizeof (unsigned HOST_WIDE_INT))); reg_sign_bit_copies = (unsigned char *) xcalloc (nregs, sizeof (unsigned char)); reg_last_death = (rtx *) xmalloc (nregs * sizeof (rtx)); reg_last_set = (rtx *) xmalloc (nregs * sizeof (rtx)); reg_last_set_value = (rtx *) xmalloc (nregs * sizeof (rtx)); reg_last_set_table_tick = (int *) xmalloc (nregs * sizeof (int)); reg_last_set_label = (int *) xmalloc (nregs * sizeof (int)); reg_last_set_invalid = (char *) xmalloc (nregs * sizeof (char)); reg_last_set_mode = (enum machine_mode *) xmalloc (nregs * sizeof (enum machine_mode)); reg_last_set_nonzero_bits = (unsigned HOST_WIDE_INT *) xmalloc (nregs * sizeof (HOST_WIDE_INT)); reg_last_set_sign_bit_copies = (char *) xmalloc (nregs * sizeof (char)); init_reg_last_arrays (); init_recog_no_volatile (); /* Compute maximum uid value so uid_cuid can be allocated. */ for (insn = f, i = 0; insn; insn = NEXT_INSN (insn)) if (INSN_UID (insn) > i) i = INSN_UID (insn); uid_cuid = (int *) xmalloc ((i + 1) * sizeof (int)); max_uid_cuid = i; nonzero_bits_mode = mode_for_size (HOST_BITS_PER_WIDE_INT, MODE_INT, 0); /* Don't use reg_nonzero_bits when computing it. This can cause problems when, for example, we have j <<= 1 in a loop. */ nonzero_sign_valid = 0; /* Compute the mapping from uids to cuids. Cuids are numbers assigned to insns, like uids, except that cuids increase monotonically through the code. Scan all SETs and see if we can deduce anything about what bits are known to be zero for some registers and how many copies of the sign bit are known to exist for those registers. Also set any known values so that we can use it while searching for what bits are known to be set. */ label_tick = 1; setup_incoming_promotions (); refresh_blocks = sbitmap_alloc (last_basic_block); sbitmap_zero (refresh_blocks); for (insn = f, i = 0; insn; insn = NEXT_INSN (insn)) { uid_cuid[INSN_UID (insn)] = ++i; subst_low_cuid = i; subst_insn = insn; if (INSN_P (insn)) { note_stores (PATTERN (insn), set_nonzero_bits_and_sign_copies, NULL); record_dead_and_set_regs (insn); #ifdef AUTO_INC_DEC for (links = REG_NOTES (insn); links; links = XEXP (links, 1)) if (REG_NOTE_KIND (links) == REG_INC) set_nonzero_bits_and_sign_copies (XEXP (links, 0), NULL_RTX, NULL); #endif } if (GET_CODE (insn) == CODE_LABEL) label_tick++; } nonzero_sign_valid = 1; /* Now scan all the insns in forward order. */ label_tick = 1; last_call_cuid = 0; mem_last_set = 0; init_reg_last_arrays (); setup_incoming_promotions (); FOR_EACH_BB (this_basic_block) { for (insn = this_basic_block->head; insn != NEXT_INSN (this_basic_block->end); insn = next ? next : NEXT_INSN (insn)) { next = 0; if (GET_CODE (insn) == CODE_LABEL) label_tick++; else if (INSN_P (insn)) { /* See if we know about function return values before this insn based upon SUBREG flags. */ check_promoted_subreg (insn, PATTERN (insn)); /* Try this insn with each insn it links back to. */ for (links = LOG_LINKS (insn); links; links = XEXP (links, 1)) if ((next = try_combine (insn, XEXP (links, 0), NULL_RTX, &new_direct_jump_p)) != 0) goto retry; /* Try each sequence of three linked insns ending with this one. */ for (links = LOG_LINKS (insn); links; links = XEXP (links, 1)) { rtx link = XEXP (links, 0); /* If the linked insn has been replaced by a note, then there is no point in pursuing this chain any further. */ if (GET_CODE (link) == NOTE) continue; for (nextlinks = LOG_LINKS (link); nextlinks; nextlinks = XEXP (nextlinks, 1)) if ((next = try_combine (insn, link, XEXP (nextlinks, 0), &new_direct_jump_p)) != 0) goto retry; } #ifdef HAVE_cc0 /* Try to combine a jump insn that uses CC0 with a preceding insn that sets CC0, and maybe with its logical predecessor as well. This is how we make decrement-and-branch insns. We need this special code because data flow connections via CC0 do not get entered in LOG_LINKS. */ if (GET_CODE (insn) == JUMP_INSN && (prev = prev_nonnote_insn (insn)) != 0 && GET_CODE (prev) == INSN && sets_cc0_p (PATTERN (prev))) { if ((next = try_combine (insn, prev, NULL_RTX, &new_direct_jump_p)) != 0) goto retry; for (nextlinks = LOG_LINKS (prev); nextlinks; nextlinks = XEXP (nextlinks, 1)) if ((next = try_combine (insn, prev, XEXP (nextlinks, 0), &new_direct_jump_p)) != 0) goto retry; } /* Do the same for an insn that explicitly references CC0. */ if (GET_CODE (insn) == INSN && (prev = prev_nonnote_insn (insn)) != 0 && GET_CODE (prev) == INSN && sets_cc0_p (PATTERN (prev)) && GET_CODE (PATTERN (insn)) == SET && reg_mentioned_p (cc0_rtx, SET_SRC (PATTERN (insn)))) { if ((next = try_combine (insn, prev, NULL_RTX, &new_direct_jump_p)) != 0) goto retry; for (nextlinks = LOG_LINKS (prev); nextlinks; nextlinks = XEXP (nextlinks, 1)) if ((next = try_combine (insn, prev, XEXP (nextlinks, 0), &new_direct_jump_p)) != 0) goto retry; } /* Finally, see if any of the insns that this insn links to explicitly references CC0. If so, try this insn, that insn, and its predecessor if it sets CC0. */ for (links = LOG_LINKS (insn); links; links = XEXP (links, 1)) if (GET_CODE (XEXP (links, 0)) == INSN && GET_CODE (PATTERN (XEXP (links, 0))) == SET && reg_mentioned_p (cc0_rtx, SET_SRC (PATTERN (XEXP (links, 0)))) && (prev = prev_nonnote_insn (XEXP (links, 0))) != 0 && GET_CODE (prev) == INSN && sets_cc0_p (PATTERN (prev)) && (next = try_combine (insn, XEXP (links, 0), prev, &new_direct_jump_p)) != 0) goto retry; #endif /* Try combining an insn with two different insns whose results it uses. */ for (links = LOG_LINKS (insn); links; links = XEXP (links, 1)) for (nextlinks = XEXP (links, 1); nextlinks; nextlinks = XEXP (nextlinks, 1)) if ((next = try_combine (insn, XEXP (links, 0), XEXP (nextlinks, 0), &new_direct_jump_p)) != 0) goto retry; if (GET_CODE (insn) != NOTE) record_dead_and_set_regs (insn); retry: ; } } } clear_bb_flags (); EXECUTE_IF_SET_IN_SBITMAP (refresh_blocks, 0, i, BASIC_BLOCK (i)->flags |= BB_DIRTY); new_direct_jump_p |= purge_all_dead_edges (0); delete_noop_moves (f); update_life_info_in_dirty_blocks (UPDATE_LIFE_GLOBAL_RM_NOTES, PROP_DEATH_NOTES | PROP_SCAN_DEAD_CODE | PROP_KILL_DEAD_CODE); /* Clean up. */ sbitmap_free (refresh_blocks); free (reg_nonzero_bits); free (reg_sign_bit_copies); free (reg_last_death); free (reg_last_set); free (reg_last_set_value); free (reg_last_set_table_tick); free (reg_last_set_label); free (reg_last_set_invalid); free (reg_last_set_mode); free (reg_last_set_nonzero_bits); free (reg_last_set_sign_bit_copies); free (uid_cuid); { struct undo *undo, *next; for (undo = undobuf.frees; undo; undo = next) { next = undo->next; free (undo); } undobuf.frees = 0; } total_attempts += combine_attempts; total_merges += combine_merges; total_extras += combine_extras; total_successes += combine_successes; nonzero_sign_valid = 0; /* Make recognizer allow volatile MEMs again. */ init_recog (); return new_direct_jump_p; } /* Wipe the reg_last_xxx arrays in preparation for another pass. */ static void init_reg_last_arrays () { unsigned int nregs = combine_max_regno; memset ((char *) reg_last_death, 0, nregs * sizeof (rtx)); memset ((char *) reg_last_set, 0, nregs * sizeof (rtx)); memset ((char *) reg_last_set_value, 0, nregs * sizeof (rtx)); memset ((char *) reg_last_set_table_tick, 0, nregs * sizeof (int)); memset ((char *) reg_last_set_label, 0, nregs * sizeof (int)); memset (reg_last_set_invalid, 0, nregs * sizeof (char)); memset ((char *) reg_last_set_mode, 0, nregs * sizeof (enum machine_mode)); memset ((char *) reg_last_set_nonzero_bits, 0, nregs * sizeof (HOST_WIDE_INT)); memset (reg_last_set_sign_bit_copies, 0, nregs * sizeof (char)); } /* Set up any promoted values for incoming argument registers. */ static void setup_incoming_promotions () { #ifdef PROMOTE_FUNCTION_ARGS unsigned int regno; rtx reg; enum machine_mode mode; int unsignedp; rtx first = get_insns (); #ifndef OUTGOING_REGNO #define OUTGOING_REGNO(N) N #endif for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++) /* Check whether this register can hold an incoming pointer argument. FUNCTION_ARG_REGNO_P tests outgoing register numbers, so translate if necessary due to register windows. */ if (FUNCTION_ARG_REGNO_P (OUTGOING_REGNO (regno)) && (reg = promoted_input_arg (regno, &mode, &unsignedp)) != 0) { record_value_for_reg (reg, first, gen_rtx_fmt_e ((unsignedp ? ZERO_EXTEND : SIGN_EXTEND), GET_MODE (reg), gen_rtx_CLOBBER (mode, const0_rtx))); } #endif } /* Called via note_stores. If X is a pseudo that is narrower than HOST_BITS_PER_WIDE_INT and is being set, record what bits are known zero. If we are setting only a portion of X and we can't figure out what portion, assume all bits will be used since we don't know what will be happening. Similarly, set how many bits of X are known to be copies of the sign bit at all locations in the function. This is the smallest number implied by any set of X. */ static void set_nonzero_bits_and_sign_copies (x, set, data) rtx x; rtx set; void *data ATTRIBUTE_UNUSED; { unsigned int num; if (GET_CODE (x) == REG && REGNO (x) >= FIRST_PSEUDO_REGISTER /* If this register is undefined at the start of the file, we can't say what its contents were. */ && ! REGNO_REG_SET_P (ENTRY_BLOCK_PTR->next_bb->global_live_at_start, REGNO (x)) && GET_MODE_BITSIZE (GET_MODE (x)) <= HOST_BITS_PER_WIDE_INT) { if (set == 0 || GET_CODE (set) == CLOBBER) { reg_nonzero_bits[REGNO (x)] = GET_MODE_MASK (GET_MODE (x)); reg_sign_bit_copies[REGNO (x)] = 1; return; } /* If this is a complex assignment, see if we can convert it into a simple assignment. */ set = expand_field_assignment (set); /* If this is a simple assignment, or we have a paradoxical SUBREG, set what we know about X. */ if (SET_DEST (set) == x || (GET_CODE (SET_DEST (set)) == SUBREG && (GET_MODE_SIZE (GET_MODE (SET_DEST (set))) > GET_MODE_SIZE (GET_MODE (SUBREG_REG (SET_DEST (set))))) && SUBREG_REG (SET_DEST (set)) == x)) { rtx src = SET_SRC (set); #ifdef SHORT_IMMEDIATES_SIGN_EXTEND /* If X is narrower than a word and SRC is a non-negative constant that would appear negative in the mode of X, sign-extend it for use in reg_nonzero_bits because some machines (maybe most) will actually do the sign-extension and this is the conservative approach. ??? For 2.5, try to tighten up the MD files in this regard instead of this kludge. */ if (GET_MODE_BITSIZE (GET_MODE (x)) < BITS_PER_WORD && GET_CODE (src) == CONST_INT && INTVAL (src) > 0 && 0 != (INTVAL (src) & ((HOST_WIDE_INT) 1 << (GET_MODE_BITSIZE (GET_MODE (x)) - 1)))) src = GEN_INT (INTVAL (src) | ((HOST_WIDE_INT) (-1) << GET_MODE_BITSIZE (GET_MODE (x)))); #endif /* Don't call nonzero_bits if it cannot change anything. */ if (reg_nonzero_bits[REGNO (x)] != ~(unsigned HOST_WIDE_INT) 0) reg_nonzero_bits[REGNO (x)] |= nonzero_bits (src, nonzero_bits_mode); num = num_sign_bit_copies (SET_SRC (set), GET_MODE (x)); if (reg_sign_bit_copies[REGNO (x)] == 0 || reg_sign_bit_copies[REGNO (x)] > num) reg_sign_bit_copies[REGNO (x)] = num; } else { reg_nonzero_bits[REGNO (x)] = GET_MODE_MASK (GET_MODE (x)); reg_sign_bit_copies[REGNO (x)] = 1; } } } /* See if INSN can be combined into I3. PRED and SUCC are optionally insns that were previously combined into I3 or that will be combined into the merger of INSN and I3. Return 0 if the combination is not allowed for any reason. If the combination is allowed, *PDEST will be set to the single destination of INSN and *PSRC to the single source, and this function will return 1. */ static int can_combine_p (insn, i3, pred, succ, pdest, psrc) rtx insn; rtx i3; rtx pred ATTRIBUTE_UNUSED; rtx succ; rtx *pdest, *psrc; { int i; rtx set = 0, src, dest; rtx p; #ifdef AUTO_INC_DEC rtx link; #endif int all_adjacent = (succ ? (next_active_insn (insn) == succ && next_active_insn (succ) == i3) : next_active_insn (insn) == i3); /* Can combine only if previous insn is a SET of a REG, a SUBREG or CC0. or a PARALLEL consisting of such a SET and CLOBBERs. If INSN has CLOBBER parallel parts, ignore them for our processing. By definition, these happen during the execution of the insn. When it is merged with another insn, all bets are off. If they are, in fact, needed and aren't also supplied in I3, they may be added by recog_for_combine. Otherwise, it won't match. We can also ignore a SET whose SET_DEST is mentioned in a REG_UNUSED note. Get the source and destination of INSN. If more than one, can't combine. */ if (GET_CODE (PATTERN (insn)) == SET) set = PATTERN (insn); else if (GET_CODE (PATTERN (insn)) == PARALLEL && GET_CODE (XVECEXP (PATTERN (insn), 0, 0)) == SET) { for (i = 0; i < XVECLEN (PATTERN (insn), 0); i++) { rtx elt = XVECEXP (PATTERN (insn), 0, i); switch (GET_CODE (elt)) { /* This is important to combine floating point insns for the SH4 port. */ case USE: /* Combining an isolated USE doesn't make sense. We depend here on combinable_i3pat to reject them. */ /* The code below this loop only verifies that the inputs of the SET in INSN do not change. We call reg_set_between_p to verify that the REG in the USE does not change between I3 and INSN. If the USE in INSN was for a pseudo register, the matching insn pattern will likely match any register; combining this with any other USE would only be safe if we knew that the used registers have identical values, or if there was something to tell them apart, e.g. different modes. For now, we forgo such complicated tests and simply disallow combining of USES of pseudo registers with any other USE. */ if (GET_CODE (XEXP (elt, 0)) == REG && GET_CODE (PATTERN (i3)) == PARALLEL) { rtx i3pat = PATTERN (i3); int i = XVECLEN (i3pat, 0) - 1; unsigned int regno = REGNO (XEXP (elt, 0)); do { rtx i3elt = XVECEXP (i3pat, 0, i); if (GET_CODE (i3elt) == USE && GET_CODE (XEXP (i3elt, 0)) == REG && (REGNO (XEXP (i3elt, 0)) == regno ? reg_set_between_p (XEXP (elt, 0), PREV_INSN (insn), i3) : regno >= FIRST_PSEUDO_REGISTER)) return 0; } while (--i >= 0); } break; /* We can ignore CLOBBERs. */ case CLOBBER: break; case SET: /* Ignore SETs whose result isn't used but not those that have side-effects. */ if (find_reg_note (insn, REG_UNUSED, SET_DEST (elt)) && ! side_effects_p (elt)) break; /* If we have already found a SET, this is a second one and so we cannot combine with this insn. */ if (set) return 0; set = elt; break; default: /* Anything else means we can't combine. */ return 0; } } if (set == 0 /* If SET_SRC is an ASM_OPERANDS we can't throw away these CLOBBERs, so don't do anything with it. */ || GET_CODE (SET_SRC (set)) == ASM_OPERANDS) return 0; } else return 0; if (set == 0) return 0; set = expand_field_assignment (set); src = SET_SRC (set), dest = SET_DEST (set); /* Don't eliminate a store in the stack pointer. */ if (dest == stack_pointer_rtx /* Don't combine with an insn that sets a register to itself if it has a REG_EQUAL note. This may be part of a REG_NO_CONFLICT sequence. */ || (rtx_equal_p (src, dest) && find_reg_note (insn, REG_EQUAL, NULL_RTX)) /* Can't merge an ASM_OPERANDS. */ || GET_CODE (src) == ASM_OPERANDS /* Can't merge a function call. */ || GET_CODE (src) == CALL /* Don't eliminate a function call argument. */ || (GET_CODE (i3) == CALL_INSN && (find_reg_fusage (i3, USE, dest) || (GET_CODE (dest) == REG && REGNO (dest) < FIRST_PSEUDO_REGISTER && global_regs[REGNO (dest)]))) /* Don't substitute into an incremented register. */ || FIND_REG_INC_NOTE (i3, dest) || (succ && FIND_REG_INC_NOTE (succ, dest)) #if 0 /* Don't combine the end of a libcall into anything. */ /* ??? This gives worse code, and appears to be unnecessary, since no pass after flow uses REG_LIBCALL/REG_RETVAL notes. Local-alloc does use REG_RETVAL notes for noconflict blocks, but other code here makes sure that those insns don't disappear. */ || find_reg_note (insn, REG_RETVAL, NULL_RTX) #endif /* Make sure that DEST is not used after SUCC but before I3. */ || (succ && ! all_adjacent && reg_used_between_p (dest, succ, i3)) /* Make sure that the value that is to be substituted for the register does not use any registers whose values alter in between. However, If the insns are adjacent, a use can't cross a set even though we think it might (this can happen for a sequence of insns each setting the same destination; reg_last_set of that register might point to a NOTE). If INSN has a REG_EQUIV note, the register is always equivalent to the memory so the substitution is valid even if there are intervening stores. Also, don't move a volatile asm or UNSPEC_VOLATILE across any other insns. */ || (! all_adjacent && (((GET_CODE (src) != MEM || ! find_reg_note (insn, REG_EQUIV, src)) && use_crosses_set_p (src, INSN_CUID (insn))) || (GET_CODE (src) == ASM_OPERANDS && MEM_VOLATILE_P (src)) || GET_CODE (src) == UNSPEC_VOLATILE)) /* If there is a REG_NO_CONFLICT note for DEST in I3 or SUCC, we get better register allocation by not doing the combine. */ || find_reg_note (i3, REG_NO_CONFLICT, dest) || (succ && find_reg_note (succ, REG_NO_CONFLICT, dest)) /* Don't combine across a CALL_INSN, because that would possibly change whether the life span of some REGs crosses calls or not, and it is a pain to update that information. Exception: if source is a constant, moving it later can't hurt. Accept that special case, because it helps -fforce-addr a lot. */ || (INSN_CUID (insn) < last_call_cuid && ! CONSTANT_P (src))) return 0; /* DEST must either be a REG or CC0. */ if (GET_CODE (dest) == REG) { /* If register alignment is being enforced for multi-word items in all cases except for parameters, it is possible to have a register copy insn referencing a hard register that is not allowed to contain the mode being copied and which would not be valid as an operand of most insns. Eliminate this problem by not combining with such an insn. Also, on some machines we don't want to extend the life of a hard register. */ if (GET_CODE (src) == REG && ((REGNO (dest) < FIRST_PSEUDO_REGISTER && ! HARD_REGNO_MODE_OK (REGNO (dest), GET_MODE (dest))) /* Don't extend the life of a hard register unless it is user variable (if we have few registers) or it can't fit into the desired register (meaning something special is going on). Also avoid substituting a return register into I3, because reload can't handle a conflict with constraints of other inputs. */ || (REGNO (src) < FIRST_PSEUDO_REGISTER && ! HARD_REGNO_MODE_OK (REGNO (src), GET_MODE (src))))) return 0; } else if (GET_CODE (dest) != CC0) return 0; /* Don't substitute for a register intended as a clobberable operand. Similarly, don't substitute an expression containing a register that will be clobbered in I3. */ if (GET_CODE (PATTERN (i3)) == PARALLEL) for (i = XVECLEN (PATTERN (i3), 0) - 1; i >= 0; i--) if (GET_CODE (XVECEXP (PATTERN (i3), 0, i)) == CLOBBER && (reg_overlap_mentioned_p (XEXP (XVECEXP (PATTERN (i3), 0, i), 0), src) || rtx_equal_p (XEXP (XVECEXP (PATTERN (i3), 0, i), 0), dest))) return 0; /* If INSN contains anything volatile, or is an `asm' (whether volatile or not), reject, unless nothing volatile comes between it and I3 */ if (GET_CODE (src) == ASM_OPERANDS || volatile_refs_p (src)) { /* Make sure succ doesn't contain a volatile reference. */ if (succ != 0 && volatile_refs_p (PATTERN (succ))) return 0; for (p = NEXT_INSN (insn); p != i3; p = NEXT_INSN (p)) if (INSN_P (p) && p != succ && volatile_refs_p (PATTERN (p))) return 0; } /* If INSN is an asm, and DEST is a hard register, reject, since it has to be an explicit register variable, and was chosen for a reason. */ if (GET_CODE (src) == ASM_OPERANDS && GET_CODE (dest) == REG && REGNO (dest) < FIRST_PSEUDO_REGISTER) return 0; /* If there are any volatile insns between INSN and I3, reject, because they might affect machine state. */ for (p = NEXT_INSN (insn); p != i3; p = NEXT_INSN (p)) if (INSN_P (p) && p != succ && volatile_insn_p (PATTERN (p))) return 0; /* If INSN or I2 contains an autoincrement or autodecrement, make sure that register is not used between there and I3, and not already used in I3 either. Also insist that I3 not be a jump; if it were one and the incremented register were spilled, we would lose. */ #ifdef AUTO_INC_DEC for (link = REG_NOTES (insn); link; link = XEXP (link, 1)) if (REG_NOTE_KIND (link) == REG_INC && (GET_CODE (i3) == JUMP_INSN || reg_used_between_p (XEXP (link, 0), insn, i3) || reg_overlap_mentioned_p (XEXP (link, 0), PATTERN (i3)))) return 0; #endif #ifdef HAVE_cc0 /* Don't combine an insn that follows a CC0-setting insn. An insn that uses CC0 must not be separated from the one that sets it. We do, however, allow I2 to follow a CC0-setting insn if that insn is passed as I1; in that case it will be deleted also. We also allow combining in this case if all the insns are adjacent because that would leave the two CC0 insns adjacent as well. It would be more logical to test whether CC0 occurs inside I1 or I2, but that would be much slower, and this ought to be equivalent. */ p = prev_nonnote_insn (insn); if (p && p != pred && GET_CODE (p) == INSN && sets_cc0_p (PATTERN (p)) && ! all_adjacent) return 0; #endif /* If we get here, we have passed all the tests and the combination is to be allowed. */ *pdest = dest; *psrc = src; return 1; } /* Check if PAT is an insn - or a part of it - used to set up an argument for a function in a hard register. */ static int sets_function_arg_p (pat) rtx pat; { int i; rtx inner_dest; switch (GET_CODE (pat)) { case INSN: return sets_function_arg_p (PATTERN (pat)); case PARALLEL: for (i = XVECLEN (pat, 0); --i >= 0;) if (sets_function_arg_p (XVECEXP (pat, 0, i))) return 1; break; case SET: inner_dest = SET_DEST (pat); while (GET_CODE (inner_dest) == STRICT_LOW_PART || GET_CODE (inner_dest) == SUBREG || GET_CODE (inner_dest) == ZERO_EXTRACT) inner_dest = XEXP (inner_dest, 0); return (GET_CODE (inner_dest) == REG && REGNO (inner_dest) < FIRST_PSEUDO_REGISTER && FUNCTION_ARG_REGNO_P (REGNO (inner_dest))); default: break; } return 0; } /* LOC is the location within I3 that contains its pattern or the component of a PARALLEL of the pattern. We validate that it is valid for combining. One problem is if I3 modifies its output, as opposed to replacing it entirely, we can't allow the output to contain I2DEST or I1DEST as doing so would produce an insn that is not equivalent to the original insns. Consider: (set (reg:DI 101) (reg:DI 100)) (set (subreg:SI (reg:DI 101) 0) ) This is NOT equivalent to: (parallel [(set (subreg:SI (reg:DI 100) 0) ) (set (reg:DI 101) (reg:DI 100))]) Not only does this modify 100 (in which case it might still be valid if 100 were dead in I2), it sets 101 to the ORIGINAL value of 100. We can also run into a problem if I2 sets a register that I1 uses and I1 gets directly substituted into I3 (not via I2). In that case, we would be getting the wrong value of I2DEST into I3, so we must reject the combination. This case occurs when I2 and I1 both feed into I3, rather than when I1 feeds into I2, which feeds into I3. If I1_NOT_IN_SRC is nonzero, it means that finding I1 in the source of a SET must prevent combination from occurring. Before doing the above check, we first try to expand a field assignment into a set of logical operations. If PI3_DEST_KILLED is nonzero, it is a pointer to a location in which we place a register that is both set and used within I3. If more than one such register is detected, we fail. Return 1 if the combination is valid, zero otherwise. */ static int combinable_i3pat (i3, loc, i2dest, i1dest, i1_not_in_src, pi3dest_killed) rtx i3; rtx *loc; rtx i2dest; rtx i1dest; int i1_not_in_src; rtx *pi3dest_killed; { rtx x = *loc; if (GET_CODE (x) == SET) { rtx set = x ; rtx dest = SET_DEST (set); rtx src = SET_SRC (set); rtx inner_dest = dest; while (GET_CODE (inner_dest) == STRICT_LOW_PART || GET_CODE (inner_dest) == SUBREG || GET_CODE (inner_dest) == ZERO_EXTRACT) inner_dest = XEXP (inner_dest, 0); /* Check for the case where I3 modifies its output, as discussed above. */ if ((inner_dest != dest && (reg_overlap_mentioned_p (i2dest, inner_dest) || (i1dest && reg_overlap_mentioned_p (i1dest, inner_dest)))) /* This is the same test done in can_combine_p except we can't test all_adjacent; we don't have to, since this instruction will stay in place, thus we are not considering increasing the lifetime of INNER_DEST. Also, if this insn sets a function argument, combining it with something that might need a spill could clobber a previous function argument; the all_adjacent test in can_combine_p also checks this; here, we do a more specific test for this case. */ || (GET_CODE (inner_dest) == REG && REGNO (inner_dest) < FIRST_PSEUDO_REGISTER && (! HARD_REGNO_MODE_OK (REGNO (inner_dest), GET_MODE (inner_dest)))) || (i1_not_in_src && reg_overlap_mentioned_p (i1dest, src))) return 0; /* If DEST is used in I3, it is being killed in this insn, so record that for later. Never add REG_DEAD notes for the FRAME_POINTER_REGNUM or the STACK_POINTER_REGNUM, since these are always considered to be live. Similarly for ARG_POINTER_REGNUM if it is fixed. */ if (pi3dest_killed && GET_CODE (dest) == REG && reg_referenced_p (dest, PATTERN (i3)) && REGNO (dest) != FRAME_POINTER_REGNUM #if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM && REGNO (dest) != HARD_FRAME_POINTER_REGNUM #endif #if ARG_POINTER_REGNUM != FRAME_POINTER_REGNUM && (REGNO (dest) != ARG_POINTER_REGNUM || ! fixed_regs [REGNO (dest)]) #endif && REGNO (dest) != STACK_POINTER_REGNUM) { if (*pi3dest_killed) return 0; *pi3dest_killed = dest; } } else if (GET_CODE (x) == PARALLEL) { int i; for (i = 0; i < XVECLEN (x, 0); i++) if (! combinable_i3pat (i3, &XVECEXP (x, 0, i), i2dest, i1dest, i1_not_in_src, pi3dest_killed)) return 0; } return 1; } /* Return 1 if X is an arithmetic expression that contains a multiplication and division. We don't count multiplications by powers of two here. */ static int contains_muldiv (x) rtx x; { switch (GET_CODE (x)) { case MOD: case DIV: case UMOD: case UDIV: return 1; case MULT: return ! (GET_CODE (XEXP (x, 1)) == CONST_INT && exact_log2 (INTVAL (XEXP (x, 1))) >= 0); default: switch (GET_RTX_CLASS (GET_CODE (x))) { case 'c': case '<': case '2': return contains_muldiv (XEXP (x, 0)) || contains_muldiv (XEXP (x, 1)); case '1': return contains_muldiv (XEXP (x, 0)); default: return 0; } } } /* Determine whether INSN can be used in a combination. Return nonzero if not. This is used in try_combine to detect early some cases where we can't perform combinations. */ static int cant_combine_insn_p (insn) rtx insn; { rtx set; rtx src, dest; /* If this isn't really an insn, we can't do anything. This can occur when flow deletes an insn that it has merged into an auto-increment address. */ if (! INSN_P (insn)) return 1; /* Never combine loads and stores involving hard regs that are likely to be spilled. The register allocator can usually handle such reg-reg moves by tying. If we allow the combiner to make substitutions of likely-spilled regs, we may abort in reload. As an exception, we allow combinations involving fixed regs; these are not available to the register allocator so there's no risk involved. */ set = single_set (insn); if (! set) return 0; src = SET_SRC (set); dest = SET_DEST (set); if (GET_CODE (src) == SUBREG) src = SUBREG_REG (src); if (GET_CODE (dest) == SUBREG) dest = SUBREG_REG (dest); if (REG_P (src) && REG_P (dest) && ((REGNO (src) < FIRST_PSEUDO_REGISTER && ! fixed_regs[REGNO (src)] && CLASS_LIKELY_SPILLED_P (REGNO_REG_CLASS (REGNO (src)))) || (REGNO (dest) < FIRST_PSEUDO_REGISTER && ! fixed_regs[REGNO (dest)] && CLASS_LIKELY_SPILLED_P (REGNO_REG_CLASS (REGNO (dest)))))) return 1; return 0; } /* Try to combine the insns I1 and I2 into I3. Here I1 and I2 appear earlier than I3. I1 can be zero; then we combine just I2 into I3. If we are combining three insns and the resulting insn is not recognized, try splitting it into two insns. If that happens, I2 and I3 are retained and I1 is pseudo-deleted by turning it into a NOTE. Otherwise, I1 and I2 are pseudo-deleted. Return 0 if the combination does not work. Then nothing is changed. If we did the combination, return the insn at which combine should resume scanning. Set NEW_DIRECT_JUMP_P to a nonzero value if try_combine creates a new direct jump instruction. */ static rtx try_combine (i3, i2, i1, new_direct_jump_p) rtx i3, i2, i1; int *new_direct_jump_p; { /* New patterns for I3 and I2, respectively. */ rtx newpat, newi2pat = 0; int substed_i2 = 0, substed_i1 = 0; /* Indicates need to preserve SET in I1 or I2 in I3 if it is not dead. */ int added_sets_1, added_sets_2; /* Total number of SETs to put into I3. */ int total_sets; /* Nonzero is I2's body now appears in I3. */ int i2_is_used; /* INSN_CODEs for new I3, new I2, and user of condition code. */ int insn_code_number, i2_code_number = 0, other_code_number = 0; /* Contains I3 if the destination of I3 is used in its source, which means that the old life of I3 is being killed. If that usage is placed into I2 and not in I3, a REG_DEAD note must be made. */ rtx i3dest_killed = 0; /* SET_DEST and SET_SRC of I2 and I1. */ rtx i2dest, i2src, i1dest = 0, i1src = 0; /* PATTERN (I2), or a copy of it in certain cases. */ rtx i2pat; /* Indicates if I2DEST or I1DEST is in I2SRC or I1_SRC. */ int i2dest_in_i2src = 0, i1dest_in_i1src = 0, i2dest_in_i1src = 0; int i1_feeds_i3 = 0; /* Notes that must be added to REG_NOTES in I3 and I2. */ rtx new_i3_notes, new_i2_notes; /* Notes that we substituted I3 into I2 instead of the normal case. */ int i3_subst_into_i2 = 0; /* Notes that I1, I2 or I3 is a MULT operation. */ int have_mult = 0; int maxreg; rtx temp; rtx link; int i; /* Exit early if one of the insns involved can't be used for combinations. */ if (cant_combine_insn_p (i3) || cant_combine_insn_p (i2) || (i1 && cant_combine_insn_p (i1)) /* We also can't do anything if I3 has a REG_LIBCALL note since we don't want to disrupt the contiguity of a libcall. */ #if 0 /* ??? This gives worse code, and appears to be unnecessary, since no pass after flow uses REG_LIBCALL/REG_RETVAL notes. */ || find_reg_note (i3, REG_LIBCALL, NULL_RTX) #endif ) return 0; combine_attempts++; undobuf.other_insn = 0; /* Reset the hard register usage information. */ CLEAR_HARD_REG_SET (newpat_used_regs); /* If I1 and I2 both feed I3, they can be in any order. To simplify the code below, set I1 to be the earlier of the two insns. */ if (i1 && INSN_CUID (i1) > INSN_CUID (i2)) temp = i1, i1 = i2, i2 = temp; added_links_insn = 0; /* First check for one important special-case that the code below will not handle. Namely, the case where I1 is zero, I2 is a PARALLEL and I3 is a SET whose SET_SRC is a SET_DEST in I2. In that case, we may be able to replace that destination with the destination of I3. This occurs in the common code where we compute both a quotient and remainder into a structure, in which case we want to do the computation directly into the structure to avoid register-register copies. Note that this case handles both multiple sets in I2 and also cases where I2 has a number of CLOBBER or PARALLELs. We make very conservative checks below and only try to handle the most common cases of this. For example, we only handle the case where I2 and I3 are adjacent to avoid making difficult register usage tests. */ if (i1 == 0 && GET_CODE (i3) == INSN && GET_CODE (PATTERN (i3)) == SET && GET_CODE (SET_SRC (PATTERN (i3))) == REG && REGNO (SET_SRC (PATTERN (i3))) >= FIRST_PSEUDO_REGISTER && find_reg_note (i3, REG_DEAD, SET_SRC (PATTERN (i3))) && GET_CODE (PATTERN (i2)) == PARALLEL && ! side_effects_p (SET_DEST (PATTERN (i3))) /* If the dest of I3 is a ZERO_EXTRACT or STRICT_LOW_PART, the code below would need to check what is inside (and reg_overlap_mentioned_p doesn't support those codes anyway). Don't allow those destinations; the resulting insn isn't likely to be recognized anyway. */ && GET_CODE (SET_DEST (PATTERN (i3))) != ZERO_EXTRACT && GET_CODE (SET_DEST (PATTERN (i3))) != STRICT_LOW_PART && ! reg_overlap_mentioned_p (SET_SRC (PATTERN (i3)), SET_DEST (PATTERN (i3))) && next_real_insn (i2) == i3) { rtx p2 = PATTERN (i2); /* Make sure that the destination of I3, which we are going to substitute into one output of I2, is not used within another output of I2. We must avoid making this: (parallel [(set (mem (reg 69)) ...) (set (reg 69) ...)]) which is not well-defined as to order of actions. (Besides, reload can't handle output reloads for this.) The problem can also happen if the dest of I3 is a memory ref, if another dest in I2 is an indirect memory ref. */ for (i = 0; i < XVECLEN (p2, 0); i++) if ((GET_CODE (XVECEXP (p2, 0, i)) == SET || GET_CODE (XVECEXP (p2, 0, i)) == CLOBBER) && reg_overlap_mentioned_p (SET_DEST (PATTERN (i3)), SET_DEST (XVECEXP (p2, 0, i)))) break; if (i == XVECLEN (p2, 0)) for (i = 0; i < XVECLEN (p2, 0); i++) if ((GET_CODE (XVECEXP (p2, 0, i)) == SET || GET_CODE (XVECEXP (p2, 0, i)) == CLOBBER) && SET_DEST (XVECEXP (p2, 0, i)) == SET_SRC (PATTERN (i3))) { combine_merges++; subst_insn = i3; subst_low_cuid = INSN_CUID (i2); added_sets_2 = added_sets_1 = 0; i2dest = SET_SRC (PATTERN (i3)); /* Replace the dest in I2 with our dest and make the resulting insn the new pattern for I3. Then skip to where we validate the pattern. Everything was set up above. */ SUBST (SET_DEST (XVECEXP (p2, 0, i)), SET_DEST (PATTERN (i3))); newpat = p2; i3_subst_into_i2 = 1; goto validate_replacement; } } /* If I2 is setting a double-word pseudo to a constant and I3 is setting one of those words to another constant, merge them by making a new constant. */ if (i1 == 0 && (temp = single_set (i2)) != 0 && (GET_CODE (SET_SRC (temp)) == CONST_INT || GET_CODE (SET_SRC (temp)) == CONST_DOUBLE) && GET_CODE (SET_DEST (temp)) == REG && GET_MODE_CLASS (GET_MODE (SET_DEST (temp))) == MODE_INT && GET_MODE_SIZE (GET_MODE (SET_DEST (temp))) == 2 * UNITS_PER_WORD && GET_CODE (PATTERN (i3)) == SET && GET_CODE (SET_DEST (PATTERN (i3))) == SUBREG && SUBREG_REG (SET_DEST (PATTERN (i3))) == SET_DEST (temp) && GET_MODE_CLASS (GET_MODE (SET_DEST (PATTERN (i3)))) == MODE_INT && GET_MODE_SIZE (GET_MODE (SET_DEST (PATTERN (i3)))) == UNITS_PER_WORD && GET_CODE (SET_SRC (PATTERN (i3))) == CONST_INT) { HOST_WIDE_INT lo, hi; if (GET_CODE (SET_SRC (temp)) == CONST_INT) lo = INTVAL (SET_SRC (temp)), hi = lo < 0 ? -1 : 0; else { lo = CONST_DOUBLE_LOW (SET_SRC (temp)); hi = CONST_DOUBLE_HIGH (SET_SRC (temp)); } if (subreg_lowpart_p (SET_DEST (PATTERN (i3)))) { /* We don't handle the case of the target word being wider than a host wide int. */ if (HOST_BITS_PER_WIDE_INT < BITS_PER_WORD) abort (); lo &= ~(UWIDE_SHIFT_LEFT_BY_BITS_PER_WORD (1) - 1); lo |= (INTVAL (SET_SRC (PATTERN (i3))) & (UWIDE_SHIFT_LEFT_BY_BITS_PER_WORD (1) - 1)); } else if (HOST_BITS_PER_WIDE_INT == BITS_PER_WORD) hi = INTVAL (SET_SRC (PATTERN (i3))); else if (HOST_BITS_PER_WIDE_INT >= 2 * BITS_PER_WORD) { int sign = -(int) ((unsigned HOST_WIDE_INT) lo >> (HOST_BITS_PER_WIDE_INT - 1)); lo &= ~ (UWIDE_SHIFT_LEFT_BY_BITS_PER_WORD (UWIDE_SHIFT_LEFT_BY_BITS_PER_WORD (1) - 1)); lo |= (UWIDE_SHIFT_LEFT_BY_BITS_PER_WORD (INTVAL (SET_SRC (PATTERN (i3))))); if (hi == sign) hi = lo < 0 ? -1 : 0; } else /* We don't handle the case of the higher word not fitting entirely in either hi or lo. */ abort (); combine_merges++; subst_insn = i3; subst_low_cuid = INSN_CUID (i2); added_sets_2 = added_sets_1 = 0; i2dest = SET_DEST (temp); SUBST (SET_SRC (temp), immed_double_const (lo, hi, GET_MODE (SET_DEST (temp)))); newpat = PATTERN (i2); goto validate_replacement; } #ifndef HAVE_cc0 /* If we have no I1 and I2 looks like: (parallel [(set (reg:CC X) (compare:CC OP (const_int 0))) (set Y OP)]) make up a dummy I1 that is (set Y OP) and change I2 to be (set (reg:CC X) (compare:CC Y (const_int 0))) (We can ignore any trailing CLOBBERs.) This undoes a previous combination and allows us to match a branch-and- decrement insn. */ if (i1 == 0 && GET_CODE (PATTERN (i2)) == PARALLEL && XVECLEN (PATTERN (i2), 0) >= 2 && GET_CODE (XVECEXP (PATTERN (i2), 0, 0)) == SET && (GET_MODE_CLASS (GET_MODE (SET_DEST (XVECEXP (PATTERN (i2), 0, 0)))) == MODE_CC) && GET_CODE (SET_SRC (XVECEXP (PATTERN (i2), 0, 0))) == COMPARE && XEXP (SET_SRC (XVECEXP (PATTERN (i2), 0, 0)), 1) == const0_rtx && GET_CODE (XVECEXP (PATTERN (i2), 0, 1)) == SET && GET_CODE (SET_DEST (XVECEXP (PATTERN (i2), 0, 1))) == REG && rtx_equal_p (XEXP (SET_SRC (XVECEXP (PATTERN (i2), 0, 0)), 0), SET_SRC (XVECEXP (PATTERN (i2), 0, 1)))) { for (i = XVECLEN (PATTERN (i2), 0) - 1; i >= 2; i--) if (GET_CODE (XVECEXP (PATTERN (i2), 0, i)) != CLOBBER) break; if (i == 1) { /* We make I1 with the same INSN_UID as I2. This gives it the same INSN_CUID for value tracking. Our fake I1 will never appear in the insn stream so giving it the same INSN_UID as I2 will not cause a problem. */ i1 = gen_rtx_INSN (VOIDmode, INSN_UID (i2), NULL_RTX, i2, BLOCK_FOR_INSN (i2), INSN_SCOPE (i2), XVECEXP (PATTERN (i2), 0, 1), -1, NULL_RTX, NULL_RTX); SUBST (PATTERN (i2), XVECEXP (PATTERN (i2), 0, 0)); SUBST (XEXP (SET_SRC (PATTERN (i2)), 0), SET_DEST (PATTERN (i1))); } } #endif /* Verify that I2 and I1 are valid for combining. */ if (! can_combine_p (i2, i3, i1, NULL_RTX, &i2dest, &i2src) || (i1 && ! can_combine_p (i1, i3, NULL_RTX, i2, &i1dest, &i1src))) { undo_all (); return 0; } /* Record whether I2DEST is used in I2SRC and similarly for the other cases. Knowing this will help in register status updating below. */ i2dest_in_i2src = reg_overlap_mentioned_p (i2dest, i2src); i1dest_in_i1src = i1 && reg_overlap_mentioned_p (i1dest, i1src); i2dest_in_i1src = i1 && reg_overlap_mentioned_p (i2dest, i1src); /* See if I1 directly feeds into I3. It does if I1DEST is not used in I2SRC. */ i1_feeds_i3 = i1 && ! reg_overlap_mentioned_p (i1dest, i2src); /* Ensure that I3's pattern can be the destination of combines. */ if (! combinable_i3pat (i3, &PATTERN (i3), i2dest, i1dest, i1 && i2dest_in_i1src && i1_feeds_i3, &i3dest_killed)) { undo_all (); return 0; } /* See if any of the insns is a MULT operation. Unless one is, we will reject a combination that is, since it must be slower. Be conservative here. */ if (GET_CODE (i2src) == MULT || (i1 != 0 && GET_CODE (i1src) == MULT) || (GET_CODE (PATTERN (i3)) == SET && GET_CODE (SET_SRC (PATTERN (i3))) == MULT)) have_mult = 1; /* If I3 has an inc, then give up if I1 or I2 uses the reg that is inc'd. We used to do this EXCEPT in one case: I3 has a post-inc in an output operand. However, that exception can give rise to insns like mov r3,(r3)+ which is a famous insn on the PDP-11 where the value of r3 used as the source was model-dependent. Avoid this sort of thing. */ #if 0 if (!(GET_CODE (PATTERN (i3)) == SET && GET_CODE (SET_SRC (PATTERN (i3))) == REG && GET_CODE (SET_DEST (PATTERN (i3))) == MEM && (GET_CODE (XEXP (SET_DEST (PATTERN (i3)), 0)) == POST_INC || GET_CODE (XEXP (SET_DEST (PATTERN (i3)), 0)) == POST_DEC))) /* It's not the exception. */ #endif #ifdef AUTO_INC_DEC for (link = REG_NOTES (i3); link; link = XEXP (link, 1)) if (REG_NOTE_KIND (link) == REG_INC && (reg_overlap_mentioned_p (XEXP (link, 0), PATTERN (i2)) || (i1 != 0 && reg_overlap_mentioned_p (XEXP (link, 0), PATTERN (i1))))) { undo_all (); return 0; } #endif /* See if the SETs in I1 or I2 need to be kept around in the merged instruction: whenever the value set there is still needed past I3. For the SETs in I2, this is easy: we see if I2DEST dies or is set in I3. For the SET in I1, we have two cases: If I1 and I2 independently feed into I3, the set in I1 needs to be kept around if I1DEST dies or is set in I3. Otherwise (if I1 feeds I2 which feeds I3), the set in I1 needs to be kept around unless I1DEST dies or is set in either I2 or I3. We can distinguish these cases by seeing if I2SRC mentions I1DEST. If so, we know I1 feeds into I2. */ added_sets_2 = ! dead_or_set_p (i3, i2dest); added_sets_1 = i1 && ! (i1_feeds_i3 ? dead_or_set_p (i3, i1dest) : (dead_or_set_p (i3, i1dest) || dead_or_set_p (i2, i1dest))); /* If the set in I2 needs to be kept around, we must make a copy of PATTERN (I2), so that when we substitute I1SRC for I1DEST in PATTERN (I2), we are only substituting for the original I1DEST, not into an already-substituted copy. This also prevents making self-referential rtx. If I2 is a PARALLEL, we just need the piece that assigns I2SRC to I2DEST. */ i2pat = (GET_CODE (PATTERN (i2)) == PARALLEL ? gen_rtx_SET (VOIDmode, i2dest, i2src) : PATTERN (i2)); if (added_sets_2) i2pat = copy_rtx (i2pat); combine_merges++; /* Substitute in the latest insn for the regs set by the earlier ones. */ maxreg = max_reg_num (); subst_insn = i3; /* It is possible that the source of I2 or I1 may be performing an unneeded operation, such as a ZERO_EXTEND of something that is known to have the high part zero. Handle that case by letting subst look at the innermost one of them. Another way to do this would be to have a function that tries to simplify a single insn instead of merging two or more insns. We don't do this because of the potential of infinite loops and because of the potential extra memory required. However, doing it the way we are is a bit of a kludge and doesn't catch all cases. But only do this if -fexpensive-optimizations since it slows things down and doesn't usually win. */ if (flag_expensive_optimizations) { /* Pass pc_rtx so no substitutions are done, just simplifications. The cases that we are interested in here do not involve the few cases were is_replaced is checked. */ if (i1) { subst_low_cuid = INSN_CUID (i1); i1src = subst (i1src, pc_rtx, pc_rtx, 0, 0); } else { subst_low_cuid = INSN_CUID (i2); i2src = subst (i2src, pc_rtx, pc_rtx, 0, 0); } } #ifndef HAVE_cc0 /* Many machines that don't use CC0 have insns that can both perform an arithmetic operation and set the condition code. These operations will be represented as a PARALLEL with the first element of the vector being a COMPARE of an arithmetic operation with the constant zero. The second element of the vector will set some pseudo to the result of the same arithmetic operation. If we simplify the COMPARE, we won't match such a pattern and so will generate an extra insn. Here we test for this case, where both the comparison and the operation result are needed, and make the PARALLEL by just replacing I2DEST in I3SRC with I2SRC. Later we will make the PARALLEL that contains I2. */ if (i1 == 0 && added_sets_2 && GET_CODE (PATTERN (i3)) == SET && GET_CODE (SET_SRC (PATTERN (i3))) == COMPARE && XEXP (SET_SRC (PATTERN (i3)), 1) == const0_rtx && rtx_equal_p (XEXP (SET_SRC (PATTERN (i3)), 0), i2dest)) { #ifdef EXTRA_CC_MODES rtx *cc_use; enum machine_mode compare_mode; #endif newpat = PATTERN (i3); SUBST (XEXP (SET_SRC (newpat), 0), i2src); i2_is_used = 1; #ifdef EXTRA_CC_MODES /* See if a COMPARE with the operand we substituted in should be done with the mode that is currently being used. If not, do the same processing we do in `subst' for a SET; namely, if the destination is used only once, try to replace it with a register of the proper mode and also replace the COMPARE. */ if (undobuf.other_insn == 0 && (cc_use = find_single_use (SET_DEST (newpat), i3, &undobuf.other_insn)) && ((compare_mode = SELECT_CC_MODE (GET_CODE (*cc_use), i2src, const0_rtx)) != GET_MODE (SET_DEST (newpat)))) { unsigned int regno = REGNO (SET_DEST (newpat)); rtx new_dest = gen_rtx_REG (compare_mode, regno); if (regno < FIRST_PSEUDO_REGISTER || (REG_N_SETS (regno) == 1 && ! added_sets_2 && ! REG_USERVAR_P (SET_DEST (newpat)))) { if (regno >= FIRST_PSEUDO_REGISTER) SUBST (regno_reg_rtx[regno], new_dest); SUBST (SET_DEST (newpat), new_dest); SUBST (XEXP (*cc_use, 0), new_dest); SUBST (SET_SRC (newpat), gen_rtx_COMPARE (compare_mode, i2src, const0_rtx)); } else undobuf.other_insn = 0; } #endif } else #endif { n_occurrences = 0; /* `subst' counts here */ /* If I1 feeds into I2 (not into I3) and I1DEST is in I1SRC, we need to make a unique copy of I2SRC each time we substitute it to avoid self-referential rtl. */ subst_low_cuid = INSN_CUID (i2); newpat = subst (PATTERN (i3), i2dest, i2src, 0, ! i1_feeds_i3 && i1dest_in_i1src); substed_i2 = 1; /* Record whether i2's body now appears within i3's body. */ i2_is_used = n_occurrences; } /* If we already got a failure, don't try to do more. Otherwise, try to substitute in I1 if we have it. */ if (i1 && GET_CODE (newpat) != CLOBBER) { /* Before we can do this substitution, we must redo the test done above (see detailed comments there) that ensures that I1DEST isn't mentioned in any SETs in NEWPAT that are field assignments. */ if (! combinable_i3pat (NULL_RTX, &newpat, i1dest, NULL_RTX, 0, (rtx*) 0)) { undo_all (); return 0; } n_occurrences = 0; subst_low_cuid = INSN_CUID (i1); newpat = subst (newpat, i1dest, i1src, 0, 0); substed_i1 = 1; } /* Fail if an autoincrement side-effect has been duplicated. Be careful to count all the ways that I2SRC and I1SRC can be used. */ if ((FIND_REG_INC_NOTE (i2, NULL_RTX) != 0 && i2_is_used + added_sets_2 > 1) || (i1 != 0 && FIND_REG_INC_NOTE (i1, NULL_RTX) != 0 && (n_occurrences + added_sets_1 + (added_sets_2 && ! i1_feeds_i3) > 1)) /* Fail if we tried to make a new register (we used to abort, but there's really no reason to). */ || max_reg_num () != maxreg /* Fail if we couldn't do something and have a CLOBBER. */ || GET_CODE (newpat) == CLOBBER /* Fail if this new pattern is a MULT and we didn't have one before at the outer level. */ || (GET_CODE (newpat) == SET && GET_CODE (SET_SRC (newpat)) == MULT && ! have_mult)) { undo_all (); return 0; } /* If the actions of the earlier insns must be kept in addition to substituting them into the latest one, we must make a new PARALLEL for the latest insn to hold additional the SETs. */ if (added_sets_1 || added_sets_2) { combine_extras++; if (GET_CODE (newpat) == PARALLEL) { rtvec old = XVEC (newpat, 0); total_sets = XVECLEN (newpat, 0) + added_sets_1 + added_sets_2; newpat = gen_rtx_PARALLEL (VOIDmode, rtvec_alloc (total_sets)); memcpy (XVEC (newpat, 0)->elem, &old->elem[0], sizeof (old->elem[0]) * old->num_elem); } else { rtx old = newpat; total_sets = 1 + added_sets_1 + added_sets_2; newpat = gen_rtx_PARALLEL (VOIDmode, rtvec_alloc (total_sets)); XVECEXP (newpat, 0, 0) = old; } if (added_sets_1) XVECEXP (newpat, 0, --total_sets) = (GET_CODE (PATTERN (i1)) == PARALLEL ? gen_rtx_SET (VOIDmode, i1dest, i1src) : PATTERN (i1)); if (added_sets_2) { /* If there is no I1, use I2's body as is. We used to also not do the subst call below if I2 was substituted into I3, but that could lose a simplification. */ if (i1 == 0) XVECEXP (newpat, 0, --total_sets) = i2pat; else /* See comment where i2pat is assigned. */ XVECEXP (newpat, 0, --total_sets) = subst (i2pat, i1dest, i1src, 0, 0); } } /* We come here when we are replacing a destination in I2 with the destination of I3. */ validate_replacement: /* Note which hard regs this insn has as inputs. */ mark_used_regs_combine (newpat); /* Is the result of combination a valid instruction? */ insn_code_number = recog_for_combine (&newpat, i3, &new_i3_notes); /* If the result isn't valid, see if it is a PARALLEL of two SETs where the second SET's destination is a register that is unused. In that case, we just need the first SET. This can occur when simplifying a divmod insn. We *must* test for this case here because the code below that splits two independent SETs doesn't handle this case correctly when it updates the register status. Also check the case where the first SET's destination is unused. That would not cause incorrect code, but does cause an unneeded insn to remain. */ if (insn_code_number < 0 && GET_CODE (newpat) == PARALLEL && XVECLEN (newpat, 0) == 2 && GET_CODE (XVECEXP (newpat, 0, 0)) == SET && GET_CODE (XVECEXP (newpat, 0, 1)) == SET && GET_CODE (SET_DEST (XVECEXP (newpat, 0, 1))) == REG && find_reg_note (i3, REG_UNUSED, SET_DEST (XVECEXP (newpat, 0, 1))) && ! side_effects_p (SET_SRC (XVECEXP (newpat, 0, 1))) && asm_noperands (newpat) < 0) { newpat = XVECEXP (newpat, 0, 0); insn_code_number = recog_for_combine (&newpat, i3, &new_i3_notes); } else if (insn_code_number < 0 && GET_CODE (newpat) == PARALLEL && XVECLEN (newpat, 0) == 2 && GET_CODE (XVECEXP (newpat, 0, 0)) == SET && GET_CODE (XVECEXP (newpat, 0, 1)) == SET && GET_CODE (SET_DEST (XVECEXP (newpat, 0, 0))) == REG && find_reg_note (i3, REG_UNUSED, SET_DEST (XVECEXP (newpat, 0, 0))) && ! side_effects_p (SET_SRC (XVECEXP (newpat, 0, 0))) && asm_noperands (newpat) < 0) { newpat = XVECEXP (newpat, 0, 1); insn_code_number = recog_for_combine (&newpat, i3, &new_i3_notes); } /* If we were combining three insns and the result is a simple SET with no ASM_OPERANDS that wasn't recognized, try to split it into two insns. There are two ways to do this. It can be split using a machine-specific method (like when you have an addition of a large constant) or by combine in the function find_split_point. */ if (i1 && insn_code_number < 0 && GET_CODE (newpat) == SET && asm_noperands (newpat) < 0) { rtx m_split, *split; rtx ni2dest = i2dest; /* See if the MD file can split NEWPAT. If it can't, see if letting it use I2DEST as a scratch register will help. In the latter case, convert I2DEST to the mode of the source of NEWPAT if we can. */ m_split = split_insns (newpat, i3); /* We can only use I2DEST as a scratch reg if it doesn't overlap any inputs of NEWPAT. */ /* ??? If I2DEST is not safe, and I1DEST exists, then it would be possible to try that as a scratch reg. This would require adding more code to make it work though. */ if (m_split == 0 && ! reg_overlap_mentioned_p (ni2dest, newpat)) { /* If I2DEST is a hard register or the only use of a pseudo, we can change its mode. */ if (GET_MODE (SET_DEST (newpat)) != GET_MODE (i2dest) && GET_MODE (SET_DEST (newpat)) != VOIDmode && GET_CODE (i2dest) == REG && (REGNO (i2dest) < FIRST_PSEUDO_REGISTER || (REG_N_SETS (REGNO (i2dest)) == 1 && ! added_sets_2 && ! REG_USERVAR_P (i2dest)))) ni2dest = gen_rtx_REG (GET_MODE (SET_DEST (newpat)), REGNO (i2dest)); m_split = split_insns (gen_rtx_PARALLEL (VOIDmode, gen_rtvec (2, newpat, gen_rtx_CLOBBER (VOIDmode, ni2dest))), i3); /* If the split with the mode-changed register didn't work, try the original register. */ if (! m_split && ni2dest != i2dest) { ni2dest = i2dest; m_split = split_insns (gen_rtx_PARALLEL (VOIDmode, gen_rtvec (2, newpat, gen_rtx_CLOBBER (VOIDmode, i2dest))), i3); } } if (m_split && NEXT_INSN (m_split) == NULL_RTX) { m_split = PATTERN (m_split); insn_code_number = recog_for_combine (&m_split, i3, &new_i3_notes); if (insn_code_number >= 0) newpat = m_split; } else if (m_split && NEXT_INSN (NEXT_INSN (m_split)) == NULL_RTX && (next_real_insn (i2) == i3 || ! use_crosses_set_p (PATTERN (m_split), INSN_CUID (i2)))) { rtx i2set, i3set; rtx newi3pat = PATTERN (NEXT_INSN (m_split)); newi2pat = PATTERN (m_split); i3set = single_set (NEXT_INSN (m_split)); i2set = single_set (m_split); /* In case we changed the mode of I2DEST, replace it in the pseudo-register table here. We can't do it above in case this code doesn't get executed and we do a split the other way. */ if (REGNO (i2dest) >= FIRST_PSEUDO_REGISTER) SUBST (regno_reg_rtx[REGNO (i2dest)], ni2dest); i2_code_number = recog_for_combine (&newi2pat, i2, &new_i2_notes); /* If I2 or I3 has multiple SETs, we won't know how to track register status, so don't use these insns. If I2's destination is used between I2 and I3, we also can't use these insns. */ if (i2_code_number >= 0 && i2set && i3set && (next_real_insn (i2) == i3 || ! reg_used_between_p (SET_DEST (i2set), i2, i3))) insn_code_number = recog_for_combine (&newi3pat, i3, &new_i3_notes); if (insn_code_number >= 0) newpat = newi3pat; /* It is possible that both insns now set the destination of I3. If so, we must show an extra use of it. */ if (insn_code_number >= 0) { rtx new_i3_dest = SET_DEST (i3set); rtx new_i2_dest = SET_DEST (i2set); while (GET_CODE (new_i3_dest) == ZERO_EXTRACT || GET_CODE (new_i3_dest) == STRICT_LOW_PART || GET_CODE (new_i3_dest) == SUBREG) new_i3_dest = XEXP (new_i3_dest, 0); while (GET_CODE (new_i2_dest) == ZERO_EXTRACT || GET_CODE (new_i2_dest) == STRICT_LOW_PART || GET_CODE (new_i2_dest) == SUBREG) new_i2_dest = XEXP (new_i2_dest, 0); if (GET_CODE (new_i3_dest) == REG && GET_CODE (new_i2_dest) == REG && REGNO (new_i3_dest) == REGNO (new_i2_dest)) REG_N_SETS (REGNO (new_i2_dest))++; } } /* If we can split it and use I2DEST, go ahead and see if that helps things be recognized. Verify that none of the registers are set between I2 and I3. */ if (insn_code_number < 0 && (split = find_split_point (&newpat, i3)) != 0 #ifdef HAVE_cc0 && GET_CODE (i2dest) == REG #endif /* We need I2DEST in the proper mode. If it is a hard register or the only use of a pseudo, we can change its mode. */ && (GET_MODE (*split) == GET_MODE (i2dest) || GET_MODE (*split) == VOIDmode || REGNO (i2dest) < FIRST_PSEUDO_REGISTER || (REG_N_SETS (REGNO (i2dest)) == 1 && ! added_sets_2 && ! REG_USERVAR_P (i2dest))) && (next_real_insn (i2) == i3 || ! use_crosses_set_p (*split, INSN_CUID (i2))) /* We can't overwrite I2DEST if its value is still used by NEWPAT. */ && ! reg_referenced_p (i2dest, newpat)) { rtx newdest = i2dest; enum rtx_code split_code = GET_CODE (*split); enum machine_mode split_mode = GET_MODE (*split); /* Get NEWDEST as a register in the proper mode. We have already validated that we can do this. */ if (GET_MODE (i2dest) != split_mode && split_mode != VOIDmode) { newdest = gen_rtx_REG (split_mode, REGNO (i2dest)); if (REGNO (i2dest) >= FIRST_PSEUDO_REGISTER) SUBST (regno_reg_rtx[REGNO (i2dest)], newdest); } /* If *SPLIT is a (mult FOO (const_int pow2)), convert it to an ASHIFT. This can occur if it was inside a PLUS and hence appeared to be a memory address. This is a kludge. */ if (split_code == MULT && GET_CODE (XEXP (*split, 1)) == CONST_INT && INTVAL (XEXP (*split, 1)) > 0 && (i = exact_log2 (INTVAL (XEXP (*split, 1)))) >= 0) { SUBST (*split, gen_rtx_ASHIFT (split_mode, XEXP (*split, 0), GEN_INT (i))); /* Update split_code because we may not have a multiply anymore. */ split_code = GET_CODE (*split); } #ifdef INSN_SCHEDULING /* If *SPLIT is a paradoxical SUBREG, when we split it, it should be written as a ZERO_EXTEND. */ if (split_code == SUBREG && GET_CODE (SUBREG_REG (*split)) == MEM) { #ifdef LOAD_EXTEND_OP /* Or as a SIGN_EXTEND if LOAD_EXTEND_OP says that that's what it really is. */ if (LOAD_EXTEND_OP (GET_MODE (SUBREG_REG (*split))) == SIGN_EXTEND) SUBST (*split, gen_rtx_SIGN_EXTEND (split_mode, SUBREG_REG (*split))); else #endif SUBST (*split, gen_rtx_ZERO_EXTEND (split_mode, SUBREG_REG (*split))); } #endif newi2pat = gen_rtx_SET (VOIDmode, newdest, *split); SUBST (*split, newdest); i2_code_number = recog_for_combine (&newi2pat, i2, &new_i2_notes); /* If the split point was a MULT and we didn't have one before, don't use one now. */ if (i2_code_number >= 0 && ! (split_code == MULT && ! have_mult)) insn_code_number = recog_for_combine (&newpat, i3, &new_i3_notes); } } /* Check for a case where we loaded from memory in a narrow mode and then sign extended it, but we need both registers. In that case, we have a PARALLEL with both loads from the same memory location. We can split this into a load from memory followed by a register-register copy. This saves at least one insn, more if register allocation can eliminate the copy. We cannot do this if the destination of the first assignment is a condition code register or cc0. We eliminate this case by making sure the SET_DEST and SET_SRC have the same mode. We cannot do this if the destination of the second assignment is a register that we have already assumed is zero-extended. Similarly for a SUBREG of such a register. */ else if (i1 && insn_code_number < 0 && asm_noperands (newpat) < 0 && GET_CODE (newpat) == PARALLEL && XVECLEN (newpat, 0) == 2 && GET_CODE (XVECEXP (newpat, 0, 0)) == SET && GET_CODE (SET_SRC (XVECEXP (newpat, 0, 0))) == SIGN_EXTEND && (GET_MODE (SET_DEST (XVECEXP (newpat, 0, 0))) == GET_MODE (SET_SRC (XVECEXP (newpat, 0, 0)))) && GET_CODE (XVECEXP (newpat, 0, 1)) == SET && rtx_equal_p (SET_SRC (XVECEXP (newpat, 0, 1)), XEXP (SET_SRC (XVECEXP (newpat, 0, 0)), 0)) && ! use_crosses_set_p (SET_SRC (XVECEXP (newpat, 0, 1)), INSN_CUID (i2)) && GET_CODE (SET_DEST (XVECEXP (newpat, 0, 1))) != ZERO_EXTRACT && GET_CODE (SET_DEST (XVECEXP (newpat, 0, 1))) != STRICT_LOW_PART && ! (temp = SET_DEST (XVECEXP (newpat, 0, 1)), (GET_CODE (temp) == REG && reg_nonzero_bits[REGNO (temp)] != 0 && GET_MODE_BITSIZE (GET_MODE (temp)) < BITS_PER_WORD && GET_MODE_BITSIZE (GET_MODE (temp)) < HOST_BITS_PER_INT && (reg_nonzero_bits[REGNO (temp)] != GET_MODE_MASK (word_mode)))) && ! (GET_CODE (SET_DEST (XVECEXP (newpat, 0, 1))) == SUBREG && (temp = SUBREG_REG (SET_DEST (XVECEXP (newpat, 0, 1))), (GET_CODE (temp) == REG && reg_nonzero_bits[REGNO (temp)] != 0 && GET_MODE_BITSIZE (GET_MODE (temp)) < BITS_PER_WORD && GET_MODE_BITSIZE (GET_MODE (temp)) < HOST_BITS_PER_INT && (reg_nonzero_bits[REGNO (temp)] != GET_MODE_MASK (word_mode))))) && ! reg_overlap_mentioned_p (SET_DEST (XVECEXP (newpat, 0, 1)), SET_SRC (XVECEXP (newpat, 0, 1))) && ! find_reg_note (i3, REG_UNUSED, SET_DEST (XVECEXP (newpat, 0, 0)))) { rtx ni2dest; newi2pat = XVECEXP (newpat, 0, 0); ni2dest = SET_DEST (XVECEXP (newpat, 0, 0)); newpat = XVECEXP (newpat, 0, 1); SUBST (SET_SRC (newpat), gen_lowpart_for_combine (GET_MODE (SET_SRC (newpat)), ni2dest)); i2_code_number = recog_for_combine (&newi2pat, i2, &new_i2_notes); if (i2_code_number >= 0) insn_code_number = recog_for_combine (&newpat, i3, &new_i3_notes); if (insn_code_number >= 0) { rtx insn; rtx link; /* If we will be able to accept this, we have made a change to the destination of I3. This can invalidate a LOG_LINKS pointing to I3. No other part of combine.c makes such a transformation. The new I3 will have a destination that was previously the destination of I1 or I2 and which was used in i2 or I3. Call distribute_links to make a LOG_LINK from the next use of that destination. */ PATTERN (i3) = newpat; distribute_links (gen_rtx_INSN_LIST (VOIDmode, i3, NULL_RTX)); /* I3 now uses what used to be its destination and which is now I2's destination. That means we need a LOG_LINK from I3 to I2. But we used to have one, so we still will. However, some later insn might be using I2's dest and have a LOG_LINK pointing at I3. We must remove this link. The simplest way to remove the link is to point it at I1, which we know will be a NOTE. */ for (insn = NEXT_INSN (i3); insn && (this_basic_block->next_bb == EXIT_BLOCK_PTR || insn != this_basic_block->next_bb->head); insn = NEXT_INSN (insn)) { if (INSN_P (insn) && reg_referenced_p (ni2dest, PATTERN (insn))) { for (link = LOG_LINKS (insn); link; link = XEXP (link, 1)) if (XEXP (link, 0) == i3) XEXP (link, 0) = i1; break; } } } } /* Similarly, check for a case where we have a PARALLEL of two independent SETs but we started with three insns. In this case, we can do the sets as two separate insns. This case occurs when some SET allows two other insns to combine, but the destination of that SET is still live. */ else if (i1 && insn_code_number < 0 && asm_noperands (newpat) < 0 && GET_CODE (newpat) == PARALLEL && XVECLEN (newpat, 0) == 2 && GET_CODE (XVECEXP (newpat, 0, 0)) == SET && GET_CODE (SET_DEST (XVECEXP (newpat, 0, 0))) != ZERO_EXTRACT && GET_CODE (SET_DEST (XVECEXP (newpat, 0, 0))) != STRICT_LOW_PART && GET_CODE (XVECEXP (newpat, 0, 1)) == SET && GET_CODE (SET_DEST (XVECEXP (newpat, 0, 1))) != ZERO_EXTRACT && GET_CODE (SET_DEST (XVECEXP (newpat, 0, 1))) != STRICT_LOW_PART && ! use_crosses_set_p (SET_SRC (XVECEXP (newpat, 0, 1)), INSN_CUID (i2)) /* Don't pass sets with (USE (MEM ...)) dests to the following. */ && GET_CODE (SET_DEST (XVECEXP (newpat, 0, 1))) != USE && GET_CODE (SET_DEST (XVECEXP (newpat, 0, 0))) != USE && ! reg_referenced_p (SET_DEST (XVECEXP (newpat, 0, 1)), XVECEXP (newpat, 0, 0)) && ! reg_referenced_p (SET_DEST (XVECEXP (newpat, 0, 0)), XVECEXP (newpat, 0, 1)) && ! (contains_muldiv (SET_SRC (XVECEXP (newpat, 0, 0))) && contains_muldiv (SET_SRC (XVECEXP (newpat, 0, 1))))) { /* Normally, it doesn't matter which of the two is done first, but it does if one references cc0. In that case, it has to be first. */ #ifdef HAVE_cc0 if (reg_referenced_p (cc0_rtx, XVECEXP (newpat, 0, 0))) { newi2pat = XVECEXP (newpat, 0, 0); newpat = XVECEXP (newpat, 0, 1); } else #endif { newi2pat = XVECEXP (newpat, 0, 1); newpat = XVECEXP (newpat, 0, 0); } i2_code_number = recog_for_combine (&newi2pat, i2, &new_i2_notes); if (i2_code_number >= 0) insn_code_number = recog_for_combine (&newpat, i3, &new_i3_notes); } /* If it still isn't recognized, fail and change things back the way they were. */ if ((insn_code_number < 0 /* Is the result a reasonable ASM_OPERANDS? */ && (! check_asm_operands (newpat) || added_sets_1 || added_sets_2))) { undo_all (); return 0; } /* If we had to change another insn, make sure it is valid also. */ if (undobuf.other_insn) { rtx other_pat = PATTERN (undobuf.other_insn); rtx new_other_notes; rtx note, next; CLEAR_HARD_REG_SET (newpat_used_regs); other_code_number = recog_for_combine (&other_pat, undobuf.other_insn, &new_other_notes); if (other_code_number < 0 && ! check_asm_operands (other_pat)) { undo_all (); return 0; } PATTERN (undobuf.other_insn) = other_pat; /* If any of the notes in OTHER_INSN were REG_UNUSED, ensure that they are still valid. Then add any non-duplicate notes added by recog_for_combine. */ for (note = REG_NOTES (undobuf.other_insn); note; note = next) { next = XEXP (note, 1); if (REG_NOTE_KIND (note) == REG_UNUSED && ! reg_set_p (XEXP (note, 0), PATTERN (undobuf.other_insn))) { if (GET_CODE (XEXP (note, 0)) == REG) REG_N_DEATHS (REGNO (XEXP (note, 0)))--; remove_note (undobuf.other_insn, note); } } for (note = new_other_notes; note; note = XEXP (note, 1)) if (GET_CODE (XEXP (note, 0)) == REG) REG_N_DEATHS (REGNO (XEXP (note, 0)))++; distribute_notes (new_other_notes, undobuf.other_insn, undobuf.other_insn, NULL_RTX); } #ifdef HAVE_cc0 /* If I2 is the setter CC0 and I3 is the user CC0 then check whether they are adjacent to each other or not. */ { rtx p = prev_nonnote_insn (i3); if (p && p != i2 && GET_CODE (p) == INSN && newi2pat && sets_cc0_p (newi2pat)) { undo_all (); return 0; } } #endif /* We now know that we can do this combination. Merge the insns and update the status of registers and LOG_LINKS. */ { rtx i3notes, i2notes, i1notes = 0; rtx i3links, i2links, i1links = 0; rtx midnotes = 0; unsigned int regno; /* Get the old REG_NOTES and LOG_LINKS from all our insns and clear them. */ i3notes = REG_NOTES (i3), i3links = LOG_LINKS (i3); i2notes = REG_NOTES (i2), i2links = LOG_LINKS (i2); if (i1) i1notes = REG_NOTES (i1), i1links = LOG_LINKS (i1); /* Ensure that we do not have something that should not be shared but occurs multiple times in the new insns. Check this by first resetting all the `used' flags and then copying anything is shared. */ reset_used_flags (i3notes); reset_used_flags (i2notes); reset_used_flags (i1notes); reset_used_flags (newpat); reset_used_flags (newi2pat); if (undobuf.other_insn) reset_used_flags (PATTERN (undobuf.other_insn)); i3notes = copy_rtx_if_shared (i3notes); i2notes = copy_rtx_if_shared (i2notes); i1notes = copy_rtx_if_shared (i1notes); newpat = copy_rtx_if_shared (newpat); newi2pat = copy_rtx_if_shared (newi2pat); if (undobuf.other_insn) reset_used_flags (PATTERN (undobuf.other_insn)); INSN_CODE (i3) = insn_code_number; PATTERN (i3) = newpat; if (GET_CODE (i3) == CALL_INSN && CALL_INSN_FUNCTION_USAGE (i3)) { rtx call_usage = CALL_INSN_FUNCTION_USAGE (i3); reset_used_flags (call_usage); call_usage = copy_rtx (call_usage); if (substed_i2) replace_rtx (call_usage, i2dest, i2src); if (substed_i1) replace_rtx (call_usage, i1dest, i1src); CALL_INSN_FUNCTION_USAGE (i3) = call_usage; } if (undobuf.other_insn) INSN_CODE (undobuf.other_insn) = other_code_number; /* We had one special case above where I2 had more than one set and we replaced a destination of one of those sets with the destination of I3. In that case, we have to update LOG_LINKS of insns later in this basic block. Note that this (expensive) case is rare. Also, in this case, we must pretend that all REG_NOTEs for I2 actually came from I3, so that REG_UNUSED notes from I2 will be properly handled. */ if (i3_subst_into_i2) { for (i = 0; i < XVECLEN (PATTERN (i2), 0); i++) if (GET_CODE (XVECEXP (PATTERN (i2), 0, i)) != USE && GET_CODE (SET_DEST (XVECEXP (PATTERN (i2), 0, i))) == REG && SET_DEST (XVECEXP (PATTERN (i2), 0, i)) != i2dest && ! find_reg_note (i2, REG_UNUSED, SET_DEST (XVECEXP (PATTERN (i2), 0, i)))) for (temp = NEXT_INSN (i2); temp && (this_basic_block->next_bb == EXIT_BLOCK_PTR || this_basic_block->head != temp); temp = NEXT_INSN (temp)) if (temp != i3 && INSN_P (temp)) for (link = LOG_LINKS (temp); link; link = XEXP (link, 1)) if (XEXP (link, 0) == i2) XEXP (link, 0) = i3; if (i3notes) { rtx link = i3notes; while (XEXP (link, 1)) link = XEXP (link, 1); XEXP (link, 1) = i2notes; } else i3notes = i2notes; i2notes = 0; } LOG_LINKS (i3) = 0; REG_NOTES (i3) = 0; LOG_LINKS (i2) = 0; REG_NOTES (i2) = 0; if (newi2pat) { INSN_CODE (i2) = i2_code_number; PATTERN (i2) = newi2pat; } else { PUT_CODE (i2, NOTE); NOTE_LINE_NUMBER (i2) = NOTE_INSN_DELETED; NOTE_SOURCE_FILE (i2) = 0; } if (i1) { LOG_LINKS (i1) = 0; REG_NOTES (i1) = 0; PUT_CODE (i1, NOTE); NOTE_LINE_NUMBER (i1) = NOTE_INSN_DELETED; NOTE_SOURCE_FILE (i1) = 0; } /* Get death notes for everything that is now used in either I3 or I2 and used to die in a previous insn. If we built two new patterns, move from I1 to I2 then I2 to I3 so that we get the proper movement on registers that I2 modifies. */ if (newi2pat) { move_deaths (newi2pat, NULL_RTX, INSN_CUID (i1), i2, &midnotes); move_deaths (newpat, newi2pat, INSN_CUID (i1), i3, &midnotes); } else move_deaths (newpat, NULL_RTX, i1 ? INSN_CUID (i1) : INSN_CUID (i2), i3, &midnotes); /* Distribute all the LOG_LINKS and REG_NOTES from I1, I2, and I3. */ if (i3notes) distribute_notes (i3notes, i3, i3, newi2pat ? i2 : NULL_RTX); if (i2notes) distribute_notes (i2notes, i2, i3, newi2pat ? i2 : NULL_RTX); if (i1notes) distribute_notes (i1notes, i1, i3, newi2pat ? i2 : NULL_RTX); if (midnotes) distribute_notes (midnotes, NULL_RTX, i3, newi2pat ? i2 : NULL_RTX); /* Distribute any notes added to I2 or I3 by recog_for_combine. We know these are REG_UNUSED and want them to go to the desired insn, so we always pass it as i3. We have not counted the notes in reg_n_deaths yet, so we need to do so now. */ if (newi2pat && new_i2_notes) { for (temp = new_i2_notes; temp; temp = XEXP (temp, 1)) if (GET_CODE (XEXP (temp, 0)) == REG) REG_N_DEATHS (REGNO (XEXP (temp, 0)))++; distribute_notes (new_i2_notes, i2, i2, NULL_RTX); } if (new_i3_notes) { for (temp = new_i3_notes; temp; temp = XEXP (temp, 1)) if (GET_CODE (XEXP (temp, 0)) == REG) REG_N_DEATHS (REGNO (XEXP (temp, 0)))++; distribute_notes (new_i3_notes, i3, i3, NULL_RTX); } /* If I3DEST was used in I3SRC, it really died in I3. We may need to put a REG_DEAD note for it somewhere. If NEWI2PAT exists and sets I3DEST, the death must be somewhere before I2, not I3. If we passed I3 in that case, it might delete I2. Similarly for I2 and I1. Show an additional death due to the REG_DEAD note we make here. If we discard it in distribute_notes, we will decrement it again. */ if (i3dest_killed) { if (GET_CODE (i3dest_killed) == REG) REG_N_DEATHS (REGNO (i3dest_killed))++; if (newi2pat && reg_set_p (i3dest_killed, newi2pat)) distribute_notes (gen_rtx_EXPR_LIST (REG_DEAD, i3dest_killed, NULL_RTX), NULL_RTX, i2, NULL_RTX); else distribute_notes (gen_rtx_EXPR_LIST (REG_DEAD, i3dest_killed, NULL_RTX), NULL_RTX, i3, newi2pat ? i2 : NULL_RTX); } if (i2dest_in_i2src) { if (GET_CODE (i2dest) == REG) REG_N_DEATHS (REGNO (i2dest))++; if (newi2pat && reg_set_p (i2dest, newi2pat)) distribute_notes (gen_rtx_EXPR_LIST (REG_DEAD, i2dest, NULL_RTX), NULL_RTX, i2, NULL_RTX); else distribute_notes (gen_rtx_EXPR_LIST (REG_DEAD, i2dest, NULL_RTX), NULL_RTX, i3, newi2pat ? i2 : NULL_RTX); } if (i1dest_in_i1src) { if (GET_CODE (i1dest) == REG) REG_N_DEATHS (REGNO (i1dest))++; if (newi2pat && reg_set_p (i1dest, newi2pat)) distribute_notes (gen_rtx_EXPR_LIST (REG_DEAD, i1dest, NULL_RTX), NULL_RTX, i2, NULL_RTX); else distribute_notes (gen_rtx_EXPR_LIST (REG_DEAD, i1dest, NULL_RTX), NULL_RTX, i3, newi2pat ? i2 : NULL_RTX); } distribute_links (i3links); distribute_links (i2links); distribute_links (i1links); if (GET_CODE (i2dest) == REG) { rtx link; rtx i2_insn = 0, i2_val = 0, set; /* The insn that used to set this register doesn't exist, and this life of the register may not exist either. See if one of I3's links points to an insn that sets I2DEST. If it does, that is now the last known value for I2DEST. If we don't update this and I2 set the register to a value that depended on its old contents, we will get confused. If this insn is used, thing will be set correctly in combine_instructions. */ for (link = LOG_LINKS (i3); link; link = XEXP (link, 1)) if ((set = single_set (XEXP (link, 0))) != 0 && rtx_equal_p (i2dest, SET_DEST (set))) i2_insn = XEXP (link, 0), i2_val = SET_SRC (set); record_value_for_reg (i2dest, i2_insn, i2_val); /* If the reg formerly set in I2 died only once and that was in I3, zero its use count so it won't make `reload' do any work. */ if (! added_sets_2 && (newi2pat == 0 || ! reg_mentioned_p (i2dest, newi2pat)) && ! i2dest_in_i2src) { regno = REGNO (i2dest); REG_N_SETS (regno)--; } } if (i1 && GET_CODE (i1dest) == REG) { rtx link; rtx i1_insn = 0, i1_val = 0, set; for (link = LOG_LINKS (i3); link; link = XEXP (link, 1)) if ((set = single_set (XEXP (link, 0))) != 0 && rtx_equal_p (i1dest, SET_DEST (set))) i1_insn = XEXP (link, 0), i1_val = SET_SRC (set); record_value_for_reg (i1dest, i1_insn, i1_val); regno = REGNO (i1dest); if (! added_sets_1 && ! i1dest_in_i1src) REG_N_SETS (regno)--; } /* Update reg_nonzero_bits et al for any changes that may have been made to this insn. The order of set_nonzero_bits_and_sign_copies() is important. Because newi2pat can affect nonzero_bits of newpat */ if (newi2pat) note_stores (newi2pat, set_nonzero_bits_and_sign_copies, NULL); note_stores (newpat, set_nonzero_bits_and_sign_copies, NULL); /* Set new_direct_jump_p if a new return or simple jump instruction has been created. If I3 is now an unconditional jump, ensure that it has a BARRIER following it since it may have initially been a conditional jump. It may also be the last nonnote insn. */ if (returnjump_p (i3) || any_uncondjump_p (i3)) { *new_direct_jump_p = 1; if ((temp = next_nonnote_insn (i3)) == NULL_RTX || GET_CODE (temp) != BARRIER) emit_barrier_after (i3); } if (undobuf.other_insn != NULL_RTX && (returnjump_p (undobuf.other_insn) || any_uncondjump_p (undobuf.other_insn))) { *new_direct_jump_p = 1; if ((temp = next_nonnote_insn (undobuf.other_insn)) == NULL_RTX || GET_CODE (temp) != BARRIER) emit_barrier_after (undobuf.other_insn); } /* An NOOP jump does not need barrier, but it does need cleaning up of CFG. */ if (GET_CODE (newpat) == SET && SET_SRC (newpat) == pc_rtx && SET_DEST (newpat) == pc_rtx) *new_direct_jump_p = 1; } combine_successes++; undo_commit (); if (added_links_insn && (newi2pat == 0 || INSN_CUID (added_links_insn) < INSN_CUID (i2)) && INSN_CUID (added_links_insn) < INSN_CUID (i3)) return added_links_insn; else return newi2pat ? i2 : i3; } /* Undo all the modifications recorded in undobuf. */ static void undo_all () { struct undo *undo, *next; for (undo = undobuf.undos; undo; undo = next) { next = undo->next; if (undo->is_int) *undo->where.i = undo->old_contents.i; else *undo->where.r = undo->old_contents.r; undo->next = undobuf.frees; undobuf.frees = undo; } undobuf.undos = 0; } /* We've committed to accepting the changes we made. Move all of the undos to the free list. */ static void undo_commit () { struct undo *undo, *next; for (undo = undobuf.undos; undo; undo = next) { next = undo->next; undo->next = undobuf.frees; undobuf.frees = undo; } undobuf.undos = 0; } /* Find the innermost point within the rtx at LOC, possibly LOC itself, where we have an arithmetic expression and return that point. LOC will be inside INSN. try_combine will call this function to see if an insn can be split into two insns. */ static rtx * find_split_point (loc, insn) rtx *loc; rtx insn; { rtx x = *loc; enum rtx_code code = GET_CODE (x); rtx *split; unsigned HOST_WIDE_INT len = 0; HOST_WIDE_INT pos = 0; int unsignedp = 0; rtx inner = NULL_RTX; /* First special-case some codes. */ switch (code) { case SUBREG: #ifdef INSN_SCHEDULING /* If we are making a paradoxical SUBREG invalid, it becomes a split point. */ if (GET_CODE (SUBREG_REG (x)) == MEM) return loc; #endif return find_split_point (&SUBREG_REG (x), insn); case MEM: #ifdef HAVE_lo_sum /* If we have (mem (const ..)) or (mem (symbol_ref ...)), split it using LO_SUM and HIGH. */ if (GET_CODE (XEXP (x, 0)) == CONST || GET_CODE (XEXP (x, 0)) == SYMBOL_REF) { SUBST (XEXP (x, 0), gen_rtx_LO_SUM (Pmode, gen_rtx_HIGH (Pmode, XEXP (x, 0)), XEXP (x, 0))); return &XEXP (XEXP (x, 0), 0); } #endif /* If we have a PLUS whose second operand is a constant and the address is not valid, perhaps will can split it up using the machine-specific way to split large constants. We use the first pseudo-reg (one of the virtual regs) as a placeholder; it will not remain in the result. */ if (GET_CODE (XEXP (x, 0)) == PLUS && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT && ! memory_address_p (GET_MODE (x), XEXP (x, 0))) { rtx reg = regno_reg_rtx[FIRST_PSEUDO_REGISTER]; rtx seq = split_insns (gen_rtx_SET (VOIDmode, reg, XEXP (x, 0)), subst_insn); /* This should have produced two insns, each of which sets our placeholder. If the source of the second is a valid address, we can make put both sources together and make a split point in the middle. */ if (seq && NEXT_INSN (seq) != NULL_RTX && NEXT_INSN (NEXT_INSN (seq)) == NULL_RTX && GET_CODE (seq) == INSN && GET_CODE (PATTERN (seq)) == SET && SET_DEST (PATTERN (seq)) == reg && ! reg_mentioned_p (reg, SET_SRC (PATTERN (seq))) && GET_CODE (NEXT_INSN (seq)) == INSN && GET_CODE (PATTERN (NEXT_INSN (seq))) == SET && SET_DEST (PATTERN (NEXT_INSN (seq))) == reg && memory_address_p (GET_MODE (x), SET_SRC (PATTERN (NEXT_INSN (seq))))) { rtx src1 = SET_SRC (PATTERN (seq)); rtx src2 = SET_SRC (PATTERN (NEXT_INSN (seq))); /* Replace the placeholder in SRC2 with SRC1. If we can find where in SRC2 it was placed, that can become our split point and we can replace this address with SRC2. Just try two obvious places. */ src2 = replace_rtx (src2, reg, src1); split = 0; if (XEXP (src2, 0) == src1) split = &XEXP (src2, 0); else if (GET_RTX_FORMAT (GET_CODE (XEXP (src2, 0)))[0] == 'e' && XEXP (XEXP (src2, 0), 0) == src1) split = &XEXP (XEXP (src2, 0), 0); if (split) { SUBST (XEXP (x, 0), src2); return split; } } /* If that didn't work, perhaps the first operand is complex and needs to be computed separately, so make a split point there. This will occur on machines that just support REG + CONST and have a constant moved through some previous computation. */ else if (GET_RTX_CLASS (GET_CODE (XEXP (XEXP (x, 0), 0))) != 'o' && ! (GET_CODE (XEXP (XEXP (x, 0), 0)) == SUBREG && (GET_RTX_CLASS (GET_CODE (SUBREG_REG (XEXP (XEXP (x, 0), 0)))) == 'o'))) return &XEXP (XEXP (x, 0), 0); } break; case SET: #ifdef HAVE_cc0 /* If SET_DEST is CC0 and SET_SRC is not an operand, a COMPARE, or a ZERO_EXTRACT, the most likely reason why this doesn't match is that we need to put the operand into a register. So split at that point. */ if (SET_DEST (x) == cc0_rtx && GET_CODE (SET_SRC (x)) != COMPARE && GET_CODE (SET_SRC (x)) != ZERO_EXTRACT && GET_RTX_CLASS (GET_CODE (SET_SRC (x))) != 'o' && ! (GET_CODE (SET_SRC (x)) == SUBREG && GET_RTX_CLASS (GET_CODE (SUBREG_REG (SET_SRC (x)))) == 'o')) return &SET_SRC (x); #endif /* See if we can split SET_SRC as it stands. */ split = find_split_point (&SET_SRC (x), insn); if (split && split != &SET_SRC (x)) return split; /* See if we can split SET_DEST as it stands. */ split = find_split_point (&SET_DEST (x), insn); if (split && split != &SET_DEST (x)) return split; /* See if this is a bitfield assignment with everything constant. If so, this is an IOR of an AND, so split it into that. */ if (GET_CODE (SET_DEST (x)) == ZERO_EXTRACT && (GET_MODE_BITSIZE (GET_MODE (XEXP (SET_DEST (x), 0))) <= HOST_BITS_PER_WIDE_INT) && GET_CODE (XEXP (SET_DEST (x), 1)) == CONST_INT && GET_CODE (XEXP (SET_DEST (x), 2)) == CONST_INT && GET_CODE (SET_SRC (x)) == CONST_INT && ((INTVAL (XEXP (SET_DEST (x), 1)) + INTVAL (XEXP (SET_DEST (x), 2))) <= GET_MODE_BITSIZE (GET_MODE (XEXP (SET_DEST (x), 0)))) && ! side_effects_p (XEXP (SET_DEST (x), 0))) { HOST_WIDE_INT pos = INTVAL (XEXP (SET_DEST (x), 2)); unsigned HOST_WIDE_INT len = INTVAL (XEXP (SET_DEST (x), 1)); unsigned HOST_WIDE_INT src = INTVAL (SET_SRC (x)); rtx dest = XEXP (SET_DEST (x), 0); enum machine_mode mode = GET_MODE (dest); unsigned HOST_WIDE_INT mask = ((HOST_WIDE_INT) 1 << len) - 1; if (BITS_BIG_ENDIAN) pos = GET_MODE_BITSIZE (mode) - len - pos; if (src == mask) SUBST (SET_SRC (x), gen_binary (IOR, mode, dest, GEN_INT (src << pos))); else SUBST (SET_SRC (x), gen_binary (IOR, mode, gen_binary (AND, mode, dest, gen_int_mode (~(mask << pos), mode)), GEN_INT (src << pos))); SUBST (SET_DEST (x), dest); split = find_split_point (&SET_SRC (x), insn); if (split && split != &SET_SRC (x)) return split; } /* Otherwise, see if this is an operation that we can split into two. If so, try to split that. */ code = GET_CODE (SET_SRC (x)); switch (code) { case AND: /* If we are AND'ing with a large constant that is only a single bit and the result is only being used in a context where we need to know if it is zero or nonzero, replace it with a bit extraction. This will avoid the large constant, which might have taken more than one insn to make. If the constant were not a valid argument to the AND but took only one insn to make, this is no worse, but if it took more than one insn, it will be better. */ if (GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT && GET_CODE (XEXP (SET_SRC (x), 0)) == REG && (pos = exact_log2 (INTVAL (XEXP (SET_SRC (x), 1)))) >= 7 && GET_CODE (SET_DEST (x)) == REG && (split = find_single_use (SET_DEST (x), insn, (rtx*) 0)) != 0 && (GET_CODE (*split) == EQ || GET_CODE (*split) == NE) && XEXP (*split, 0) == SET_DEST (x) && XEXP (*split, 1) == const0_rtx) { rtx extraction = make_extraction (GET_MODE (SET_DEST (x)), XEXP (SET_SRC (x), 0), pos, NULL_RTX, 1, 1, 0, 0); if (extraction != 0) { SUBST (SET_SRC (x), extraction); return find_split_point (loc, insn); } } break; case NE: /* if STORE_FLAG_VALUE is -1, this is (NE X 0) and only one bit of X is known to be on, this can be converted into a NEG of a shift. */ if (STORE_FLAG_VALUE == -1 && XEXP (SET_SRC (x), 1) == const0_rtx && GET_MODE (SET_SRC (x)) == GET_MODE (XEXP (SET_SRC (x), 0)) && 1 <= (pos = exact_log2 (nonzero_bits (XEXP (SET_SRC (x), 0), GET_MODE (XEXP (SET_SRC (x), 0)))))) { enum machine_mode mode = GET_MODE (XEXP (SET_SRC (x), 0)); SUBST (SET_SRC (x), gen_rtx_NEG (mode, gen_rtx_LSHIFTRT (mode, XEXP (SET_SRC (x), 0), GEN_INT (pos)))); split = find_split_point (&SET_SRC (x), insn); if (split && split != &SET_SRC (x)) return split; } break; case SIGN_EXTEND: inner = XEXP (SET_SRC (x), 0); /* We can't optimize if either mode is a partial integer mode as we don't know how many bits are significant in those modes. */ if (GET_MODE_CLASS (GET_MODE (inner)) == MODE_PARTIAL_INT || GET_MODE_CLASS (GET_MODE (SET_SRC (x))) == MODE_PARTIAL_INT) break; pos = 0; len = GET_MODE_BITSIZE (GET_MODE (inner)); unsignedp = 0; break; case SIGN_EXTRACT: case ZERO_EXTRACT: if (GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT && GET_CODE (XEXP (SET_SRC (x), 2)) == CONST_INT) { inner = XEXP (SET_SRC (x), 0); len = INTVAL (XEXP (SET_SRC (x), 1)); pos = INTVAL (XEXP (SET_SRC (x), 2)); if (BITS_BIG_ENDIAN) pos = GET_MODE_BITSIZE (GET_MODE (inner)) - len - pos; unsignedp = (code == ZERO_EXTRACT); } break; default: break; } if (len && pos >= 0 && pos + len <= GET_MODE_BITSIZE (GET_MODE (inner))) { enum machine_mode mode = GET_MODE (SET_SRC (x)); /* For unsigned, we have a choice of a shift followed by an AND or two shifts. Use two shifts for field sizes where the constant might be too large. We assume here that we can always at least get 8-bit constants in an AND insn, which is true for every current RISC. */ if (unsignedp && len <= 8) { SUBST (SET_SRC (x), gen_rtx_AND (mode, gen_rtx_LSHIFTRT (mode, gen_lowpart_for_combine (mode, inner), GEN_INT (pos)), GEN_INT (((HOST_WIDE_INT) 1 << len) - 1))); split = find_split_point (&SET_SRC (x), insn); if (split && split != &SET_SRC (x)) return split; } else { SUBST (SET_SRC (x), gen_rtx_fmt_ee (unsignedp ? LSHIFTRT : ASHIFTRT, mode, gen_rtx_ASHIFT (mode, gen_lowpart_for_combine (mode, inner), GEN_INT (GET_MODE_BITSIZE (mode) - len - pos)), GEN_INT (GET_MODE_BITSIZE (mode) - len))); split = find_split_point (&SET_SRC (x), insn); if (split && split != &SET_SRC (x)) return split; } } /* See if this is a simple operation with a constant as the second operand. It might be that this constant is out of range and hence could be used as a split point. */ if ((GET_RTX_CLASS (GET_CODE (SET_SRC (x))) == '2' || GET_RTX_CLASS (GET_CODE (SET_SRC (x))) == 'c' || GET_RTX_CLASS (GET_CODE (SET_SRC (x))) == '<') && CONSTANT_P (XEXP (SET_SRC (x), 1)) && (GET_RTX_CLASS (GET_CODE (XEXP (SET_SRC (x), 0))) == 'o' || (GET_CODE (XEXP (SET_SRC (x), 0)) == SUBREG && (GET_RTX_CLASS (GET_CODE (SUBREG_REG (XEXP (SET_SRC (x), 0)))) == 'o')))) return &XEXP (SET_SRC (x), 1); /* Finally, see if this is a simple operation with its first operand not in a register. The operation might require this operand in a register, so return it as a split point. We can always do this because if the first operand were another operation, we would have already found it as a split point. */ if ((GET_RTX_CLASS (GET_CODE (SET_SRC (x))) == '2' || GET_RTX_CLASS (GET_CODE (SET_SRC (x))) == 'c' || GET_RTX_CLASS (GET_CODE (SET_SRC (x))) == '<' || GET_RTX_CLASS (GET_CODE (SET_SRC (x))) == '1') && ! register_operand (XEXP (SET_SRC (x), 0), VOIDmode)) return &XEXP (SET_SRC (x), 0); return 0; case AND: case IOR: /* We write NOR as (and (not A) (not B)), but if we don't have a NOR, it is better to write this as (not (ior A B)) so we can split it. Similarly for IOR. */ if (GET_CODE (XEXP (x, 0)) == NOT && GET_CODE (XEXP (x, 1)) == NOT) { SUBST (*loc, gen_rtx_NOT (GET_MODE (x), gen_rtx_fmt_ee (code == IOR ? AND : IOR, GET_MODE (x), XEXP (XEXP (x, 0), 0), XEXP (XEXP (x, 1), 0)))); return find_split_point (loc, insn); } /* Many RISC machines have a large set of logical insns. If the second operand is a NOT, put it first so we will try to split the other operand first. */ if (GET_CODE (XEXP (x, 1)) == NOT) { rtx tem = XEXP (x, 0); SUBST (XEXP (x, 0), XEXP (x, 1)); SUBST (XEXP (x, 1), tem); } break; default: break; } /* Otherwise, select our actions depending on our rtx class. */ switch (GET_RTX_CLASS (code)) { case 'b': /* This is ZERO_EXTRACT and SIGN_EXTRACT. */ case '3': split = find_split_point (&XEXP (x, 2), insn); if (split) return split; /* ... fall through ... */ case '2': case 'c': case '<': split = find_split_point (&XEXP (x, 1), insn); if (split) return split; /* ... fall through ... */ case '1': /* Some machines have (and (shift ...) ...) insns. If X is not an AND, but XEXP (X, 0) is, use it as our split point. */ if (GET_CODE (x) != AND && GET_CODE (XEXP (x, 0)) == AND) return &XEXP (x, 0); split = find_split_point (&XEXP (x, 0), insn); if (split) return split; return loc; } /* Otherwise, we don't have a split point. */ return 0; } /* Throughout X, replace FROM with TO, and return the result. The result is TO if X is FROM; otherwise the result is X, but its contents may have been modified. If they were modified, a record was made in undobuf so that undo_all will (among other things) return X to its original state. If the number of changes necessary is too much to record to undo, the excess changes are not made, so the result is invalid. The changes already made can still be undone. undobuf.num_undo is incremented for such changes, so by testing that the caller can tell whether the result is valid. `n_occurrences' is incremented each time FROM is replaced. IN_DEST is nonzero if we are processing the SET_DEST of a SET. UNIQUE_COPY is nonzero if each substitution must be unique. We do this by copying if `n_occurrences' is nonzero. */ static rtx subst (x, from, to, in_dest, unique_copy) rtx x, from, to; int in_dest; int unique_copy; { enum rtx_code code = GET_CODE (x); enum machine_mode op0_mode = VOIDmode; const char *fmt; int len, i; rtx new; /* Two expressions are equal if they are identical copies of a shared RTX or if they are both registers with the same register number and mode. */ #define COMBINE_RTX_EQUAL_P(X,Y) \ ((X) == (Y) \ || (GET_CODE (X) == REG && GET_CODE (Y) == REG \ && REGNO (X) == REGNO (Y) && GET_MODE (X) == GET_MODE (Y))) if (! in_dest && COMBINE_RTX_EQUAL_P (x, from)) { n_occurrences++; return (unique_copy && n_occurrences > 1 ? copy_rtx (to) : to); } /* If X and FROM are the same register but different modes, they will not have been seen as equal above. However, flow.c will make a LOG_LINKS entry for that case. If we do nothing, we will try to rerecognize our original insn and, when it succeeds, we will delete the feeding insn, which is incorrect. So force this insn not to match in this (rare) case. */ if (! in_dest && code == REG && GET_CODE (from) == REG && REGNO (x) == REGNO (from)) return gen_rtx_CLOBBER (GET_MODE (x), const0_rtx); /* If this is an object, we are done unless it is a MEM or LO_SUM, both of which may contain things that can be combined. */ if (code != MEM && code != LO_SUM && GET_RTX_CLASS (code) == 'o') return x; /* It is possible to have a subexpression appear twice in the insn. Suppose that FROM is a register that appears within TO. Then, after that subexpression has been scanned once by `subst', the second time it is scanned, TO may be found. If we were to scan TO here, we would find FROM within it and create a self-referent rtl structure which is completely wrong. */ if (COMBINE_RTX_EQUAL_P (x, to)) return to; /* Parallel asm_operands need special attention because all of the inputs are shared across the arms. Furthermore, unsharing the rtl results in recognition failures. Failure to handle this case specially can result in circular rtl. Solve this by doing a normal pass across the first entry of the parallel, and only processing the SET_DESTs of the subsequent entries. Ug. */ if (code == PARALLEL && GET_CODE (XVECEXP (x, 0, 0)) == SET && GET_CODE (SET_SRC (XVECEXP (x, 0, 0))) == ASM_OPERANDS) { new = subst (XVECEXP (x, 0, 0), from, to, 0, unique_copy); /* If this substitution failed, this whole thing fails. */ if (GET_CODE (new) == CLOBBER && XEXP (new, 0) == const0_rtx) return new; SUBST (XVECEXP (x, 0, 0), new); for (i = XVECLEN (x, 0) - 1; i >= 1; i--) { rtx dest = SET_DEST (XVECEXP (x, 0, i)); if (GET_CODE (dest) != REG && GET_CODE (dest) != CC0 && GET_CODE (dest) != PC) { new = subst (dest, from, to, 0, unique_copy); /* If this substitution failed, this whole thing fails. */ if (GET_CODE (new) == CLOBBER && XEXP (new, 0) == const0_rtx) return new; SUBST (SET_DEST (XVECEXP (x, 0, i)), new); } } } else { len = GET_RTX_LENGTH (code); fmt = GET_RTX_FORMAT (code); /* We don't need to process a SET_DEST that is a register, CC0, or PC, so set up to skip this common case. All other cases where we want to suppress replacing something inside a SET_SRC are handled via the IN_DEST operand. */ if (code == SET && (GET_CODE (SET_DEST (x)) == REG || GET_CODE (SET_DEST (x)) == CC0 || GET_CODE (SET_DEST (x)) == PC)) fmt = "ie"; /* Get the mode of operand 0 in case X is now a SIGN_EXTEND of a constant. */ if (fmt[0] == 'e') op0_mode = GET_MODE (XEXP (x, 0)); for (i = 0; i < len; i++) { if (fmt[i] == 'E') { int j; for (j = XVECLEN (x, i) - 1; j >= 0; j--) { if (COMBINE_RTX_EQUAL_P (XVECEXP (x, i, j), from)) { new = (unique_copy && n_occurrences ? copy_rtx (to) : to); n_occurrences++; } else { new = subst (XVECEXP (x, i, j), from, to, 0, unique_copy); /* If this substitution failed, this whole thing fails. */ if (GET_CODE (new) == CLOBBER && XEXP (new, 0) == const0_rtx) return new; } SUBST (XVECEXP (x, i, j), new); } } else if (fmt[i] == 'e') { /* If this is a register being set, ignore it. */ new = XEXP (x, i); if (in_dest && (code == SUBREG || code == STRICT_LOW_PART || code == ZERO_EXTRACT) && i == 0 && GET_CODE (new) == REG) ; else if (COMBINE_RTX_EQUAL_P (XEXP (x, i), from)) { /* In general, don't install a subreg involving two modes not tieable. It can worsen register allocation, and can even make invalid reload insns, since the reg inside may need to be copied from in the outside mode, and that may be invalid if it is an fp reg copied in integer mode. We allow two exceptions to this: It is valid if it is inside another SUBREG and the mode of that SUBREG and the mode of the inside of TO is tieable and it is valid if X is a SET that copies FROM to CC0. */ if (GET_CODE (to) == SUBREG && ! MODES_TIEABLE_P (GET_MODE (to), GET_MODE (SUBREG_REG (to))) && ! (code == SUBREG && MODES_TIEABLE_P (GET_MODE (x), GET_MODE (SUBREG_REG (to)))) #ifdef HAVE_cc0 && ! (code == SET && i == 1 && XEXP (x, 0) == cc0_rtx) #endif ) return gen_rtx_CLOBBER (VOIDmode, const0_rtx); #ifdef CANNOT_CHANGE_MODE_CLASS if (code == SUBREG && GET_CODE (to) == REG && REGNO (to) < FIRST_PSEUDO_REGISTER && REG_CANNOT_CHANGE_MODE_P (REGNO (to), GET_MODE (to), GET_MODE (x))) return gen_rtx_CLOBBER (VOIDmode, const0_rtx); #endif new = (unique_copy && n_occurrences ? copy_rtx (to) : to); n_occurrences++; } else /* If we are in a SET_DEST, suppress most cases unless we have gone inside a MEM, in which case we want to simplify the address. We assume here that things that are actually part of the destination have their inner parts in the first expression. This is true for SUBREG, STRICT_LOW_PART, and ZERO_EXTRACT, which are the only things aside from REG and MEM that should appear in a SET_DEST. */ new = subst (XEXP (x, i), from, to, (((in_dest && (code == SUBREG || code == STRICT_LOW_PART || code == ZERO_EXTRACT)) || code == SET) && i == 0), unique_copy); /* If we found that we will have to reject this combination, indicate that by returning the CLOBBER ourselves, rather than an expression containing it. This will speed things up as well as prevent accidents where two CLOBBERs are considered to be equal, thus producing an incorrect simplification. */ if (GET_CODE (new) == CLOBBER && XEXP (new, 0) == const0_rtx) return new; if (GET_CODE (new) == CONST_INT && GET_CODE (x) == SUBREG) { enum machine_mode mode = GET_MODE (x); x = simplify_subreg (GET_MODE (x), new, GET_MODE (SUBREG_REG (x)), SUBREG_BYTE (x)); if (! x) x = gen_rtx_CLOBBER (mode, const0_rtx); } else if (GET_CODE (new) == CONST_INT && GET_CODE (x) == ZERO_EXTEND) { x = simplify_unary_operation (ZERO_EXTEND, GET_MODE (x), new, GET_MODE (XEXP (x, 0))); if (! x) abort (); } else SUBST (XEXP (x, i), new); } } } /* Try to simplify X. If the simplification changed the code, it is likely that further simplification will help, so loop, but limit the number of repetitions that will be performed. */ for (i = 0; i < 4; i++) { /* If X is sufficiently simple, don't bother trying to do anything with it. */ if (code != CONST_INT && code != REG && code != CLOBBER) x = combine_simplify_rtx (x, op0_mode, i == 3, in_dest); if (GET_CODE (x) == code) break; code = GET_CODE (x); /* We no longer know the original mode of operand 0 since we have changed the form of X) */ op0_mode = VOIDmode; } return x; } /* Simplify X, a piece of RTL. We just operate on the expression at the outer level; call `subst' to simplify recursively. Return the new expression. OP0_MODE is the original mode of XEXP (x, 0); LAST is nonzero if this will be the iteration even if an expression with a code different from X is returned; IN_DEST is nonzero if we are inside a SET_DEST. */ static rtx combine_simplify_rtx (x, op0_mode, last, in_dest) rtx x; enum machine_mode op0_mode; int last; int in_dest; { enum rtx_code code = GET_CODE (x); enum machine_mode mode = GET_MODE (x); rtx temp; rtx reversed; int i; /* If this is a commutative operation, put a constant last and a complex expression first. We don't need to do this for comparisons here. */ if (GET_RTX_CLASS (code) == 'c' && swap_commutative_operands_p (XEXP (x, 0), XEXP (x, 1))) { temp = XEXP (x, 0); SUBST (XEXP (x, 0), XEXP (x, 1)); SUBST (XEXP (x, 1), temp); } /* If this is a PLUS, MINUS, or MULT, and the first operand is the sign extension of a PLUS with a constant, reverse the order of the sign extension and the addition. Note that this not the same as the original code, but overflow is undefined for signed values. Also note that the PLUS will have been partially moved "inside" the sign-extension, so that the first operand of X will really look like: (ashiftrt (plus (ashift A C4) C5) C4). We convert this to (plus (ashiftrt (ashift A C4) C2) C4) and replace the first operand of X with that expression. Later parts of this function may simplify the expression further. For example, if we start with (mult (sign_extend (plus A C1)) C2), we swap the SIGN_EXTEND and PLUS. Later code will apply the distributive law to produce (plus (mult (sign_extend X) C1) C3). We do this to simplify address expressions. */ if ((code == PLUS || code == MINUS || code == MULT) && GET_CODE (XEXP (x, 0)) == ASHIFTRT && GET_CODE (XEXP (XEXP (x, 0), 0)) == PLUS && GET_CODE (XEXP (XEXP (XEXP (x, 0), 0), 0)) == ASHIFT && GET_CODE (XEXP (XEXP (XEXP (XEXP (x, 0), 0), 0), 1)) == CONST_INT && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT && XEXP (XEXP (XEXP (XEXP (x, 0), 0), 0), 1) == XEXP (XEXP (x, 0), 1) && GET_CODE (XEXP (XEXP (XEXP (x, 0), 0), 1)) == CONST_INT && (temp = simplify_binary_operation (ASHIFTRT, mode, XEXP (XEXP (XEXP (x, 0), 0), 1), XEXP (XEXP (x, 0), 1))) != 0) { rtx new = simplify_shift_const (NULL_RTX, ASHIFT, mode, XEXP (XEXP (XEXP (XEXP (x, 0), 0), 0), 0), INTVAL (XEXP (XEXP (x, 0), 1))); new = simplify_shift_const (NULL_RTX, ASHIFTRT, mode, new, INTVAL (XEXP (XEXP (x, 0), 1))); SUBST (XEXP (x, 0), gen_binary (PLUS, mode, new, temp)); } /* If this is a simple operation applied to an IF_THEN_ELSE, try applying it to the arms of the IF_THEN_ELSE. This often simplifies things. Check for cases where both arms are testing the same condition. Don't do anything if all operands are very simple. */ if (((GET_RTX_CLASS (code) == '2' || GET_RTX_CLASS (code) == 'c' || GET_RTX_CLASS (code) == '<') && ((GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) != 'o' && ! (GET_CODE (XEXP (x, 0)) == SUBREG && (GET_RTX_CLASS (GET_CODE (SUBREG_REG (XEXP (x, 0)))) == 'o'))) || (GET_RTX_CLASS (GET_CODE (XEXP (x, 1))) != 'o' && ! (GET_CODE (XEXP (x, 1)) == SUBREG && (GET_RTX_CLASS (GET_CODE (SUBREG_REG (XEXP (x, 1)))) == 'o'))))) || (GET_RTX_CLASS (code) == '1' && ((GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) != 'o' && ! (GET_CODE (XEXP (x, 0)) == SUBREG && (GET_RTX_CLASS (GET_CODE (SUBREG_REG (XEXP (x, 0)))) == 'o')))))) { rtx cond, true_rtx, false_rtx; cond = if_then_else_cond (x, &true_rtx, &false_rtx); if (cond != 0 /* If everything is a comparison, what we have is highly unlikely to be simpler, so don't use it. */ && ! (GET_RTX_CLASS (code) == '<' && (GET_RTX_CLASS (GET_CODE (true_rtx)) == '<' || GET_RTX_CLASS (GET_CODE (false_rtx)) == '<'))) { rtx cop1 = const0_rtx; enum rtx_code cond_code = simplify_comparison (NE, &cond, &cop1); if (cond_code == NE && GET_RTX_CLASS (GET_CODE (cond)) == '<') return x; /* Simplify the alternative arms; this may collapse the true and false arms to store-flag values. */ true_rtx = subst (true_rtx, pc_rtx, pc_rtx, 0, 0); false_rtx = subst (false_rtx, pc_rtx, pc_rtx, 0, 0); /* If true_rtx and false_rtx are not general_operands, an if_then_else is unlikely to be simpler. */ if (general_operand (true_rtx, VOIDmode) && general_operand (false_rtx, VOIDmode)) { enum rtx_code reversed; /* Restarting if we generate a store-flag expression will cause us to loop. Just drop through in this case. */ /* If the result values are STORE_FLAG_VALUE and zero, we can just make the comparison operation. */ if (true_rtx == const_true_rtx && false_rtx == const0_rtx) x = gen_binary (cond_code, mode, cond, cop1); else if (true_rtx == const0_rtx && false_rtx == const_true_rtx && ((reversed = reversed_comparison_code_parts (cond_code, cond, cop1, NULL)) != UNKNOWN)) x = gen_binary (reversed, mode, cond, cop1); /* Likewise, we can make the negate of a comparison operation if the result values are - STORE_FLAG_VALUE and zero. */ else if (GET_CODE (true_rtx) == CONST_INT && INTVAL (true_rtx) == - STORE_FLAG_VALUE && false_rtx == const0_rtx) x = simplify_gen_unary (NEG, mode, gen_binary (cond_code, mode, cond, cop1), mode); else if (GET_CODE (false_rtx) == CONST_INT && INTVAL (false_rtx) == - STORE_FLAG_VALUE && true_rtx == const0_rtx && ((reversed = reversed_comparison_code_parts (cond_code, cond, cop1, NULL)) != UNKNOWN)) x = simplify_gen_unary (NEG, mode, gen_binary (reversed, mode, cond, cop1), mode); else return gen_rtx_IF_THEN_ELSE (mode, gen_binary (cond_code, VOIDmode, cond, cop1), true_rtx, false_rtx); code = GET_CODE (x); op0_mode = VOIDmode; } } } /* Try to fold this expression in case we have constants that weren't present before. */ temp = 0; switch (GET_RTX_CLASS (code)) { case '1': temp = simplify_unary_operation (code, mode, XEXP (x, 0), op0_mode); break; case '<': { enum machine_mode cmp_mode = GET_MODE (XEXP (x, 0)); if (cmp_mode == VOIDmode) { cmp_mode = GET_MODE (XEXP (x, 1)); if (cmp_mode == VOIDmode) cmp_mode = op0_mode; } temp = simplify_relational_operation (code, cmp_mode, XEXP (x, 0), XEXP (x, 1)); } #ifdef FLOAT_STORE_FLAG_VALUE if (temp != 0 && GET_MODE_CLASS (mode) == MODE_FLOAT) { if (temp == const0_rtx) temp = CONST0_RTX (mode); else temp = CONST_DOUBLE_FROM_REAL_VALUE (FLOAT_STORE_FLAG_VALUE (mode), mode); } #endif break; case 'c': case '2': temp = simplify_binary_operation (code, mode, XEXP (x, 0), XEXP (x, 1)); break; case 'b': case '3': temp = simplify_ternary_operation (code, mode, op0_mode, XEXP (x, 0), XEXP (x, 1), XEXP (x, 2)); break; } if (temp) { x = temp; code = GET_CODE (temp); op0_mode = VOIDmode; mode = GET_MODE (temp); } /* First see if we can apply the inverse distributive law. */ if (code == PLUS || code == MINUS || code == AND || code == IOR || code == XOR) { x = apply_distributive_law (x); code = GET_CODE (x); op0_mode = VOIDmode; } /* If CODE is an associative operation not otherwise handled, see if we can associate some operands. This can win if they are constants or if they are logically related (i.e. (a & b) & a). */ if ((code == PLUS || code == MINUS || code == MULT || code == DIV || code == AND || code == IOR || code == XOR || code == SMAX || code == SMIN || code == UMAX || code == UMIN) && ((INTEGRAL_MODE_P (mode) && code != DIV) || (flag_unsafe_math_optimizations && FLOAT_MODE_P (mode)))) { if (GET_CODE (XEXP (x, 0)) == code) { rtx other = XEXP (XEXP (x, 0), 0); rtx inner_op0 = XEXP (XEXP (x, 0), 1); rtx inner_op1 = XEXP (x, 1); rtx inner; /* Make sure we pass the constant operand if any as the second one if this is a commutative operation. */ if (CONSTANT_P (inner_op0) && GET_RTX_CLASS (code) == 'c') { rtx tem = inner_op0; inner_op0 = inner_op1; inner_op1 = tem; } inner = simplify_binary_operation (code == MINUS ? PLUS : code == DIV ? MULT : code, mode, inner_op0, inner_op1); /* For commutative operations, try the other pair if that one didn't simplify. */ if (inner == 0 && GET_RTX_CLASS (code) == 'c') { other = XEXP (XEXP (x, 0), 1); inner = simplify_binary_operation (code, mode, XEXP (XEXP (x, 0), 0), XEXP (x, 1)); } if (inner) return gen_binary (code, mode, other, inner); } } /* A little bit of algebraic simplification here. */ switch (code) { case MEM: /* Ensure that our address has any ASHIFTs converted to MULT in case address-recognizing predicates are called later. */ temp = make_compound_operation (XEXP (x, 0), MEM); SUBST (XEXP (x, 0), temp); break; case SUBREG: if (op0_mode == VOIDmode) op0_mode = GET_MODE (SUBREG_REG (x)); /* simplify_subreg can't use gen_lowpart_for_combine. */ if (CONSTANT_P (SUBREG_REG (x)) && subreg_lowpart_offset (mode, op0_mode) == SUBREG_BYTE (x) /* Don't call gen_lowpart_for_combine if the inner mode is VOIDmode and we cannot simplify it, as SUBREG without inner mode is invalid. */ && (GET_MODE (SUBREG_REG (x)) != VOIDmode || gen_lowpart_common (mode, SUBREG_REG (x)))) return gen_lowpart_for_combine (mode, SUBREG_REG (x)); if (GET_MODE_CLASS (GET_MODE (SUBREG_REG (x))) == MODE_CC) break; { rtx temp; temp = simplify_subreg (mode, SUBREG_REG (x), op0_mode, SUBREG_BYTE (x)); if (temp) return temp; } /* Don't change the mode of the MEM if that would change the meaning of the address. */ if (GET_CODE (SUBREG_REG (x)) == MEM && (MEM_VOLATILE_P (SUBREG_REG (x)) || mode_dependent_address_p (XEXP (SUBREG_REG (x), 0)))) return gen_rtx_CLOBBER (mode, const0_rtx); /* Note that we cannot do any narrowing for non-constants since we might have been counting on using the fact that some bits were zero. We now do this in the SET. */ break; case NOT: /* (not (plus X -1)) can become (neg X). */ if (GET_CODE (XEXP (x, 0)) == PLUS && XEXP (XEXP (x, 0), 1) == constm1_rtx) return gen_rtx_NEG (mode, XEXP (XEXP (x, 0), 0)); /* Similarly, (not (neg X)) is (plus X -1). */ if (GET_CODE (XEXP (x, 0)) == NEG) return gen_rtx_PLUS (mode, XEXP (XEXP (x, 0), 0), constm1_rtx); /* (not (xor X C)) for C constant is (xor X D) with D = ~C. */ if (GET_CODE (XEXP (x, 0)) == XOR && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT && (temp = simplify_unary_operation (NOT, mode, XEXP (XEXP (x, 0), 1), mode)) != 0) return gen_binary (XOR, mode, XEXP (XEXP (x, 0), 0), temp); /* (not (ashift 1 X)) is (rotate ~1 X). We used to do this for operands other than 1, but that is not valid. We could do a similar simplification for (not (lshiftrt C X)) where C is just the sign bit, but this doesn't seem common enough to bother with. */ if (GET_CODE (XEXP (x, 0)) == ASHIFT && XEXP (XEXP (x, 0), 0) == const1_rtx) return gen_rtx_ROTATE (mode, simplify_gen_unary (NOT, mode, const1_rtx, mode), XEXP (XEXP (x, 0), 1)); if (GET_CODE (XEXP (x, 0)) == SUBREG && subreg_lowpart_p (XEXP (x, 0)) && (GET_MODE_SIZE (GET_MODE (XEXP (x, 0))) < GET_MODE_SIZE (GET_MODE (SUBREG_REG (XEXP (x, 0))))) && GET_CODE (SUBREG_REG (XEXP (x, 0))) == ASHIFT && XEXP (SUBREG_REG (XEXP (x, 0)), 0) == const1_rtx) { enum machine_mode inner_mode = GET_MODE (SUBREG_REG (XEXP (x, 0))); x = gen_rtx_ROTATE (inner_mode, simplify_gen_unary (NOT, inner_mode, const1_rtx, inner_mode), XEXP (SUBREG_REG (XEXP (x, 0)), 1)); return gen_lowpart_for_combine (mode, x); } /* If STORE_FLAG_VALUE is -1, (not (comparison foo bar)) can be done by reversing the comparison code if valid. */ if (STORE_FLAG_VALUE == -1 && GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) == '<' && (reversed = reversed_comparison (x, mode, XEXP (XEXP (x, 0), 0), XEXP (XEXP (x, 0), 1)))) return reversed; /* (not (ashiftrt foo C)) where C is the number of bits in FOO minus 1 is (ge foo (const_int 0)) if STORE_FLAG_VALUE is -1, so we can perform the above simplification. */ if (STORE_FLAG_VALUE == -1 && GET_CODE (XEXP (x, 0)) == ASHIFTRT && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT && INTVAL (XEXP (XEXP (x, 0), 1)) == GET_MODE_BITSIZE (mode) - 1) return gen_rtx_GE (mode, XEXP (XEXP (x, 0), 0), const0_rtx); /* Apply De Morgan's laws to reduce number of patterns for machines with negating logical insns (and-not, nand, etc.). If result has only one NOT, put it first, since that is how the patterns are coded. */ if (GET_CODE (XEXP (x, 0)) == IOR || GET_CODE (XEXP (x, 0)) == AND) { rtx in1 = XEXP (XEXP (x, 0), 0), in2 = XEXP (XEXP (x, 0), 1); enum machine_mode op_mode; op_mode = GET_MODE (in1); in1 = simplify_gen_unary (NOT, op_mode, in1, op_mode); op_mode = GET_MODE (in2); if (op_mode == VOIDmode) op_mode = mode; in2 = simplify_gen_unary (NOT, op_mode, in2, op_mode); if (GET_CODE (in2) == NOT && GET_CODE (in1) != NOT) { rtx tem = in2; in2 = in1; in1 = tem; } return gen_rtx_fmt_ee (GET_CODE (XEXP (x, 0)) == IOR ? AND : IOR, mode, in1, in2); } break; case NEG: /* (neg (plus X 1)) can become (not X). */ if (GET_CODE (XEXP (x, 0)) == PLUS && XEXP (XEXP (x, 0), 1) == const1_rtx) return gen_rtx_NOT (mode, XEXP (XEXP (x, 0), 0)); /* Similarly, (neg (not X)) is (plus X 1). */ if (GET_CODE (XEXP (x, 0)) == NOT) return plus_constant (XEXP (XEXP (x, 0), 0), 1); /* (neg (minus X Y)) can become (minus Y X). This transformation isn't safe for modes with signed zeros, since if X and Y are both +0, (minus Y X) is the same as (minus X Y). If the rounding mode is towards +infinity (or -infinity) then the two expressions will be rounded differently. */ if (GET_CODE (XEXP (x, 0)) == MINUS && !HONOR_SIGNED_ZEROS (mode) && !HONOR_SIGN_DEPENDENT_ROUNDING (mode)) return gen_binary (MINUS, mode, XEXP (XEXP (x, 0), 1), XEXP (XEXP (x, 0), 0)); /* (neg (plus A B)) is canonicalized to (minus (neg A) B). */ if (GET_CODE (XEXP (x, 0)) == PLUS && !HONOR_SIGNED_ZEROS (mode) && !HONOR_SIGN_DEPENDENT_ROUNDING (mode)) { temp = simplify_gen_unary (NEG, mode, XEXP (XEXP (x, 0), 0), mode); temp = combine_simplify_rtx (temp, mode, last, in_dest); return gen_binary (MINUS, mode, temp, XEXP (XEXP (x, 0), 1)); } /* (neg (mult A B)) becomes (mult (neg A) B). This works even for floating-point values. */ if (GET_CODE (XEXP (x, 0)) == MULT) { temp = simplify_gen_unary (NEG, mode, XEXP (XEXP (x, 0), 0), mode); return gen_binary (MULT, mode, temp, XEXP (XEXP (x, 0), 1)); } /* (neg (xor A 1)) is (plus A -1) if A is known to be either 0 or 1. */ if (GET_CODE (XEXP (x, 0)) == XOR && XEXP (XEXP (x, 0), 1) == const1_rtx && nonzero_bits (XEXP (XEXP (x, 0), 0), mode) == 1) return gen_binary (PLUS, mode, XEXP (XEXP (x, 0), 0), constm1_rtx); /* NEG commutes with ASHIFT since it is multiplication. Only do this if we can then eliminate the NEG (e.g., if the operand is a constant). */ if (GET_CODE (XEXP (x, 0)) == ASHIFT) { temp = simplify_unary_operation (NEG, mode, XEXP (XEXP (x, 0), 0), mode); if (temp) return gen_binary (ASHIFT, mode, temp, XEXP (XEXP (x, 0), 1)); } temp = expand_compound_operation (XEXP (x, 0)); /* For C equal to the width of MODE minus 1, (neg (ashiftrt X C)) can be replaced by (lshiftrt X C). This will convert (neg (sign_extract X 1 Y)) to (zero_extract X 1 Y). */ if (GET_CODE (temp) == ASHIFTRT && GET_CODE (XEXP (temp, 1)) == CONST_INT && INTVAL (XEXP (temp, 1)) == GET_MODE_BITSIZE (mode) - 1) return simplify_shift_const (temp, LSHIFTRT, mode, XEXP (temp, 0), INTVAL (XEXP (temp, 1))); /* If X has only a single bit that might be nonzero, say, bit I, convert (neg X) to (ashiftrt (ashift X C-I) C-I) where C is the bitsize of MODE minus 1. This will convert (neg (zero_extract X 1 Y)) to (sign_extract X 1 Y). But only do this if TEMP isn't a register or a SUBREG of one since we'd be making the expression more complex if it was just a register. */ if (GET_CODE (temp) != REG && ! (GET_CODE (temp) == SUBREG && GET_CODE (SUBREG_REG (temp)) == REG) && (i = exact_log2 (nonzero_bits (temp, mode))) >= 0) { rtx temp1 = simplify_shift_const (NULL_RTX, ASHIFTRT, mode, simplify_shift_const (NULL_RTX, ASHIFT, mode, temp, GET_MODE_BITSIZE (mode) - 1 - i), GET_MODE_BITSIZE (mode) - 1 - i); /* If all we did was surround TEMP with the two shifts, we haven't improved anything, so don't use it. Otherwise, we are better off with TEMP1. */ if (GET_CODE (temp1) != ASHIFTRT || GET_CODE (XEXP (temp1, 0)) != ASHIFT || XEXP (XEXP (temp1, 0), 0) != temp) return temp1; } break; case TRUNCATE: /* We can't handle truncation to a partial integer mode here because we don't know the real bitsize of the partial integer mode. */ if (GET_MODE_CLASS (mode) == MODE_PARTIAL_INT) break; if (GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT && TRULY_NOOP_TRUNCATION (GET_MODE_BITSIZE (mode), GET_MODE_BITSIZE (GET_MODE (XEXP (x, 0))))) SUBST (XEXP (x, 0), force_to_mode (XEXP (x, 0), GET_MODE (XEXP (x, 0)), GET_MODE_MASK (mode), NULL_RTX, 0)); /* (truncate:SI ({sign,zero}_extend:DI foo:SI)) == foo:SI. */ if ((GET_CODE (XEXP (x, 0)) == SIGN_EXTEND || GET_CODE (XEXP (x, 0)) == ZERO_EXTEND) && GET_MODE (XEXP (XEXP (x, 0), 0)) == mode) return XEXP (XEXP (x, 0), 0); /* (truncate:SI (OP:DI ({sign,zero}_extend:DI foo:SI))) is (OP:SI foo:SI) if OP is NEG or ABS. */ if ((GET_CODE (XEXP (x, 0)) == ABS || GET_CODE (XEXP (x, 0)) == NEG) && (GET_CODE (XEXP (XEXP (x, 0), 0)) == SIGN_EXTEND || GET_CODE (XEXP (XEXP (x, 0), 0)) == ZERO_EXTEND) && GET_MODE (XEXP (XEXP (XEXP (x, 0), 0), 0)) == mode) return simplify_gen_unary (GET_CODE (XEXP (x, 0)), mode, XEXP (XEXP (XEXP (x, 0), 0), 0), mode); /* (truncate:SI (subreg:DI (truncate:SI X) 0)) is (truncate:SI x). */ if (GET_CODE (XEXP (x, 0)) == SUBREG && GET_CODE (SUBREG_REG (XEXP (x, 0))) == TRUNCATE && subreg_lowpart_p (XEXP (x, 0))) return SUBREG_REG (XEXP (x, 0)); /* If we know that the value is already truncated, we can replace the TRUNCATE with a SUBREG if TRULY_NOOP_TRUNCATION is nonzero for the corresponding modes. But don't do this for an (LSHIFTRT (MULT ...)) since this will cause problems with the umulXi3_highpart patterns. */ if (TRULY_NOOP_TRUNCATION (GET_MODE_BITSIZE (mode), GET_MODE_BITSIZE (GET_MODE (XEXP (x, 0)))) && num_sign_bit_copies (XEXP (x, 0), GET_MODE (XEXP (x, 0))) >= (unsigned int) (GET_MODE_BITSIZE (mode) + 1) && ! (GET_CODE (XEXP (x, 0)) == LSHIFTRT && GET_CODE (XEXP (XEXP (x, 0), 0)) == MULT)) return gen_lowpart_for_combine (mode, XEXP (x, 0)); /* A truncate of a comparison can be replaced with a subreg if STORE_FLAG_VALUE permits. This is like the previous test, but it works even if the comparison is done in a mode larger than HOST_BITS_PER_WIDE_INT. */ if (GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT && GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) == '<' && ((HOST_WIDE_INT) STORE_FLAG_VALUE & ~GET_MODE_MASK (mode)) == 0) return gen_lowpart_for_combine (mode, XEXP (x, 0)); /* Similarly, a truncate of a register whose value is a comparison can be replaced with a subreg if STORE_FLAG_VALUE permits. */ if (GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT && ((HOST_WIDE_INT) STORE_FLAG_VALUE & ~GET_MODE_MASK (mode)) == 0 && (temp = get_last_value (XEXP (x, 0))) && GET_RTX_CLASS (GET_CODE (temp)) == '<') return gen_lowpart_for_combine (mode, XEXP (x, 0)); break; case FLOAT_TRUNCATE: /* (float_truncate:SF (float_extend:DF foo:SF)) = foo:SF. */ if (GET_CODE (XEXP (x, 0)) == FLOAT_EXTEND && GET_MODE (XEXP (XEXP (x, 0), 0)) == mode) return XEXP (XEXP (x, 0), 0); /* (float_truncate:SF (float_truncate:DF foo:XF)) = (float_truncate:SF foo:XF). This may elliminate double rounding, so it is unsafe. (float_truncate:SF (float_extend:XF foo:DF)) = (float_truncate:SF foo:DF). (float_truncate:DF (float_extend:XF foo:SF)) = (float_extend:SF foo:DF). */ if ((GET_CODE (XEXP (x, 0)) == FLOAT_TRUNCATE && flag_unsafe_math_optimizations) || GET_CODE (XEXP (x, 0)) == FLOAT_EXTEND) return simplify_gen_unary (GET_MODE_SIZE (GET_MODE (XEXP (XEXP (x, 0), 0))) > GET_MODE_SIZE (mode) ? FLOAT_TRUNCATE : FLOAT_EXTEND, mode, XEXP (XEXP (x, 0), 0), mode); /* (float_truncate (float x)) is (float x) */ if (GET_CODE (XEXP (x, 0)) == FLOAT && (flag_unsafe_math_optimizations || ((unsigned)significand_size (GET_MODE (XEXP (x, 0))) >= (GET_MODE_BITSIZE (GET_MODE (XEXP (XEXP (x, 0), 0))) - num_sign_bit_copies (XEXP (XEXP (x, 0), 0), GET_MODE (XEXP (XEXP (x, 0), 0))))))) return simplify_gen_unary (FLOAT, mode, XEXP (XEXP (x, 0), 0), GET_MODE (XEXP (XEXP (x, 0), 0))); /* (float_truncate:SF (OP:DF (float_extend:DF foo:sf))) is (OP:SF foo:SF) if OP is NEG or ABS. */ if ((GET_CODE (XEXP (x, 0)) == ABS || GET_CODE (XEXP (x, 0)) == NEG) && GET_CODE (XEXP (XEXP (x, 0), 0)) == FLOAT_EXTEND && GET_MODE (XEXP (XEXP (XEXP (x, 0), 0), 0)) == mode) return simplify_gen_unary (GET_CODE (XEXP (x, 0)), mode, XEXP (XEXP (XEXP (x, 0), 0), 0), mode); /* (float_truncate:SF (subreg:DF (float_truncate:SF X) 0)) is (float_truncate:SF x). */ if (GET_CODE (XEXP (x, 0)) == SUBREG && subreg_lowpart_p (XEXP (x, 0)) && GET_CODE (SUBREG_REG (XEXP (x, 0))) == FLOAT_TRUNCATE) return SUBREG_REG (XEXP (x, 0)); break; case FLOAT_EXTEND: /* (float_extend (float_extend x)) is (float_extend x) (float_extend (float x)) is (float x) assuming that double rounding can't happen. */ if (GET_CODE (XEXP (x, 0)) == FLOAT_EXTEND || (GET_CODE (XEXP (x, 0)) == FLOAT && ((unsigned)significand_size (GET_MODE (XEXP (x, 0))) >= (GET_MODE_BITSIZE (GET_MODE (XEXP (XEXP (x, 0), 0))) - num_sign_bit_copies (XEXP (XEXP (x, 0), 0), GET_MODE (XEXP (XEXP (x, 0), 0))))))) return simplify_gen_unary (GET_CODE (XEXP (x, 0)), mode, XEXP (XEXP (x, 0), 0), GET_MODE (XEXP (XEXP (x, 0), 0))); break; #ifdef HAVE_cc0 case COMPARE: /* Convert (compare FOO (const_int 0)) to FOO unless we aren't using cc0, in which case we want to leave it as a COMPARE so we can distinguish it from a register-register-copy. */ if (XEXP (x, 1) == const0_rtx) return XEXP (x, 0); /* x - 0 is the same as x unless x's mode has signed zeros and allows rounding towards -infinity. Under those conditions, 0 - 0 is -0. */ if (!(HONOR_SIGNED_ZEROS (GET_MODE (XEXP (x, 0))) && HONOR_SIGN_DEPENDENT_ROUNDING (GET_MODE (XEXP (x, 0)))) && XEXP (x, 1) == CONST0_RTX (GET_MODE (XEXP (x, 0)))) return XEXP (x, 0); break; #endif case CONST: /* (const (const X)) can become (const X). Do it this way rather than returning the inner CONST since CONST can be shared with a REG_EQUAL note. */ if (GET_CODE (XEXP (x, 0)) == CONST) SUBST (XEXP (x, 0), XEXP (XEXP (x, 0), 0)); break; #ifdef HAVE_lo_sum case LO_SUM: /* Convert (lo_sum (high FOO) FOO) to FOO. This is necessary so we can add in an offset. find_split_point will split this address up again if it doesn't match. */ if (GET_CODE (XEXP (x, 0)) == HIGH && rtx_equal_p (XEXP (XEXP (x, 0), 0), XEXP (x, 1))) return XEXP (x, 1); break; #endif case PLUS: /* Canonicalize (plus (mult (neg B) C) A) to (minus A (mult B C)). */ if (GET_CODE (XEXP (x, 0)) == MULT && GET_CODE (XEXP (XEXP (x, 0), 0)) == NEG) { rtx in1, in2; in1 = XEXP (XEXP (XEXP (x, 0), 0), 0); in2 = XEXP (XEXP (x, 0), 1); return gen_binary (MINUS, mode, XEXP (x, 1), gen_binary (MULT, mode, in1, in2)); } /* If we have (plus (plus (A const) B)), associate it so that CONST is outermost. That's because that's the way indexed addresses are supposed to appear. This code used to check many more cases, but they are now checked elsewhere. */ if (GET_CODE (XEXP (x, 0)) == PLUS && CONSTANT_ADDRESS_P (XEXP (XEXP (x, 0), 1))) return gen_binary (PLUS, mode, gen_binary (PLUS, mode, XEXP (XEXP (x, 0), 0), XEXP (x, 1)), XEXP (XEXP (x, 0), 1)); /* (plus (xor (and (const_int pow2 - 1)) ) <-c>) when c is (const_int (pow2 + 1) / 2) is a sign extension of a bit-field and can be replaced by either a sign_extend or a sign_extract. The `and' may be a zero_extend and the two , - constants may be reversed. */ if (GET_CODE (XEXP (x, 0)) == XOR && GET_CODE (XEXP (x, 1)) == CONST_INT && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT && INTVAL (XEXP (x, 1)) == -INTVAL (XEXP (XEXP (x, 0), 1)) && ((i = exact_log2 (INTVAL (XEXP (XEXP (x, 0), 1)))) >= 0 || (i = exact_log2 (INTVAL (XEXP (x, 1)))) >= 0) && GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT && ((GET_CODE (XEXP (XEXP (x, 0), 0)) == AND && GET_CODE (XEXP (XEXP (XEXP (x, 0), 0), 1)) == CONST_INT && (INTVAL (XEXP (XEXP (XEXP (x, 0), 0), 1)) == ((HOST_WIDE_INT) 1 << (i + 1)) - 1)) || (GET_CODE (XEXP (XEXP (x, 0), 0)) == ZERO_EXTEND && (GET_MODE_BITSIZE (GET_MODE (XEXP (XEXP (XEXP (x, 0), 0), 0))) == (unsigned int) i + 1)))) return simplify_shift_const (NULL_RTX, ASHIFTRT, mode, simplify_shift_const (NULL_RTX, ASHIFT, mode, XEXP (XEXP (XEXP (x, 0), 0), 0), GET_MODE_BITSIZE (mode) - (i + 1)), GET_MODE_BITSIZE (mode) - (i + 1)); /* (plus (comparison A B) C) can become (neg (rev-comp A B)) if C is 1 and STORE_FLAG_VALUE is -1 or if C is -1 and STORE_FLAG_VALUE is 1. This produces better code than the alternative immediately below. */ if (GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) == '<' && ((STORE_FLAG_VALUE == -1 && XEXP (x, 1) == const1_rtx) || (STORE_FLAG_VALUE == 1 && XEXP (x, 1) == constm1_rtx)) && (reversed = reversed_comparison (XEXP (x, 0), mode, XEXP (XEXP (x, 0), 0), XEXP (XEXP (x, 0), 1)))) return simplify_gen_unary (NEG, mode, reversed, mode); /* If only the low-order bit of X is possibly nonzero, (plus x -1) can become (ashiftrt (ashift (xor x 1) C) C) where C is the bitsize of the mode - 1. This allows simplification of "a = (b & 8) == 0;" */ if (XEXP (x, 1) == constm1_rtx && GET_CODE (XEXP (x, 0)) != REG && ! (GET_CODE (XEXP (x, 0)) == SUBREG && GET_CODE (SUBREG_REG (XEXP (x, 0))) == REG) && nonzero_bits (XEXP (x, 0), mode) == 1) return simplify_shift_const (NULL_RTX, ASHIFTRT, mode, simplify_shift_const (NULL_RTX, ASHIFT, mode, gen_rtx_XOR (mode, XEXP (x, 0), const1_rtx), GET_MODE_BITSIZE (mode) - 1), GET_MODE_BITSIZE (mode) - 1); /* If we are adding two things that have no bits in common, convert the addition into an IOR. This will often be further simplified, for example in cases like ((a & 1) + (a & 2)), which can become a & 3. */ if (GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT && (nonzero_bits (XEXP (x, 0), mode) & nonzero_bits (XEXP (x, 1), mode)) == 0) { /* Try to simplify the expression further. */ rtx tor = gen_binary (IOR, mode, XEXP (x, 0), XEXP (x, 1)); temp = combine_simplify_rtx (tor, mode, last, in_dest); /* If we could, great. If not, do not go ahead with the IOR replacement, since PLUS appears in many special purpose address arithmetic instructions. */ if (GET_CODE (temp) != CLOBBER && temp != tor) return temp; } break; case MINUS: /* If STORE_FLAG_VALUE is 1, (minus 1 (comparison foo bar)) can be done by reversing the comparison code if valid. */ if (STORE_FLAG_VALUE == 1 && XEXP (x, 0) == const1_rtx && GET_RTX_CLASS (GET_CODE (XEXP (x, 1))) == '<' && (reversed = reversed_comparison (XEXP (x, 1), mode, XEXP (XEXP (x, 1), 0), XEXP (XEXP (x, 1), 1)))) return reversed; /* (minus (and (const_int -pow2))) becomes (and (const_int pow2-1)) */ if (GET_CODE (XEXP (x, 1)) == AND && GET_CODE (XEXP (XEXP (x, 1), 1)) == CONST_INT && exact_log2 (-INTVAL (XEXP (XEXP (x, 1), 1))) >= 0 && rtx_equal_p (XEXP (XEXP (x, 1), 0), XEXP (x, 0))) return simplify_and_const_int (NULL_RTX, mode, XEXP (x, 0), -INTVAL (XEXP (XEXP (x, 1), 1)) - 1); /* Canonicalize (minus A (mult (neg B) C)) to (plus (mult B C) A). */ if (GET_CODE (XEXP (x, 1)) == MULT && GET_CODE (XEXP (XEXP (x, 1), 0)) == NEG) { rtx in1, in2; in1 = XEXP (XEXP (XEXP (x, 1), 0), 0); in2 = XEXP (XEXP (x, 1), 1); return gen_binary (PLUS, mode, gen_binary (MULT, mode, in1, in2), XEXP (x, 0)); } /* Canonicalize (minus (neg A) (mult B C)) to (minus (mult (neg B) C) A). */ if (GET_CODE (XEXP (x, 1)) == MULT && GET_CODE (XEXP (x, 0)) == NEG) { rtx in1, in2; in1 = simplify_gen_unary (NEG, mode, XEXP (XEXP (x, 1), 0), mode); in2 = XEXP (XEXP (x, 1), 1); return gen_binary (MINUS, mode, gen_binary (MULT, mode, in1, in2), XEXP (XEXP (x, 0), 0)); } /* Canonicalize (minus A (plus B C)) to (minus (minus A B) C) for integers. */ if (GET_CODE (XEXP (x, 1)) == PLUS && INTEGRAL_MODE_P (mode)) return gen_binary (MINUS, mode, gen_binary (MINUS, mode, XEXP (x, 0), XEXP (XEXP (x, 1), 0)), XEXP (XEXP (x, 1), 1)); break; case MULT: /* If we have (mult (plus A B) C), apply the distributive law and then the inverse distributive law to see if things simplify. This occurs mostly in addresses, often when unrolling loops. */ if (GET_CODE (XEXP (x, 0)) == PLUS) { x = apply_distributive_law (gen_binary (PLUS, mode, gen_binary (MULT, mode, XEXP (XEXP (x, 0), 0), XEXP (x, 1)), gen_binary (MULT, mode, XEXP (XEXP (x, 0), 1), copy_rtx (XEXP (x, 1))))); if (GET_CODE (x) != MULT) return x; } /* Try simplify a*(b/c) as (a*b)/c. */ if (FLOAT_MODE_P (mode) && flag_unsafe_math_optimizations && GET_CODE (XEXP (x, 0)) == DIV) { rtx tem = simplify_binary_operation (MULT, mode, XEXP (XEXP (x, 0), 0), XEXP (x, 1)); if (tem) return gen_binary (DIV, mode, tem, XEXP (XEXP (x, 0), 1)); } break; case UDIV: /* If this is a divide by a power of two, treat it as a shift if its first operand is a shift. */ if (GET_CODE (XEXP (x, 1)) == CONST_INT && (i = exact_log2 (INTVAL (XEXP (x, 1)))) >= 0 && (GET_CODE (XEXP (x, 0)) == ASHIFT || GET_CODE (XEXP (x, 0)) == LSHIFTRT || GET_CODE (XEXP (x, 0)) == ASHIFTRT || GET_CODE (XEXP (x, 0)) == ROTATE || GET_CODE (XEXP (x, 0)) == ROTATERT)) return simplify_shift_const (NULL_RTX, LSHIFTRT, mode, XEXP (x, 0), i); break; case EQ: case NE: case GT: case GTU: case GE: case GEU: case LT: case LTU: case LE: case LEU: case UNEQ: case LTGT: case UNGT: case UNGE: case UNLT: case UNLE: case UNORDERED: case ORDERED: /* If the first operand is a condition code, we can't do anything with it. */ if (GET_CODE (XEXP (x, 0)) == COMPARE || (GET_MODE_CLASS (GET_MODE (XEXP (x, 0))) != MODE_CC && ! CC0_P (XEXP (x, 0)))) { rtx op0 = XEXP (x, 0); rtx op1 = XEXP (x, 1); enum rtx_code new_code; if (GET_CODE (op0) == COMPARE) op1 = XEXP (op0, 1), op0 = XEXP (op0, 0); /* Simplify our comparison, if possible. */ new_code = simplify_comparison (code, &op0, &op1); /* If STORE_FLAG_VALUE is 1, we can convert (ne x 0) to simply X if only the low-order bit is possibly nonzero in X (such as when X is a ZERO_EXTRACT of one bit). Similarly, we can convert EQ to (xor X 1) or (minus 1 X); we use the former. Finally, if X is known to be either 0 or -1, NE becomes a NEG and EQ becomes (plus X 1). Remove any ZERO_EXTRACT we made when thinking this was a comparison. It may now be simpler to use, e.g., an AND. If a ZERO_EXTRACT is indeed appropriate, it will be placed back by the call to make_compound_operation in the SET case. */ if (STORE_FLAG_VALUE == 1 && new_code == NE && GET_MODE_CLASS (mode) == MODE_INT && op1 == const0_rtx && mode == GET_MODE (op0) && nonzero_bits (op0, mode) == 1) return gen_lowpart_for_combine (mode, expand_compound_operation (op0)); else if (STORE_FLAG_VALUE == 1 && new_code == NE && GET_MODE_CLASS (mode) == MODE_INT && op1 == const0_rtx && mode == GET_MODE (op0) && (num_sign_bit_copies (op0, mode) == GET_MODE_BITSIZE (mode))) { op0 = expand_compound_operation (op0); return simplify_gen_unary (NEG, mode, gen_lowpart_for_combine (mode, op0), mode); } else if (STORE_FLAG_VALUE == 1 && new_code == EQ && GET_MODE_CLASS (mode) == MODE_INT && op1 == const0_rtx && mode == GET_MODE (op0) && nonzero_bits (op0, mode) == 1) { op0 = expand_compound_operation (op0); return gen_binary (XOR, mode, gen_lowpart_for_combine (mode, op0), const1_rtx); } else if (STORE_FLAG_VALUE == 1 && new_code == EQ && GET_MODE_CLASS (mode) == MODE_INT && op1 == const0_rtx && mode == GET_MODE (op0) && (num_sign_bit_copies (op0, mode) == GET_MODE_BITSIZE (mode))) { op0 = expand_compound_operation (op0); return plus_constant (gen_lowpart_for_combine (mode, op0), 1); } /* If STORE_FLAG_VALUE is -1, we have cases similar to those above. */ if (STORE_FLAG_VALUE == -1 && new_code == NE && GET_MODE_CLASS (mode) == MODE_INT && op1 == const0_rtx && (num_sign_bit_copies (op0, mode) == GET_MODE_BITSIZE (mode))) return gen_lowpart_for_combine (mode, expand_compound_operation (op0)); else if (STORE_FLAG_VALUE == -1 && new_code == NE && GET_MODE_CLASS (mode) == MODE_INT && op1 == const0_rtx && mode == GET_MODE (op0) && nonzero_bits (op0, mode) == 1) { op0 = expand_compound_operation (op0); return simplify_gen_unary (NEG, mode, gen_lowpart_for_combine (mode, op0), mode); } else if (STORE_FLAG_VALUE == -1 && new_code == EQ && GET_MODE_CLASS (mode) == MODE_INT && op1 == const0_rtx && mode == GET_MODE (op0) && (num_sign_bit_copies (op0, mode) == GET_MODE_BITSIZE (mode))) { op0 = expand_compound_operation (op0); return simplify_gen_unary (NOT, mode, gen_lowpart_for_combine (mode, op0), mode); } /* If X is 0/1, (eq X 0) is X-1. */ else if (STORE_FLAG_VALUE == -1 && new_code == EQ && GET_MODE_CLASS (mode) == MODE_INT && op1 == const0_rtx && mode == GET_MODE (op0) && nonzero_bits (op0, mode) == 1) { op0 = expand_compound_operation (op0); return plus_constant (gen_lowpart_for_combine (mode, op0), -1); } /* If STORE_FLAG_VALUE says to just test the sign bit and X has just one bit that might be nonzero, we can convert (ne x 0) to (ashift x c) where C puts the bit in the sign bit. Remove any AND with STORE_FLAG_VALUE when we are done, since we are only going to test the sign bit. */ if (new_code == NE && GET_MODE_CLASS (mode) == MODE_INT && GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT && ((STORE_FLAG_VALUE & GET_MODE_MASK (mode)) == (unsigned HOST_WIDE_INT) 1 << (GET_MODE_BITSIZE (mode) - 1)) && op1 == const0_rtx && mode == GET_MODE (op0) && (i = exact_log2 (nonzero_bits (op0, mode))) >= 0) { x = simplify_shift_const (NULL_RTX, ASHIFT, mode, expand_compound_operation (op0), GET_MODE_BITSIZE (mode) - 1 - i); if (GET_CODE (x) == AND && XEXP (x, 1) == const_true_rtx) return XEXP (x, 0); else return x; } /* If the code changed, return a whole new comparison. */ if (new_code != code) return gen_rtx_fmt_ee (new_code, mode, op0, op1); /* Otherwise, keep this operation, but maybe change its operands. This also converts (ne (compare FOO BAR) 0) to (ne FOO BAR). */ SUBST (XEXP (x, 0), op0); SUBST (XEXP (x, 1), op1); } break; case IF_THEN_ELSE: return simplify_if_then_else (x); case ZERO_EXTRACT: case SIGN_EXTRACT: case ZERO_EXTEND: case SIGN_EXTEND: /* If we are processing SET_DEST, we are done. */ if (in_dest) return x; return expand_compound_operation (x); case SET: return simplify_set (x); case AND: case IOR: case XOR: return simplify_logical (x, last); case ABS: /* (abs (neg )) -> (abs ) */ if (GET_CODE (XEXP (x, 0)) == NEG) SUBST (XEXP (x, 0), XEXP (XEXP (x, 0), 0)); /* If the mode of the operand is VOIDmode (i.e. if it is ASM_OPERANDS), do nothing. */ if (GET_MODE (XEXP (x, 0)) == VOIDmode) break; /* If operand is something known to be positive, ignore the ABS. */ if (GET_CODE (XEXP (x, 0)) == FFS || GET_CODE (XEXP (x, 0)) == ABS || ((GET_MODE_BITSIZE (GET_MODE (XEXP (x, 0))) <= HOST_BITS_PER_WIDE_INT) && ((nonzero_bits (XEXP (x, 0), GET_MODE (XEXP (x, 0))) & ((HOST_WIDE_INT) 1 << (GET_MODE_BITSIZE (GET_MODE (XEXP (x, 0))) - 1))) == 0))) return XEXP (x, 0); /* If operand is known to be only -1 or 0, convert ABS to NEG. */ if (num_sign_bit_copies (XEXP (x, 0), mode) == GET_MODE_BITSIZE (mode)) return gen_rtx_NEG (mode, XEXP (x, 0)); break; case FFS: /* (ffs (*_extend )) = (ffs ) */ if (GET_CODE (XEXP (x, 0)) == SIGN_EXTEND || GET_CODE (XEXP (x, 0)) == ZERO_EXTEND) SUBST (XEXP (x, 0), XEXP (XEXP (x, 0), 0)); break; case POPCOUNT: case PARITY: /* (pop* (zero_extend )) = (pop* ) */ if (GET_CODE (XEXP (x, 0)) == ZERO_EXTEND) SUBST (XEXP (x, 0), XEXP (XEXP (x, 0), 0)); break; case FLOAT: /* (float (sign_extend )) = (float ). */ if (GET_CODE (XEXP (x, 0)) == SIGN_EXTEND) SUBST (XEXP (x, 0), XEXP (XEXP (x, 0), 0)); break; case ASHIFT: case LSHIFTRT: case ASHIFTRT: case ROTATE: case ROTATERT: /* If this is a shift by a constant amount, simplify it. */ if (GET_CODE (XEXP (x, 1)) == CONST_INT) return simplify_shift_const (x, code, mode, XEXP (x, 0), INTVAL (XEXP (x, 1))); #ifdef SHIFT_COUNT_TRUNCATED else if (SHIFT_COUNT_TRUNCATED && GET_CODE (XEXP (x, 1)) != REG) SUBST (XEXP (x, 1), force_to_mode (XEXP (x, 1), GET_MODE (XEXP (x, 1)), ((HOST_WIDE_INT) 1 << exact_log2 (GET_MODE_BITSIZE (GET_MODE (x)))) - 1, NULL_RTX, 0)); #endif break; case VEC_SELECT: { rtx op0 = XEXP (x, 0); rtx op1 = XEXP (x, 1); int len; if (GET_CODE (op1) != PARALLEL) abort (); len = XVECLEN (op1, 0); if (len == 1 && GET_CODE (XVECEXP (op1, 0, 0)) == CONST_INT && GET_CODE (op0) == VEC_CONCAT) { int offset = INTVAL (XVECEXP (op1, 0, 0)) * GET_MODE_SIZE (GET_MODE (x)); /* Try to find the element in the VEC_CONCAT. */ for (;;) { if (GET_MODE (op0) == GET_MODE (x)) return op0; if (GET_CODE (op0) == VEC_CONCAT) { HOST_WIDE_INT op0_size = GET_MODE_SIZE (GET_MODE (XEXP (op0, 0))); if (op0_size < offset) op0 = XEXP (op0, 0); else { offset -= op0_size; op0 = XEXP (op0, 1); } } else break; } } } break; default: break; } return x; } /* Simplify X, an IF_THEN_ELSE expression. Return the new expression. */ static rtx simplify_if_then_else (x) rtx x; { enum machine_mode mode = GET_MODE (x); rtx cond = XEXP (x, 0); rtx true_rtx = XEXP (x, 1); rtx false_rtx = XEXP (x, 2); enum rtx_code true_code = GET_CODE (cond); int comparison_p = GET_RTX_CLASS (true_code) == '<'; rtx temp; int i; enum rtx_code false_code; rtx reversed; /* Simplify storing of the truth value. */ if (comparison_p && true_rtx == const_true_rtx && false_rtx == const0_rtx) return gen_binary (true_code, mode, XEXP (cond, 0), XEXP (cond, 1)); /* Also when the truth value has to be reversed. */ if (comparison_p && true_rtx == const0_rtx && false_rtx == const_true_rtx && (reversed = reversed_comparison (cond, mode, XEXP (cond, 0), XEXP (cond, 1)))) return reversed; /* Sometimes we can simplify the arm of an IF_THEN_ELSE if a register used in it is being compared against certain values. Get the true and false comparisons and see if that says anything about the value of each arm. */ if (comparison_p && ((false_code = combine_reversed_comparison_code (cond)) != UNKNOWN) && GET_CODE (XEXP (cond, 0)) == REG) { HOST_WIDE_INT nzb; rtx from = XEXP (cond, 0); rtx true_val = XEXP (cond, 1); rtx false_val = true_val; int swapped = 0; /* If FALSE_CODE is EQ, swap the codes and arms. */ if (false_code == EQ) { swapped = 1, true_code = EQ, false_code = NE; temp = true_rtx, true_rtx = false_rtx, false_rtx = temp; } /* If we are comparing against zero and the expression being tested has only a single bit that might be nonzero, that is its value when it is not equal to zero. Similarly if it is known to be -1 or 0. */ if (true_code == EQ && true_val == const0_rtx && exact_log2 (nzb = nonzero_bits (from, GET_MODE (from))) >= 0) false_code = EQ, false_val = GEN_INT (nzb); else if (true_code == EQ && true_val == const0_rtx && (num_sign_bit_copies (from, GET_MODE (from)) == GET_MODE_BITSIZE (GET_MODE (from)))) false_code = EQ, false_val = constm1_rtx; /* Now simplify an arm if we know the value of the register in the branch and it is used in the arm. Be careful due to the potential of locally-shared RTL. */ if (reg_mentioned_p (from, true_rtx)) true_rtx = subst (known_cond (copy_rtx (true_rtx), true_code, from, true_val), pc_rtx, pc_rtx, 0, 0); if (reg_mentioned_p (from, false_rtx)) false_rtx = subst (known_cond (copy_rtx (false_rtx), false_code, from, false_val), pc_rtx, pc_rtx, 0, 0); SUBST (XEXP (x, 1), swapped ? false_rtx : true_rtx); SUBST (XEXP (x, 2), swapped ? true_rtx : false_rtx); true_rtx = XEXP (x, 1); false_rtx = XEXP (x, 2); true_code = GET_CODE (cond); } /* If we have (if_then_else FOO (pc) (label_ref BAR)) and FOO can be reversed, do so to avoid needing two sets of patterns for subtract-and-branch insns. Similarly if we have a constant in the true arm, the false arm is the same as the first operand of the comparison, or the false arm is more complicated than the true arm. */ if (comparison_p && combine_reversed_comparison_code (cond) != UNKNOWN && (true_rtx == pc_rtx || (CONSTANT_P (true_rtx) && GET_CODE (false_rtx) != CONST_INT && false_rtx != pc_rtx) || true_rtx == const0_rtx || (GET_RTX_CLASS (GET_CODE (true_rtx)) == 'o' && GET_RTX_CLASS (GET_CODE (false_rtx)) != 'o') || (GET_CODE (true_rtx) == SUBREG && GET_RTX_CLASS (GET_CODE (SUBREG_REG (true_rtx))) == 'o' && GET_RTX_CLASS (GET_CODE (false_rtx)) != 'o') || reg_mentioned_p (true_rtx, false_rtx) || rtx_equal_p (false_rtx, XEXP (cond, 0)))) { true_code = reversed_comparison_code (cond, NULL); SUBST (XEXP (x, 0), reversed_comparison (cond, GET_MODE (cond), XEXP (cond, 0), XEXP (cond, 1))); SUBST (XEXP (x, 1), false_rtx); SUBST (XEXP (x, 2), true_rtx); temp = true_rtx, true_rtx = false_rtx, false_rtx = temp; cond = XEXP (x, 0); /* It is possible that the conditional has been simplified out. */ true_code = GET_CODE (cond); comparison_p = GET_RTX_CLASS (true_code) == '<'; } /* If the two arms are identical, we don't need the comparison. */ if (rtx_equal_p (true_rtx, false_rtx) && ! side_effects_p (cond)) return true_rtx; /* Convert a == b ? b : a to "a". */ if (true_code == EQ && ! side_effects_p (cond) && !HONOR_NANS (mode) && rtx_equal_p (XEXP (cond, 0), false_rtx) && rtx_equal_p (XEXP (cond, 1), true_rtx)) return false_rtx; else if (true_code == NE && ! side_effects_p (cond) && !HONOR_NANS (mode) && rtx_equal_p (XEXP (cond, 0), true_rtx) && rtx_equal_p (XEXP (cond, 1), false_rtx)) return true_rtx; /* Look for cases where we have (abs x) or (neg (abs X)). */ if (GET_MODE_CLASS (mode) == MODE_INT && GET_CODE (false_rtx) == NEG && rtx_equal_p (true_rtx, XEXP (false_rtx, 0)) && comparison_p && rtx_equal_p (true_rtx, XEXP (cond, 0)) && ! side_effects_p (true_rtx)) switch (true_code) { case GT: case GE: return simplify_gen_unary (ABS, mode, true_rtx, mode); case LT: case LE: return simplify_gen_unary (NEG, mode, simplify_gen_unary (ABS, mode, true_rtx, mode), mode); default: break; } /* Look for MIN or MAX. */ if ((! FLOAT_MODE_P (mode) || flag_unsafe_math_optimizations) && comparison_p && rtx_equal_p (XEXP (cond, 0), true_rtx) && rtx_equal_p (XEXP (cond, 1), false_rtx) && ! side_effects_p (cond)) switch (true_code) { case GE: case GT: return gen_binary (SMAX, mode, true_rtx, false_rtx); case LE: case LT: return gen_binary (SMIN, mode, true_rtx, false_rtx); case GEU: case GTU: return gen_binary (UMAX, mode, true_rtx, false_rtx); case LEU: case LTU: return gen_binary (UMIN, mode, true_rtx, false_rtx); default: break; } /* If we have (if_then_else COND (OP Z C1) Z) and OP is an identity when its second operand is zero, this can be done as (OP Z (mult COND C2)) where C2 = C1 * STORE_FLAG_VALUE. Similarly if OP has an outer ZERO_EXTEND or SIGN_EXTEND as long as Z is already extended (so we don't destroy it). We can do this kind of thing in some cases when STORE_FLAG_VALUE is neither 1 or -1, but it isn't worth checking for. */ if ((STORE_FLAG_VALUE == 1 || STORE_FLAG_VALUE == -1) && comparison_p && GET_MODE_CLASS (mode) == MODE_INT && ! side_effects_p (x)) { rtx t = make_compound_operation (true_rtx, SET); rtx f = make_compound_operation (false_rtx, SET); rtx cond_op0 = XEXP (cond, 0); rtx cond_op1 = XEXP (cond, 1); enum rtx_code op = NIL, extend_op = NIL; enum machine_mode m = mode; rtx z = 0, c1 = NULL_RTX; if ((GET_CODE (t) == PLUS || GET_CODE (t) == MINUS || GET_CODE (t) == IOR || GET_CODE (t) == XOR || GET_CODE (t) == ASHIFT || GET_CODE (t) == LSHIFTRT || GET_CODE (t) == ASHIFTRT) && rtx_equal_p (XEXP (t, 0), f)) c1 = XEXP (t, 1), op = GET_CODE (t), z = f; /* If an identity-zero op is commutative, check whether there would be a match if we swapped the operands. */ else if ((GET_CODE (t) == PLUS || GET_CODE (t) == IOR || GET_CODE (t) == XOR) && rtx_equal_p (XEXP (t, 1), f)) c1 = XEXP (t, 0), op = GET_CODE (t), z = f; else if (GET_CODE (t) == SIGN_EXTEND && (GET_CODE (XEXP (t, 0)) == PLUS || GET_CODE (XEXP (t, 0)) == MINUS || GET_CODE (XEXP (t, 0)) == IOR || GET_CODE (XEXP (t, 0)) == XOR || GET_CODE (XEXP (t, 0)) == ASHIFT || GET_CODE (XEXP (t, 0)) == LSHIFTRT || GET_CODE (XEXP (t, 0)) == ASHIFTRT) && GET_CODE (XEXP (XEXP (t, 0), 0)) == SUBREG && subreg_lowpart_p (XEXP (XEXP (t, 0), 0)) && rtx_equal_p (SUBREG_REG (XEXP (XEXP (t, 0), 0)), f) && (num_sign_bit_copies (f, GET_MODE (f)) > (unsigned int) (GET_MODE_BITSIZE (mode) - GET_MODE_BITSIZE (GET_MODE (XEXP (XEXP (t, 0), 0)))))) { c1 = XEXP (XEXP (t, 0), 1); z = f; op = GET_CODE (XEXP (t, 0)); extend_op = SIGN_EXTEND; m = GET_MODE (XEXP (t, 0)); } else if (GET_CODE (t) == SIGN_EXTEND && (GET_CODE (XEXP (t, 0)) == PLUS || GET_CODE (XEXP (t, 0)) == IOR || GET_CODE (XEXP (t, 0)) == XOR) && GET_CODE (XEXP (XEXP (t, 0), 1)) == SUBREG && subreg_lowpart_p (XEXP (XEXP (t, 0), 1)) && rtx_equal_p (SUBREG_REG (XEXP (XEXP (t, 0), 1)), f) && (num_sign_bit_copies (f, GET_MODE (f)) > (unsigned int) (GET_MODE_BITSIZE (mode) - GET_MODE_BITSIZE (GET_MODE (XEXP (XEXP (t, 0), 1)))))) { c1 = XEXP (XEXP (t, 0), 0); z = f; op = GET_CODE (XEXP (t, 0)); extend_op = SIGN_EXTEND; m = GET_MODE (XEXP (t, 0)); } else if (GET_CODE (t) == ZERO_EXTEND && (GET_CODE (XEXP (t, 0)) == PLUS || GET_CODE (XEXP (t, 0)) == MINUS || GET_CODE (XEXP (t, 0)) == IOR || GET_CODE (XEXP (t, 0)) == XOR || GET_CODE (XEXP (t, 0)) == ASHIFT || GET_CODE (XEXP (t, 0)) == LSHIFTRT || GET_CODE (XEXP (t, 0)) == ASHIFTRT) && GET_CODE (XEXP (XEXP (t, 0), 0)) == SUBREG && GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT && subreg_lowpart_p (XEXP (XEXP (t, 0), 0)) && rtx_equal_p (SUBREG_REG (XEXP (XEXP (t, 0), 0)), f) && ((nonzero_bits (f, GET_MODE (f)) & ~GET_MODE_MASK (GET_MODE (XEXP (XEXP (t, 0), 0)))) == 0)) { c1 = XEXP (XEXP (t, 0), 1); z = f; op = GET_CODE (XEXP (t, 0)); extend_op = ZERO_EXTEND; m = GET_MODE (XEXP (t, 0)); } else if (GET_CODE (t) == ZERO_EXTEND && (GET_CODE (XEXP (t, 0)) == PLUS || GET_CODE (XEXP (t, 0)) == IOR || GET_CODE (XEXP (t, 0)) == XOR) && GET_CODE (XEXP (XEXP (t, 0), 1)) == SUBREG && GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT && subreg_lowpart_p (XEXP (XEXP (t, 0), 1)) && rtx_equal_p (SUBREG_REG (XEXP (XEXP (t, 0), 1)), f) && ((nonzero_bits (f, GET_MODE (f)) & ~GET_MODE_MASK (GET_MODE (XEXP (XEXP (t, 0), 1)))) == 0)) { c1 = XEXP (XEXP (t, 0), 0); z = f; op = GET_CODE (XEXP (t, 0)); extend_op = ZERO_EXTEND; m = GET_MODE (XEXP (t, 0)); } if (z) { temp = subst (gen_binary (true_code, m, cond_op0, cond_op1), pc_rtx, pc_rtx, 0, 0); temp = gen_binary (MULT, m, temp, gen_binary (MULT, m, c1, const_true_rtx)); temp = subst (temp, pc_rtx, pc_rtx, 0, 0); temp = gen_binary (op, m, gen_lowpart_for_combine (m, z), temp); if (extend_op != NIL) temp = simplify_gen_unary (extend_op, mode, temp, m); return temp; } } /* If we have (if_then_else (ne A 0) C1 0) and either A is known to be 0 or 1 and C1 is a single bit or A is known to be 0 or -1 and C1 is the negation of a single bit, we can convert this operation to a shift. We can actually do this more generally, but it doesn't seem worth it. */ if (true_code == NE && XEXP (cond, 1) == const0_rtx && false_rtx == const0_rtx && GET_CODE (true_rtx) == CONST_INT && ((1 == nonzero_bits (XEXP (cond, 0), mode) && (i = exact_log2 (INTVAL (true_rtx))) >= 0) || ((num_sign_bit_copies (XEXP (cond, 0), mode) == GET_MODE_BITSIZE (mode)) && (i = exact_log2 (-INTVAL (true_rtx))) >= 0))) return simplify_shift_const (NULL_RTX, ASHIFT, mode, gen_lowpart_for_combine (mode, XEXP (cond, 0)), i); return x; } /* Simplify X, a SET expression. Return the new expression. */ static rtx simplify_set (x) rtx x; { rtx src = SET_SRC (x); rtx dest = SET_DEST (x); enum machine_mode mode = GET_MODE (src) != VOIDmode ? GET_MODE (src) : GET_MODE (dest); rtx other_insn; rtx *cc_use; /* (set (pc) (return)) gets written as (return). */ if (GET_CODE (dest) == PC && GET_CODE (src) == RETURN) return src; /* Now that we know for sure which bits of SRC we are using, see if we can simplify the expression for the object knowing that we only need the low-order bits. */ if (GET_MODE_CLASS (mode) == MODE_INT && GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT) { src = force_to_mode (src, mode, ~(HOST_WIDE_INT) 0, NULL_RTX, 0); SUBST (SET_SRC (x), src); } /* If we are setting CC0 or if the source is a COMPARE, look for the use of the comparison result and try to simplify it unless we already have used undobuf.other_insn. */ if ((GET_MODE_CLASS (mode) == MODE_CC || GET_CODE (src) == COMPARE || CC0_P (dest)) && (cc_use = find_single_use (dest, subst_insn, &other_insn)) != 0 && (undobuf.other_insn == 0 || other_insn == undobuf.other_insn) && GET_RTX_CLASS (GET_CODE (*cc_use)) == '<' && rtx_equal_p (XEXP (*cc_use, 0), dest)) { enum rtx_code old_code = GET_CODE (*cc_use); enum rtx_code new_code; rtx op0, op1, tmp; int other_changed = 0; enum machine_mode compare_mode = GET_MODE (dest); enum machine_mode tmp_mode; if (GET_CODE (src) == COMPARE) op0 = XEXP (src, 0), op1 = XEXP (src, 1); else op0 = src, op1 = const0_rtx; /* Check whether the comparison is known at compile time. */ if (GET_MODE (op0) != VOIDmode) tmp_mode = GET_MODE (op0); else if (GET_MODE (op1) != VOIDmode) tmp_mode = GET_MODE (op1); else tmp_mode = compare_mode; tmp = simplify_relational_operation (old_code, tmp_mode, op0, op1); if (tmp != NULL_RTX) { rtx pat = PATTERN (other_insn); undobuf.other_insn = other_insn; SUBST (*cc_use, tmp); /* Attempt to simplify CC user. */ if (GET_CODE (pat) == SET) { rtx new = simplify_rtx (SET_SRC (pat)); if (new != NULL_RTX) SUBST (SET_SRC (pat), new); } /* Convert X into a no-op move. */ SUBST (SET_DEST (x), pc_rtx); SUBST (SET_SRC (x), pc_rtx); return x; } /* Simplify our comparison, if possible. */ new_code = simplify_comparison (old_code, &op0, &op1); #ifdef EXTRA_CC_MODES /* If this machine has CC modes other than CCmode, check to see if we need to use a different CC mode here. */ compare_mode = SELECT_CC_MODE (new_code, op0, op1); #endif /* EXTRA_CC_MODES */ #if !defined (HAVE_cc0) && defined (EXTRA_CC_MODES) /* If the mode changed, we have to change SET_DEST, the mode in the compare, and the mode in the place SET_DEST is used. If SET_DEST is a hard register, just build new versions with the proper mode. If it is a pseudo, we lose unless it is only time we set the pseudo, in which case we can safely change its mode. */ if (compare_mode != GET_MODE (dest)) { unsigned int regno = REGNO (dest); rtx new_dest = gen_rtx_REG (compare_mode, regno); if (regno < FIRST_PSEUDO_REGISTER || (REG_N_SETS (regno) == 1 && ! REG_USERVAR_P (dest))) { if (regno >= FIRST_PSEUDO_REGISTER) SUBST (regno_reg_rtx[regno], new_dest); SUBST (SET_DEST (x), new_dest); SUBST (XEXP (*cc_use, 0), new_dest); other_changed = 1; dest = new_dest; } } #endif /* If the code changed, we have to build a new comparison in undobuf.other_insn. */ if (new_code != old_code) { unsigned HOST_WIDE_INT mask; SUBST (*cc_use, gen_rtx_fmt_ee (new_code, GET_MODE (*cc_use), dest, const0_rtx)); /* If the only change we made was to change an EQ into an NE or vice versa, OP0 has only one bit that might be nonzero, and OP1 is zero, check if changing the user of the condition code will produce a valid insn. If it won't, we can keep the original code in that insn by surrounding our operation with an XOR. */ if (((old_code == NE && new_code == EQ) || (old_code == EQ && new_code == NE)) && ! other_changed && op1 == const0_rtx && GET_MODE_BITSIZE (GET_MODE (op0)) <= HOST_BITS_PER_WIDE_INT && exact_log2 (mask = nonzero_bits (op0, GET_MODE (op0))) >= 0) { rtx pat = PATTERN (other_insn), note = 0; if ((recog_for_combine (&pat, other_insn, ¬e) < 0 && ! check_asm_operands (pat))) { PUT_CODE (*cc_use, old_code); other_insn = 0; op0 = gen_binary (XOR, GET_MODE (op0), op0, GEN_INT (mask)); } } other_changed = 1; } if (other_changed) undobuf.other_insn = other_insn; #ifdef HAVE_cc0 /* If we are now comparing against zero, change our source if needed. If we do not use cc0, we always have a COMPARE. */ if (op1 == const0_rtx && dest == cc0_rtx) { SUBST (SET_SRC (x), op0); src = op0; } else #endif /* Otherwise, if we didn't previously have a COMPARE in the correct mode, we need one. */ if (GET_CODE (src) != COMPARE || GET_MODE (src) != compare_mode) { SUBST (SET_SRC (x), gen_rtx_COMPARE (compare_mode, op0, op1)); src = SET_SRC (x); } else { /* Otherwise, update the COMPARE if needed. */ SUBST (XEXP (src, 0), op0); SUBST (XEXP (src, 1), op1); } } else { /* Get SET_SRC in a form where we have placed back any compound expressions. Then do the checks below. */ src = make_compound_operation (src, SET); SUBST (SET_SRC (x), src); } /* If we have (set x (subreg:m1 (op:m2 ...) 0)) with OP being some operation, and X being a REG or (subreg (reg)), we may be able to convert this to (set (subreg:m2 x) (op)). We can always do this if M1 is narrower than M2 because that means that we only care about the low bits of the result. However, on machines without WORD_REGISTER_OPERATIONS defined, we cannot perform a narrower operation than requested since the high-order bits will be undefined. On machine where it is defined, this transformation is safe as long as M1 and M2 have the same number of words. */ if (GET_CODE (src) == SUBREG && subreg_lowpart_p (src) && GET_RTX_CLASS (GET_CODE (SUBREG_REG (src))) != 'o' && (((GET_MODE_SIZE (GET_MODE (src)) + (UNITS_PER_WORD - 1)) / UNITS_PER_WORD) == ((GET_MODE_SIZE (GET_MODE (SUBREG_REG (src))) + (UNITS_PER_WORD - 1)) / UNITS_PER_WORD)) #ifndef WORD_REGISTER_OPERATIONS && (GET_MODE_SIZE (GET_MODE (src)) < GET_MODE_SIZE (GET_MODE (SUBREG_REG (src)))) #endif #ifdef CANNOT_CHANGE_MODE_CLASS && ! (GET_CODE (dest) == REG && REGNO (dest) < FIRST_PSEUDO_REGISTER && REG_CANNOT_CHANGE_MODE_P (REGNO (dest), GET_MODE (SUBREG_REG (src)), GET_MODE (src))) #endif && (GET_CODE (dest) == REG || (GET_CODE (dest) == SUBREG && GET_CODE (SUBREG_REG (dest)) == REG))) { SUBST (SET_DEST (x), gen_lowpart_for_combine (GET_MODE (SUBREG_REG (src)), dest)); SUBST (SET_SRC (x), SUBREG_REG (src)); src = SET_SRC (x), dest = SET_DEST (x); } #ifdef HAVE_cc0 /* If we have (set (cc0) (subreg ...)), we try to remove the subreg in SRC. */ if (dest == cc0_rtx && GET_CODE (src) == SUBREG && subreg_lowpart_p (src) && (GET_MODE_BITSIZE (GET_MODE (src)) < GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (src))))) { rtx inner = SUBREG_REG (src); enum machine_mode inner_mode = GET_MODE (inner); /* Here we make sure that we don't have a sign bit on. */ if (GET_MODE_BITSIZE (inner_mode) <= HOST_BITS_PER_WIDE_INT && (nonzero_bits (inner, inner_mode) < ((unsigned HOST_WIDE_INT) 1 << (GET_MODE_BITSIZE (GET_MODE (src)) - 1)))) { SUBST (SET_SRC (x), inner); src = SET_SRC (x); } } #endif #ifdef LOAD_EXTEND_OP /* If we have (set FOO (subreg:M (mem:N BAR) 0)) with M wider than N, this would require a paradoxical subreg. Replace the subreg with a zero_extend to avoid the reload that would otherwise be required. */ if (GET_CODE (src) == SUBREG && subreg_lowpart_p (src) && LOAD_EXTEND_OP (GET_MODE (SUBREG_REG (src))) != NIL && SUBREG_BYTE (src) == 0 && (GET_MODE_SIZE (GET_MODE (src)) > GET_MODE_SIZE (GET_MODE (SUBREG_REG (src)))) && GET_CODE (SUBREG_REG (src)) == MEM) { SUBST (SET_SRC (x), gen_rtx (LOAD_EXTEND_OP (GET_MODE (SUBREG_REG (src))), GET_MODE (src), SUBREG_REG (src))); src = SET_SRC (x); } #endif /* If we don't have a conditional move, SET_SRC is an IF_THEN_ELSE, and we are comparing an item known to be 0 or -1 against 0, use a logical operation instead. Check for one of the arms being an IOR of the other arm with some value. We compute three terms to be IOR'ed together. In practice, at most two will be nonzero. Then we do the IOR's. */ if (GET_CODE (dest) != PC && GET_CODE (src) == IF_THEN_ELSE && GET_MODE_CLASS (GET_MODE (src)) == MODE_INT && (GET_CODE (XEXP (src, 0)) == EQ || GET_CODE (XEXP (src, 0)) == NE) && XEXP (XEXP (src, 0), 1) == const0_rtx && GET_MODE (src) == GET_MODE (XEXP (XEXP (src, 0), 0)) #ifdef HAVE_conditional_move && ! can_conditionally_move_p (GET_MODE (src)) #endif && (num_sign_bit_copies (XEXP (XEXP (src, 0), 0), GET_MODE (XEXP (XEXP (src, 0), 0))) == GET_MODE_BITSIZE (GET_MODE (XEXP (XEXP (src, 0), 0)))) && ! side_effects_p (src)) { rtx true_rtx = (GET_CODE (XEXP (src, 0)) == NE ? XEXP (src, 1) : XEXP (src, 2)); rtx false_rtx = (GET_CODE (XEXP (src, 0)) == NE ? XEXP (src, 2) : XEXP (src, 1)); rtx term1 = const0_rtx, term2, term3; if (GET_CODE (true_rtx) == IOR && rtx_equal_p (XEXP (true_rtx, 0), false_rtx)) term1 = false_rtx, true_rtx = XEXP (true_rtx, 1), false_rtx = const0_rtx; else if (GET_CODE (true_rtx) == IOR && rtx_equal_p (XEXP (true_rtx, 1), false_rtx)) term1 = false_rtx, true_rtx = XEXP (true_rtx, 0), false_rtx = const0_rtx; else if (GET_CODE (false_rtx) == IOR && rtx_equal_p (XEXP (false_rtx, 0), true_rtx)) term1 = true_rtx, false_rtx = XEXP (false_rtx, 1), true_rtx = const0_rtx; else if (GET_CODE (false_rtx) == IOR && rtx_equal_p (XEXP (false_rtx, 1), true_rtx)) term1 = true_rtx, false_rtx = XEXP (false_rtx, 0), true_rtx = const0_rtx; term2 = gen_binary (AND, GET_MODE (src), XEXP (XEXP (src, 0), 0), true_rtx); term3 = gen_binary (AND, GET_MODE (src), simplify_gen_unary (NOT, GET_MODE (src), XEXP (XEXP (src, 0), 0), GET_MODE (src)), false_rtx); SUBST (SET_SRC (x), gen_binary (IOR, GET_MODE (src), gen_binary (IOR, GET_MODE (src), term1, term2), term3)); src = SET_SRC (x); } /* If either SRC or DEST is a CLOBBER of (const_int 0), make this whole thing fail. */ if (GET_CODE (src) == CLOBBER && XEXP (src, 0) == const0_rtx) return src; else if (GET_CODE (dest) == CLOBBER && XEXP (dest, 0) == const0_rtx) return dest; else /* Convert this into a field assignment operation, if possible. */ return make_field_assignment (x); } /* Simplify, X, and AND, IOR, or XOR operation, and return the simplified result. LAST is nonzero if this is the last retry. */ static rtx simplify_logical (x, last) rtx x; int last; { enum machine_mode mode = GET_MODE (x); rtx op0 = XEXP (x, 0); rtx op1 = XEXP (x, 1); rtx reversed; switch (GET_CODE (x)) { case AND: /* Convert (A ^ B) & A to A & (~B) since the latter is often a single insn (and may simplify more). */ if (GET_CODE (op0) == XOR && rtx_equal_p (XEXP (op0, 0), op1) && ! side_effects_p (op1)) x = gen_binary (AND, mode, simplify_gen_unary (NOT, mode, XEXP (op0, 1), mode), op1); if (GET_CODE (op0) == XOR && rtx_equal_p (XEXP (op0, 1), op1) && ! side_effects_p (op1)) x = gen_binary (AND, mode, simplify_gen_unary (NOT, mode, XEXP (op0, 0), mode), op1); /* Similarly for (~(A ^ B)) & A. */ if (GET_CODE (op0) == NOT && GET_CODE (XEXP (op0, 0)) == XOR && rtx_equal_p (XEXP (XEXP (op0, 0), 0), op1) && ! side_effects_p (op1)) x = gen_binary (AND, mode, XEXP (XEXP (op0, 0), 1), op1); if (GET_CODE (op0) == NOT && GET_CODE (XEXP (op0, 0)) == XOR && rtx_equal_p (XEXP (XEXP (op0, 0), 1), op1) && ! side_effects_p (op1)) x = gen_binary (AND, mode, XEXP (XEXP (op0, 0), 0), op1); /* We can call simplify_and_const_int only if we don't lose any (sign) bits when converting INTVAL (op1) to "unsigned HOST_WIDE_INT". */ if (GET_CODE (op1) == CONST_INT && (GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT || INTVAL (op1) > 0)) { x = simplify_and_const_int (x, mode, op0, INTVAL (op1)); /* If we have (ior (and (X C1) C2)) and the next restart would be the last, simplify this by making C1 as small as possible and then exit. */ if (last && GET_CODE (x) == IOR && GET_CODE (op0) == AND && GET_CODE (XEXP (op0, 1)) == CONST_INT && GET_CODE (op1) == CONST_INT) return gen_binary (IOR, mode, gen_binary (AND, mode, XEXP (op0, 0), GEN_INT (INTVAL (XEXP (op0, 1)) & ~INTVAL (op1))), op1); if (GET_CODE (x) != AND) return x; if (GET_RTX_CLASS (GET_CODE (x)) == 'c' || GET_RTX_CLASS (GET_CODE (x)) == '2') op0 = XEXP (x, 0), op1 = XEXP (x, 1); } /* Convert (A | B) & A to A. */ if (GET_CODE (op0) == IOR && (rtx_equal_p (XEXP (op0, 0), op1) || rtx_equal_p (XEXP (op0, 1), op1)) && ! side_effects_p (XEXP (op0, 0)) && ! side_effects_p (XEXP (op0, 1))) return op1; /* In the following group of tests (and those in case IOR below), we start with some combination of logical operations and apply the distributive law followed by the inverse distributive law. Most of the time, this results in no change. However, if some of the operands are the same or inverses of each other, simplifications will result. For example, (and (ior A B) (not B)) can occur as the result of expanding a bit field assignment. When we apply the distributive law to this, we get (ior (and (A (not B))) (and (B (not B)))), which then simplifies to (and (A (not B))). If we have (and (ior A B) C), apply the distributive law and then the inverse distributive law to see if things simplify. */ if (GET_CODE (op0) == IOR || GET_CODE (op0) == XOR) { x = apply_distributive_law (gen_binary (GET_CODE (op0), mode, gen_binary (AND, mode, XEXP (op0, 0), op1), gen_binary (AND, mode, XEXP (op0, 1), copy_rtx (op1)))); if (GET_CODE (x) != AND) return x; } if (GET_CODE (op1) == IOR || GET_CODE (op1) == XOR) return apply_distributive_law (gen_binary (GET_CODE (op1), mode, gen_binary (AND, mode, XEXP (op1, 0), op0), gen_binary (AND, mode, XEXP (op1, 1), copy_rtx (op0)))); /* Similarly, taking advantage of the fact that (and (not A) (xor B C)) == (xor (ior A B) (ior A C)) */ if (GET_CODE (op0) == NOT && GET_CODE (op1) == XOR) return apply_distributive_law (gen_binary (XOR, mode, gen_binary (IOR, mode, XEXP (op0, 0), XEXP (op1, 0)), gen_binary (IOR, mode, copy_rtx (XEXP (op0, 0)), XEXP (op1, 1)))); else if (GET_CODE (op1) == NOT && GET_CODE (op0) == XOR) return apply_distributive_law (gen_binary (XOR, mode, gen_binary (IOR, mode, XEXP (op1, 0), XEXP (op0, 0)), gen_binary (IOR, mode, copy_rtx (XEXP (op1, 0)), XEXP (op0, 1)))); break; case IOR: /* (ior A C) is C if all bits of A that might be nonzero are on in C. */ if (GET_CODE (op1) == CONST_INT && GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT && (nonzero_bits (op0, mode) & ~INTVAL (op1)) == 0) return op1; /* Convert (A & B) | A to A. */ if (GET_CODE (op0) == AND && (rtx_equal_p (XEXP (op0, 0), op1) || rtx_equal_p (XEXP (op0, 1), op1)) && ! side_effects_p (XEXP (op0, 0)) && ! side_effects_p (XEXP (op0, 1))) return op1; /* If we have (ior (and A B) C), apply the distributive law and then the inverse distributive law to see if things simplify. */ if (GET_CODE (op0) == AND) { x = apply_distributive_law (gen_binary (AND, mode, gen_binary (IOR, mode, XEXP (op0, 0), op1), gen_binary (IOR, mode, XEXP (op0, 1), copy_rtx (op1)))); if (GET_CODE (x) != IOR) return x; } if (GET_CODE (op1) == AND) { x = apply_distributive_law (gen_binary (AND, mode, gen_binary (IOR, mode, XEXP (op1, 0), op0), gen_binary (IOR, mode, XEXP (op1, 1), copy_rtx (op0)))); if (GET_CODE (x) != IOR) return x; } /* Convert (ior (ashift A CX) (lshiftrt A CY)) where CX+CY equals the mode size to (rotate A CX). */ if (((GET_CODE (op0) == ASHIFT && GET_CODE (op1) == LSHIFTRT) || (GET_CODE (op1) == ASHIFT && GET_CODE (op0) == LSHIFTRT)) && rtx_equal_p (XEXP (op0, 0), XEXP (op1, 0)) && GET_CODE (XEXP (op0, 1)) == CONST_INT && GET_CODE (XEXP (op1, 1)) == CONST_INT && (INTVAL (XEXP (op0, 1)) + INTVAL (XEXP (op1, 1)) == GET_MODE_BITSIZE (mode))) return gen_rtx_ROTATE (mode, XEXP (op0, 0), (GET_CODE (op0) == ASHIFT ? XEXP (op0, 1) : XEXP (op1, 1))); /* If OP0 is (ashiftrt (plus ...) C), it might actually be a (sign_extend (plus ...)). If so, OP1 is a CONST_INT, and the PLUS does not affect any of the bits in OP1, it can really be done as a PLUS and we can associate. We do this by seeing if OP1 can be safely shifted left C bits. */ if (GET_CODE (op1) == CONST_INT && GET_CODE (op0) == ASHIFTRT && GET_CODE (XEXP (op0, 0)) == PLUS && GET_CODE (XEXP (XEXP (op0, 0), 1)) == CONST_INT && GET_CODE (XEXP (op0, 1)) == CONST_INT && INTVAL (XEXP (op0, 1)) < HOST_BITS_PER_WIDE_INT) { int count = INTVAL (XEXP (op0, 1)); HOST_WIDE_INT mask = INTVAL (op1) << count; if (mask >> count == INTVAL (op1) && (mask & nonzero_bits (XEXP (op0, 0), mode)) == 0) { SUBST (XEXP (XEXP (op0, 0), 1), GEN_INT (INTVAL (XEXP (XEXP (op0, 0), 1)) | mask)); return op0; } } break; case XOR: /* If we are XORing two things that have no bits in common, convert them into an IOR. This helps to detect rotation encoded using those methods and possibly other simplifications. */ if (GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT && (nonzero_bits (op0, mode) & nonzero_bits (op1, mode)) == 0) return (gen_binary (IOR, mode, op0, op1)); /* Convert (XOR (NOT x) (NOT y)) to (XOR x y). Also convert (XOR (NOT x) y) to (NOT (XOR x y)), similarly for (NOT y). */ { int num_negated = 0; if (GET_CODE (op0) == NOT) num_negated++, op0 = XEXP (op0, 0); if (GET_CODE (op1) == NOT) num_negated++, op1 = XEXP (op1, 0); if (num_negated == 2) { SUBST (XEXP (x, 0), op0); SUBST (XEXP (x, 1), op1); } else if (num_negated == 1) return simplify_gen_unary (NOT, mode, gen_binary (XOR, mode, op0, op1), mode); } /* Convert (xor (and A B) B) to (and (not A) B). The latter may correspond to a machine insn or result in further simplifications if B is a constant. */ if (GET_CODE (op0) == AND && rtx_equal_p (XEXP (op0, 1), op1) && ! side_effects_p (op1)) return gen_binary (AND, mode, simplify_gen_unary (NOT, mode, XEXP (op0, 0), mode), op1); else if (GET_CODE (op0) == AND && rtx_equal_p (XEXP (op0, 0), op1) && ! side_effects_p (op1)) return gen_binary (AND, mode, simplify_gen_unary (NOT, mode, XEXP (op0, 1), mode), op1); /* (xor (comparison foo bar) (const_int 1)) can become the reversed comparison if STORE_FLAG_VALUE is 1. */ if (STORE_FLAG_VALUE == 1 && op1 == const1_rtx && GET_RTX_CLASS (GET_CODE (op0)) == '<' && (reversed = reversed_comparison (op0, mode, XEXP (op0, 0), XEXP (op0, 1)))) return reversed; /* (lshiftrt foo C) where C is the number of bits in FOO minus 1 is (lt foo (const_int 0)), so we can perform the above simplification if STORE_FLAG_VALUE is 1. */ if (STORE_FLAG_VALUE == 1 && op1 == const1_rtx && GET_CODE (op0) == LSHIFTRT && GET_CODE (XEXP (op0, 1)) == CONST_INT && INTVAL (XEXP (op0, 1)) == GET_MODE_BITSIZE (mode) - 1) return gen_rtx_GE (mode, XEXP (op0, 0), const0_rtx); /* (xor (comparison foo bar) (const_int sign-bit)) when STORE_FLAG_VALUE is the sign bit. */ if (GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT && ((STORE_FLAG_VALUE & GET_MODE_MASK (mode)) == (unsigned HOST_WIDE_INT) 1 << (GET_MODE_BITSIZE (mode) - 1)) && op1 == const_true_rtx && GET_RTX_CLASS (GET_CODE (op0)) == '<' && (reversed = reversed_comparison (op0, mode, XEXP (op0, 0), XEXP (op0, 1)))) return reversed; break; default: abort (); } return x; } /* We consider ZERO_EXTRACT, SIGN_EXTRACT, and SIGN_EXTEND as "compound operations" because they can be replaced with two more basic operations. ZERO_EXTEND is also considered "compound" because it can be replaced with an AND operation, which is simpler, though only one operation. The function expand_compound_operation is called with an rtx expression and will convert it to the appropriate shifts and AND operations, simplifying at each stage. The function make_compound_operation is called to convert an expression consisting of shifts and ANDs into the equivalent compound expression. It is the inverse of this function, loosely speaking. */ static rtx expand_compound_operation (x) rtx x; { unsigned HOST_WIDE_INT pos = 0, len; int unsignedp = 0; unsigned int modewidth; rtx tem; switch (GET_CODE (x)) { case ZERO_EXTEND: unsignedp = 1; case SIGN_EXTEND: /* We can't necessarily use a const_int for a multiword mode; it depends on implicitly extending the value. Since we don't know the right way to extend it, we can't tell whether the implicit way is right. Even for a mode that is no wider than a const_int, we can't win, because we need to sign extend one of its bits through the rest of it, and we don't know which bit. */ if (GET_CODE (XEXP (x, 0)) == CONST_INT) return x; /* Return if (subreg:MODE FROM 0) is not a safe replacement for (zero_extend:MODE FROM) or (sign_extend:MODE FROM). It is for any MEM because (SUBREG (MEM...)) is guaranteed to cause the MEM to be reloaded. If not for that, MEM's would very rarely be safe. Reject MODEs bigger than a word, because we might not be able to reference a two-register group starting with an arbitrary register (and currently gen_lowpart might crash for a SUBREG). */ if (GET_MODE_SIZE (GET_MODE (XEXP (x, 0))) > UNITS_PER_WORD) return x; /* Reject MODEs that aren't scalar integers because turning vector or complex modes into shifts causes problems. */ if (! SCALAR_INT_MODE_P (GET_MODE (XEXP (x, 0)))) return x; len = GET_MODE_BITSIZE (GET_MODE (XEXP (x, 0))); /* If the inner object has VOIDmode (the only way this can happen is if it is an ASM_OPERANDS), we can't do anything since we don't know how much masking to do. */ if (len == 0) return x; break; case ZERO_EXTRACT: unsignedp = 1; case SIGN_EXTRACT: /* If the operand is a CLOBBER, just return it. */ if (GET_CODE (XEXP (x, 0)) == CLOBBER) return XEXP (x, 0); if (GET_CODE (XEXP (x, 1)) != CONST_INT || GET_CODE (XEXP (x, 2)) != CONST_INT || GET_MODE (XEXP (x, 0)) == VOIDmode) return x; /* Reject MODEs that aren't scalar integers because turning vector or complex modes into shifts causes problems. */ if (! SCALAR_INT_MODE_P (GET_MODE (XEXP (x, 0)))) return x; len = INTVAL (XEXP (x, 1)); pos = INTVAL (XEXP (x, 2)); /* If this goes outside the object being extracted, replace the object with a (use (mem ...)) construct that only combine understands and is used only for this purpose. */ if (len + pos > GET_MODE_BITSIZE (GET_MODE (XEXP (x, 0)))) SUBST (XEXP (x, 0), gen_rtx_USE (GET_MODE (x), XEXP (x, 0))); if (BITS_BIG_ENDIAN) pos = GET_MODE_BITSIZE (GET_MODE (XEXP (x, 0))) - len - pos; break; default: return x; } /* Convert sign extension to zero extension, if we know that the high bit is not set, as this is easier to optimize. It will be converted back to cheaper alternative in make_extraction. */ if (GET_CODE (x) == SIGN_EXTEND && (GET_MODE_BITSIZE (GET_MODE (x)) <= HOST_BITS_PER_WIDE_INT && ((nonzero_bits (XEXP (x, 0), GET_MODE (XEXP (x, 0))) & ~(((unsigned HOST_WIDE_INT) GET_MODE_MASK (GET_MODE (XEXP (x, 0)))) >> 1)) == 0))) { rtx temp = gen_rtx_ZERO_EXTEND (GET_MODE (x), XEXP (x, 0)); rtx temp2 = expand_compound_operation (temp); /* Make sure this is a profitable operation. */ if (rtx_cost (x, SET) > rtx_cost (temp2, SET)) return temp2; else if (rtx_cost (x, SET) > rtx_cost (temp, SET)) return temp; else return x; } /* We can optimize some special cases of ZERO_EXTEND. */ if (GET_CODE (x) == ZERO_EXTEND) { /* (zero_extend:DI (truncate:SI foo:DI)) is just foo:DI if we know that the last value didn't have any inappropriate bits set. */ if (GET_CODE (XEXP (x, 0)) == TRUNCATE && GET_MODE (XEXP (XEXP (x, 0), 0)) == GET_MODE (x) && GET_MODE_BITSIZE (GET_MODE (x)) <= HOST_BITS_PER_WIDE_INT && (nonzero_bits (XEXP (XEXP (x, 0), 0), GET_MODE (x)) & ~GET_MODE_MASK (GET_MODE (XEXP (x, 0)))) == 0) return XEXP (XEXP (x, 0), 0); /* Likewise for (zero_extend:DI (subreg:SI foo:DI 0)). */ if (GET_CODE (XEXP (x, 0)) == SUBREG && GET_MODE (SUBREG_REG (XEXP (x, 0))) == GET_MODE (x) && subreg_lowpart_p (XEXP (x, 0)) && GET_MODE_BITSIZE (GET_MODE (x)) <= HOST_BITS_PER_WIDE_INT && (nonzero_bits (SUBREG_REG (XEXP (x, 0)), GET_MODE (x)) & ~GET_MODE_MASK (GET_MODE (XEXP (x, 0)))) == 0) return SUBREG_REG (XEXP (x, 0)); /* (zero_extend:DI (truncate:SI foo:DI)) is just foo:DI when foo is a comparison and STORE_FLAG_VALUE permits. This is like the first case, but it works even when GET_MODE (x) is larger than HOST_WIDE_INT. */ if (GET_CODE (XEXP (x, 0)) == TRUNCATE && GET_MODE (XEXP (XEXP (x, 0), 0)) == GET_MODE (x) && GET_RTX_CLASS (GET_CODE (XEXP (XEXP (x, 0), 0))) == '<' && (GET_MODE_BITSIZE (GET_MODE (XEXP (x, 0))) <= HOST_BITS_PER_WIDE_INT) && ((HOST_WIDE_INT) STORE_FLAG_VALUE & ~GET_MODE_MASK (GET_MODE (XEXP (x, 0)))) == 0) return XEXP (XEXP (x, 0), 0); /* Likewise for (zero_extend:DI (subreg:SI foo:DI 0)). */ if (GET_CODE (XEXP (x, 0)) == SUBREG && GET_MODE (SUBREG_REG (XEXP (x, 0))) == GET_MODE (x) && subreg_lowpart_p (XEXP (x, 0)) && GET_RTX_CLASS (GET_CODE (SUBREG_REG (XEXP (x, 0)))) == '<' && (GET_MODE_BITSIZE (GET_MODE (XEXP (x, 0))) <= HOST_BITS_PER_WIDE_INT) && ((HOST_WIDE_INT) STORE_FLAG_VALUE & ~GET_MODE_MASK (GET_MODE (XEXP (x, 0)))) == 0) return SUBREG_REG (XEXP (x, 0)); } /* If we reach here, we want to return a pair of shifts. The inner shift is a left shift of BITSIZE - POS - LEN bits. The outer shift is a right shift of BITSIZE - LEN bits. It is arithmetic or logical depending on the value of UNSIGNEDP. If this was a ZERO_EXTEND or ZERO_EXTRACT, this pair of shifts will be converted into an AND of a shift. We must check for the case where the left shift would have a negative count. This can happen in a case like (x >> 31) & 255 on machines that can't shift by a constant. On those machines, we would first combine the shift with the AND to produce a variable-position extraction. Then the constant of 31 would be substituted in to produce a such a position. */ modewidth = GET_MODE_BITSIZE (GET_MODE (x)); if (modewidth + len >= pos) tem = simplify_shift_const (NULL_RTX, unsignedp ? LSHIFTRT : ASHIFTRT, GET_MODE (x), simplify_shift_const (NULL_RTX, ASHIFT, GET_MODE (x), XEXP (x, 0), modewidth - pos - len), modewidth - len); else if (unsignedp && len < HOST_BITS_PER_WIDE_INT) tem = simplify_and_const_int (NULL_RTX, GET_MODE (x), simplify_shift_const (NULL_RTX, LSHIFTRT, GET_MODE (x), XEXP (x, 0), pos), ((HOST_WIDE_INT) 1 << len) - 1); else /* Any other cases we can't handle. */ return x; /* If we couldn't do this for some reason, return the original expression. */ if (GET_CODE (tem) == CLOBBER) return x; return tem; } /* X is a SET which contains an assignment of one object into a part of another (such as a bit-field assignment, STRICT_LOW_PART, or certain SUBREGS). If possible, convert it into a series of logical operations. We half-heartedly support variable positions, but do not at all support variable lengths. */ static rtx expand_field_assignment (x) rtx x; { rtx inner; rtx pos; /* Always counts from low bit. */ int len; rtx mask; enum machine_mode compute_mode; /* Loop until we find something we can't simplify. */ while (1) { if (GET_CODE (SET_DEST (x)) == STRICT_LOW_PART && GET_CODE (XEXP (SET_DEST (x), 0)) == SUBREG) { inner = SUBREG_REG (XEXP (SET_DEST (x), 0)); len = GET_MODE_BITSIZE (GET_MODE (XEXP (SET_DEST (x), 0))); pos = GEN_INT (subreg_lsb (XEXP (SET_DEST (x), 0))); } else if (GET_CODE (SET_DEST (x)) == ZERO_EXTRACT && GET_CODE (XEXP (SET_DEST (x), 1)) == CONST_INT) { inner = XEXP (SET_DEST (x), 0); len = INTVAL (XEXP (SET_DEST (x), 1)); pos = XEXP (SET_DEST (x), 2); /* If the position is constant and spans the width of INNER, surround INNER with a USE to indicate this. */ if (GET_CODE (pos) == CONST_INT && INTVAL (pos) + len > GET_MODE_BITSIZE (GET_MODE (inner))) inner = gen_rtx_USE (GET_MODE (SET_DEST (x)), inner); if (BITS_BIG_ENDIAN) { if (GET_CODE (pos) == CONST_INT) pos = GEN_INT (GET_MODE_BITSIZE (GET_MODE (inner)) - len - INTVAL (pos)); else if (GET_CODE (pos) == MINUS && GET_CODE (XEXP (pos, 1)) == CONST_INT && (INTVAL (XEXP (pos, 1)) == GET_MODE_BITSIZE (GET_MODE (inner)) - len)) /* If position is ADJUST - X, new position is X. */ pos = XEXP (pos, 0); else pos = gen_binary (MINUS, GET_MODE (pos), GEN_INT (GET_MODE_BITSIZE (GET_MODE (inner)) - len), pos); } } /* A SUBREG between two modes that occupy the same numbers of words can be done by moving the SUBREG to the source. */ else if (GET_CODE (SET_DEST (x)) == SUBREG /* We need SUBREGs to compute nonzero_bits properly. */ && nonzero_sign_valid && (((GET_MODE_SIZE (GET_MODE (SET_DEST (x))) + (UNITS_PER_WORD - 1)) / UNITS_PER_WORD) == ((GET_MODE_SIZE (GET_MODE (SUBREG_REG (SET_DEST (x)))) + (UNITS_PER_WORD - 1)) / UNITS_PER_WORD))) { x = gen_rtx_SET (VOIDmode, SUBREG_REG (SET_DEST (x)), gen_lowpart_for_combine (GET_MODE (SUBREG_REG (SET_DEST (x))), SET_SRC (x))); continue; } else break; while (GET_CODE (inner) == SUBREG && subreg_lowpart_p (inner)) inner = SUBREG_REG (inner); compute_mode = GET_MODE (inner); /* Don't attempt bitwise arithmetic on non scalar integer modes. */ if (! SCALAR_INT_MODE_P (compute_mode)) { enum machine_mode imode; /* Don't do anything for vector or complex integral types. */ if (! FLOAT_MODE_P (compute_mode)) break; /* Try to find an integral mode to pun with. */ imode = mode_for_size (GET_MODE_BITSIZE (compute_mode), MODE_INT, 0); if (imode == BLKmode) break; compute_mode = imode; inner = gen_lowpart_for_combine (imode, inner); } /* Compute a mask of LEN bits, if we can do this on the host machine. */ if (len < HOST_BITS_PER_WIDE_INT) mask = GEN_INT (((HOST_WIDE_INT) 1 << len) - 1); else break; /* Now compute the equivalent expression. Make a copy of INNER for the SET_DEST in case it is a MEM into which we will substitute; we don't want shared RTL in that case. */ x = gen_rtx_SET (VOIDmode, copy_rtx (inner), gen_binary (IOR, compute_mode, gen_binary (AND, compute_mode, simplify_gen_unary (NOT, compute_mode, gen_binary (ASHIFT, compute_mode, mask, pos), compute_mode), inner), gen_binary (ASHIFT, compute_mode, gen_binary (AND, compute_mode, gen_lowpart_for_combine (compute_mode, SET_SRC (x)), mask), pos))); } return x; } /* Return an RTX for a reference to LEN bits of INNER. If POS_RTX is nonzero, it is an RTX that represents a variable starting position; otherwise, POS is the (constant) starting bit position (counted from the LSB). INNER may be a USE. This will occur when we started with a bitfield that went outside the boundary of the object in memory, which is allowed on most machines. To isolate this case, we produce a USE whose mode is wide enough and surround the MEM with it. The only code that understands the USE is this routine. If it is not removed, it will cause the resulting insn not to match. UNSIGNEDP is nonzero for an unsigned reference and zero for a signed reference. IN_DEST is nonzero if this is a reference in the destination of a SET. This is used when a ZERO_ or SIGN_EXTRACT isn't needed. If nonzero, a STRICT_LOW_PART will be used, if zero, ZERO_EXTEND or SIGN_EXTEND will be used. IN_COMPARE is nonzero if we are in a COMPARE. This means that a ZERO_EXTRACT should be built even for bits starting at bit 0. MODE is the desired mode of the result (if IN_DEST == 0). The result is an RTX for the extraction or NULL_RTX if the target can't handle it. */ static rtx make_extraction (mode, inner, pos, pos_rtx, len, unsignedp, in_dest, in_compare) enum machine_mode mode; rtx inner; HOST_WIDE_INT pos; rtx pos_rtx; unsigned HOST_WIDE_INT len; int unsignedp; int in_dest, in_compare; { /* This mode describes the size of the storage area to fetch the overall value from. Within that, we ignore the POS lowest bits, etc. */ enum machine_mode is_mode = GET_MODE (inner); enum machine_mode inner_mode; enum machine_mode wanted_inner_mode = byte_mode; enum machine_mode wanted_inner_reg_mode = word_mode; enum machine_mode pos_mode = word_mode; enum machine_mode extraction_mode = word_mode; enum machine_mode tmode = mode_for_size (len, MODE_INT, 1); int spans_byte = 0; rtx new = 0; rtx orig_pos_rtx = pos_rtx; HOST_WIDE_INT orig_pos; /* Get some information about INNER and get the innermost object. */ if (GET_CODE (inner) == USE) /* (use:SI (mem:QI foo)) stands for (mem:SI foo). */ /* We don't need to adjust the position because we set up the USE to pretend that it was a full-word object. */ spans_byte = 1, inner = XEXP (inner, 0); else if (GET_CODE (inner) == SUBREG && subreg_lowpart_p (inner)) { /* If going from (subreg:SI (mem:QI ...)) to (mem:QI ...), consider just the QI as the memory to extract from. The subreg adds or removes high bits; its mode is irrelevant to the meaning of this extraction, since POS and LEN count from the lsb. */ if (GET_CODE (SUBREG_REG (inner)) == MEM) is_mode = GET_MODE (SUBREG_REG (inner)); inner = SUBREG_REG (inner); } else if (GET_CODE (inner) == ASHIFT && GET_CODE (XEXP (inner, 1)) == CONST_INT && pos_rtx == 0 && pos == 0 && len > (unsigned HOST_WIDE_INT) INTVAL (XEXP (inner, 1))) { /* We're extracting the least significant bits of an rtx (ashift X (const_int C)), where LEN > C. Extract the least significant (LEN - C) bits of X, giving an rtx whose mode is MODE, then shift it left C times. */ new = make_extraction (mode, XEXP (inner, 0), 0, 0, len - INTVAL (XEXP (inner, 1)), unsignedp, in_dest, in_compare); if (new != 0) return gen_rtx_ASHIFT (mode, new, XEXP (inner, 1)); } inner_mode = GET_MODE (inner); if (pos_rtx && GET_CODE (pos_rtx) == CONST_INT) pos = INTVAL (pos_rtx), pos_rtx = 0; /* See if this can be done without an extraction. We never can if the width of the field is not the same as that of some integer mode. For registers, we can only avoid the extraction if the position is at the low-order bit and this is either not in the destination or we have the appropriate STRICT_LOW_PART operation available. For MEM, we can avoid an extract if the field starts on an appropriate boundary and we can change the mode of the memory reference. However, we cannot directly access the MEM if we have a USE and the underlying MEM is not TMODE. This combination means that MEM was being used in a context where bits outside its mode were being referenced; that is only valid in bit-field insns. */ if (tmode != BLKmode && ! (spans_byte && inner_mode != tmode) && ((pos_rtx == 0 && (pos % BITS_PER_WORD) == 0 && GET_CODE (inner) != MEM && (! in_dest || (GET_CODE (inner) == REG && have_insn_for (STRICT_LOW_PART, tmode)))) || (GET_CODE (inner) == MEM && pos_rtx == 0 && (pos % (STRICT_ALIGNMENT ? GET_MODE_ALIGNMENT (tmode) : BITS_PER_UNIT)) == 0 /* We can't do this if we are widening INNER_MODE (it may not be aligned, for one thing). */ && GET_MODE_BITSIZE (inner_mode) >= GET_MODE_BITSIZE (tmode) && (inner_mode == tmode || (! mode_dependent_address_p (XEXP (inner, 0)) && ! MEM_VOLATILE_P (inner)))))) { /* If INNER is a MEM, make a new MEM that encompasses just the desired field. If the original and current mode are the same, we need not adjust the offset. Otherwise, we do if bytes big endian. If INNER is not a MEM, get a piece consisting of just the field of interest (in this case POS % BITS_PER_WORD must be 0). */ if (GET_CODE (inner) == MEM) { HOST_WIDE_INT offset; /* POS counts from lsb, but make OFFSET count in memory order. */ if (BYTES_BIG_ENDIAN) offset = (GET_MODE_BITSIZE (is_mode) - len - pos) / BITS_PER_UNIT; else offset = pos / BITS_PER_UNIT; new = adjust_address_nv (inner, tmode, offset); } else if (GET_CODE (inner) == REG) { /* We can't call gen_lowpart_for_combine here since we always want a SUBREG and it would sometimes return a new hard register. */ if (tmode != inner_mode) { HOST_WIDE_INT final_word = pos / BITS_PER_WORD; if (WORDS_BIG_ENDIAN && GET_MODE_SIZE (inner_mode) > UNITS_PER_WORD) final_word = ((GET_MODE_SIZE (inner_mode) - GET_MODE_SIZE (tmode)) / UNITS_PER_WORD) - final_word; final_word *= UNITS_PER_WORD; if (BYTES_BIG_ENDIAN && GET_MODE_SIZE (inner_mode) > GET_MODE_SIZE (tmode)) final_word += (GET_MODE_SIZE (inner_mode) - GET_MODE_SIZE (tmode)) % UNITS_PER_WORD; /* Avoid creating invalid subregs, for example when simplifying (x>>32)&255. */ if (final_word >= GET_MODE_SIZE (inner_mode)) return NULL_RTX; new = gen_rtx_SUBREG (tmode, inner, final_word); } else new = inner; } else new = force_to_mode (inner, tmode, len >= HOST_BITS_PER_WIDE_INT ? ~(unsigned HOST_WIDE_INT) 0 : ((unsigned HOST_WIDE_INT) 1 << len) - 1, NULL_RTX, 0); /* If this extraction is going into the destination of a SET, make a STRICT_LOW_PART unless we made a MEM. */ if (in_dest) return (GET_CODE (new) == MEM ? new : (GET_CODE (new) != SUBREG ? gen_rtx_CLOBBER (tmode, const0_rtx) : gen_rtx_STRICT_LOW_PART (VOIDmode, new))); if (mode == tmode) return new; if (GET_CODE (new) == CONST_INT) return gen_int_mode (INTVAL (new), mode); /* If we know that no extraneous bits are set, and that the high bit is not set, convert the extraction to the cheaper of sign and zero extension, that are equivalent in these cases. */ if (flag_expensive_optimizations && (GET_MODE_BITSIZE (tmode) <= HOST_BITS_PER_WIDE_INT && ((nonzero_bits (new, tmode) & ~(((unsigned HOST_WIDE_INT) GET_MODE_MASK (tmode)) >> 1)) == 0))) { rtx temp = gen_rtx_ZERO_EXTEND (mode, new); rtx temp1 = gen_rtx_SIGN_EXTEND (mode, new); /* Prefer ZERO_EXTENSION, since it gives more information to backends. */ if (rtx_cost (temp, SET) <= rtx_cost (temp1, SET)) return temp; return temp1; } /* Otherwise, sign- or zero-extend unless we already are in the proper mode. */ return (gen_rtx_fmt_e (unsignedp ? ZERO_EXTEND : SIGN_EXTEND, mode, new)); } /* Unless this is a COMPARE or we have a funny memory reference, don't do anything with zero-extending field extracts starting at the low-order bit since they are simple AND operations. */ if (pos_rtx == 0 && pos == 0 && ! in_dest && ! in_compare && ! spans_byte && unsignedp) return 0; /* Unless we are allowed to span bytes or INNER is not MEM, reject this if we would be spanning bytes or if the position is not a constant and the length is not 1. In all other cases, we would only be going outside our object in cases when an original shift would have been undefined. */ if (! spans_byte && GET_CODE (inner) == MEM && ((pos_rtx == 0 && pos + len > GET_MODE_BITSIZE (is_mode)) || (pos_rtx != 0 && len != 1))) return 0; /* Get the mode to use should INNER not be a MEM, the mode for the position, and the mode for the result. */ if (in_dest && mode_for_extraction (EP_insv, -1) != MAX_MACHINE_MODE) { wanted_inner_reg_mode = mode_for_extraction (EP_insv, 0); pos_mode = mode_for_extraction (EP_insv, 2); extraction_mode = mode_for_extraction (EP_insv, 3); } if (! in_dest && unsignedp && mode_for_extraction (EP_extzv, -1) != MAX_MACHINE_MODE) { wanted_inner_reg_mode = mode_for_extraction (EP_extzv, 1); pos_mode = mode_for_extraction (EP_extzv, 3); extraction_mode = mode_for_extraction (EP_extzv, 0); } if (! in_dest && ! unsignedp && mode_for_extraction (EP_extv, -1) != MAX_MACHINE_MODE) { wanted_inner_reg_mode = mode_for_extraction (EP_extv, 1); pos_mode = mode_for_extraction (EP_extv, 3); extraction_mode = mode_for_extraction (EP_extv, 0); } /* Never narrow an object, since that might not be safe. */ if (mode != VOIDmode && GET_MODE_SIZE (extraction_mode) < GET_MODE_SIZE (mode)) extraction_mode = mode; if (pos_rtx && GET_MODE (pos_rtx) != VOIDmode && GET_MODE_SIZE (pos_mode) < GET_MODE_SIZE (GET_MODE (pos_rtx))) pos_mode = GET_MODE (pos_rtx); /* If this is not from memory, the desired mode is wanted_inner_reg_mode; if we have to change the mode of memory and cannot, the desired mode is EXTRACTION_MODE. */ if (GET_CODE (inner) != MEM) wanted_inner_mode = wanted_inner_reg_mode; else if (inner_mode != wanted_inner_mode && (mode_dependent_address_p (XEXP (inner, 0)) || MEM_VOLATILE_P (inner))) wanted_inner_mode = extraction_mode; orig_pos = pos; if (BITS_BIG_ENDIAN) { /* POS is passed as if BITS_BIG_ENDIAN == 0, so we need to convert it to BITS_BIG_ENDIAN style. If position is constant, compute new position. Otherwise, build subtraction. Note that POS is relative to the mode of the original argument. If it's a MEM we need to recompute POS relative to that. However, if we're extracting from (or inserting into) a register, we want to recompute POS relative to wanted_inner_mode. */ int width = (GET_CODE (inner) == MEM ? GET_MODE_BITSIZE (is_mode) : GET_MODE_BITSIZE (wanted_inner_mode)); if (pos_rtx == 0) pos = width - len - pos; else pos_rtx = gen_rtx_MINUS (GET_MODE (pos_rtx), GEN_INT (width - len), pos_rtx); /* POS may be less than 0 now, but we check for that below. Note that it can only be less than 0 if GET_CODE (inner) != MEM. */ } /* If INNER has a wider mode, make it smaller. If this is a constant extract, try to adjust the byte to point to the byte containing the value. */ if (wanted_inner_mode != VOIDmode && GET_MODE_SIZE (wanted_inner_mode) < GET_MODE_SIZE (is_mode) && ((GET_CODE (inner) == MEM && (inner_mode == wanted_inner_mode || (! mode_dependent_address_p (XEXP (inner, 0)) && ! MEM_VOLATILE_P (inner)))))) { int offset = 0; /* The computations below will be correct if the machine is big endian in both bits and bytes or little endian in bits and bytes. If it is mixed, we must adjust. */ /* If bytes are big endian and we had a paradoxical SUBREG, we must adjust OFFSET to compensate. */ if (BYTES_BIG_ENDIAN && ! spans_byte && GET_MODE_SIZE (inner_mode) < GET_MODE_SIZE (is_mode)) offset -= GET_MODE_SIZE (is_mode) - GET_MODE_SIZE (inner_mode); /* If this is a constant position, we can move to the desired byte. */ if (pos_rtx == 0) { offset += pos / BITS_PER_UNIT; pos %= GET_MODE_BITSIZE (wanted_inner_mode); } if (BYTES_BIG_ENDIAN != BITS_BIG_ENDIAN && ! spans_byte && is_mode != wanted_inner_mode) offset = (GET_MODE_SIZE (is_mode) - GET_MODE_SIZE (wanted_inner_mode) - offset); if (offset != 0 || inner_mode != wanted_inner_mode) inner = adjust_address_nv (inner, wanted_inner_mode, offset); } /* If INNER is not memory, we can always get it into the proper mode. If we are changing its mode, POS must be a constant and smaller than the size of the new mode. */ else if (GET_CODE (inner) != MEM) { if (GET_MODE (inner) != wanted_inner_mode && (pos_rtx != 0 || orig_pos + len > GET_MODE_BITSIZE (wanted_inner_mode))) return 0; inner = force_to_mode (inner, wanted_inner_mode, pos_rtx || len + orig_pos >= HOST_BITS_PER_WIDE_INT ? ~(unsigned HOST_WIDE_INT) 0 : ((((unsigned HOST_WIDE_INT) 1 << len) - 1) << orig_pos), NULL_RTX, 0); } /* Adjust mode of POS_RTX, if needed. If we want a wider mode, we have to zero extend. Otherwise, we can just use a SUBREG. */ if (pos_rtx != 0 && GET_MODE_SIZE (pos_mode) > GET_MODE_SIZE (GET_MODE (pos_rtx))) { rtx temp = gen_rtx_ZERO_EXTEND (pos_mode, pos_rtx); /* If we know that no extraneous bits are set, and that the high bit is not set, convert extraction to cheaper one - either SIGN_EXTENSION or ZERO_EXTENSION, that are equivalent in these cases. */ if (flag_expensive_optimizations && (GET_MODE_BITSIZE (GET_MODE (pos_rtx)) <= HOST_BITS_PER_WIDE_INT && ((nonzero_bits (pos_rtx, GET_MODE (pos_rtx)) & ~(((unsigned HOST_WIDE_INT) GET_MODE_MASK (GET_MODE (pos_rtx))) >> 1)) == 0))) { rtx temp1 = gen_rtx_SIGN_EXTEND (pos_mode, pos_rtx); /* Prefer ZERO_EXTENSION, since it gives more information to backends. */ if (rtx_cost (temp1, SET) < rtx_cost (temp, SET)) temp = temp1; } pos_rtx = temp; } else if (pos_rtx != 0 && GET_MODE_SIZE (pos_mode) < GET_MODE_SIZE (GET_MODE (pos_rtx))) pos_rtx = gen_lowpart_for_combine (pos_mode, pos_rtx); /* Make POS_RTX unless we already have it and it is correct. If we don't have a POS_RTX but we do have an ORIG_POS_RTX, the latter must be a CONST_INT. */ if (pos_rtx == 0 && orig_pos_rtx != 0 && INTVAL (orig_pos_rtx) == pos) pos_rtx = orig_pos_rtx; else if (pos_rtx == 0) pos_rtx = GEN_INT (pos); /* Make the required operation. See if we can use existing rtx. */ new = gen_rtx_fmt_eee (unsignedp ? ZERO_EXTRACT : SIGN_EXTRACT, extraction_mode, inner, GEN_INT (len), pos_rtx); if (! in_dest) new = gen_lowpart_for_combine (mode, new); return new; } /* See if X contains an ASHIFT of COUNT or more bits that can be commuted with any other operations in X. Return X without that shift if so. */ static rtx extract_left_shift (x, count) rtx x; int count; { enum rtx_code code = GET_CODE (x); enum machine_mode mode = GET_MODE (x); rtx tem; switch (code) { case ASHIFT: /* This is the shift itself. If it is wide enough, we will return either the value being shifted if the shift count is equal to COUNT or a shift for the difference. */ if (GET_CODE (XEXP (x, 1)) == CONST_INT && INTVAL (XEXP (x, 1)) >= count) return simplify_shift_const (NULL_RTX, ASHIFT, mode, XEXP (x, 0), INTVAL (XEXP (x, 1)) - count); break; case NEG: case NOT: if ((tem = extract_left_shift (XEXP (x, 0), count)) != 0) return simplify_gen_unary (code, mode, tem, mode); break; case PLUS: case IOR: case XOR: case AND: /* If we can safely shift this constant and we find the inner shift, make a new operation. */ if (GET_CODE (XEXP (x, 1)) == CONST_INT && (INTVAL (XEXP (x, 1)) & ((((HOST_WIDE_INT) 1 << count)) - 1)) == 0 && (tem = extract_left_shift (XEXP (x, 0), count)) != 0) return gen_binary (code, mode, tem, GEN_INT (INTVAL (XEXP (x, 1)) >> count)); break; default: break; } return 0; } /* Look at the expression rooted at X. Look for expressions equivalent to ZERO_EXTRACT, SIGN_EXTRACT, ZERO_EXTEND, SIGN_EXTEND. Form these expressions. Return the new rtx, usually just X. Also, for machines like the VAX that don't have logical shift insns, try to convert logical to arithmetic shift operations in cases where they are equivalent. This undoes the canonicalizations to logical shifts done elsewhere. We try, as much as possible, to re-use rtl expressions to save memory. IN_CODE says what kind of expression we are processing. Normally, it is SET. In a memory address (inside a MEM, PLUS or minus, the latter two being kludges), it is MEM. When processing the arguments of a comparison or a COMPARE against zero, it is COMPARE. */ static rtx make_compound_operation (x, in_code) rtx x; enum rtx_code in_code; { enum rtx_code code = GET_CODE (x); enum machine_mode mode = GET_MODE (x); int mode_width = GET_MODE_BITSIZE (mode); rtx rhs, lhs; enum rtx_code next_code; int i; rtx new = 0; rtx tem; const char *fmt; /* Select the code to be used in recursive calls. Once we are inside an address, we stay there. If we have a comparison, set to COMPARE, but once inside, go back to our default of SET. */ next_code = (code == MEM || code == PLUS || code == MINUS ? MEM : ((code == COMPARE || GET_RTX_CLASS (code) == '<') && XEXP (x, 1) == const0_rtx) ? COMPARE : in_code == COMPARE ? SET : in_code); /* Process depending on the code of this operation. If NEW is set nonzero, it will be returned. */ switch (code) { case ASHIFT: /* Convert shifts by constants into multiplications if inside an address. */ if (in_code == MEM && GET_CODE (XEXP (x, 1)) == CONST_INT && INTVAL (XEXP (x, 1)) < HOST_BITS_PER_WIDE_INT && INTVAL (XEXP (x, 1)) >= 0) { new = make_compound_operation (XEXP (x, 0), next_code); new = gen_rtx_MULT (mode, new, GEN_INT ((HOST_WIDE_INT) 1 << INTVAL (XEXP (x, 1)))); } break; case AND: /* If the second operand is not a constant, we can't do anything with it. */ if (GET_CODE (XEXP (x, 1)) != CONST_INT) break; /* If the constant is a power of two minus one and the first operand is a logical right shift, make an extraction. */ if (GET_CODE (XEXP (x, 0)) == LSHIFTRT && (i = exact_log2 (INTVAL (XEXP (x, 1)) + 1)) >= 0) { new = make_compound_operation (XEXP (XEXP (x, 0), 0), next_code); new = make_extraction (mode, new, 0, XEXP (XEXP (x, 0), 1), i, 1, 0, in_code == COMPARE); } /* Same as previous, but for (subreg (lshiftrt ...)) in first op. */ else if (GET_CODE (XEXP (x, 0)) == SUBREG && subreg_lowpart_p (XEXP (x, 0)) && GET_CODE (SUBREG_REG (XEXP (x, 0))) == LSHIFTRT && (i = exact_log2 (INTVAL (XEXP (x, 1)) + 1)) >= 0) { new = make_compound_operation (XEXP (SUBREG_REG (XEXP (x, 0)), 0), next_code); new = make_extraction (GET_MODE (SUBREG_REG (XEXP (x, 0))), new, 0, XEXP (SUBREG_REG (XEXP (x, 0)), 1), i, 1, 0, in_code == COMPARE); } /* Same as previous, but for (xor/ior (lshiftrt...) (lshiftrt...)). */ else if ((GET_CODE (XEXP (x, 0)) == XOR || GET_CODE (XEXP (x, 0)) == IOR) && GET_CODE (XEXP (XEXP (x, 0), 0)) == LSHIFTRT && GET_CODE (XEXP (XEXP (x, 0), 1)) == LSHIFTRT && (i = exact_log2 (INTVAL (XEXP (x, 1)) + 1)) >= 0) { /* Apply the distributive law, and then try to make extractions. */ new = gen_rtx_fmt_ee (GET_CODE (XEXP (x, 0)), mode, gen_rtx_AND (mode, XEXP (XEXP (x, 0), 0), XEXP (x, 1)), gen_rtx_AND (mode, XEXP (XEXP (x, 0), 1), XEXP (x, 1))); new = make_compound_operation (new, in_code); } /* If we are have (and (rotate X C) M) and C is larger than the number of bits in M, this is an extraction. */ else if (GET_CODE (XEXP (x, 0)) == ROTATE && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT && (i = exact_log2 (INTVAL (XEXP (x, 1)) + 1)) >= 0 && i <= INTVAL (XEXP (XEXP (x, 0), 1))) { new = make_compound_operation (XEXP (XEXP (x, 0), 0), next_code); new = make_extraction (mode, new, (GET_MODE_BITSIZE (mode) - INTVAL (XEXP (XEXP (x, 0), 1))), NULL_RTX, i, 1, 0, in_code == COMPARE); } /* On machines without logical shifts, if the operand of the AND is a logical shift and our mask turns off all the propagated sign bits, we can replace the logical shift with an arithmetic shift. */ else if (GET_CODE (XEXP (x, 0)) == LSHIFTRT && !have_insn_for (LSHIFTRT, mode) && have_insn_for (ASHIFTRT, mode) && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT && INTVAL (XEXP (XEXP (x, 0), 1)) >= 0 && INTVAL (XEXP (XEXP (x, 0), 1)) < HOST_BITS_PER_WIDE_INT && mode_width <= HOST_BITS_PER_WIDE_INT) { unsigned HOST_WIDE_INT mask = GET_MODE_MASK (mode); mask >>= INTVAL (XEXP (XEXP (x, 0), 1)); if ((INTVAL (XEXP (x, 1)) & ~mask) == 0) SUBST (XEXP (x, 0), gen_rtx_ASHIFTRT (mode, make_compound_operation (XEXP (XEXP (x, 0), 0), next_code), XEXP (XEXP (x, 0), 1))); } /* If the constant is one less than a power of two, this might be representable by an extraction even if no shift is present. If it doesn't end up being a ZERO_EXTEND, we will ignore it unless we are in a COMPARE. */ else if ((i = exact_log2 (INTVAL (XEXP (x, 1)) + 1)) >= 0) new = make_extraction (mode, make_compound_operation (XEXP (x, 0), next_code), 0, NULL_RTX, i, 1, 0, in_code == COMPARE); /* If we are in a comparison and this is an AND with a power of two, convert this into the appropriate bit extract. */ else if (in_code == COMPARE && (i = exact_log2 (INTVAL (XEXP (x, 1)))) >= 0) new = make_extraction (mode, make_compound_operation (XEXP (x, 0), next_code), i, NULL_RTX, 1, 1, 0, 1); break; case LSHIFTRT: /* If the sign bit is known to be zero, replace this with an arithmetic shift. */ if (have_insn_for (ASHIFTRT, mode) && ! have_insn_for (LSHIFTRT, mode) && mode_width <= HOST_BITS_PER_WIDE_INT && (nonzero_bits (XEXP (x, 0), mode) & (1 << (mode_width - 1))) == 0) { new = gen_rtx_ASHIFTRT (mode, make_compound_operation (XEXP (x, 0), next_code), XEXP (x, 1)); break; } /* ... fall through ... */ case ASHIFTRT: lhs = XEXP (x, 0); rhs = XEXP (x, 1); /* If we have (ashiftrt (ashift foo C1) C2) with C2 >= C1, this is a SIGN_EXTRACT. */ if (GET_CODE (rhs) == CONST_INT && GET_CODE (lhs) == ASHIFT && GET_CODE (XEXP (lhs, 1)) == CONST_INT && INTVAL (rhs) >= INTVAL (XEXP (lhs, 1))) { new = make_compound_operation (XEXP (lhs, 0), next_code); new = make_extraction (mode, new, INTVAL (rhs) - INTVAL (XEXP (lhs, 1)), NULL_RTX, mode_width - INTVAL (rhs), code == LSHIFTRT, 0, in_code == COMPARE); break; } /* See if we have operations between an ASHIFTRT and an ASHIFT. If so, try to merge the shifts into a SIGN_EXTEND. We could also do this for some cases of SIGN_EXTRACT, but it doesn't seem worth the effort; the case checked for occurs on Alpha. */ if (GET_RTX_CLASS (GET_CODE (lhs)) != 'o' && ! (GET_CODE (lhs) == SUBREG && (GET_RTX_CLASS (GET_CODE (SUBREG_REG (lhs))) == 'o')) && GET_CODE (rhs) == CONST_INT && INTVAL (rhs) < HOST_BITS_PER_WIDE_INT && (new = extract_left_shift (lhs, INTVAL (rhs))) != 0) new = make_extraction (mode, make_compound_operation (new, next_code), 0, NULL_RTX, mode_width - INTVAL (rhs), code == LSHIFTRT, 0, in_code == COMPARE); break; case SUBREG: /* Call ourselves recursively on the inner expression. If we are narrowing the object and it has a different RTL code from what it originally did, do this SUBREG as a force_to_mode. */ tem = make_compound_operation (SUBREG_REG (x), in_code); if (GET_CODE (tem) != GET_CODE (SUBREG_REG (x)) && GET_MODE_SIZE (mode) < GET_MODE_SIZE (GET_MODE (tem)) && subreg_lowpart_p (x)) { rtx newer = force_to_mode (tem, mode, ~(HOST_WIDE_INT) 0, NULL_RTX, 0); /* If we have something other than a SUBREG, we might have done an expansion, so rerun ourselves. */ if (GET_CODE (newer) != SUBREG) newer = make_compound_operation (newer, in_code); return newer; } /* If this is a paradoxical subreg, and the new code is a sign or zero extension, omit the subreg and widen the extension. If it is a regular subreg, we can still get rid of the subreg by not widening so much, or in fact removing the extension entirely. */ if ((GET_CODE (tem) == SIGN_EXTEND || GET_CODE (tem) == ZERO_EXTEND) && subreg_lowpart_p (x)) { if (GET_MODE_SIZE (mode) > GET_MODE_SIZE (GET_MODE (tem)) || (GET_MODE_SIZE (mode) > GET_MODE_SIZE (GET_MODE (XEXP (tem, 0))))) { if (! SCALAR_INT_MODE_P (mode)) break; tem = gen_rtx_fmt_e (GET_CODE (tem), mode, XEXP (tem, 0)); } else tem = gen_lowpart_for_combine (mode, XEXP (tem, 0)); return tem; } break; default: break; } if (new) { x = gen_lowpart_for_combine (mode, new); code = GET_CODE (x); } /* Now recursively process each operand of this operation. */ fmt = GET_RTX_FORMAT (code); for (i = 0; i < GET_RTX_LENGTH (code); i++) if (fmt[i] == 'e') { new = make_compound_operation (XEXP (x, i), next_code); SUBST (XEXP (x, i), new); } return x; } /* Given M see if it is a value that would select a field of bits within an item, but not the entire word. Return -1 if not. Otherwise, return the starting position of the field, where 0 is the low-order bit. *PLEN is set to the length of the field. */ static int get_pos_from_mask (m, plen) unsigned HOST_WIDE_INT m; unsigned HOST_WIDE_INT *plen; { /* Get the bit number of the first 1 bit from the right, -1 if none. */ int pos = exact_log2 (m & -m); int len; if (pos < 0) return -1; /* Now shift off the low-order zero bits and see if we have a power of two minus 1. */ len = exact_log2 ((m >> pos) + 1); if (len <= 0) return -1; *plen = len; return pos; } /* See if X can be simplified knowing that we will only refer to it in MODE and will only refer to those bits that are nonzero in MASK. If other bits are being computed or if masking operations are done that select a superset of the bits in MASK, they can sometimes be ignored. Return a possibly simplified expression, but always convert X to MODE. If X is a CONST_INT, AND the CONST_INT with MASK. Also, if REG is nonzero and X is a register equal in value to REG, replace X with REG. If JUST_SELECT is nonzero, don't optimize by noticing that bits in MASK are all off in X. This is used when X will be complemented, by either NOT, NEG, or XOR. */ static rtx force_to_mode (x, mode, mask, reg, just_select) rtx x; enum machine_mode mode; unsigned HOST_WIDE_INT mask; rtx reg; int just_select; { enum rtx_code code = GET_CODE (x); int next_select = just_select || code == XOR || code == NOT || code == NEG; enum machine_mode op_mode; unsigned HOST_WIDE_INT fuller_mask, nonzero; rtx op0, op1, temp; /* If this is a CALL or ASM_OPERANDS, don't do anything. Some of the code below will do the wrong thing since the mode of such an expression is VOIDmode. Also do nothing if X is a CLOBBER; this can happen if X was the return value from a call to gen_lowpart_for_combine. */ if (code == CALL || code == ASM_OPERANDS || code == CLOBBER) return x; /* We want to perform the operation is its present mode unless we know that the operation is valid in MODE, in which case we do the operation in MODE. */ op_mode = ((GET_MODE_CLASS (mode) == GET_MODE_CLASS (GET_MODE (x)) && have_insn_for (code, mode)) ? mode : GET_MODE (x)); /* It is not valid to do a right-shift in a narrower mode than the one it came in with. */ if ((code == LSHIFTRT || code == ASHIFTRT) && GET_MODE_BITSIZE (mode) < GET_MODE_BITSIZE (GET_MODE (x))) op_mode = GET_MODE (x); /* Truncate MASK to fit OP_MODE. */ if (op_mode) mask &= GET_MODE_MASK (op_mode); /* When we have an arithmetic operation, or a shift whose count we do not know, we need to assume that all bit the up to the highest-order bit in MASK will be needed. This is how we form such a mask. */ if (op_mode) fuller_mask = (GET_MODE_BITSIZE (op_mode) >= HOST_BITS_PER_WIDE_INT ? GET_MODE_MASK (op_mode) : (((unsigned HOST_WIDE_INT) 1 << (floor_log2 (mask) + 1)) - 1)); else fuller_mask = ~(HOST_WIDE_INT) 0; /* Determine what bits of X are guaranteed to be (non)zero. */ nonzero = nonzero_bits (x, mode); /* If none of the bits in X are needed, return a zero. */ if (! just_select && (nonzero & mask) == 0) x = const0_rtx; /* If X is a CONST_INT, return a new one. Do this here since the test below will fail. */ if (GET_CODE (x) == CONST_INT) { if (SCALAR_INT_MODE_P (mode)) return gen_int_mode (INTVAL (x) & mask, mode); else { x = GEN_INT (INTVAL (x) & mask); return gen_lowpart_common (mode, x); } } /* If X is narrower than MODE and we want all the bits in X's mode, just get X in the proper mode. */ if (GET_MODE_SIZE (GET_MODE (x)) < GET_MODE_SIZE (mode) && (GET_MODE_MASK (GET_MODE (x)) & ~mask) == 0) return gen_lowpart_for_combine (mode, x); /* If we aren't changing the mode, X is not a SUBREG, and all zero bits in MASK are already known to be zero in X, we need not do anything. */ if (GET_MODE (x) == mode && code != SUBREG && (~mask & nonzero) == 0) return x; switch (code) { case CLOBBER: /* If X is a (clobber (const_int)), return it since we know we are generating something that won't match. */ return x; case USE: /* X is a (use (mem ..)) that was made from a bit-field extraction that spanned the boundary of the MEM. If we are now masking so it is within that boundary, we don't need the USE any more. */ if (! BITS_BIG_ENDIAN && (mask & ~GET_MODE_MASK (GET_MODE (XEXP (x, 0)))) == 0) return force_to_mode (XEXP (x, 0), mode, mask, reg, next_select); break; case SIGN_EXTEND: case ZERO_EXTEND: case ZERO_EXTRACT: case SIGN_EXTRACT: x = expand_compound_operation (x); if (GET_CODE (x) != code) return force_to_mode (x, mode, mask, reg, next_select); break; case REG: if (reg != 0 && (rtx_equal_p (get_last_value (reg), x) || rtx_equal_p (reg, get_last_value (x)))) x = reg; break; case SUBREG: if (subreg_lowpart_p (x) /* We can ignore the effect of this SUBREG if it narrows the mode or if the constant masks to zero all the bits the mode doesn't have. */ && ((GET_MODE_SIZE (GET_MODE (x)) < GET_MODE_SIZE (GET_MODE (SUBREG_REG (x)))) || (0 == (mask & GET_MODE_MASK (GET_MODE (x)) & ~GET_MODE_MASK (GET_MODE (SUBREG_REG (x))))))) return force_to_mode (SUBREG_REG (x), mode, mask, reg, next_select); break; case AND: /* If this is an AND with a constant, convert it into an AND whose constant is the AND of that constant with MASK. If it remains an AND of MASK, delete it since it is redundant. */ if (GET_CODE (XEXP (x, 1)) == CONST_INT) { x = simplify_and_const_int (x, op_mode, XEXP (x, 0), mask & INTVAL (XEXP (x, 1))); /* If X is still an AND, see if it is an AND with a mask that is just some low-order bits. If so, and it is MASK, we don't need it. */ if (GET_CODE (x) == AND && GET_CODE (XEXP (x, 1)) == CONST_INT && ((INTVAL (XEXP (x, 1)) & GET_MODE_MASK (GET_MODE (x))) == mask)) x = XEXP (x, 0); /* If it remains an AND, try making another AND with the bits in the mode mask that aren't in MASK turned on. If the constant in the AND is wide enough, this might make a cheaper constant. */ if (GET_CODE (x) == AND && GET_CODE (XEXP (x, 1)) == CONST_INT && GET_MODE_MASK (GET_MODE (x)) != mask && GET_MODE_BITSIZE (GET_MODE (x)) <= HOST_BITS_PER_WIDE_INT) { HOST_WIDE_INT cval = (INTVAL (XEXP (x, 1)) | (GET_MODE_MASK (GET_MODE (x)) & ~mask)); int width = GET_MODE_BITSIZE (GET_MODE (x)); rtx y; /* If MODE is narrower that HOST_WIDE_INT and CVAL is a negative number, sign extend it. */ if (width > 0 && width < HOST_BITS_PER_WIDE_INT && (cval & ((HOST_WIDE_INT) 1 << (width - 1))) != 0) cval |= (HOST_WIDE_INT) -1 << width; y = gen_binary (AND, GET_MODE (x), XEXP (x, 0), GEN_INT (cval)); if (rtx_cost (y, SET) < rtx_cost (x, SET)) x = y; } break; } goto binop; case PLUS: /* In (and (plus FOO C1) M), if M is a mask that just turns off low-order bits (as in an alignment operation) and FOO is already aligned to that boundary, mask C1 to that boundary as well. This may eliminate that PLUS and, later, the AND. */ { unsigned int width = GET_MODE_BITSIZE (mode); unsigned HOST_WIDE_INT smask = mask; /* If MODE is narrower than HOST_WIDE_INT and mask is a negative number, sign extend it. */ if (width < HOST_BITS_PER_WIDE_INT && (smask & ((HOST_WIDE_INT) 1 << (width - 1))) != 0) smask |= (HOST_WIDE_INT) -1 << width; if (GET_CODE (XEXP (x, 1)) == CONST_INT && exact_log2 (- smask) >= 0 && (nonzero_bits (XEXP (x, 0), mode) & ~smask) == 0 && (INTVAL (XEXP (x, 1)) & ~smask) != 0) return force_to_mode (plus_constant (XEXP (x, 0), (INTVAL (XEXP (x, 1)) & smask)), mode, smask, reg, next_select); } /* ... fall through ... */ case MULT: /* For PLUS, MINUS and MULT, we need any bits less significant than the most significant bit in MASK since carries from those bits will affect the bits we are interested in. */ mask = fuller_mask; goto binop; case MINUS: /* If X is (minus C Y) where C's least set bit is larger than any bit in the mask, then we may replace with (neg Y). */ if (GET_CODE (XEXP (x, 0)) == CONST_INT && (((unsigned HOST_WIDE_INT) (INTVAL (XEXP (x, 0)) & -INTVAL (XEXP (x, 0)))) > mask)) { x = simplify_gen_unary (NEG, GET_MODE (x), XEXP (x, 1), GET_MODE (x)); return force_to_mode (x, mode, mask, reg, next_select); } /* Similarly, if C contains every bit in the fuller_mask, then we may replace with (not Y). */ if (GET_CODE (XEXP (x, 0)) == CONST_INT && ((INTVAL (XEXP (x, 0)) | (HOST_WIDE_INT) fuller_mask) == INTVAL (XEXP (x, 0)))) { x = simplify_gen_unary (NOT, GET_MODE (x), XEXP (x, 1), GET_MODE (x)); return force_to_mode (x, mode, mask, reg, next_select); } mask = fuller_mask; goto binop; case IOR: case XOR: /* If X is (ior (lshiftrt FOO C1) C2), try to commute the IOR and LSHIFTRT so we end up with an (and (lshiftrt (ior ...) ...) ...) operation which may be a bitfield extraction. Ensure that the constant we form is not wider than the mode of X. */ if (GET_CODE (XEXP (x, 0)) == LSHIFTRT && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT && INTVAL (XEXP (XEXP (x, 0), 1)) >= 0 && INTVAL (XEXP (XEXP (x, 0), 1)) < HOST_BITS_PER_WIDE_INT && GET_CODE (XEXP (x, 1)) == CONST_INT && ((INTVAL (XEXP (XEXP (x, 0), 1)) + floor_log2 (INTVAL (XEXP (x, 1)))) < GET_MODE_BITSIZE (GET_MODE (x))) && (INTVAL (XEXP (x, 1)) & ~nonzero_bits (XEXP (x, 0), GET_MODE (x))) == 0) { temp = GEN_INT ((INTVAL (XEXP (x, 1)) & mask) << INTVAL (XEXP (XEXP (x, 0), 1))); temp = gen_binary (GET_CODE (x), GET_MODE (x), XEXP (XEXP (x, 0), 0), temp); x = gen_binary (LSHIFTRT, GET_MODE (x), temp, XEXP (XEXP (x, 0), 1)); return force_to_mode (x, mode, mask, reg, next_select); } binop: /* For most binary operations, just propagate into the operation and change the mode if we have an operation of that mode. */ op0 = gen_lowpart_for_combine (op_mode, force_to_mode (XEXP (x, 0), mode, mask, reg, next_select)); op1 = gen_lowpart_for_combine (op_mode, force_to_mode (XEXP (x, 1), mode, mask, reg, next_select)); if (op_mode != GET_MODE (x) || op0 != XEXP (x, 0) || op1 != XEXP (x, 1)) x = gen_binary (code, op_mode, op0, op1); break; case ASHIFT: /* For left shifts, do the same, but just for the first operand. However, we cannot do anything with shifts where we cannot guarantee that the counts are smaller than the size of the mode because such a count will have a different meaning in a wider mode. */ if (! (GET_CODE (XEXP (x, 1)) == CONST_INT && INTVAL (XEXP (x, 1)) >= 0 && INTVAL (XEXP (x, 1)) < GET_MODE_BITSIZE (mode)) && ! (GET_MODE (XEXP (x, 1)) != VOIDmode && (nonzero_bits (XEXP (x, 1), GET_MODE (XEXP (x, 1))) < (unsigned HOST_WIDE_INT) GET_MODE_BITSIZE (mode)))) break; /* If the shift count is a constant and we can do arithmetic in the mode of the shift, refine which bits we need. Otherwise, use the conservative form of the mask. */ if (GET_CODE (XEXP (x, 1)) == CONST_INT && INTVAL (XEXP (x, 1)) >= 0 && INTVAL (XEXP (x, 1)) < GET_MODE_BITSIZE (op_mode) && GET_MODE_BITSIZE (op_mode) <= HOST_BITS_PER_WIDE_INT) mask >>= INTVAL (XEXP (x, 1)); else mask = fuller_mask; op0 = gen_lowpart_for_combine (op_mode, force_to_mode (XEXP (x, 0), op_mode, mask, reg, next_select)); if (op_mode != GET_MODE (x) || op0 != XEXP (x, 0)) x = gen_binary (code, op_mode, op0, XEXP (x, 1)); break; case LSHIFTRT: /* Here we can only do something if the shift count is a constant, this shift constant is valid for the host, and we can do arithmetic in OP_MODE. */ if (GET_CODE (XEXP (x, 1)) == CONST_INT && INTVAL (XEXP (x, 1)) < HOST_BITS_PER_WIDE_INT && GET_MODE_BITSIZE (op_mode) <= HOST_BITS_PER_WIDE_INT) { rtx inner = XEXP (x, 0); unsigned HOST_WIDE_INT inner_mask; /* Select the mask of the bits we need for the shift operand. */ inner_mask = mask << INTVAL (XEXP (x, 1)); /* We can only change the mode of the shift if we can do arithmetic in the mode of the shift and INNER_MASK is no wider than the width of OP_MODE. */ if (GET_MODE_BITSIZE (op_mode) > HOST_BITS_PER_WIDE_INT || (inner_mask & ~GET_MODE_MASK (op_mode)) != 0) op_mode = GET_MODE (x); inner = force_to_mode (inner, op_mode, inner_mask, reg, next_select); if (GET_MODE (x) != op_mode || inner != XEXP (x, 0)) x = gen_binary (LSHIFTRT, op_mode, inner, XEXP (x, 1)); } /* If we have (and (lshiftrt FOO C1) C2) where the combination of the shift and AND produces only copies of the sign bit (C2 is one less than a power of two), we can do this with just a shift. */ if (GET_CODE (x) == LSHIFTRT && GET_CODE (XEXP (x, 1)) == CONST_INT /* The shift puts one of the sign bit copies in the least significant bit. */ && ((INTVAL (XEXP (x, 1)) + num_sign_bit_copies (XEXP (x, 0), GET_MODE (XEXP (x, 0)))) >= GET_MODE_BITSIZE (GET_MODE (x))) && exact_log2 (mask + 1) >= 0 /* Number of bits left after the shift must be more than the mask needs. */ && ((INTVAL (XEXP (x, 1)) + exact_log2 (mask + 1)) <= GET_MODE_BITSIZE (GET_MODE (x))) /* Must be more sign bit copies than the mask needs. */ && ((int) num_sign_bit_copies (XEXP (x, 0), GET_MODE (XEXP (x, 0))) >= exact_log2 (mask + 1))) x = gen_binary (LSHIFTRT, GET_MODE (x), XEXP (x, 0), GEN_INT (GET_MODE_BITSIZE (GET_MODE (x)) - exact_log2 (mask + 1))); goto shiftrt; case ASHIFTRT: /* If we are just looking for the sign bit, we don't need this shift at all, even if it has a variable count. */ if (GET_MODE_BITSIZE (GET_MODE (x)) <= HOST_BITS_PER_WIDE_INT && (mask == ((unsigned HOST_WIDE_INT) 1 << (GET_MODE_BITSIZE (GET_MODE (x)) - 1)))) return force_to_mode (XEXP (x, 0), mode, mask, reg, next_select); /* If this is a shift by a constant, get a mask that contains those bits that are not copies of the sign bit. We then have two cases: If MASK only includes those bits, this can be a logical shift, which may allow simplifications. If MASK is a single-bit field not within those bits, we are requesting a copy of the sign bit and hence can shift the sign bit to the appropriate location. */ if (GET_CODE (XEXP (x, 1)) == CONST_INT && INTVAL (XEXP (x, 1)) >= 0 && INTVAL (XEXP (x, 1)) < HOST_BITS_PER_WIDE_INT) { int i = -1; /* If the considered data is wider than HOST_WIDE_INT, we can't represent a mask for all its bits in a single scalar. But we only care about the lower bits, so calculate these. */ if (GET_MODE_BITSIZE (GET_MODE (x)) > HOST_BITS_PER_WIDE_INT) { nonzero = ~(HOST_WIDE_INT) 0; /* GET_MODE_BITSIZE (GET_MODE (x)) - INTVAL (XEXP (x, 1)) is the number of bits a full-width mask would have set. We need only shift if these are fewer than nonzero can hold. If not, we must keep all bits set in nonzero. */ if (GET_MODE_BITSIZE (GET_MODE (x)) - INTVAL (XEXP (x, 1)) < HOST_BITS_PER_WIDE_INT) nonzero >>= INTVAL (XEXP (x, 1)) + HOST_BITS_PER_WIDE_INT - GET_MODE_BITSIZE (GET_MODE (x)) ; } else { nonzero = GET_MODE_MASK (GET_MODE (x)); nonzero >>= INTVAL (XEXP (x, 1)); } if ((mask & ~nonzero) == 0 || (i = exact_log2 (mask)) >= 0) { x = simplify_shift_const (x, LSHIFTRT, GET_MODE (x), XEXP (x, 0), i < 0 ? INTVAL (XEXP (x, 1)) : GET_MODE_BITSIZE (GET_MODE (x)) - 1 - i); if (GET_CODE (x) != ASHIFTRT) return force_to_mode (x, mode, mask, reg, next_select); } } /* If MASK is 1, convert this to an LSHIFTRT. This can be done even if the shift count isn't a constant. */ if (mask == 1) x = gen_binary (LSHIFTRT, GET_MODE (x), XEXP (x, 0), XEXP (x, 1)); shiftrt: /* If this is a zero- or sign-extension operation that just affects bits we don't care about, remove it. Be sure the call above returned something that is still a shift. */ if ((GET_CODE (x) == LSHIFTRT || GET_CODE (x) == ASHIFTRT) && GET_CODE (XEXP (x, 1)) == CONST_INT && INTVAL (XEXP (x, 1)) >= 0 && (INTVAL (XEXP (x, 1)) <= GET_MODE_BITSIZE (GET_MODE (x)) - (floor_log2 (mask) + 1)) && GET_CODE (XEXP (x, 0)) == ASHIFT && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT && INTVAL (XEXP (XEXP (x, 0), 1)) == INTVAL (XEXP (x, 1))) return force_to_mode (XEXP (XEXP (x, 0), 0), mode, mask, reg, next_select); break; case ROTATE: case ROTATERT: /* If the shift count is constant and we can do computations in the mode of X, compute where the bits we care about are. Otherwise, we can't do anything. Don't change the mode of the shift or propagate MODE into the shift, though. */ if (GET_CODE (XEXP (x, 1)) == CONST_INT && INTVAL (XEXP (x, 1)) >= 0) { temp = simplify_binary_operation (code == ROTATE ? ROTATERT : ROTATE, GET_MODE (x), GEN_INT (mask), XEXP (x, 1)); if (temp && GET_CODE (temp) == CONST_INT) SUBST (XEXP (x, 0), force_to_mode (XEXP (x, 0), GET_MODE (x), INTVAL (temp), reg, next_select)); } break; case NEG: /* If we just want the low-order bit, the NEG isn't needed since it won't change the low-order bit. */ if (mask == 1) return force_to_mode (XEXP (x, 0), mode, mask, reg, just_select); /* We need any bits less significant than the most significant bit in MASK since carries from those bits will affect the bits we are interested in. */ mask = fuller_mask; goto unop; case NOT: /* (not FOO) is (xor FOO CONST), so if FOO is an LSHIFTRT, we can do the same as the XOR case above. Ensure that the constant we form is not wider than the mode of X. */ if (GET_CODE (XEXP (x, 0)) == LSHIFTRT && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT && INTVAL (XEXP (XEXP (x, 0), 1)) >= 0 && (INTVAL (XEXP (XEXP (x, 0), 1)) + floor_log2 (mask) < GET_MODE_BITSIZE (GET_MODE (x))) && INTVAL (XEXP (XEXP (x, 0), 1)) < HOST_BITS_PER_WIDE_INT) { temp = gen_int_mode (mask << INTVAL (XEXP (XEXP (x, 0), 1)), GET_MODE (x)); temp = gen_binary (XOR, GET_MODE (x), XEXP (XEXP (x, 0), 0), temp); x = gen_binary (LSHIFTRT, GET_MODE (x), temp, XEXP (XEXP (x, 0), 1)); return force_to_mode (x, mode, mask, reg, next_select); } /* (and (not FOO) CONST) is (not (or FOO (not CONST))), so we must use the full mask inside the NOT. */ mask = fuller_mask; unop: op0 = gen_lowpart_for_combine (op_mode, force_to_mode (XEXP (x, 0), mode, mask, reg, next_select)); if (op_mode != GET_MODE (x) || op0 != XEXP (x, 0)) x = simplify_gen_unary (code, op_mode, op0, op_mode); break; case NE: /* (and (ne FOO 0) CONST) can be (and FOO CONST) if CONST is included in STORE_FLAG_VALUE and FOO has a single bit that might be nonzero, which is equal to STORE_FLAG_VALUE. */ if ((mask & ~STORE_FLAG_VALUE) == 0 && XEXP (x, 1) == const0_rtx && exact_log2 (nonzero_bits (XEXP (x, 0), mode)) >= 0 && (nonzero_bits (XEXP (x, 0), mode) == (unsigned HOST_WIDE_INT) STORE_FLAG_VALUE)) return force_to_mode (XEXP (x, 0), mode, mask, reg, next_select); break; case IF_THEN_ELSE: /* We have no way of knowing if the IF_THEN_ELSE can itself be written in a narrower mode. We play it safe and do not do so. */ SUBST (XEXP (x, 1), gen_lowpart_for_combine (GET_MODE (x), force_to_mode (XEXP (x, 1), mode, mask, reg, next_select))); SUBST (XEXP (x, 2), gen_lowpart_for_combine (GET_MODE (x), force_to_mode (XEXP (x, 2), mode, mask, reg, next_select))); break; default: break; } /* Ensure we return a value of the proper mode. */ return gen_lowpart_for_combine (mode, x); } /* Return nonzero if X is an expression that has one of two values depending on whether some other value is zero or nonzero. In that case, we return the value that is being tested, *PTRUE is set to the value if the rtx being returned has a nonzero value, and *PFALSE is set to the other alternative. If we return zero, we set *PTRUE and *PFALSE to X. */ static rtx if_then_else_cond (x, ptrue, pfalse) rtx x; rtx *ptrue, *pfalse; { enum machine_mode mode = GET_MODE (x); enum rtx_code code = GET_CODE (x); rtx cond0, cond1, true0, true1, false0, false1; unsigned HOST_WIDE_INT nz; /* If we are comparing a value against zero, we are done. */ if ((code == NE || code == EQ) && GET_CODE (XEXP (x, 1)) == CONST_INT && INTVAL (XEXP (x, 1)) == 0) { *ptrue = (code == NE) ? const_true_rtx : const0_rtx; *pfalse = (code == NE) ? const0_rtx : const_true_rtx; return XEXP (x, 0); } /* If this is a unary operation whose operand has one of two values, apply our opcode to compute those values. */ else if (GET_RTX_CLASS (code) == '1' && (cond0 = if_then_else_cond (XEXP (x, 0), &true0, &false0)) != 0) { *ptrue = simplify_gen_unary (code, mode, true0, GET_MODE (XEXP (x, 0))); *pfalse = simplify_gen_unary (code, mode, false0, GET_MODE (XEXP (x, 0))); return cond0; } /* If this is a COMPARE, do nothing, since the IF_THEN_ELSE we would make can't possibly match and would suppress other optimizations. */ else if (code == COMPARE) ; /* If this is a binary operation, see if either side has only one of two values. If either one does or if both do and they are conditional on the same value, compute the new true and false values. */ else if (GET_RTX_CLASS (code) == 'c' || GET_RTX_CLASS (code) == '2' || GET_RTX_CLASS (code) == '<') { cond0 = if_then_else_cond (XEXP (x, 0), &true0, &false0); cond1 = if_then_else_cond (XEXP (x, 1), &true1, &false1); if ((cond0 != 0 || cond1 != 0) && ! (cond0 != 0 && cond1 != 0 && ! rtx_equal_p (cond0, cond1))) { /* If if_then_else_cond returned zero, then true/false are the same rtl. We must copy one of them to prevent invalid rtl sharing. */ if (cond0 == 0) true0 = copy_rtx (true0); else if (cond1 == 0) true1 = copy_rtx (true1); *ptrue = gen_binary (code, mode, true0, true1); *pfalse = gen_binary (code, mode, false0, false1); return cond0 ? cond0 : cond1; } /* See if we have PLUS, IOR, XOR, MINUS or UMAX, where one of the operands is zero when the other is nonzero, and vice-versa, and STORE_FLAG_VALUE is 1 or -1. */ if ((STORE_FLAG_VALUE == 1 || STORE_FLAG_VALUE == -1) && (code == PLUS || code == IOR || code == XOR || code == MINUS || code == UMAX) && GET_CODE (XEXP (x, 0)) == MULT && GET_CODE (XEXP (x, 1)) == MULT) { rtx op0 = XEXP (XEXP (x, 0), 1); rtx op1 = XEXP (XEXP (x, 1), 1); cond0 = XEXP (XEXP (x, 0), 0); cond1 = XEXP (XEXP (x, 1), 0); if (GET_RTX_CLASS (GET_CODE (cond0)) == '<' && GET_RTX_CLASS (GET_CODE (cond1)) == '<' && ((GET_CODE (cond0) == combine_reversed_comparison_code (cond1) && rtx_equal_p (XEXP (cond0, 0), XEXP (cond1, 0)) && rtx_equal_p (XEXP (cond0, 1), XEXP (cond1, 1))) || ((swap_condition (GET_CODE (cond0)) == combine_reversed_comparison_code (cond1)) && rtx_equal_p (XEXP (cond0, 0), XEXP (cond1, 1)) && rtx_equal_p (XEXP (cond0, 1), XEXP (cond1, 0)))) && ! side_effects_p (x)) { *ptrue = gen_binary (MULT, mode, op0, const_true_rtx); *pfalse = gen_binary (MULT, mode, (code == MINUS ? simplify_gen_unary (NEG, mode, op1, mode) : op1), const_true_rtx); return cond0; } } /* Similarly for MULT, AND and UMIN, except that for these the result is always zero. */ if ((STORE_FLAG_VALUE == 1 || STORE_FLAG_VALUE == -1) && (code == MULT || code == AND || code == UMIN) && GET_CODE (XEXP (x, 0)) == MULT && GET_CODE (XEXP (x, 1)) == MULT) { cond0 = XEXP (XEXP (x, 0), 0); cond1 = XEXP (XEXP (x, 1), 0); if (GET_RTX_CLASS (GET_CODE (cond0)) == '<' && GET_RTX_CLASS (GET_CODE (cond1)) == '<' && ((GET_CODE (cond0) == combine_reversed_comparison_code (cond1) && rtx_equal_p (XEXP (cond0, 0), XEXP (cond1, 0)) && rtx_equal_p (XEXP (cond0, 1), XEXP (cond1, 1))) || ((swap_condition (GET_CODE (cond0)) == combine_reversed_comparison_code (cond1)) && rtx_equal_p (XEXP (cond0, 0), XEXP (cond1, 1)) && rtx_equal_p (XEXP (cond0, 1), XEXP (cond1, 0)))) && ! side_effects_p (x)) { *ptrue = *pfalse = const0_rtx; return cond0; } } } else if (code == IF_THEN_ELSE) { /* If we have IF_THEN_ELSE already, extract the condition and canonicalize it if it is NE or EQ. */ cond0 = XEXP (x, 0); *ptrue = XEXP (x, 1), *pfalse = XEXP (x, 2); if (GET_CODE (cond0) == NE && XEXP (cond0, 1) == const0_rtx) return XEXP (cond0, 0); else if (GET_CODE (cond0) == EQ && XEXP (cond0, 1) == const0_rtx) { *ptrue = XEXP (x, 2), *pfalse = XEXP (x, 1); return XEXP (cond0, 0); } else return cond0; } /* If X is a SUBREG, we can narrow both the true and false values if the inner expression, if there is a condition. */ else if (code == SUBREG && 0 != (cond0 = if_then_else_cond (SUBREG_REG (x), &true0, &false0))) { *ptrue = simplify_gen_subreg (mode, true0, GET_MODE (SUBREG_REG (x)), SUBREG_BYTE (x)); *pfalse = simplify_gen_subreg (mode, false0, GET_MODE (SUBREG_REG (x)), SUBREG_BYTE (x)); return cond0; } /* If X is a constant, this isn't special and will cause confusions if we treat it as such. Likewise if it is equivalent to a constant. */ else if (CONSTANT_P (x) || ((cond0 = get_last_value (x)) != 0 && CONSTANT_P (cond0))) ; /* If we're in BImode, canonicalize on 0 and STORE_FLAG_VALUE, as that will be least confusing to the rest of the compiler. */ else if (mode == BImode) { *ptrue = GEN_INT (STORE_FLAG_VALUE), *pfalse = const0_rtx; return x; } /* If X is known to be either 0 or -1, those are the true and false values when testing X. */ else if (x == constm1_rtx || x == const0_rtx || (mode != VOIDmode && num_sign_bit_copies (x, mode) == GET_MODE_BITSIZE (mode))) { *ptrue = constm1_rtx, *pfalse = const0_rtx; return x; } /* Likewise for 0 or a single bit. */ else if (mode != VOIDmode && GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT && exact_log2 (nz = nonzero_bits (x, mode)) >= 0) { *ptrue = gen_int_mode (nz, mode), *pfalse = const0_rtx; return x; } /* Otherwise fail; show no condition with true and false values the same. */ *ptrue = *pfalse = x; return 0; } /* Return the value of expression X given the fact that condition COND is known to be true when applied to REG as its first operand and VAL as its second. X is known to not be shared and so can be modified in place. We only handle the simplest cases, and specifically those cases that arise with IF_THEN_ELSE expressions. */ static rtx known_cond (x, cond, reg, val) rtx x; enum rtx_code cond; rtx reg, val; { enum rtx_code code = GET_CODE (x); rtx temp; const char *fmt; int i, j; if (side_effects_p (x)) return x; /* If either operand of the condition is a floating point value, then we have to avoid collapsing an EQ comparison. */ if (cond == EQ && rtx_equal_p (x, reg) && ! FLOAT_MODE_P (GET_MODE (x)) && ! FLOAT_MODE_P (GET_MODE (val))) return val; if (cond == UNEQ && rtx_equal_p (x, reg)) return val; /* If X is (abs REG) and we know something about REG's relationship with zero, we may be able to simplify this. */ if (code == ABS && rtx_equal_p (XEXP (x, 0), reg) && val == const0_rtx) switch (cond) { case GE: case GT: case EQ: return XEXP (x, 0); case LT: case LE: return simplify_gen_unary (NEG, GET_MODE (XEXP (x, 0)), XEXP (x, 0), GET_MODE (XEXP (x, 0))); default: break; } /* The only other cases we handle are MIN, MAX, and comparisons if the operands are the same as REG and VAL. */ else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == 'c') { if (rtx_equal_p (XEXP (x, 0), val)) cond = swap_condition (cond), temp = val, val = reg, reg = temp; if (rtx_equal_p (XEXP (x, 0), reg) && rtx_equal_p (XEXP (x, 1), val)) { if (GET_RTX_CLASS (code) == '<') { if (comparison_dominates_p (cond, code)) return const_true_rtx; code = combine_reversed_comparison_code (x); if (code != UNKNOWN && comparison_dominates_p (cond, code)) return const0_rtx; else return x; } else if (code == SMAX || code == SMIN || code == UMIN || code == UMAX) { int unsignedp = (code == UMIN || code == UMAX); /* Do not reverse the condition when it is NE or EQ. This is because we cannot conclude anything about the value of 'SMAX (x, y)' when x is not equal to y, but we can when x equals y. */ if ((code == SMAX || code == UMAX) && ! (cond == EQ || cond == NE)) cond = reverse_condition (cond); switch (cond) { case GE: case GT: return unsignedp ? x : XEXP (x, 1); case LE: case LT: return unsignedp ? x : XEXP (x, 0); case GEU: case GTU: return unsignedp ? XEXP (x, 1) : x; case LEU: case LTU: return unsignedp ? XEXP (x, 0) : x; default: break; } } } } else if (code == SUBREG) { enum machine_mode inner_mode = GET_MODE (SUBREG_REG (x)); rtx new, r = known_cond (SUBREG_REG (x), cond, reg, val); if (SUBREG_REG (x) != r) { /* We must simplify subreg here, before we lose track of the original inner_mode. */ new = simplify_subreg (GET_MODE (x), r, inner_mode, SUBREG_BYTE (x)); if (new) return new; else SUBST (SUBREG_REG (x), r); } return x; } /* We don't have to handle SIGN_EXTEND here, because even in the case of replacing something with a modeless CONST_INT, a CONST_INT is already (supposed to be) a valid sign extension for its narrower mode, which implies it's already properly sign-extended for the wider mode. Now, for ZERO_EXTEND, the story is different. */ else if (code == ZERO_EXTEND) { enum machine_mode inner_mode = GET_MODE (XEXP (x, 0)); rtx new, r = known_cond (XEXP (x, 0), cond, reg, val); if (XEXP (x, 0) != r) { /* We must simplify the zero_extend here, before we lose track of the original inner_mode. */ new = simplify_unary_operation (ZERO_EXTEND, GET_MODE (x), r, inner_mode); if (new) return new; else SUBST (XEXP (x, 0), r); } return x; } fmt = GET_RTX_FORMAT (code); for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) { if (fmt[i] == 'e') SUBST (XEXP (x, i), known_cond (XEXP (x, i), cond, reg, val)); else if (fmt[i] == 'E') for (j = XVECLEN (x, i) - 1; j >= 0; j--) SUBST (XVECEXP (x, i, j), known_cond (XVECEXP (x, i, j), cond, reg, val)); } return x; } /* See if X and Y are equal for the purposes of seeing if we can rewrite an assignment as a field assignment. */ static int rtx_equal_for_field_assignment_p (x, y) rtx x; rtx y; { if (x == y || rtx_equal_p (x, y)) return 1; if (x == 0 || y == 0 || GET_MODE (x) != GET_MODE (y)) return 0; /* Check for a paradoxical SUBREG of a MEM compared with the MEM. Note that all SUBREGs of MEM are paradoxical; otherwise they would have been rewritten. */ if (GET_CODE (x) == MEM && GET_CODE (y) == SUBREG && GET_CODE (SUBREG_REG (y)) == MEM && rtx_equal_p (SUBREG_REG (y), gen_lowpart_for_combine (GET_MODE (SUBREG_REG (y)), x))) return 1; if (GET_CODE (y) == MEM && GET_CODE (x) == SUBREG && GET_CODE (SUBREG_REG (x)) == MEM && rtx_equal_p (SUBREG_REG (x), gen_lowpart_for_combine (GET_MODE (SUBREG_REG (x)), y))) return 1; /* We used to see if get_last_value of X and Y were the same but that's not correct. In one direction, we'll cause the assignment to have the wrong destination and in the case, we'll import a register into this insn that might have already have been dead. So fail if none of the above cases are true. */ return 0; } /* See if X, a SET operation, can be rewritten as a bit-field assignment. Return that assignment if so. We only handle the most common cases. */ static rtx make_field_assignment (x) rtx x; { rtx dest = SET_DEST (x); rtx src = SET_SRC (x); rtx assign; rtx rhs, lhs; HOST_WIDE_INT c1; HOST_WIDE_INT pos; unsigned HOST_WIDE_INT len; rtx other; enum machine_mode mode; /* If SRC was (and (not (ashift (const_int 1) POS)) DEST), this is a clear of a one-bit field. We will have changed it to (and (rotate (const_int -2) POS) DEST), so check for that. Also check for a SUBREG. */ if (GET_CODE (src) == AND && GET_CODE (XEXP (src, 0)) == ROTATE && GET_CODE (XEXP (XEXP (src, 0), 0)) == CONST_INT && INTVAL (XEXP (XEXP (src, 0), 0)) == -2 && rtx_equal_for_field_assignment_p (dest, XEXP (src, 1))) { assign = make_extraction (VOIDmode, dest, 0, XEXP (XEXP (src, 0), 1), 1, 1, 1, 0); if (assign != 0) return gen_rtx_SET (VOIDmode, assign, const0_rtx); return x; } else if (GET_CODE (src) == AND && GET_CODE (XEXP (src, 0)) == SUBREG && subreg_lowpart_p (XEXP (src, 0)) && (GET_MODE_SIZE (GET_MODE (XEXP (src, 0))) < GET_MODE_SIZE (GET_MODE (SUBREG_REG (XEXP (src, 0))))) && GET_CODE (SUBREG_REG (XEXP (src, 0))) == ROTATE && INTVAL (XEXP (SUBREG_REG (XEXP (src, 0)), 0)) == -2 && rtx_equal_for_field_assignment_p (dest, XEXP (src, 1))) { assign = make_extraction (VOIDmode, dest, 0, XEXP (SUBREG_REG (XEXP (src, 0)), 1), 1, 1, 1, 0); if (assign != 0) return gen_rtx_SET (VOIDmode, assign, const0_rtx); return x; } /* If SRC is (ior (ashift (const_int 1) POS) DEST), this is a set of a one-bit field. */ else if (GET_CODE (src) == IOR && GET_CODE (XEXP (src, 0)) == ASHIFT && XEXP (XEXP (src, 0), 0) == const1_rtx && rtx_equal_for_field_assignment_p (dest, XEXP (src, 1))) { assign = make_extraction (VOIDmode, dest, 0, XEXP (XEXP (src, 0), 1), 1, 1, 1, 0); if (assign != 0) return gen_rtx_SET (VOIDmode, assign, const1_rtx); return x; } /* The other case we handle is assignments into a constant-position field. They look like (ior/xor (and DEST C1) OTHER). If C1 represents a mask that has all one bits except for a group of zero bits and OTHER is known to have zeros where C1 has ones, this is such an assignment. Compute the position and length from C1. Shift OTHER to the appropriate position, force it to the required mode, and make the extraction. Check for the AND in both operands. */ if (GET_CODE (src) != IOR && GET_CODE (src) != XOR) return x; rhs = expand_compound_operation (XEXP (src, 0)); lhs = expand_compound_operation (XEXP (src, 1)); if (GET_CODE (rhs) == AND && GET_CODE (XEXP (rhs, 1)) == CONST_INT && rtx_equal_for_field_assignment_p (XEXP (rhs, 0), dest)) c1 = INTVAL (XEXP (rhs, 1)), other = lhs; else if (GET_CODE (lhs) == AND && GET_CODE (XEXP (lhs, 1)) == CONST_INT && rtx_equal_for_field_assignment_p (XEXP (lhs, 0), dest)) c1 = INTVAL (XEXP (lhs, 1)), other = rhs; else return x; pos = get_pos_from_mask ((~c1) & GET_MODE_MASK (GET_MODE (dest)), &len); if (pos < 0 || pos + len > GET_MODE_BITSIZE (GET_MODE (dest)) || GET_MODE_BITSIZE (GET_MODE (dest)) > HOST_BITS_PER_WIDE_INT || (c1 & nonzero_bits (other, GET_MODE (dest))) != 0) return x; assign = make_extraction (VOIDmode, dest, pos, NULL_RTX, len, 1, 1, 0); if (assign == 0) return x; /* The mode to use for the source is the mode of the assignment, or of what is inside a possible STRICT_LOW_PART. */ mode = (GET_CODE (assign) == STRICT_LOW_PART ? GET_MODE (XEXP (assign, 0)) : GET_MODE (assign)); /* Shift OTHER right POS places and make it the source, restricting it to the proper length and mode. */ src = force_to_mode (simplify_shift_const (NULL_RTX, LSHIFTRT, GET_MODE (src), other, pos), mode, GET_MODE_BITSIZE (mode) >= HOST_BITS_PER_WIDE_INT ? ~(unsigned HOST_WIDE_INT) 0 : ((unsigned HOST_WIDE_INT) 1 << len) - 1, dest, 0); /* If SRC is masked by an AND that does not make a difference in the value being stored, strip it. */ if (GET_CODE (assign) == ZERO_EXTRACT && GET_CODE (XEXP (assign, 1)) == CONST_INT && INTVAL (XEXP (assign, 1)) < HOST_BITS_PER_WIDE_INT && GET_CODE (src) == AND && GET_CODE (XEXP (src, 1)) == CONST_INT && ((unsigned HOST_WIDE_INT) INTVAL (XEXP (src, 1)) == ((unsigned HOST_WIDE_INT) 1 << INTVAL (XEXP (assign, 1))) - 1)) src = XEXP (src, 0); return gen_rtx_SET (VOIDmode, assign, src); } /* See if X is of the form (+ (* a c) (* b c)) and convert to (* (+ a b) c) if so. */ static rtx apply_distributive_law (x) rtx x; { enum rtx_code code = GET_CODE (x); rtx lhs, rhs, other; rtx tem; enum rtx_code inner_code; /* Distributivity is not true for floating point. It can change the value. So don't do it. -- rms and moshier@world.std.com. */ if (FLOAT_MODE_P (GET_MODE (x))) return x; /* The outer operation can only be one of the following: */ if (code != IOR && code != AND && code != XOR && code != PLUS && code != MINUS) return x; lhs = XEXP (x, 0), rhs = XEXP (x, 1); /* If either operand is a primitive we can't do anything, so get out fast. */ if (GET_RTX_CLASS (GET_CODE (lhs)) == 'o' || GET_RTX_CLASS (GET_CODE (rhs)) == 'o') return x; lhs = expand_compound_operation (lhs); rhs = expand_compound_operation (rhs); inner_code = GET_CODE (lhs); if (inner_code != GET_CODE (rhs)) return x; /* See if the inner and outer operations distribute. */ switch (inner_code) { case LSHIFTRT: case ASHIFTRT: case AND: case IOR: /* These all distribute except over PLUS. */ if (code == PLUS || code == MINUS) return x; break; case MULT: if (code != PLUS && code != MINUS) return x; break; case ASHIFT: /* This is also a multiply, so it distributes over everything. */ break; case SUBREG: /* Non-paradoxical SUBREGs distributes over all operations, provided the inner modes and byte offsets are the same, this is an extraction of a low-order part, we don't convert an fp operation to int or vice versa, and we would not be converting a single-word operation into a multi-word operation. The latter test is not required, but it prevents generating unneeded multi-word operations. Some of the previous tests are redundant given the latter test, but are retained because they are required for correctness. We produce the result slightly differently in this case. */ if (GET_MODE (SUBREG_REG (lhs)) != GET_MODE (SUBREG_REG (rhs)) || SUBREG_BYTE (lhs) != SUBREG_BYTE (rhs) || ! subreg_lowpart_p (lhs) || (GET_MODE_CLASS (GET_MODE (lhs)) != GET_MODE_CLASS (GET_MODE (SUBREG_REG (lhs)))) || (GET_MODE_SIZE (GET_MODE (lhs)) > GET_MODE_SIZE (GET_MODE (SUBREG_REG (lhs)))) || GET_MODE_SIZE (GET_MODE (SUBREG_REG (lhs))) > UNITS_PER_WORD) return x; tem = gen_binary (code, GET_MODE (SUBREG_REG (lhs)), SUBREG_REG (lhs), SUBREG_REG (rhs)); return gen_lowpart_for_combine (GET_MODE (x), tem); default: return x; } /* Set LHS and RHS to the inner operands (A and B in the example above) and set OTHER to the common operand (C in the example). These is only one way to do this unless the inner operation is commutative. */ if (GET_RTX_CLASS (inner_code) == 'c' && rtx_equal_p (XEXP (lhs, 0), XEXP (rhs, 0))) other = XEXP (lhs, 0), lhs = XEXP (lhs, 1), rhs = XEXP (rhs, 1); else if (GET_RTX_CLASS (inner_code) == 'c' && rtx_equal_p (XEXP (lhs, 0), XEXP (rhs, 1))) other = XEXP (lhs, 0), lhs = XEXP (lhs, 1), rhs = XEXP (rhs, 0); else if (GET_RTX_CLASS (inner_code) == 'c' && rtx_equal_p (XEXP (lhs, 1), XEXP (rhs, 0))) other = XEXP (lhs, 1), lhs = XEXP (lhs, 0), rhs = XEXP (rhs, 1); else if (rtx_equal_p (XEXP (lhs, 1), XEXP (rhs, 1))) other = XEXP (lhs, 1), lhs = XEXP (lhs, 0), rhs = XEXP (rhs, 0); else return x; /* Form the new inner operation, seeing if it simplifies first. */ tem = gen_binary (code, GET_MODE (x), lhs, rhs); /* There is one exception to the general way of distributing: (a ^ b) | (a ^ c) -> (~a) & (b ^ c) */ if (code == XOR && inner_code == IOR) { inner_code = AND; other = simplify_gen_unary (NOT, GET_MODE (x), other, GET_MODE (x)); } /* We may be able to continuing distributing the result, so call ourselves recursively on the inner operation before forming the outer operation, which we return. */ return gen_binary (inner_code, GET_MODE (x), apply_distributive_law (tem), other); } /* We have X, a logical `and' of VAROP with the constant CONSTOP, to be done in MODE. Return an equivalent form, if different from X. Otherwise, return X. If X is zero, we are to always construct the equivalent form. */ static rtx simplify_and_const_int (x, mode, varop, constop) rtx x; enum machine_mode mode; rtx varop; unsigned HOST_WIDE_INT constop; { unsigned HOST_WIDE_INT nonzero; int i; /* Simplify VAROP knowing that we will be only looking at some of the bits in it. Note by passing in CONSTOP, we guarantee that the bits not set in CONSTOP are not significant and will never be examined. We must ensure that is the case by explicitly masking out those bits before returning. */ varop = force_to_mode (varop, mode, constop, NULL_RTX, 0); /* If VAROP is a CLOBBER, we will fail so return it. */ if (GET_CODE (varop) == CLOBBER) return varop; /* If VAROP is a CONST_INT, then we need to apply the mask in CONSTOP to VAROP and return the new constant. */ if (GET_CODE (varop) == CONST_INT) return GEN_INT (trunc_int_for_mode (INTVAL (varop) & constop, mode)); /* See what bits may be nonzero in VAROP. Unlike the general case of a call to nonzero_bits, here we don't care about bits outside MODE. */ nonzero = nonzero_bits (varop, mode) & GET_MODE_MASK (mode); /* Turn off all bits in the constant that are known to already be zero. Thus, if the AND isn't needed at all, we will have CONSTOP == NONZERO_BITS which is tested below. */ constop &= nonzero; /* If we don't have any bits left, return zero. */ if (constop == 0) return const0_rtx; /* If VAROP is a NEG of something known to be zero or 1 and CONSTOP is a power of two, we can replace this with an ASHIFT. */ if (GET_CODE (varop) == NEG && nonzero_bits (XEXP (varop, 0), mode) == 1 && (i = exact_log2 (constop)) >= 0) return simplify_shift_const (NULL_RTX, ASHIFT, mode, XEXP (varop, 0), i); /* If VAROP is an IOR or XOR, apply the AND to both branches of the IOR or XOR, then try to apply the distributive law. This may eliminate operations if either branch can be simplified because of the AND. It may also make some cases more complex, but those cases probably won't match a pattern either with or without this. */ if (GET_CODE (varop) == IOR || GET_CODE (varop) == XOR) return gen_lowpart_for_combine (mode, apply_distributive_law (gen_binary (GET_CODE (varop), GET_MODE (varop), simplify_and_const_int (NULL_RTX, GET_MODE (varop), XEXP (varop, 0), constop), simplify_and_const_int (NULL_RTX, GET_MODE (varop), XEXP (varop, 1), constop)))); /* If VAROP is PLUS, and the constant is a mask of low bite, distribute the AND and see if one of the operands simplifies to zero. If so, we may eliminate it. */ if (GET_CODE (varop) == PLUS && exact_log2 (constop + 1) >= 0) { rtx o0, o1; o0 = simplify_and_const_int (NULL_RTX, mode, XEXP (varop, 0), constop); o1 = simplify_and_const_int (NULL_RTX, mode, XEXP (varop, 1), constop); if (o0 == const0_rtx) return o1; if (o1 == const0_rtx) return o0; } /* Get VAROP in MODE. Try to get a SUBREG if not. Don't make a new SUBREG if we already had one (just check for the simplest cases). */ if (x && GET_CODE (XEXP (x, 0)) == SUBREG && GET_MODE (XEXP (x, 0)) == mode && SUBREG_REG (XEXP (x, 0)) == varop) varop = XEXP (x, 0); else varop = gen_lowpart_for_combine (mode, varop); /* If we can't make the SUBREG, try to return what we were given. */ if (GET_CODE (varop) == CLOBBER) return x ? x : varop; /* If we are only masking insignificant bits, return VAROP. */ if (constop == nonzero) x = varop; else { /* Otherwise, return an AND. */ constop = trunc_int_for_mode (constop, mode); /* See how much, if any, of X we can use. */ if (x == 0 || GET_CODE (x) != AND || GET_MODE (x) != mode) x = gen_binary (AND, mode, varop, GEN_INT (constop)); else { if (GET_CODE (XEXP (x, 1)) != CONST_INT || (unsigned HOST_WIDE_INT) INTVAL (XEXP (x, 1)) != constop) SUBST (XEXP (x, 1), GEN_INT (constop)); SUBST (XEXP (x, 0), varop); } } return x; } #define nonzero_bits_with_known(X, MODE) \ cached_nonzero_bits (X, MODE, known_x, known_mode, known_ret) /* The function cached_nonzero_bits is a wrapper around nonzero_bits1. It avoids exponential behavior in nonzero_bits1 when X has identical subexpressions on the first or the second level. */ static unsigned HOST_WIDE_INT cached_nonzero_bits (x, mode, known_x, known_mode, known_ret) rtx x; enum machine_mode mode; rtx known_x; enum machine_mode known_mode; unsigned HOST_WIDE_INT known_ret; { if (x == known_x && mode == known_mode) return known_ret; /* Try to find identical subexpressions. If found call nonzero_bits1 on X with the subexpressions as KNOWN_X and the precomputed value for the subexpression as KNOWN_RET. */ if (GET_RTX_CLASS (GET_CODE (x)) == '2' || GET_RTX_CLASS (GET_CODE (x)) == 'c') { rtx x0 = XEXP (x, 0); rtx x1 = XEXP (x, 1); /* Check the first level. */ if (x0 == x1) return nonzero_bits1 (x, mode, x0, mode, nonzero_bits_with_known (x0, mode)); /* Check the second level. */ if ((GET_RTX_CLASS (GET_CODE (x0)) == '2' || GET_RTX_CLASS (GET_CODE (x0)) == 'c') && (x1 == XEXP (x0, 0) || x1 == XEXP (x0, 1))) return nonzero_bits1 (x, mode, x1, mode, nonzero_bits_with_known (x1, mode)); if ((GET_RTX_CLASS (GET_CODE (x1)) == '2' || GET_RTX_CLASS (GET_CODE (x1)) == 'c') && (x0 == XEXP (x1, 0) || x0 == XEXP (x1, 1))) return nonzero_bits1 (x, mode, x0, mode, nonzero_bits_with_known (x0, mode)); } return nonzero_bits1 (x, mode, known_x, known_mode, known_ret); } /* We let num_sign_bit_copies recur into nonzero_bits as that is useful. We don't let nonzero_bits recur into num_sign_bit_copies, because that is less useful. We can't allow both, because that results in exponential run time recursion. There is a nullstone testcase that triggered this. This macro avoids accidental uses of num_sign_bit_copies. */ #define cached_num_sign_bit_copies() /* Given an expression, X, compute which bits in X can be nonzero. We don't care about bits outside of those defined in MODE. For most X this is simply GET_MODE_MASK (GET_MODE (MODE)), but if X is a shift, AND, or zero_extract, we can do better. */ static unsigned HOST_WIDE_INT nonzero_bits1 (x, mode, known_x, known_mode, known_ret) rtx x; enum machine_mode mode; rtx known_x; enum machine_mode known_mode; unsigned HOST_WIDE_INT known_ret; { unsigned HOST_WIDE_INT nonzero = GET_MODE_MASK (mode); unsigned HOST_WIDE_INT inner_nz; enum rtx_code code; unsigned int mode_width = GET_MODE_BITSIZE (mode); rtx tem; /* For floating-point values, assume all bits are needed. */ if (FLOAT_MODE_P (GET_MODE (x)) || FLOAT_MODE_P (mode)) return nonzero; /* If X is wider than MODE, use its mode instead. */ if (GET_MODE_BITSIZE (GET_MODE (x)) > mode_width) { mode = GET_MODE (x); nonzero = GET_MODE_MASK (mode); mode_width = GET_MODE_BITSIZE (mode); } if (mode_width > HOST_BITS_PER_WIDE_INT) /* Our only callers in this case look for single bit values. So just return the mode mask. Those tests will then be false. */ return nonzero; #ifndef WORD_REGISTER_OPERATIONS /* If MODE is wider than X, but both are a single word for both the host and target machines, we can compute this from which bits of the object might be nonzero in its own mode, taking into account the fact that on many CISC machines, accessing an object in a wider mode causes the high-order bits to become undefined. So they are not known to be zero. */ if (GET_MODE (x) != VOIDmode && GET_MODE (x) != mode && GET_MODE_BITSIZE (GET_MODE (x)) <= BITS_PER_WORD && GET_MODE_BITSIZE (GET_MODE (x)) <= HOST_BITS_PER_WIDE_INT && GET_MODE_BITSIZE (mode) > GET_MODE_BITSIZE (GET_MODE (x))) { nonzero &= nonzero_bits_with_known (x, GET_MODE (x)); nonzero |= GET_MODE_MASK (mode) & ~GET_MODE_MASK (GET_MODE (x)); return nonzero; } #endif code = GET_CODE (x); switch (code) { case REG: #if defined(POINTERS_EXTEND_UNSIGNED) && !defined(HAVE_ptr_extend) /* If pointers extend unsigned and this is a pointer in Pmode, say that all the bits above ptr_mode are known to be zero. */ if (POINTERS_EXTEND_UNSIGNED && GET_MODE (x) == Pmode && REG_POINTER (x)) nonzero &= GET_MODE_MASK (ptr_mode); #endif /* Include declared information about alignment of pointers. */ /* ??? We don't properly preserve REG_POINTER changes across pointer-to-integer casts, so we can't trust it except for things that we know must be pointers. See execute/960116-1.c. */ if ((x == stack_pointer_rtx || x == frame_pointer_rtx || x == arg_pointer_rtx) && REGNO_POINTER_ALIGN (REGNO (x))) { unsigned HOST_WIDE_INT alignment = REGNO_POINTER_ALIGN (REGNO (x)) / BITS_PER_UNIT; #ifdef PUSH_ROUNDING /* If PUSH_ROUNDING is defined, it is possible for the stack to be momentarily aligned only to that amount, so we pick the least alignment. */ if (x == stack_pointer_rtx && PUSH_ARGS) alignment = MIN (PUSH_ROUNDING (1), alignment); #endif nonzero &= ~(alignment - 1); } /* If X is a register whose nonzero bits value is current, use it. Otherwise, if X is a register whose value we can find, use that value. Otherwise, use the previously-computed global nonzero bits for this register. */ if (reg_last_set_value[REGNO (x)] != 0 && (reg_last_set_mode[REGNO (x)] == mode || (GET_MODE_CLASS (reg_last_set_mode[REGNO (x)]) == MODE_INT && GET_MODE_CLASS (mode) == MODE_INT)) && (reg_last_set_label[REGNO (x)] == label_tick || (REGNO (x) >= FIRST_PSEUDO_REGISTER && REG_N_SETS (REGNO (x)) == 1 && ! REGNO_REG_SET_P (ENTRY_BLOCK_PTR->next_bb->global_live_at_start, REGNO (x)))) && INSN_CUID (reg_last_set[REGNO (x)]) < subst_low_cuid) return reg_last_set_nonzero_bits[REGNO (x)] & nonzero; tem = get_last_value (x); if (tem) { #ifdef SHORT_IMMEDIATES_SIGN_EXTEND /* If X is narrower than MODE and TEM is a non-negative constant that would appear negative in the mode of X, sign-extend it for use in reg_nonzero_bits because some machines (maybe most) will actually do the sign-extension and this is the conservative approach. ??? For 2.5, try to tighten up the MD files in this regard instead of this kludge. */ if (GET_MODE_BITSIZE (GET_MODE (x)) < mode_width && GET_CODE (tem) == CONST_INT && INTVAL (tem) > 0 && 0 != (INTVAL (tem) & ((HOST_WIDE_INT) 1 << (GET_MODE_BITSIZE (GET_MODE (x)) - 1)))) tem = GEN_INT (INTVAL (tem) | ((HOST_WIDE_INT) (-1) << GET_MODE_BITSIZE (GET_MODE (x)))); #endif return nonzero_bits_with_known (tem, mode) & nonzero; } else if (nonzero_sign_valid && reg_nonzero_bits[REGNO (x)]) { unsigned HOST_WIDE_INT mask = reg_nonzero_bits[REGNO (x)]; if (GET_MODE_BITSIZE (GET_MODE (x)) < mode_width) /* We don't know anything about the upper bits. */ mask |= GET_MODE_MASK (mode) ^ GET_MODE_MASK (GET_MODE (x)); return nonzero & mask; } else return nonzero; case CONST_INT: #ifdef SHORT_IMMEDIATES_SIGN_EXTEND /* If X is negative in MODE, sign-extend the value. */ if (INTVAL (x) > 0 && mode_width < BITS_PER_WORD && 0 != (INTVAL (x) & ((HOST_WIDE_INT) 1 << (mode_width - 1)))) return (INTVAL (x) | ((HOST_WIDE_INT) (-1) << mode_width)); #endif return INTVAL (x); case MEM: #ifdef LOAD_EXTEND_OP /* In many, if not most, RISC machines, reading a byte from memory zeros the rest of the register. Noticing that fact saves a lot of extra zero-extends. */ if (LOAD_EXTEND_OP (GET_MODE (x)) == ZERO_EXTEND) nonzero &= GET_MODE_MASK (GET_MODE (x)); #endif break; case EQ: case NE: case UNEQ: case LTGT: case GT: case GTU: case UNGT: case LT: case LTU: case UNLT: case GE: case GEU: case UNGE: case LE: case LEU: case UNLE: case UNORDERED: case ORDERED: /* If this produces an integer result, we know which bits are set. Code here used to clear bits outside the mode of X, but that is now done above. */ if (GET_MODE_CLASS (mode) == MODE_INT && mode_width <= HOST_BITS_PER_WIDE_INT) nonzero = STORE_FLAG_VALUE; break; case NEG: #if 0 /* Disabled to avoid exponential mutual recursion between nonzero_bits and num_sign_bit_copies. */ if (num_sign_bit_copies (XEXP (x, 0), GET_MODE (x)) == GET_MODE_BITSIZE (GET_MODE (x))) nonzero = 1; #endif if (GET_MODE_SIZE (GET_MODE (x)) < mode_width) nonzero |= (GET_MODE_MASK (mode) & ~GET_MODE_MASK (GET_MODE (x))); break; case ABS: #if 0 /* Disabled to avoid exponential mutual recursion between nonzero_bits and num_sign_bit_copies. */ if (num_sign_bit_copies (XEXP (x, 0), GET_MODE (x)) == GET_MODE_BITSIZE (GET_MODE (x))) nonzero = 1; #endif break; case TRUNCATE: nonzero &= (nonzero_bits_with_known (XEXP (x, 0), mode) & GET_MODE_MASK (mode)); break; case ZERO_EXTEND: nonzero &= nonzero_bits_with_known (XEXP (x, 0), mode); if (GET_MODE (XEXP (x, 0)) != VOIDmode) nonzero &= GET_MODE_MASK (GET_MODE (XEXP (x, 0))); break; case SIGN_EXTEND: /* If the sign bit is known clear, this is the same as ZERO_EXTEND. Otherwise, show all the bits in the outer mode but not the inner may be nonzero. */ inner_nz = nonzero_bits_with_known (XEXP (x, 0), mode); if (GET_MODE (XEXP (x, 0)) != VOIDmode) { inner_nz &= GET_MODE_MASK (GET_MODE (XEXP (x, 0))); if (inner_nz & (((HOST_WIDE_INT) 1 << (GET_MODE_BITSIZE (GET_MODE (XEXP (x, 0))) - 1)))) inner_nz |= (GET_MODE_MASK (mode) & ~GET_MODE_MASK (GET_MODE (XEXP (x, 0)))); } nonzero &= inner_nz; break; case AND: nonzero &= (nonzero_bits_with_known (XEXP (x, 0), mode) & nonzero_bits_with_known (XEXP (x, 1), mode)); break; case XOR: case IOR: case UMIN: case UMAX: case SMIN: case SMAX: { unsigned HOST_WIDE_INT nonzero0 = nonzero_bits_with_known (XEXP (x, 0), mode); /* Don't call nonzero_bits for the second time if it cannot change anything. */ if ((nonzero & nonzero0) != nonzero) nonzero &= (nonzero0 | nonzero_bits_with_known (XEXP (x, 1), mode)); } break; case PLUS: case MINUS: case MULT: case DIV: case UDIV: case MOD: case UMOD: /* We can apply the rules of arithmetic to compute the number of high- and low-order zero bits of these operations. We start by computing the width (position of the highest-order nonzero bit) and the number of low-order zero bits for each value. */ { unsigned HOST_WIDE_INT nz0 = nonzero_bits_with_known (XEXP (x, 0), mode); unsigned HOST_WIDE_INT nz1 = nonzero_bits_with_known (XEXP (x, 1), mode); int sign_index = GET_MODE_BITSIZE (GET_MODE (x)) - 1; int width0 = floor_log2 (nz0) + 1; int width1 = floor_log2 (nz1) + 1; int low0 = floor_log2 (nz0 & -nz0); int low1 = floor_log2 (nz1 & -nz1); HOST_WIDE_INT op0_maybe_minusp = (nz0 & ((HOST_WIDE_INT) 1 << sign_index)); HOST_WIDE_INT op1_maybe_minusp = (nz1 & ((HOST_WIDE_INT) 1 << sign_index)); unsigned int result_width = mode_width; int result_low = 0; switch (code) { case PLUS: result_width = MAX (width0, width1) + 1; result_low = MIN (low0, low1); break; case MINUS: result_low = MIN (low0, low1); break; case MULT: result_width = width0 + width1; result_low = low0 + low1; break; case DIV: if (width1 == 0) break; if (! op0_maybe_minusp && ! op1_maybe_minusp) result_width = width0; break; case UDIV: if (width1 == 0) break; result_width = width0; break; case MOD: if (width1 == 0) break; if (! op0_maybe_minusp && ! op1_maybe_minusp) result_width = MIN (width0, width1); result_low = MIN (low0, low1); break; case UMOD: if (width1 == 0) break; result_width = MIN (width0, width1); result_low = MIN (low0, low1); break; default: abort (); } if (result_width < mode_width) nonzero &= ((HOST_WIDE_INT) 1 << result_width) - 1; if (result_low > 0) nonzero &= ~(((HOST_WIDE_INT) 1 << result_low) - 1); #ifdef POINTERS_EXTEND_UNSIGNED /* If pointers extend unsigned and this is an addition or subtraction to a pointer in Pmode, all the bits above ptr_mode are known to be zero. */ if (POINTERS_EXTEND_UNSIGNED > 0 && GET_MODE (x) == Pmode && (code == PLUS || code == MINUS) && GET_CODE (XEXP (x, 0)) == REG && REG_POINTER (XEXP (x, 0))) nonzero &= GET_MODE_MASK (ptr_mode); #endif } break; case ZERO_EXTRACT: if (GET_CODE (XEXP (x, 1)) == CONST_INT && INTVAL (XEXP (x, 1)) < HOST_BITS_PER_WIDE_INT) nonzero &= ((HOST_WIDE_INT) 1 << INTVAL (XEXP (x, 1))) - 1; break; case SUBREG: /* If this is a SUBREG formed for a promoted variable that has been zero-extended, we know that at least the high-order bits are zero, though others might be too. */ if (SUBREG_PROMOTED_VAR_P (x) && SUBREG_PROMOTED_UNSIGNED_P (x) > 0) nonzero = (GET_MODE_MASK (GET_MODE (x)) & nonzero_bits_with_known (SUBREG_REG (x), GET_MODE (x))); /* If the inner mode is a single word for both the host and target machines, we can compute this from which bits of the inner object might be nonzero. */ if (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (x))) <= BITS_PER_WORD && (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (x))) <= HOST_BITS_PER_WIDE_INT)) { nonzero &= nonzero_bits_with_known (SUBREG_REG (x), mode); #if defined (WORD_REGISTER_OPERATIONS) && defined (LOAD_EXTEND_OP) /* If this is a typical RISC machine, we only have to worry about the way loads are extended. */ if ((LOAD_EXTEND_OP (GET_MODE (SUBREG_REG (x))) == SIGN_EXTEND ? (((nonzero & (((unsigned HOST_WIDE_INT) 1 << (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (x))) - 1)))) != 0)) : LOAD_EXTEND_OP (GET_MODE (SUBREG_REG (x))) != ZERO_EXTEND) || GET_CODE (SUBREG_REG (x)) != MEM) #endif { /* On many CISC machines, accessing an object in a wider mode causes the high-order bits to become undefined. So they are not known to be zero. */ if (GET_MODE_SIZE (GET_MODE (x)) > GET_MODE_SIZE (GET_MODE (SUBREG_REG (x)))) nonzero |= (GET_MODE_MASK (GET_MODE (x)) & ~GET_MODE_MASK (GET_MODE (SUBREG_REG (x)))); } } break; case ASHIFTRT: case LSHIFTRT: case ASHIFT: case ROTATE: /* The nonzero bits are in two classes: any bits within MODE that aren't in GET_MODE (x) are always significant. The rest of the nonzero bits are those that are significant in the operand of the shift when shifted the appropriate number of bits. This shows that high-order bits are cleared by the right shift and low-order bits by left shifts. */ if (GET_CODE (XEXP (x, 1)) == CONST_INT && INTVAL (XEXP (x, 1)) >= 0 && INTVAL (XEXP (x, 1)) < HOST_BITS_PER_WIDE_INT) { enum machine_mode inner_mode = GET_MODE (x); unsigned int width = GET_MODE_BITSIZE (inner_mode); int count = INTVAL (XEXP (x, 1)); unsigned HOST_WIDE_INT mode_mask = GET_MODE_MASK (inner_mode); unsigned HOST_WIDE_INT op_nonzero = nonzero_bits_with_known (XEXP (x, 0), mode); unsigned HOST_WIDE_INT inner = op_nonzero & mode_mask; unsigned HOST_WIDE_INT outer = 0; if (mode_width > width) outer = (op_nonzero & nonzero & ~mode_mask); if (code == LSHIFTRT) inner >>= count; else if (code == ASHIFTRT) { inner >>= count; /* If the sign bit may have been nonzero before the shift, we need to mark all the places it could have been copied to by the shift as possibly nonzero. */ if (inner & ((HOST_WIDE_INT) 1 << (width - 1 - count))) inner |= (((HOST_WIDE_INT) 1 << count) - 1) << (width - count); } else if (code == ASHIFT) inner <<= count; else inner = ((inner << (count % width) | (inner >> (width - (count % width)))) & mode_mask); nonzero &= (outer | inner); } break; case FFS: case POPCOUNT: /* This is at most the number of bits in the mode. */ nonzero = ((HOST_WIDE_INT) 2 << (floor_log2 (mode_width))) - 1; break; case CLZ: /* If CLZ has a known value at zero, then the nonzero bits are that value, plus the number of bits in the mode minus one. */ if (CLZ_DEFINED_VALUE_AT_ZERO (mode, nonzero)) nonzero |= ((HOST_WIDE_INT) 1 << (floor_log2 (mode_width))) - 1; else nonzero = -1; break; case CTZ: /* If CTZ has a known value at zero, then the nonzero bits are that value, plus the number of bits in the mode minus one. */ if (CTZ_DEFINED_VALUE_AT_ZERO (mode, nonzero)) nonzero |= ((HOST_WIDE_INT) 1 << (floor_log2 (mode_width))) - 1; else nonzero = -1; break; case PARITY: nonzero = 1; break; case IF_THEN_ELSE: nonzero &= (nonzero_bits_with_known (XEXP (x, 1), mode) | nonzero_bits_with_known (XEXP (x, 2), mode)); break; default: break; } return nonzero; } /* See the macro definition above. */ #undef cached_num_sign_bit_copies #define num_sign_bit_copies_with_known(X, M) \ cached_num_sign_bit_copies (X, M, known_x, known_mode, known_ret) /* The function cached_num_sign_bit_copies is a wrapper around num_sign_bit_copies1. It avoids exponential behavior in num_sign_bit_copies1 when X has identical subexpressions on the first or the second level. */ static unsigned int cached_num_sign_bit_copies (x, mode, known_x, known_mode, known_ret) rtx x; enum machine_mode mode; rtx known_x; enum machine_mode known_mode; unsigned int known_ret; { if (x == known_x && mode == known_mode) return known_ret; /* Try to find identical subexpressions. If found call num_sign_bit_copies1 on X with the subexpressions as KNOWN_X and the precomputed value for the subexpression as KNOWN_RET. */ if (GET_RTX_CLASS (GET_CODE (x)) == '2' || GET_RTX_CLASS (GET_CODE (x)) == 'c') { rtx x0 = XEXP (x, 0); rtx x1 = XEXP (x, 1); /* Check the first level. */ if (x0 == x1) return num_sign_bit_copies1 (x, mode, x0, mode, num_sign_bit_copies_with_known (x0, mode)); /* Check the second level. */ if ((GET_RTX_CLASS (GET_CODE (x0)) == '2' || GET_RTX_CLASS (GET_CODE (x0)) == 'c') && (x1 == XEXP (x0, 0) || x1 == XEXP (x0, 1))) return num_sign_bit_copies1 (x, mode, x1, mode, num_sign_bit_copies_with_known (x1, mode)); if ((GET_RTX_CLASS (GET_CODE (x1)) == '2' || GET_RTX_CLASS (GET_CODE (x1)) == 'c') && (x0 == XEXP (x1, 0) || x0 == XEXP (x1, 1))) return num_sign_bit_copies1 (x, mode, x0, mode, num_sign_bit_copies_with_known (x0, mode)); } return num_sign_bit_copies1 (x, mode, known_x, known_mode, known_ret); } /* Return the number of bits at the high-order end of X that are known to be equal to the sign bit. X will be used in mode MODE; if MODE is VOIDmode, X will be used in its own mode. The returned value will always be between 1 and the number of bits in MODE. */ static unsigned int num_sign_bit_copies1 (x, mode, known_x, known_mode, known_ret) rtx x; enum machine_mode mode; rtx known_x; enum machine_mode known_mode; unsigned int known_ret; { enum rtx_code code = GET_CODE (x); unsigned int bitwidth; int num0, num1, result; unsigned HOST_WIDE_INT nonzero; rtx tem; /* If we weren't given a mode, use the mode of X. If the mode is still VOIDmode, we don't know anything. Likewise if one of the modes is floating-point. */ if (mode == VOIDmode) mode = GET_MODE (x); if (mode == VOIDmode || FLOAT_MODE_P (mode) || FLOAT_MODE_P (GET_MODE (x))) return 1; bitwidth = GET_MODE_BITSIZE (mode); /* For a smaller object, just ignore the high bits. */ if (bitwidth < GET_MODE_BITSIZE (GET_MODE (x))) { num0 = num_sign_bit_copies_with_known (x, GET_MODE (x)); return MAX (1, num0 - (int) (GET_MODE_BITSIZE (GET_MODE (x)) - bitwidth)); } if (GET_MODE (x) != VOIDmode && bitwidth > GET_MODE_BITSIZE (GET_MODE (x))) { #ifndef WORD_REGISTER_OPERATIONS /* If this machine does not do all register operations on the entire register and MODE is wider than the mode of X, we can say nothing at all about the high-order bits. */ return 1; #else /* Likewise on machines that do, if the mode of the object is smaller than a word and loads of that size don't sign extend, we can say nothing about the high order bits. */ if (GET_MODE_BITSIZE (GET_MODE (x)) < BITS_PER_WORD #ifdef LOAD_EXTEND_OP && LOAD_EXTEND_OP (GET_MODE (x)) != SIGN_EXTEND #endif ) return 1; #endif } switch (code) { case REG: #if defined(POINTERS_EXTEND_UNSIGNED) && !defined(HAVE_ptr_extend) /* If pointers extend signed and this is a pointer in Pmode, say that all the bits above ptr_mode are known to be sign bit copies. */ if (! POINTERS_EXTEND_UNSIGNED && GET_MODE (x) == Pmode && mode == Pmode && REG_POINTER (x)) return GET_MODE_BITSIZE (Pmode) - GET_MODE_BITSIZE (ptr_mode) + 1; #endif if (reg_last_set_value[REGNO (x)] != 0 && reg_last_set_mode[REGNO (x)] == mode && (reg_last_set_label[REGNO (x)] == label_tick || (REGNO (x) >= FIRST_PSEUDO_REGISTER && REG_N_SETS (REGNO (x)) == 1 && ! REGNO_REG_SET_P (ENTRY_BLOCK_PTR->next_bb->global_live_at_start, REGNO (x)))) && INSN_CUID (reg_last_set[REGNO (x)]) < subst_low_cuid) return reg_last_set_sign_bit_copies[REGNO (x)]; tem = get_last_value (x); if (tem != 0) return num_sign_bit_copies_with_known (tem, mode); if (nonzero_sign_valid && reg_sign_bit_copies[REGNO (x)] != 0 && GET_MODE_BITSIZE (GET_MODE (x)) == bitwidth) return reg_sign_bit_copies[REGNO (x)]; break; case MEM: #ifdef LOAD_EXTEND_OP /* Some RISC machines sign-extend all loads of smaller than a word. */ if (LOAD_EXTEND_OP (GET_MODE (x)) == SIGN_EXTEND) return MAX (1, ((int) bitwidth - (int) GET_MODE_BITSIZE (GET_MODE (x)) + 1)); #endif break; case CONST_INT: /* If the constant is negative, take its 1's complement and remask. Then see how many zero bits we have. */ nonzero = INTVAL (x) & GET_MODE_MASK (mode); if (bitwidth <= HOST_BITS_PER_WIDE_INT && (nonzero & ((HOST_WIDE_INT) 1 << (bitwidth - 1))) != 0) nonzero = (~nonzero) & GET_MODE_MASK (mode); return (nonzero == 0 ? bitwidth : bitwidth - floor_log2 (nonzero) - 1); case SUBREG: /* If this is a SUBREG for a promoted object that is sign-extended and we are looking at it in a wider mode, we know that at least the high-order bits are known to be sign bit copies. */ if (SUBREG_PROMOTED_VAR_P (x) && ! SUBREG_PROMOTED_UNSIGNED_P (x)) { num0 = num_sign_bit_copies_with_known (SUBREG_REG (x), mode); return MAX ((int) bitwidth - (int) GET_MODE_BITSIZE (GET_MODE (x)) + 1, num0); } /* For a smaller object, just ignore the high bits. */ if (bitwidth <= GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (x)))) { num0 = num_sign_bit_copies_with_known (SUBREG_REG (x), VOIDmode); return MAX (1, (num0 - (int) (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (x))) - bitwidth))); } #ifdef WORD_REGISTER_OPERATIONS #ifdef LOAD_EXTEND_OP /* For paradoxical SUBREGs on machines where all register operations affect the entire register, just look inside. Note that we are passing MODE to the recursive call, so the number of sign bit copies will remain relative to that mode, not the inner mode. */ /* This works only if loads sign extend. Otherwise, if we get a reload for the inner part, it may be loaded from the stack, and then we lose all sign bit copies that existed before the store to the stack. */ if ((GET_MODE_SIZE (GET_MODE (x)) > GET_MODE_SIZE (GET_MODE (SUBREG_REG (x)))) && LOAD_EXTEND_OP (GET_MODE (SUBREG_REG (x))) == SIGN_EXTEND && GET_CODE (SUBREG_REG (x)) == MEM) return num_sign_bit_copies_with_known (SUBREG_REG (x), mode); #endif #endif break; case SIGN_EXTRACT: if (GET_CODE (XEXP (x, 1)) == CONST_INT) return MAX (1, (int) bitwidth - INTVAL (XEXP (x, 1))); break; case SIGN_EXTEND: return (bitwidth - GET_MODE_BITSIZE (GET_MODE (XEXP (x, 0))) + num_sign_bit_copies_with_known (XEXP (x, 0), VOIDmode)); case TRUNCATE: /* For a smaller object, just ignore the high bits. */ num0 = num_sign_bit_copies_with_known (XEXP (x, 0), VOIDmode); return MAX (1, (num0 - (int) (GET_MODE_BITSIZE (GET_MODE (XEXP (x, 0))) - bitwidth))); case NOT: return num_sign_bit_copies_with_known (XEXP (x, 0), mode); case ROTATE: case ROTATERT: /* If we are rotating left by a number of bits less than the number of sign bit copies, we can just subtract that amount from the number. */ if (GET_CODE (XEXP (x, 1)) == CONST_INT && INTVAL (XEXP (x, 1)) >= 0 && INTVAL (XEXP (x, 1)) < (int) bitwidth) { num0 = num_sign_bit_copies_with_known (XEXP (x, 0), mode); return MAX (1, num0 - (code == ROTATE ? INTVAL (XEXP (x, 1)) : (int) bitwidth - INTVAL (XEXP (x, 1)))); } break; case NEG: /* In general, this subtracts one sign bit copy. But if the value is known to be positive, the number of sign bit copies is the same as that of the input. Finally, if the input has just one bit that might be nonzero, all the bits are copies of the sign bit. */ num0 = num_sign_bit_copies_with_known (XEXP (x, 0), mode); if (bitwidth > HOST_BITS_PER_WIDE_INT) return num0 > 1 ? num0 - 1 : 1; nonzero = nonzero_bits (XEXP (x, 0), mode); if (nonzero == 1) return bitwidth; if (num0 > 1 && (((HOST_WIDE_INT) 1 << (bitwidth - 1)) & nonzero)) num0--; return num0; case IOR: case AND: case XOR: case SMIN: case SMAX: case UMIN: case UMAX: /* Logical operations will preserve the number of sign-bit copies. MIN and MAX operations always return one of the operands. */ num0 = num_sign_bit_copies_with_known (XEXP (x, 0), mode); num1 = num_sign_bit_copies_with_known (XEXP (x, 1), mode); return MIN (num0, num1); case PLUS: case MINUS: /* For addition and subtraction, we can have a 1-bit carry. However, if we are subtracting 1 from a positive number, there will not be such a carry. Furthermore, if the positive number is known to be 0 or 1, we know the result is either -1 or 0. */ if (code == PLUS && XEXP (x, 1) == constm1_rtx && bitwidth <= HOST_BITS_PER_WIDE_INT) { nonzero = nonzero_bits (XEXP (x, 0), mode); if ((((HOST_WIDE_INT) 1 << (bitwidth - 1)) & nonzero) == 0) return (nonzero == 1 || nonzero == 0 ? bitwidth : bitwidth - floor_log2 (nonzero) - 1); } num0 = num_sign_bit_copies_with_known (XEXP (x, 0), mode); num1 = num_sign_bit_copies_with_known (XEXP (x, 1), mode); result = MAX (1, MIN (num0, num1) - 1); #ifdef POINTERS_EXTEND_UNSIGNED /* If pointers extend signed and this is an addition or subtraction to a pointer in Pmode, all the bits above ptr_mode are known to be sign bit copies. */ if (! POINTERS_EXTEND_UNSIGNED && GET_MODE (x) == Pmode && (code == PLUS || code == MINUS) && GET_CODE (XEXP (x, 0)) == REG && REG_POINTER (XEXP (x, 0))) result = MAX ((int) (GET_MODE_BITSIZE (Pmode) - GET_MODE_BITSIZE (ptr_mode) + 1), result); #endif return result; case MULT: /* The number of bits of the product is the sum of the number of bits of both terms. However, unless one of the terms if known to be positive, we must allow for an additional bit since negating a negative number can remove one sign bit copy. */ num0 = num_sign_bit_copies_with_known (XEXP (x, 0), mode); num1 = num_sign_bit_copies_with_known (XEXP (x, 1), mode); result = bitwidth - (bitwidth - num0) - (bitwidth - num1); if (result > 0 && (bitwidth > HOST_BITS_PER_WIDE_INT || (((nonzero_bits (XEXP (x, 0), mode) & ((HOST_WIDE_INT) 1 << (bitwidth - 1))) != 0) && ((nonzero_bits (XEXP (x, 1), mode) & ((HOST_WIDE_INT) 1 << (bitwidth - 1))) != 0)))) result--; return MAX (1, result); case UDIV: /* The result must be <= the first operand. If the first operand has the high bit set, we know nothing about the number of sign bit copies. */ if (bitwidth > HOST_BITS_PER_WIDE_INT) return 1; else if ((nonzero_bits (XEXP (x, 0), mode) & ((HOST_WIDE_INT) 1 << (bitwidth - 1))) != 0) return 1; else return num_sign_bit_copies_with_known (XEXP (x, 0), mode); case UMOD: /* The result must be <= the second operand. */ return num_sign_bit_copies_with_known (XEXP (x, 1), mode); case DIV: /* Similar to unsigned division, except that we have to worry about the case where the divisor is negative, in which case we have to add 1. */ result = num_sign_bit_copies_with_known (XEXP (x, 0), mode); if (result > 1 && (bitwidth > HOST_BITS_PER_WIDE_INT || (nonzero_bits (XEXP (x, 1), mode) & ((HOST_WIDE_INT) 1 << (bitwidth - 1))) != 0)) result--; return result; case MOD: result = num_sign_bit_copies_with_known (XEXP (x, 1), mode); if (result > 1 && (bitwidth > HOST_BITS_PER_WIDE_INT || (nonzero_bits (XEXP (x, 1), mode) & ((HOST_WIDE_INT) 1 << (bitwidth - 1))) != 0)) result--; return result; case ASHIFTRT: /* Shifts by a constant add to the number of bits equal to the sign bit. */ num0 = num_sign_bit_copies_with_known (XEXP (x, 0), mode); if (GET_CODE (XEXP (x, 1)) == CONST_INT && INTVAL (XEXP (x, 1)) > 0) num0 = MIN ((int) bitwidth, num0 + INTVAL (XEXP (x, 1))); return num0; case ASHIFT: /* Left shifts destroy copies. */ if (GET_CODE (XEXP (x, 1)) != CONST_INT || INTVAL (XEXP (x, 1)) < 0 || INTVAL (XEXP (x, 1)) >= (int) bitwidth) return 1; num0 = num_sign_bit_copies_with_known (XEXP (x, 0), mode); return MAX (1, num0 - INTVAL (XEXP (x, 1))); case IF_THEN_ELSE: num0 = num_sign_bit_copies_with_known (XEXP (x, 1), mode); num1 = num_sign_bit_copies_with_known (XEXP (x, 2), mode); return MIN (num0, num1); case EQ: case NE: case GE: case GT: case LE: case LT: case UNEQ: case LTGT: case UNGE: case UNGT: case UNLE: case UNLT: case GEU: case GTU: case LEU: case LTU: case UNORDERED: case ORDERED: /* If the constant is negative, take its 1's complement and remask. Then see how many zero bits we have. */ nonzero = STORE_FLAG_VALUE; if (bitwidth <= HOST_BITS_PER_WIDE_INT && (nonzero & ((HOST_WIDE_INT) 1 << (bitwidth - 1))) != 0) nonzero = (~nonzero) & GET_MODE_MASK (mode); return (nonzero == 0 ? bitwidth : bitwidth - floor_log2 (nonzero) - 1); break; default: break; } /* If we haven't been able to figure it out by one of the above rules, see if some of the high-order bits are known to be zero. If so, count those bits and return one less than that amount. If we can't safely compute the mask for this mode, always return BITWIDTH. */ if (bitwidth > HOST_BITS_PER_WIDE_INT) return 1; nonzero = nonzero_bits (x, mode); return (nonzero & ((HOST_WIDE_INT) 1 << (bitwidth - 1)) ? 1 : bitwidth - floor_log2 (nonzero) - 1); } /* Return the number of "extended" bits there are in X, when interpreted as a quantity in MODE whose signedness is indicated by UNSIGNEDP. For unsigned quantities, this is the number of high-order zero bits. For signed quantities, this is the number of copies of the sign bit minus 1. In both case, this function returns the number of "spare" bits. For example, if two quantities for which this function returns at least 1 are added, the addition is known not to overflow. This function will always return 0 unless called during combine, which implies that it must be called from a define_split. */ unsigned int extended_count (x, mode, unsignedp) rtx x; enum machine_mode mode; int unsignedp; { if (nonzero_sign_valid == 0) return 0; return (unsignedp ? (GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT ? (unsigned int) (GET_MODE_BITSIZE (mode) - 1 - floor_log2 (nonzero_bits (x, mode))) : 0) : num_sign_bit_copies (x, mode) - 1); } /* This function is called from `simplify_shift_const' to merge two outer operations. Specifically, we have already found that we need to perform operation *POP0 with constant *PCONST0 at the outermost position. We would now like to also perform OP1 with constant CONST1 (with *POP0 being done last). Return 1 if we can do the operation and update *POP0 and *PCONST0 with the resulting operation. *PCOMP_P is set to 1 if we would need to complement the innermost operand, otherwise it is unchanged. MODE is the mode in which the operation will be done. No bits outside the width of this mode matter. It is assumed that the width of this mode is smaller than or equal to HOST_BITS_PER_WIDE_INT. If *POP0 or OP1 are NIL, it means no operation is required. Only NEG, PLUS, IOR, XOR, and AND are supported. We may set *POP0 to SET if the proper result is simply *PCONST0. If the resulting operation cannot be expressed as one operation, we return 0 and do not change *POP0, *PCONST0, and *PCOMP_P. */ static int merge_outer_ops (pop0, pconst0, op1, const1, mode, pcomp_p) enum rtx_code *pop0; HOST_WIDE_INT *pconst0; enum rtx_code op1; HOST_WIDE_INT const1; enum machine_mode mode; int *pcomp_p; { enum rtx_code op0 = *pop0; HOST_WIDE_INT const0 = *pconst0; const0 &= GET_MODE_MASK (mode); const1 &= GET_MODE_MASK (mode); /* If OP0 is an AND, clear unimportant bits in CONST1. */ if (op0 == AND) const1 &= const0; /* If OP0 or OP1 is NIL, this is easy. Similarly if they are the same or if OP0 is SET. */ if (op1 == NIL || op0 == SET) return 1; else if (op0 == NIL) op0 = op1, const0 = const1; else if (op0 == op1) { switch (op0) { case AND: const0 &= const1; break; case IOR: const0 |= const1; break; case XOR: const0 ^= const1; break; case PLUS: const0 += const1; break; case NEG: op0 = NIL; break; default: break; } } /* Otherwise, if either is a PLUS or NEG, we can't do anything. */ else if (op0 == PLUS || op1 == PLUS || op0 == NEG || op1 == NEG) return 0; /* If the two constants aren't the same, we can't do anything. The remaining six cases can all be done. */ else if (const0 != const1) return 0; else switch (op0) { case IOR: if (op1 == AND) /* (a & b) | b == b */ op0 = SET; else /* op1 == XOR */ /* (a ^ b) | b == a | b */ {;} break; case XOR: if (op1 == AND) /* (a & b) ^ b == (~a) & b */ op0 = AND, *pcomp_p = 1; else /* op1 == IOR */ /* (a | b) ^ b == a & ~b */ op0 = AND, const0 = ~const0; break; case AND: if (op1 == IOR) /* (a | b) & b == b */ op0 = SET; else /* op1 == XOR */ /* (a ^ b) & b) == (~a) & b */ *pcomp_p = 1; break; default: break; } /* Check for NO-OP cases. */ const0 &= GET_MODE_MASK (mode); if (const0 == 0 && (op0 == IOR || op0 == XOR || op0 == PLUS)) op0 = NIL; else if (const0 == 0 && op0 == AND) op0 = SET; else if ((unsigned HOST_WIDE_INT) const0 == GET_MODE_MASK (mode) && op0 == AND) op0 = NIL; /* ??? Slightly redundant with the above mask, but not entirely. Moving this above means we'd have to sign-extend the mode mask for the final test. */ const0 = trunc_int_for_mode (const0, mode); *pop0 = op0; *pconst0 = const0; return 1; } /* Simplify a shift of VAROP by COUNT bits. CODE says what kind of shift. The result of the shift is RESULT_MODE. X, if nonzero, is an expression that we started with. The shift is normally computed in the widest mode we find in VAROP, as long as it isn't a different number of words than RESULT_MODE. Exceptions are ASHIFTRT and ROTATE, which are always done in their original mode, */ static rtx simplify_shift_const (x, code, result_mode, varop, orig_count) rtx x; enum rtx_code code; enum machine_mode result_mode; rtx varop; int orig_count; { enum rtx_code orig_code = code; unsigned int count; int signed_count; enum machine_mode mode = result_mode; enum machine_mode shift_mode, tmode; unsigned int mode_words = (GET_MODE_SIZE (mode) + (UNITS_PER_WORD - 1)) / UNITS_PER_WORD; /* We form (outer_op (code varop count) (outer_const)). */ enum rtx_code outer_op = NIL; HOST_WIDE_INT outer_const = 0; rtx const_rtx; int complement_p = 0; rtx new; /* Make sure and truncate the "natural" shift on the way in. We don't want to do this inside the loop as it makes it more difficult to combine shifts. */ #ifdef SHIFT_COUNT_TRUNCATED if (SHIFT_COUNT_TRUNCATED) orig_count &= GET_MODE_BITSIZE (mode) - 1; #endif /* If we were given an invalid count, don't do anything except exactly what was requested. */ if (orig_count < 0 || orig_count >= (int) GET_MODE_BITSIZE (mode)) { if (x) return x; return gen_rtx_fmt_ee (code, mode, varop, GEN_INT (orig_count)); } count = orig_count; /* Unless one of the branches of the `if' in this loop does a `continue', we will `break' the loop after the `if'. */ while (count != 0) { /* If we have an operand of (clobber (const_int 0)), just return that value. */ if (GET_CODE (varop) == CLOBBER) return varop; /* If we discovered we had to complement VAROP, leave. Making a NOT here would cause an infinite loop. */ if (complement_p) break; /* Convert ROTATERT to ROTATE. */ if (code == ROTATERT) { unsigned int bitsize = GET_MODE_BITSIZE (result_mode);; code = ROTATE; if (VECTOR_MODE_P (result_mode)) count = bitsize / GET_MODE_NUNITS (result_mode) - count; else count = bitsize - count; } /* We need to determine what mode we will do the shift in. If the shift is a right shift or a ROTATE, we must always do it in the mode it was originally done in. Otherwise, we can do it in MODE, the widest mode encountered. */ shift_mode = (code == ASHIFTRT || code == LSHIFTRT || code == ROTATE ? result_mode : mode); /* Handle cases where the count is greater than the size of the mode minus 1. For ASHIFT, use the size minus one as the count (this can occur when simplifying (lshiftrt (ashiftrt ..))). For rotates, take the count modulo the size. For other shifts, the result is zero. Since these shifts are being produced by the compiler by combining multiple operations, each of which are defined, we know what the result is supposed to be. */ if (count > (unsigned int) (GET_MODE_BITSIZE (shift_mode) - 1)) { if (code == ASHIFTRT) count = GET_MODE_BITSIZE (shift_mode) - 1; else if (code == ROTATE || code == ROTATERT) count %= GET_MODE_BITSIZE (shift_mode); else { /* We can't simply return zero because there may be an outer op. */ varop = const0_rtx; count = 0; break; } } /* An arithmetic right shift of a quantity known to be -1 or 0 is a no-op. */ if (code == ASHIFTRT && (num_sign_bit_copies (varop, shift_mode) == GET_MODE_BITSIZE (shift_mode))) { count = 0; break; } /* If we are doing an arithmetic right shift and discarding all but the sign bit copies, this is equivalent to doing a shift by the bitsize minus one. Convert it into that shift because it will often allow other simplifications. */ if (code == ASHIFTRT && (count + num_sign_bit_copies (varop, shift_mode) >= GET_MODE_BITSIZE (shift_mode))) count = GET_MODE_BITSIZE (shift_mode) - 1; /* We simplify the tests below and elsewhere by converting ASHIFTRT to LSHIFTRT if we know the sign bit is clear. `make_compound_operation' will convert it to an ASHIFTRT for those machines (such as VAX) that don't have an LSHIFTRT. */ if (GET_MODE_BITSIZE (shift_mode) <= HOST_BITS_PER_WIDE_INT && code == ASHIFTRT && ((nonzero_bits (varop, shift_mode) & ((HOST_WIDE_INT) 1 << (GET_MODE_BITSIZE (shift_mode) - 1))) == 0)) code = LSHIFTRT; if (code == LSHIFTRT && GET_MODE_BITSIZE (shift_mode) <= HOST_BITS_PER_WIDE_INT && !(nonzero_bits (varop, shift_mode) >> count)) varop = const0_rtx; if (code == ASHIFT && GET_MODE_BITSIZE (shift_mode) <= HOST_BITS_PER_WIDE_INT && !((nonzero_bits (varop, shift_mode) << count) & GET_MODE_MASK (shift_mode))) varop = const0_rtx; switch (GET_CODE (varop)) { case SIGN_EXTEND: case ZERO_EXTEND: case SIGN_EXTRACT: case ZERO_EXTRACT: new = expand_compound_operation (varop); if (new != varop) { varop = new; continue; } break; case MEM: /* If we have (xshiftrt (mem ...) C) and C is MODE_WIDTH minus the width of a smaller mode, we can do this with a SIGN_EXTEND or ZERO_EXTEND from the narrower memory location. */ if ((code == ASHIFTRT || code == LSHIFTRT) && ! mode_dependent_address_p (XEXP (varop, 0)) && ! MEM_VOLATILE_P (varop) && (tmode = mode_for_size (GET_MODE_BITSIZE (mode) - count, MODE_INT, 1)) != BLKmode) { new = adjust_address_nv (varop, tmode, BYTES_BIG_ENDIAN ? 0 : count / BITS_PER_UNIT); varop = gen_rtx_fmt_e (code == ASHIFTRT ? SIGN_EXTEND : ZERO_EXTEND, mode, new); count = 0; continue; } break; case USE: /* Similar to the case above, except that we can only do this if the resulting mode is the same as that of the underlying MEM and adjust the address depending on the *bits* endianness because of the way that bit-field extract insns are defined. */ if ((code == ASHIFTRT || code == LSHIFTRT) && (tmode = mode_for_size (GET_MODE_BITSIZE (mode) - count, MODE_INT, 1)) != BLKmode && tmode == GET_MODE (XEXP (varop, 0))) { if (BITS_BIG_ENDIAN) new = XEXP (varop, 0); else { new = copy_rtx (XEXP (varop, 0)); SUBST (XEXP (new, 0), plus_constant (XEXP (new, 0), count / BITS_PER_UNIT)); } varop = gen_rtx_fmt_e (code == ASHIFTRT ? SIGN_EXTEND : ZERO_EXTEND, mode, new); count = 0; continue; } break; case SUBREG: /* If VAROP is a SUBREG, strip it as long as the inner operand has the same number of words as what we've seen so far. Then store the widest mode in MODE. */ if (subreg_lowpart_p (varop) && (GET_MODE_SIZE (GET_MODE (SUBREG_REG (varop))) > GET_MODE_SIZE (GET_MODE (varop))) && (unsigned int) ((GET_MODE_SIZE (GET_MODE (SUBREG_REG (varop))) + (UNITS_PER_WORD - 1)) / UNITS_PER_WORD) == mode_words) { varop = SUBREG_REG (varop); if (GET_MODE_SIZE (GET_MODE (varop)) > GET_MODE_SIZE (mode)) mode = GET_MODE (varop); continue; } break; case MULT: /* Some machines use MULT instead of ASHIFT because MULT is cheaper. But it is still better on those machines to merge two shifts into one. */ if (GET_CODE (XEXP (varop, 1)) == CONST_INT && exact_log2 (INTVAL (XEXP (varop, 1))) >= 0) { varop = gen_binary (ASHIFT, GET_MODE (varop), XEXP (varop, 0), GEN_INT (exact_log2 (INTVAL (XEXP (varop, 1))))); continue; } break; case UDIV: /* Similar, for when divides are cheaper. */ if (GET_CODE (XEXP (varop, 1)) == CONST_INT && exact_log2 (INTVAL (XEXP (varop, 1))) >= 0) { varop = gen_binary (LSHIFTRT, GET_MODE (varop), XEXP (varop, 0), GEN_INT (exact_log2 (INTVAL (XEXP (varop, 1))))); continue; } break; case ASHIFTRT: /* If we are extracting just the sign bit of an arithmetic right shift, that shift is not needed. However, the sign bit of a wider mode may be different from what would be interpreted as the sign bit in a narrower mode, so, if the result is narrower, don't discard the shift. */ if (code == LSHIFTRT && count == (unsigned int) (GET_MODE_BITSIZE (result_mode) - 1) && (GET_MODE_BITSIZE (result_mode) >= GET_MODE_BITSIZE (GET_MODE (varop)))) { varop = XEXP (varop, 0); continue; } /* ... fall through ... */ case LSHIFTRT: case ASHIFT: case ROTATE: /* Here we have two nested shifts. The result is usually the AND of a new shift with a mask. We compute the result below. */ if (GET_CODE (XEXP (varop, 1)) == CONST_INT && INTVAL (XEXP (varop, 1)) >= 0 && INTVAL (XEXP (varop, 1)) < GET_MODE_BITSIZE (GET_MODE (varop)) && GET_MODE_BITSIZE (result_mode) <= HOST_BITS_PER_WIDE_INT && GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT) { enum rtx_code first_code = GET_CODE (varop); unsigned int first_count = INTVAL (XEXP (varop, 1)); unsigned HOST_WIDE_INT mask; rtx mask_rtx; /* We have one common special case. We can't do any merging if the inner code is an ASHIFTRT of a smaller mode. However, if we have (ashift:M1 (subreg:M1 (ashiftrt:M2 FOO C1) 0) C2) with C2 == GET_MODE_BITSIZE (M1) - GET_MODE_BITSIZE (M2), we can convert it to (ashiftrt:M1 (ashift:M1 (and:M1 (subreg:M1 FOO 0 C2) C3) C1). This simplifies certain SIGN_EXTEND operations. */ if (code == ASHIFT && first_code == ASHIFTRT && count == (unsigned int) (GET_MODE_BITSIZE (result_mode) - GET_MODE_BITSIZE (GET_MODE (varop)))) { /* C3 has the low-order C1 bits zero. */ mask = (GET_MODE_MASK (mode) & ~(((HOST_WIDE_INT) 1 << first_count) - 1)); varop = simplify_and_const_int (NULL_RTX, result_mode, XEXP (varop, 0), mask); varop = simplify_shift_const (NULL_RTX, ASHIFT, result_mode, varop, count); count = first_count; code = ASHIFTRT; continue; } /* If this was (ashiftrt (ashift foo C1) C2) and FOO has more than C1 high-order bits equal to the sign bit, we can convert this to either an ASHIFT or an ASHIFTRT depending on the two counts. We cannot do this if VAROP's mode is not SHIFT_MODE. */ if (code == ASHIFTRT && first_code == ASHIFT && GET_MODE (varop) == shift_mode && (num_sign_bit_copies (XEXP (varop, 0), shift_mode) > first_count)) { varop = XEXP (varop, 0); signed_count = count - first_count; if (signed_count < 0) count = -signed_count, code = ASHIFT; else count = signed_count; continue; } /* There are some cases we can't do. If CODE is ASHIFTRT, we can only do this if FIRST_CODE is also ASHIFTRT. We can't do the case when CODE is ROTATE and FIRST_CODE is ASHIFTRT. If the mode of this shift is not the mode of the outer shift, we can't do this if either shift is a right shift or ROTATE. Finally, we can't do any of these if the mode is too wide unless the codes are the same. Handle the case where the shift codes are the same first. */ if (code == first_code) { if (GET_MODE (varop) != result_mode && (code == ASHIFTRT || code == LSHIFTRT || code == ROTATE)) break; count += first_count; varop = XEXP (varop, 0); continue; } if (code == ASHIFTRT || (code == ROTATE && first_code == ASHIFTRT) || GET_MODE_BITSIZE (mode) > HOST_BITS_PER_WIDE_INT || (GET_MODE (varop) != result_mode && (first_code == ASHIFTRT || first_code == LSHIFTRT || first_code == ROTATE || code == ROTATE))) break; /* To compute the mask to apply after the shift, shift the nonzero bits of the inner shift the same way the outer shift will. */ mask_rtx = GEN_INT (nonzero_bits (varop, GET_MODE (varop))); mask_rtx = simplify_binary_operation (code, result_mode, mask_rtx, GEN_INT (count)); /* Give up if we can't compute an outer operation to use. */ if (mask_rtx == 0 || GET_CODE (mask_rtx) != CONST_INT || ! merge_outer_ops (&outer_op, &outer_const, AND, INTVAL (mask_rtx), result_mode, &complement_p)) break; /* If the shifts are in the same direction, we add the counts. Otherwise, we subtract them. */ signed_count = count; if ((code == ASHIFTRT || code == LSHIFTRT) == (first_code == ASHIFTRT || first_code == LSHIFTRT)) signed_count += first_count; else signed_count -= first_count; /* If COUNT is positive, the new shift is usually CODE, except for the two exceptions below, in which case it is FIRST_CODE. If the count is negative, FIRST_CODE should always be used */ if (signed_count > 0 && ((first_code == ROTATE && code == ASHIFT) || (first_code == ASHIFTRT && code == LSHIFTRT))) code = first_code, count = signed_count; else if (signed_count < 0) code = first_code, count = -signed_count; else count = signed_count; varop = XEXP (varop, 0); continue; } /* If we have (A << B << C) for any shift, we can convert this to (A << C << B). This wins if A is a constant. Only try this if B is not a constant. */ else if (GET_CODE (varop) == code && GET_CODE (XEXP (varop, 1)) != CONST_INT && 0 != (new = simplify_binary_operation (code, mode, XEXP (varop, 0), GEN_INT (count)))) { varop = gen_rtx_fmt_ee (code, mode, new, XEXP (varop, 1)); count = 0; continue; } break; case NOT: /* Make this fit the case below. */ varop = gen_rtx_XOR (mode, XEXP (varop, 0), GEN_INT (GET_MODE_MASK (mode))); continue; case IOR: case AND: case XOR: /* If we have (xshiftrt (ior (plus X (const_int -1)) X) C) with C the size of VAROP - 1 and the shift is logical if STORE_FLAG_VALUE is 1 and arithmetic if STORE_FLAG_VALUE is -1, we have an (le X 0) operation. If we have an arithmetic shift and STORE_FLAG_VALUE is 1 or we have a logical shift with STORE_FLAG_VALUE of -1, we have a (neg (le X 0)) operation. */ if (GET_CODE (varop) == IOR && GET_CODE (XEXP (varop, 0)) == PLUS && XEXP (XEXP (varop, 0), 1) == constm1_rtx && (STORE_FLAG_VALUE == 1 || STORE_FLAG_VALUE == -1) && (code == LSHIFTRT || code == ASHIFTRT) && count == (unsigned int) (GET_MODE_BITSIZE (GET_MODE (varop)) - 1) && rtx_equal_p (XEXP (XEXP (varop, 0), 0), XEXP (varop, 1))) { count = 0; varop = gen_rtx_LE (GET_MODE (varop), XEXP (varop, 1), const0_rtx); if (STORE_FLAG_VALUE == 1 ? code == ASHIFTRT : code == LSHIFTRT) varop = gen_rtx_NEG (GET_MODE (varop), varop); continue; } /* If we have (shift (logical)), move the logical to the outside to allow it to possibly combine with another logical and the shift to combine with another shift. This also canonicalizes to what a ZERO_EXTRACT looks like. Also, some machines have (and (shift)) insns. */ if (GET_CODE (XEXP (varop, 1)) == CONST_INT && (new = simplify_binary_operation (code, result_mode, XEXP (varop, 1), GEN_INT (count))) != 0 && GET_CODE (new) == CONST_INT && merge_outer_ops (&outer_op, &outer_const, GET_CODE (varop), INTVAL (new), result_mode, &complement_p)) { varop = XEXP (varop, 0); continue; } /* If we can't do that, try to simplify the shift in each arm of the logical expression, make a new logical expression, and apply the inverse distributive law. */ { rtx lhs = simplify_shift_const (NULL_RTX, code, shift_mode, XEXP (varop, 0), count); rtx rhs = simplify_shift_const (NULL_RTX, code, shift_mode, XEXP (varop, 1), count); varop = gen_binary (GET_CODE (varop), shift_mode, lhs, rhs); varop = apply_distributive_law (varop); count = 0; } break; case EQ: /* convert (lshiftrt (eq FOO 0) C) to (xor FOO 1) if STORE_FLAG_VALUE says that the sign bit can be tested, FOO has mode MODE, C is GET_MODE_BITSIZE (MODE) - 1, and FOO has only its low-order bit that may be nonzero. */ if (code == LSHIFTRT && XEXP (varop, 1) == const0_rtx && GET_MODE (XEXP (varop, 0)) == result_mode && count == (unsigned int) (GET_MODE_BITSIZE (result_mode) - 1) && GET_MODE_BITSIZE (result_mode) <= HOST_BITS_PER_WIDE_INT && ((STORE_FLAG_VALUE & ((HOST_WIDE_INT) 1 < (GET_MODE_BITSIZE (result_mode) - 1)))) && nonzero_bits (XEXP (varop, 0), result_mode) == 1 && merge_outer_ops (&outer_op, &outer_const, XOR, (HOST_WIDE_INT) 1, result_mode, &complement_p)) { varop = XEXP (varop, 0); count = 0; continue; } break; case NEG: /* (lshiftrt (neg A) C) where A is either 0 or 1 and C is one less than the number of bits in the mode is equivalent to A. */ if (code == LSHIFTRT && count == (unsigned int) (GET_MODE_BITSIZE (result_mode) - 1) && nonzero_bits (XEXP (varop, 0), result_mode) == 1) { varop = XEXP (varop, 0); count = 0; continue; } /* NEG commutes with ASHIFT since it is multiplication. Move the NEG outside to allow shifts to combine. */ if (code == ASHIFT && merge_outer_ops (&outer_op, &outer_const, NEG, (HOST_WIDE_INT) 0, result_mode, &complement_p)) { varop = XEXP (varop, 0); continue; } break; case PLUS: /* (lshiftrt (plus A -1) C) where A is either 0 or 1 and C is one less than the number of bits in the mode is equivalent to (xor A 1). */ if (code == LSHIFTRT && count == (unsigned int) (GET_MODE_BITSIZE (result_mode) - 1) && XEXP (varop, 1) == constm1_rtx && nonzero_bits (XEXP (varop, 0), result_mode) == 1 && merge_outer_ops (&outer_op, &outer_const, XOR, (HOST_WIDE_INT) 1, result_mode, &complement_p)) { count = 0; varop = XEXP (varop, 0); continue; } /* If we have (xshiftrt (plus FOO BAR) C), and the only bits that might be nonzero in BAR are those being shifted out and those bits are known zero in FOO, we can replace the PLUS with FOO. Similarly in the other operand order. This code occurs when we are computing the size of a variable-size array. */ if ((code == ASHIFTRT || code == LSHIFTRT) && count < HOST_BITS_PER_WIDE_INT && nonzero_bits (XEXP (varop, 1), result_mode) >> count == 0 && (nonzero_bits (XEXP (varop, 1), result_mode) & nonzero_bits (XEXP (varop, 0), result_mode)) == 0) { varop = XEXP (varop, 0); continue; } else if ((code == ASHIFTRT || code == LSHIFTRT) && count < HOST_BITS_PER_WIDE_INT && GET_MODE_BITSIZE (result_mode) <= HOST_BITS_PER_WIDE_INT && 0 == (nonzero_bits (XEXP (varop, 0), result_mode) >> count) && 0 == (nonzero_bits (XEXP (varop, 0), result_mode) & nonzero_bits (XEXP (varop, 1), result_mode))) { varop = XEXP (varop, 1); continue; } /* (ashift (plus foo C) N) is (plus (ashift foo N) C'). */ if (code == ASHIFT && GET_CODE (XEXP (varop, 1)) == CONST_INT && (new = simplify_binary_operation (ASHIFT, result_mode, XEXP (varop, 1), GEN_INT (count))) != 0 && GET_CODE (new) == CONST_INT && merge_outer_ops (&outer_op, &outer_const, PLUS, INTVAL (new), result_mode, &complement_p)) { varop = XEXP (varop, 0); continue; } break; case MINUS: /* If we have (xshiftrt (minus (ashiftrt X C)) X) C) with C the size of VAROP - 1 and the shift is logical if STORE_FLAG_VALUE is 1 and arithmetic if STORE_FLAG_VALUE is -1, we have a (gt X 0) operation. If the shift is arithmetic with STORE_FLAG_VALUE of 1 or logical with STORE_FLAG_VALUE == -1, we have a (neg (gt X 0)) operation. */ if ((STORE_FLAG_VALUE == 1 || STORE_FLAG_VALUE == -1) && GET_CODE (XEXP (varop, 0)) == ASHIFTRT && count == (unsigned int) (GET_MODE_BITSIZE (GET_MODE (varop)) - 1) && (code == LSHIFTRT || code == ASHIFTRT) && GET_CODE (XEXP (XEXP (varop, 0), 1)) == CONST_INT && (unsigned HOST_WIDE_INT) INTVAL (XEXP (XEXP (varop, 0), 1)) == count && rtx_equal_p (XEXP (XEXP (varop, 0), 0), XEXP (varop, 1))) { count = 0; varop = gen_rtx_GT (GET_MODE (varop), XEXP (varop, 1), const0_rtx); if (STORE_FLAG_VALUE == 1 ? code == ASHIFTRT : code == LSHIFTRT) varop = gen_rtx_NEG (GET_MODE (varop), varop); continue; } break; case TRUNCATE: /* Change (lshiftrt (truncate (lshiftrt))) to (truncate (lshiftrt)) if the truncate does not affect the value. */ if (code == LSHIFTRT && GET_CODE (XEXP (varop, 0)) == LSHIFTRT && GET_CODE (XEXP (XEXP (varop, 0), 1)) == CONST_INT && (INTVAL (XEXP (XEXP (varop, 0), 1)) >= (GET_MODE_BITSIZE (GET_MODE (XEXP (varop, 0))) - GET_MODE_BITSIZE (GET_MODE (varop))))) { rtx varop_inner = XEXP (varop, 0); varop_inner = gen_rtx_LSHIFTRT (GET_MODE (varop_inner), XEXP (varop_inner, 0), GEN_INT (count + INTVAL (XEXP (varop_inner, 1)))); varop = gen_rtx_TRUNCATE (GET_MODE (varop), varop_inner); count = 0; continue; } break; default: break; } break; } /* We need to determine what mode to do the shift in. If the shift is a right shift or ROTATE, we must always do it in the mode it was originally done in. Otherwise, we can do it in MODE, the widest mode encountered. The code we care about is that of the shift that will actually be done, not the shift that was originally requested. */ shift_mode = (code == ASHIFTRT || code == LSHIFTRT || code == ROTATE ? result_mode : mode); /* We have now finished analyzing the shift. The result should be a shift of type CODE with SHIFT_MODE shifting VAROP COUNT places. If OUTER_OP is non-NIL, it is an operation that needs to be applied to the result of the shift. OUTER_CONST is the relevant constant, but we must turn off all bits turned off in the shift. If we were passed a value for X, see if we can use any pieces of it. If not, make new rtx. */ if (x && GET_RTX_CLASS (GET_CODE (x)) == '2' && GET_CODE (XEXP (x, 1)) == CONST_INT && (unsigned HOST_WIDE_INT) INTVAL (XEXP (x, 1)) == count) const_rtx = XEXP (x, 1); else const_rtx = GEN_INT (count); if (x && GET_CODE (XEXP (x, 0)) == SUBREG && GET_MODE (XEXP (x, 0)) == shift_mode && SUBREG_REG (XEXP (x, 0)) == varop) varop = XEXP (x, 0); else if (GET_MODE (varop) != shift_mode) varop = gen_lowpart_for_combine (shift_mode, varop); /* If we can't make the SUBREG, try to return what we were given. */ if (GET_CODE (varop) == CLOBBER) return x ? x : varop; new = simplify_binary_operation (code, shift_mode, varop, const_rtx); if (new != 0) x = new; else x = gen_rtx_fmt_ee (code, shift_mode, varop, const_rtx); /* If we have an outer operation and we just made a shift, it is possible that we could have simplified the shift were it not for the outer operation. So try to do the simplification recursively. */ if (outer_op != NIL && GET_CODE (x) == code && GET_CODE (XEXP (x, 1)) == CONST_INT) x = simplify_shift_const (x, code, shift_mode, XEXP (x, 0), INTVAL (XEXP (x, 1))); /* If we were doing an LSHIFTRT in a wider mode than it was originally, turn off all the bits that the shift would have turned off. */ if (orig_code == LSHIFTRT && result_mode != shift_mode) x = simplify_and_const_int (NULL_RTX, shift_mode, x, GET_MODE_MASK (result_mode) >> orig_count); /* Do the remainder of the processing in RESULT_MODE. */ x = gen_lowpart_for_combine (result_mode, x); /* If COMPLEMENT_P is set, we have to complement X before doing the outer operation. */ if (complement_p) x = simplify_gen_unary (NOT, result_mode, x, result_mode); if (outer_op != NIL) { if (GET_MODE_BITSIZE (result_mode) < HOST_BITS_PER_WIDE_INT) outer_const = trunc_int_for_mode (outer_const, result_mode); if (outer_op == AND) x = simplify_and_const_int (NULL_RTX, result_mode, x, outer_const); else if (outer_op == SET) /* This means that we have determined that the result is equivalent to a constant. This should be rare. */ x = GEN_INT (outer_const); else if (GET_RTX_CLASS (outer_op) == '1') x = simplify_gen_unary (outer_op, result_mode, x, result_mode); else x = gen_binary (outer_op, result_mode, x, GEN_INT (outer_const)); } return x; } /* Like recog, but we receive the address of a pointer to a new pattern. We try to match the rtx that the pointer points to. If that fails, we may try to modify or replace the pattern, storing the replacement into the same pointer object. Modifications include deletion or addition of CLOBBERs. PNOTES is a pointer to a location where any REG_UNUSED notes added for the CLOBBERs are placed. The value is the final insn code from the pattern ultimately matched, or -1. */ static int recog_for_combine (pnewpat, insn, pnotes) rtx *pnewpat; rtx insn; rtx *pnotes; { rtx pat = *pnewpat; int insn_code_number; int num_clobbers_to_add = 0; int i; rtx notes = 0; rtx dummy_insn; /* If PAT is a PARALLEL, check to see if it contains the CLOBBER we use to indicate that something didn't match. If we find such a thing, force rejection. */ if (GET_CODE (pat) == PARALLEL) for (i = XVECLEN (pat, 0) - 1; i >= 0; i--) if (GET_CODE (XVECEXP (pat, 0, i)) == CLOBBER && XEXP (XVECEXP (pat, 0, i), 0) == const0_rtx) return -1; /* *pnewpat does not have to be actual PATTERN (insn), so make a dummy instruction for pattern recognition. */ dummy_insn = shallow_copy_rtx (insn); PATTERN (dummy_insn) = pat; REG_NOTES (dummy_insn) = 0; insn_code_number = recog (pat, dummy_insn, &num_clobbers_to_add); /* If it isn't, there is the possibility that we previously had an insn that clobbered some register as a side effect, but the combined insn doesn't need to do that. So try once more without the clobbers unless this represents an ASM insn. */ if (insn_code_number < 0 && ! check_asm_operands (pat) && GET_CODE (pat) == PARALLEL) { int pos; for (pos = 0, i = 0; i < XVECLEN (pat, 0); i++) if (GET_CODE (XVECEXP (pat, 0, i)) != CLOBBER) { if (i != pos) SUBST (XVECEXP (pat, 0, pos), XVECEXP (pat, 0, i)); pos++; } SUBST_INT (XVECLEN (pat, 0), pos); if (pos == 1) pat = XVECEXP (pat, 0, 0); PATTERN (dummy_insn) = pat; insn_code_number = recog (pat, dummy_insn, &num_clobbers_to_add); } /* Recognize all noop sets, these will be killed by followup pass. */ if (insn_code_number < 0 && GET_CODE (pat) == SET && set_noop_p (pat)) insn_code_number = NOOP_MOVE_INSN_CODE, num_clobbers_to_add = 0; /* If we had any clobbers to add, make a new pattern than contains them. Then check to make sure that all of them are dead. */ if (num_clobbers_to_add) { rtx newpat = gen_rtx_PARALLEL (VOIDmode, rtvec_alloc (GET_CODE (pat) == PARALLEL ? (XVECLEN (pat, 0) + num_clobbers_to_add) : num_clobbers_to_add + 1)); if (GET_CODE (pat) == PARALLEL) for (i = 0; i < XVECLEN (pat, 0); i++) XVECEXP (newpat, 0, i) = XVECEXP (pat, 0, i); else XVECEXP (newpat, 0, 0) = pat; add_clobbers (newpat, insn_code_number); for (i = XVECLEN (newpat, 0) - num_clobbers_to_add; i < XVECLEN (newpat, 0); i++) { if (GET_CODE (XEXP (XVECEXP (newpat, 0, i), 0)) == REG && ! reg_dead_at_p (XEXP (XVECEXP (newpat, 0, i), 0), insn)) return -1; notes = gen_rtx_EXPR_LIST (REG_UNUSED, XEXP (XVECEXP (newpat, 0, i), 0), notes); } pat = newpat; } *pnewpat = pat; *pnotes = notes; return insn_code_number; } /* Like gen_lowpart but for use by combine. In combine it is not possible to create any new pseudoregs. However, it is safe to create invalid memory addresses, because combine will try to recognize them and all they will do is make the combine attempt fail. If for some reason this cannot do its job, an rtx (clobber (const_int 0)) is returned. An insn containing that will not be recognized. */ #undef gen_lowpart static rtx gen_lowpart_for_combine (mode, x) enum machine_mode mode; rtx x; { rtx result; if (GET_MODE (x) == mode) return x; /* Return identity if this is a CONST or symbolic reference. */ if (mode == Pmode && (GET_CODE (x) == CONST || GET_CODE (x) == SYMBOL_REF || GET_CODE (x) == LABEL_REF)) return x; /* We can only support MODE being wider than a word if X is a constant integer or has a mode the same size. */ if (GET_MODE_SIZE (mode) > UNITS_PER_WORD && ! ((GET_MODE (x) == VOIDmode && (GET_CODE (x) == CONST_INT || GET_CODE (x) == CONST_DOUBLE)) || GET_MODE_SIZE (GET_MODE (x)) == GET_MODE_SIZE (mode))) return gen_rtx_CLOBBER (GET_MODE (x), const0_rtx); /* X might be a paradoxical (subreg (mem)). In that case, gen_lowpart won't know what to do. So we will strip off the SUBREG here and process normally. */ if (GET_CODE (x) == SUBREG && GET_CODE (SUBREG_REG (x)) == MEM) { x = SUBREG_REG (x); if (GET_MODE (x) == mode) return x; } result = gen_lowpart_common (mode, x); #ifdef CANNOT_CHANGE_MODE_CLASS if (result != 0 && GET_CODE (result) == SUBREG && GET_CODE (SUBREG_REG (result)) == REG && REGNO (SUBREG_REG (result)) >= FIRST_PSEUDO_REGISTER) bitmap_set_bit (&subregs_of_mode, REGNO (SUBREG_REG (result)) * MAX_MACHINE_MODE + GET_MODE (result)); #endif if (result) return result; if (GET_CODE (x) == MEM) { int offset = 0; /* Refuse to work on a volatile memory ref or one with a mode-dependent address. */ if (MEM_VOLATILE_P (x) || mode_dependent_address_p (XEXP (x, 0))) return gen_rtx_CLOBBER (GET_MODE (x), const0_rtx); /* If we want to refer to something bigger than the original memref, generate a perverse subreg instead. That will force a reload of the original memref X. */ if (GET_MODE_SIZE (GET_MODE (x)) < GET_MODE_SIZE (mode)) return gen_rtx_SUBREG (mode, x, 0); if (WORDS_BIG_ENDIAN) offset = (MAX (GET_MODE_SIZE (GET_MODE (x)), UNITS_PER_WORD) - MAX (GET_MODE_SIZE (mode), UNITS_PER_WORD)); if (BYTES_BIG_ENDIAN) { /* Adjust the address so that the address-after-the-data is unchanged. */ offset -= (MIN (UNITS_PER_WORD, GET_MODE_SIZE (mode)) - MIN (UNITS_PER_WORD, GET_MODE_SIZE (GET_MODE (x)))); } return adjust_address_nv (x, mode, offset); } /* If X is a comparison operator, rewrite it in a new mode. This probably won't match, but may allow further simplifications. */ else if (GET_RTX_CLASS (GET_CODE (x)) == '<') return gen_rtx_fmt_ee (GET_CODE (x), mode, XEXP (x, 0), XEXP (x, 1)); /* If we couldn't simplify X any other way, just enclose it in a SUBREG. Normally, this SUBREG won't match, but some patterns may include an explicit SUBREG or we may simplify it further in combine. */ else { int offset = 0; rtx res; enum machine_mode sub_mode = GET_MODE (x); offset = subreg_lowpart_offset (mode, sub_mode); if (sub_mode == VOIDmode) { sub_mode = int_mode_for_mode (mode); x = gen_lowpart_common (sub_mode, x); if (x == 0) return gen_rtx_CLOBBER (VOIDmode, const0_rtx); } res = simplify_gen_subreg (mode, x, sub_mode, offset); if (res) return res; return gen_rtx_CLOBBER (GET_MODE (x), const0_rtx); } } /* These routines make binary and unary operations by first seeing if they fold; if not, a new expression is allocated. */ static rtx gen_binary (code, mode, op0, op1) enum rtx_code code; enum machine_mode mode; rtx op0, op1; { rtx result; rtx tem; if (GET_RTX_CLASS (code) == 'c' && swap_commutative_operands_p (op0, op1)) tem = op0, op0 = op1, op1 = tem; if (GET_RTX_CLASS (code) == '<') { enum machine_mode op_mode = GET_MODE (op0); /* Strip the COMPARE from (REL_OP (compare X Y) 0) to get just (REL_OP X Y). */ if (GET_CODE (op0) == COMPARE && op1 == const0_rtx) { op1 = XEXP (op0, 1); op0 = XEXP (op0, 0); op_mode = GET_MODE (op0); } if (op_mode == VOIDmode) op_mode = GET_MODE (op1); result = simplify_relational_operation (code, op_mode, op0, op1); } else result = simplify_binary_operation (code, mode, op0, op1); if (result) return result; /* Put complex operands first and constants second. */ if (GET_RTX_CLASS (code) == 'c' && swap_commutative_operands_p (op0, op1)) return gen_rtx_fmt_ee (code, mode, op1, op0); /* If we are turning off bits already known off in OP0, we need not do an AND. */ else if (code == AND && GET_CODE (op1) == CONST_INT && GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT && (nonzero_bits (op0, mode) & ~INTVAL (op1)) == 0) return op0; return gen_rtx_fmt_ee (code, mode, op0, op1); } /* Simplify a comparison between *POP0 and *POP1 where CODE is the comparison code that will be tested. The result is a possibly different comparison code to use. *POP0 and *POP1 may be updated. It is possible that we might detect that a comparison is either always true or always false. However, we do not perform general constant folding in combine, so this knowledge isn't useful. Such tautologies should have been detected earlier. Hence we ignore all such cases. */ static enum rtx_code simplify_comparison (code, pop0, pop1) enum rtx_code code; rtx *pop0; rtx *pop1; { rtx op0 = *pop0; rtx op1 = *pop1; rtx tem, tem1; int i; enum machine_mode mode, tmode; /* Try a few ways of applying the same transformation to both operands. */ while (1) { #ifndef WORD_REGISTER_OPERATIONS /* The test below this one won't handle SIGN_EXTENDs on these machines, so check specially. */ if (code != GTU && code != GEU && code != LTU && code != LEU && GET_CODE (op0) == ASHIFTRT && GET_CODE (op1) == ASHIFTRT && GET_CODE (XEXP (op0, 0)) == ASHIFT && GET_CODE (XEXP (op1, 0)) == ASHIFT && GET_CODE (XEXP (XEXP (op0, 0), 0)) == SUBREG && GET_CODE (XEXP (XEXP (op1, 0), 0)) == SUBREG && (GET_MODE (SUBREG_REG (XEXP (XEXP (op0, 0), 0))) == GET_MODE (SUBREG_REG (XEXP (XEXP (op1, 0), 0)))) && GET_CODE (XEXP (op0, 1)) == CONST_INT && GET_CODE (XEXP (op1, 1)) == CONST_INT && GET_CODE (XEXP (XEXP (op0, 0), 1)) == CONST_INT && GET_CODE (XEXP (XEXP (op1, 0), 1)) == CONST_INT && INTVAL (XEXP (op0, 1)) == INTVAL (XEXP (op1, 1)) && INTVAL (XEXP (op0, 1)) == INTVAL (XEXP (XEXP (op0, 0), 1)) && INTVAL (XEXP (op0, 1)) == INTVAL (XEXP (XEXP (op1, 0), 1)) && (INTVAL (XEXP (op0, 1)) == (GET_MODE_BITSIZE (GET_MODE (op0)) - (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (XEXP (XEXP (op0, 0), 0)))))))) { op0 = SUBREG_REG (XEXP (XEXP (op0, 0), 0)); op1 = SUBREG_REG (XEXP (XEXP (op1, 0), 0)); } #endif /* If both operands are the same constant shift, see if we can ignore the shift. We can if the shift is a rotate or if the bits shifted out of this shift are known to be zero for both inputs and if the type of comparison is compatible with the shift. */ if (GET_CODE (op0) == GET_CODE (op1) && GET_MODE_BITSIZE (GET_MODE (op0)) <= HOST_BITS_PER_WIDE_INT && ((GET_CODE (op0) == ROTATE && (code == NE || code == EQ)) || ((GET_CODE (op0) == LSHIFTRT || GET_CODE (op0) == ASHIFT) && (code != GT && code != LT && code != GE && code != LE)) || (GET_CODE (op0) == ASHIFTRT && (code != GTU && code != LTU && code != GEU && code != LEU))) && GET_CODE (XEXP (op0, 1)) == CONST_INT && INTVAL (XEXP (op0, 1)) >= 0 && INTVAL (XEXP (op0, 1)) < HOST_BITS_PER_WIDE_INT && XEXP (op0, 1) == XEXP (op1, 1)) { enum machine_mode mode = GET_MODE (op0); unsigned HOST_WIDE_INT mask = GET_MODE_MASK (mode); int shift_count = INTVAL (XEXP (op0, 1)); if (GET_CODE (op0) == LSHIFTRT || GET_CODE (op0) == ASHIFTRT) mask &= (mask >> shift_count) << shift_count; else if (GET_CODE (op0) == ASHIFT) mask = (mask & (mask << shift_count)) >> shift_count; if ((nonzero_bits (XEXP (op0, 0), mode) & ~mask) == 0 && (nonzero_bits (XEXP (op1, 0), mode) & ~mask) == 0) op0 = XEXP (op0, 0), op1 = XEXP (op1, 0); else break; } /* If both operands are AND's of a paradoxical SUBREG by constant, the SUBREGs are of the same mode, and, in both cases, the AND would be redundant if the comparison was done in the narrower mode, do the comparison in the narrower mode (e.g., we are AND'ing with 1 and the operand's possibly nonzero bits are 0xffffff01; in that case if we only care about QImode, we don't need the AND). This case occurs if the output mode of an scc insn is not SImode and STORE_FLAG_VALUE == 1 (e.g., the 386). Similarly, check for a case where the AND's are ZERO_EXTEND operations from some narrower mode even though a SUBREG is not present. */ else if (GET_CODE (op0) == AND && GET_CODE (op1) == AND && GET_CODE (XEXP (op0, 1)) == CONST_INT && GET_CODE (XEXP (op1, 1)) == CONST_INT) { rtx inner_op0 = XEXP (op0, 0); rtx inner_op1 = XEXP (op1, 0); HOST_WIDE_INT c0 = INTVAL (XEXP (op0, 1)); HOST_WIDE_INT c1 = INTVAL (XEXP (op1, 1)); int changed = 0; if (GET_CODE (inner_op0) == SUBREG && GET_CODE (inner_op1) == SUBREG && (GET_MODE_SIZE (GET_MODE (inner_op0)) > GET_MODE_SIZE (GET_MODE (SUBREG_REG (inner_op0)))) && (GET_MODE (SUBREG_REG (inner_op0)) == GET_MODE (SUBREG_REG (inner_op1))) && (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (inner_op0))) <= HOST_BITS_PER_WIDE_INT) && (0 == ((~c0) & nonzero_bits (SUBREG_REG (inner_op0), GET_MODE (SUBREG_REG (inner_op0))))) && (0 == ((~c1) & nonzero_bits (SUBREG_REG (inner_op1), GET_MODE (SUBREG_REG (inner_op1)))))) { op0 = SUBREG_REG (inner_op0); op1 = SUBREG_REG (inner_op1); /* The resulting comparison is always unsigned since we masked off the original sign bit. */ code = unsigned_condition (code); changed = 1; } else if (c0 == c1) for (tmode = GET_CLASS_NARROWEST_MODE (GET_MODE_CLASS (GET_MODE (op0))); tmode != GET_MODE (op0); tmode = GET_MODE_WIDER_MODE (tmode)) if ((unsigned HOST_WIDE_INT) c0 == GET_MODE_MASK (tmode)) { op0 = gen_lowpart_for_combine (tmode, inner_op0); op1 = gen_lowpart_for_combine (tmode, inner_op1); code = unsigned_condition (code); changed = 1; break; } if (! changed) break; } /* If both operands are NOT, we can strip off the outer operation and adjust the comparison code for swapped operands; similarly for NEG, except that this must be an equality comparison. */ else if ((GET_CODE (op0) == NOT && GET_CODE (op1) == NOT) || (GET_CODE (op0) == NEG && GET_CODE (op1) == NEG && (code == EQ || code == NE))) op0 = XEXP (op0, 0), op1 = XEXP (op1, 0), code = swap_condition (code); else break; } /* If the first operand is a constant, swap the operands and adjust the comparison code appropriately, but don't do this if the second operand is already a constant integer. */ if (swap_commutative_operands_p (op0, op1)) { tem = op0, op0 = op1, op1 = tem; code = swap_condition (code); } /* We now enter a loop during which we will try to simplify the comparison. For the most part, we only are concerned with comparisons with zero, but some things may really be comparisons with zero but not start out looking that way. */ while (GET_CODE (op1) == CONST_INT) { enum machine_mode mode = GET_MODE (op0); unsigned int mode_width = GET_MODE_BITSIZE (mode); unsigned HOST_WIDE_INT mask = GET_MODE_MASK (mode); int equality_comparison_p; int sign_bit_comparison_p; int unsigned_comparison_p; HOST_WIDE_INT const_op; /* We only want to handle integral modes. This catches VOIDmode, CCmode, and the floating-point modes. An exception is that we can handle VOIDmode if OP0 is a COMPARE or a comparison operation. */ if (GET_MODE_CLASS (mode) != MODE_INT && ! (mode == VOIDmode && (GET_CODE (op0) == COMPARE || GET_RTX_CLASS (GET_CODE (op0)) == '<'))) break; /* Get the constant we are comparing against and turn off all bits not on in our mode. */ const_op = INTVAL (op1); if (mode != VOIDmode) const_op = trunc_int_for_mode (const_op, mode); op1 = GEN_INT (const_op); /* If we are comparing against a constant power of two and the value being compared can only have that single bit nonzero (e.g., it was `and'ed with that bit), we can replace this with a comparison with zero. */ if (const_op && (code == EQ || code == NE || code == GE || code == GEU || code == LT || code == LTU) && mode_width <= HOST_BITS_PER_WIDE_INT && exact_log2 (const_op) >= 0 && nonzero_bits (op0, mode) == (unsigned HOST_WIDE_INT) const_op) { code = (code == EQ || code == GE || code == GEU ? NE : EQ); op1 = const0_rtx, const_op = 0; } /* Similarly, if we are comparing a value known to be either -1 or 0 with -1, change it to the opposite comparison against zero. */ if (const_op == -1 && (code == EQ || code == NE || code == GT || code == LE || code == GEU || code == LTU) && num_sign_bit_copies (op0, mode) == mode_width) { code = (code == EQ || code == LE || code == GEU ? NE : EQ); op1 = const0_rtx, const_op = 0; } /* Do some canonicalizations based on the comparison code. We prefer comparisons against zero and then prefer equality comparisons. If we can reduce the size of a constant, we will do that too. */ switch (code) { case LT: /* < C is equivalent to <= (C - 1) */ if (const_op > 0) { const_op -= 1; op1 = GEN_INT (const_op); code = LE; /* ... fall through to LE case below. */ } else break; case LE: /* <= C is equivalent to < (C + 1); we do this for C < 0 */ if (const_op < 0) { const_op += 1; op1 = GEN_INT (const_op); code = LT; } /* If we are doing a <= 0 comparison on a value known to have a zero sign bit, we can replace this with == 0. */ else if (const_op == 0 && mode_width <= HOST_BITS_PER_WIDE_INT && (nonzero_bits (op0, mode) & ((HOST_WIDE_INT) 1 << (mode_width - 1))) == 0) code = EQ; break; case GE: /* >= C is equivalent to > (C - 1). */ if (const_op > 0) { const_op -= 1; op1 = GEN_INT (const_op); code = GT; /* ... fall through to GT below. */ } else break; case GT: /* > C is equivalent to >= (C + 1); we do this for C < 0. */ if (const_op < 0) { const_op += 1; op1 = GEN_INT (const_op); code = GE; } /* If we are doing a > 0 comparison on a value known to have a zero sign bit, we can replace this with != 0. */ else if (const_op == 0 && mode_width <= HOST_BITS_PER_WIDE_INT && (nonzero_bits (op0, mode) & ((HOST_WIDE_INT) 1 << (mode_width - 1))) == 0) code = NE; break; case LTU: /* < C is equivalent to <= (C - 1). */ if (const_op > 0) { const_op -= 1; op1 = GEN_INT (const_op); code = LEU; /* ... fall through ... */ } /* (unsigned) < 0x80000000 is equivalent to >= 0. */ else if ((mode_width <= HOST_BITS_PER_WIDE_INT) && (const_op == (HOST_WIDE_INT) 1 << (mode_width - 1))) { const_op = 0, op1 = const0_rtx; code = GE; break; } else break; case LEU: /* unsigned <= 0 is equivalent to == 0 */ if (const_op == 0) code = EQ; /* (unsigned) <= 0x7fffffff is equivalent to >= 0. */ else if ((mode_width <= HOST_BITS_PER_WIDE_INT) && (const_op == ((HOST_WIDE_INT) 1 << (mode_width - 1)) - 1)) { const_op = 0, op1 = const0_rtx; code = GE; } break; case GEU: /* >= C is equivalent to < (C - 1). */ if (const_op > 1) { const_op -= 1; op1 = GEN_INT (const_op); code = GTU; /* ... fall through ... */ } /* (unsigned) >= 0x80000000 is equivalent to < 0. */ else if ((mode_width <= HOST_BITS_PER_WIDE_INT) && (const_op == (HOST_WIDE_INT) 1 << (mode_width - 1))) { const_op = 0, op1 = const0_rtx; code = LT; break; } else break; case GTU: /* unsigned > 0 is equivalent to != 0 */ if (const_op == 0) code = NE; /* (unsigned) > 0x7fffffff is equivalent to < 0. */ else if ((mode_width <= HOST_BITS_PER_WIDE_INT) && (const_op == ((HOST_WIDE_INT) 1 << (mode_width - 1)) - 1)) { const_op = 0, op1 = const0_rtx; code = LT; } break; default: break; } /* Compute some predicates to simplify code below. */ equality_comparison_p = (code == EQ || code == NE); sign_bit_comparison_p = ((code == LT || code == GE) && const_op == 0); unsigned_comparison_p = (code == LTU || code == LEU || code == GTU || code == GEU); /* If this is a sign bit comparison and we can do arithmetic in MODE, say that we will only be needing the sign bit of OP0. */ if (sign_bit_comparison_p && GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT) op0 = force_to_mode (op0, mode, ((HOST_WIDE_INT) 1 << (GET_MODE_BITSIZE (mode) - 1)), NULL_RTX, 0); /* Now try cases based on the opcode of OP0. If none of the cases does a "continue", we exit this loop immediately after the switch. */ switch (GET_CODE (op0)) { case ZERO_EXTRACT: /* If we are extracting a single bit from a variable position in a constant that has only a single bit set and are comparing it with zero, we can convert this into an equality comparison between the position and the location of the single bit. */ if (GET_CODE (XEXP (op0, 0)) == CONST_INT && XEXP (op0, 1) == const1_rtx && equality_comparison_p && const_op == 0 && (i = exact_log2 (INTVAL (XEXP (op0, 0)))) >= 0) { if (BITS_BIG_ENDIAN) { enum machine_mode new_mode = mode_for_extraction (EP_extzv, 1); if (new_mode == MAX_MACHINE_MODE) i = BITS_PER_WORD - 1 - i; else { mode = new_mode; i = (GET_MODE_BITSIZE (mode) - 1 - i); } } op0 = XEXP (op0, 2); op1 = GEN_INT (i); const_op = i; /* Result is nonzero iff shift count is equal to I. */ code = reverse_condition (code); continue; } /* ... fall through ... */ case SIGN_EXTRACT: tem = expand_compound_operation (op0); if (tem != op0) { op0 = tem; continue; } break; case NOT: /* If testing for equality, we can take the NOT of the constant. */ if (equality_comparison_p && (tem = simplify_unary_operation (NOT, mode, op1, mode)) != 0) { op0 = XEXP (op0, 0); op1 = tem; continue; } /* If just looking at the sign bit, reverse the sense of the comparison. */ if (sign_bit_comparison_p) { op0 = XEXP (op0, 0); code = (code == GE ? LT : GE); continue; } break; case NEG: /* If testing for equality, we can take the NEG of the constant. */ if (equality_comparison_p && (tem = simplify_unary_operation (NEG, mode, op1, mode)) != 0) { op0 = XEXP (op0, 0); op1 = tem; continue; } /* The remaining cases only apply to comparisons with zero. */ if (const_op != 0) break; /* When X is ABS or is known positive, (neg X) is < 0 if and only if X != 0. */ if (sign_bit_comparison_p && (GET_CODE (XEXP (op0, 0)) == ABS || (mode_width <= HOST_BITS_PER_WIDE_INT && (nonzero_bits (XEXP (op0, 0), mode) & ((HOST_WIDE_INT) 1 << (mode_width - 1))) == 0))) { op0 = XEXP (op0, 0); code = (code == LT ? NE : EQ); continue; } /* If we have NEG of something whose two high-order bits are the same, we know that "(-a) < 0" is equivalent to "a > 0". */ if (num_sign_bit_copies (op0, mode) >= 2) { op0 = XEXP (op0, 0); code = swap_condition (code); continue; } break; case ROTATE: /* If we are testing equality and our count is a constant, we can perform the inverse operation on our RHS. */ if (equality_comparison_p && GET_CODE (XEXP (op0, 1)) == CONST_INT && (tem = simplify_binary_operation (ROTATERT, mode, op1, XEXP (op0, 1))) != 0) { op0 = XEXP (op0, 0); op1 = tem; continue; } /* If we are doing a < 0 or >= 0 comparison, it means we are testing a particular bit. Convert it to an AND of a constant of that bit. This will be converted into a ZERO_EXTRACT. */ if (const_op == 0 && sign_bit_comparison_p && GET_CODE (XEXP (op0, 1)) == CONST_INT && mode_width <= HOST_BITS_PER_WIDE_INT) { op0 = simplify_and_const_int (NULL_RTX, mode, XEXP (op0, 0), ((HOST_WIDE_INT) 1 << (mode_width - 1 - INTVAL (XEXP (op0, 1))))); code = (code == LT ? NE : EQ); continue; } /* Fall through. */ case ABS: /* ABS is ignorable inside an equality comparison with zero. */ if (const_op == 0 && equality_comparison_p) { op0 = XEXP (op0, 0); continue; } break; case SIGN_EXTEND: /* Can simplify (compare (zero/sign_extend FOO) CONST) to (compare FOO CONST) if CONST fits in FOO's mode and we are either testing inequality or have an unsigned comparison with ZERO_EXTEND or a signed comparison with SIGN_EXTEND. */ if (! unsigned_comparison_p && (GET_MODE_BITSIZE (GET_MODE (XEXP (op0, 0))) <= HOST_BITS_PER_WIDE_INT) && ((unsigned HOST_WIDE_INT) const_op < (((unsigned HOST_WIDE_INT) 1 << (GET_MODE_BITSIZE (GET_MODE (XEXP (op0, 0))) - 1))))) { op0 = XEXP (op0, 0); continue; } break; case SUBREG: /* Check for the case where we are comparing A - C1 with C2, both constants are smaller than 1/2 the maximum positive value in MODE, and the comparison is equality or unsigned. In that case, if A is either zero-extended to MODE or has sufficient sign bits so that the high-order bit in MODE is a copy of the sign in the inner mode, we can prove that it is safe to do the operation in the wider mode. This simplifies many range checks. */ if (mode_width <= HOST_BITS_PER_WIDE_INT && subreg_lowpart_p (op0) && GET_CODE (SUBREG_REG (op0)) == PLUS && GET_CODE (XEXP (SUBREG_REG (op0), 1)) == CONST_INT && INTVAL (XEXP (SUBREG_REG (op0), 1)) < 0 && (-INTVAL (XEXP (SUBREG_REG (op0), 1)) < (HOST_WIDE_INT) (GET_MODE_MASK (mode) / 2)) && (unsigned HOST_WIDE_INT) const_op < GET_MODE_MASK (mode) / 2 && (0 == (nonzero_bits (XEXP (SUBREG_REG (op0), 0), GET_MODE (SUBREG_REG (op0))) & ~GET_MODE_MASK (mode)) || (num_sign_bit_copies (XEXP (SUBREG_REG (op0), 0), GET_MODE (SUBREG_REG (op0))) > (unsigned int) (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (op0))) - GET_MODE_BITSIZE (mode))))) { op0 = SUBREG_REG (op0); continue; } /* If the inner mode is narrower and we are extracting the low part, we can treat the SUBREG as if it were a ZERO_EXTEND. */ if (subreg_lowpart_p (op0) && GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (op0))) < mode_width) /* Fall through */ ; else break; /* ... fall through ... */ case ZERO_EXTEND: if ((unsigned_comparison_p || equality_comparison_p) && (GET_MODE_BITSIZE (GET_MODE (XEXP (op0, 0))) <= HOST_BITS_PER_WIDE_INT) && ((unsigned HOST_WIDE_INT) const_op < GET_MODE_MASK (GET_MODE (XEXP (op0, 0))))) { op0 = XEXP (op0, 0); continue; } break; case PLUS: /* (eq (plus X A) B) -> (eq X (minus B A)). We can only do this for equality comparisons due to pathological cases involving overflows. */ if (equality_comparison_p && 0 != (tem = simplify_binary_operation (MINUS, mode, op1, XEXP (op0, 1)))) { op0 = XEXP (op0, 0); op1 = tem; continue; } /* (plus (abs X) (const_int -1)) is < 0 if and only if X == 0. */ if (const_op == 0 && XEXP (op0, 1) == constm1_rtx && GET_CODE (XEXP (op0, 0)) == ABS && sign_bit_comparison_p) { op0 = XEXP (XEXP (op0, 0), 0); code = (code == LT ? EQ : NE); continue; } break; case MINUS: /* We used to optimize signed comparisons against zero, but that was incorrect. Unsigned comparisons against zero (GTU, LEU) arrive here as equality comparisons, or (GEU, LTU) are optimized away. No need to special-case them. */ /* (eq (minus A B) C) -> (eq A (plus B C)) or (eq B (minus A C)), whichever simplifies. We can only do this for equality comparisons due to pathological cases involving overflows. */ if (equality_comparison_p && 0 != (tem = simplify_binary_operation (PLUS, mode, XEXP (op0, 1), op1))) { op0 = XEXP (op0, 0); op1 = tem; continue; } if (equality_comparison_p && 0 != (tem = simplify_binary_operation (MINUS, mode, XEXP (op0, 0), op1))) { op0 = XEXP (op0, 1); op1 = tem; continue; } /* The sign bit of (minus (ashiftrt X C) X), where C is the number of bits in X minus 1, is one iff X > 0. */ if (sign_bit_comparison_p && GET_CODE (XEXP (op0, 0)) == ASHIFTRT && GET_CODE (XEXP (XEXP (op0, 0), 1)) == CONST_INT && (unsigned HOST_WIDE_INT) INTVAL (XEXP (XEXP (op0, 0), 1)) == mode_width - 1 && rtx_equal_p (XEXP (XEXP (op0, 0), 0), XEXP (op0, 1))) { op0 = XEXP (op0, 1); code = (code == GE ? LE : GT); continue; } break; case XOR: /* (eq (xor A B) C) -> (eq A (xor B C)). This is a simplification if C is zero or B is a constant. */ if (equality_comparison_p && 0 != (tem = simplify_binary_operation (XOR, mode, XEXP (op0, 1), op1))) { op0 = XEXP (op0, 0); op1 = tem; continue; } break; case EQ: case NE: case UNEQ: case LTGT: case LT: case LTU: case UNLT: case LE: case LEU: case UNLE: case GT: case GTU: case UNGT: case GE: case GEU: case UNGE: case UNORDERED: case ORDERED: /* We can't do anything if OP0 is a condition code value, rather than an actual data value. */ if (const_op != 0 || CC0_P (XEXP (op0, 0)) || GET_MODE_CLASS (GET_MODE (XEXP (op0, 0))) == MODE_CC) break; /* Get the two operands being compared. */ if (GET_CODE (XEXP (op0, 0)) == COMPARE) tem = XEXP (XEXP (op0, 0), 0), tem1 = XEXP (XEXP (op0, 0), 1); else tem = XEXP (op0, 0), tem1 = XEXP (op0, 1); /* Check for the cases where we simply want the result of the earlier test or the opposite of that result. */ if (code == NE || code == EQ || (GET_MODE_BITSIZE (GET_MODE (op0)) <= HOST_BITS_PER_WIDE_INT && GET_MODE_CLASS (GET_MODE (op0)) == MODE_INT && (STORE_FLAG_VALUE & (((HOST_WIDE_INT) 1 << (GET_MODE_BITSIZE (GET_MODE (op0)) - 1)))) && (code == LT || code == GE))) { enum rtx_code new_code; if (code == LT || code == NE) new_code = GET_CODE (op0); else new_code = combine_reversed_comparison_code (op0); if (new_code != UNKNOWN) { code = new_code; op0 = tem; op1 = tem1; continue; } } break; case IOR: /* The sign bit of (ior (plus X (const_int -1)) X) is nonzero iff X <= 0. */ if (sign_bit_comparison_p && GET_CODE (XEXP (op0, 0)) == PLUS && XEXP (XEXP (op0, 0), 1) == constm1_rtx && rtx_equal_p (XEXP (XEXP (op0, 0), 0), XEXP (op0, 1))) { op0 = XEXP (op0, 1); code = (code == GE ? GT : LE); continue; } break; case AND: /* Convert (and (xshift 1 X) Y) to (and (lshiftrt Y X) 1). This will be converted to a ZERO_EXTRACT later. */ if (const_op == 0 && equality_comparison_p && GET_CODE (XEXP (op0, 0)) == ASHIFT && XEXP (XEXP (op0, 0), 0) == const1_rtx) { op0 = simplify_and_const_int (op0, mode, gen_rtx_LSHIFTRT (mode, XEXP (op0, 1), XEXP (XEXP (op0, 0), 1)), (HOST_WIDE_INT) 1); continue; } /* If we are comparing (and (lshiftrt X C1) C2) for equality with zero and X is a comparison and C1 and C2 describe only bits set in STORE_FLAG_VALUE, we can compare with X. */ if (const_op == 0 && equality_comparison_p && mode_width <= HOST_BITS_PER_WIDE_INT && GET_CODE (XEXP (op0, 1)) == CONST_INT && GET_CODE (XEXP (op0, 0)) == LSHIFTRT && GET_CODE (XEXP (XEXP (op0, 0), 1)) == CONST_INT && INTVAL (XEXP (XEXP (op0, 0), 1)) >= 0 && INTVAL (XEXP (XEXP (op0, 0), 1)) < HOST_BITS_PER_WIDE_INT) { mask = ((INTVAL (XEXP (op0, 1)) & GET_MODE_MASK (mode)) << INTVAL (XEXP (XEXP (op0, 0), 1))); if ((~STORE_FLAG_VALUE & mask) == 0 && (GET_RTX_CLASS (GET_CODE (XEXP (XEXP (op0, 0), 0))) == '<' || ((tem = get_last_value (XEXP (XEXP (op0, 0), 0))) != 0 && GET_RTX_CLASS (GET_CODE (tem)) == '<'))) { op0 = XEXP (XEXP (op0, 0), 0); continue; } } /* If we are doing an equality comparison of an AND of a bit equal to the sign bit, replace this with a LT or GE comparison of the underlying value. */ if (equality_comparison_p && const_op == 0 && GET_CODE (XEXP (op0, 1)) == CONST_INT && mode_width <= HOST_BITS_PER_WIDE_INT && ((INTVAL (XEXP (op0, 1)) & GET_MODE_MASK (mode)) == (unsigned HOST_WIDE_INT) 1 << (mode_width - 1))) { op0 = XEXP (op0, 0); code = (code == EQ ? GE : LT); continue; } /* If this AND operation is really a ZERO_EXTEND from a narrower mode, the constant fits within that mode, and this is either an equality or unsigned comparison, try to do this comparison in the narrower mode. */ if ((equality_comparison_p || unsigned_comparison_p) && GET_CODE (XEXP (op0, 1)) == CONST_INT && (i = exact_log2 ((INTVAL (XEXP (op0, 1)) & GET_MODE_MASK (mode)) + 1)) >= 0 && const_op >> i == 0 && (tmode = mode_for_size (i, MODE_INT, 1)) != BLKmode) { op0 = gen_lowpart_for_combine (tmode, XEXP (op0, 0)); continue; } /* If this is (and:M1 (subreg:M2 X 0) (const_int C1)) where C1 fits in both M1 and M2 and the SUBREG is either paradoxical or represents the low part, permute the SUBREG and the AND and try again. */ if (GET_CODE (XEXP (op0, 0)) == SUBREG) { unsigned HOST_WIDE_INT c1; tmode = GET_MODE (SUBREG_REG (XEXP (op0, 0))); /* Require an integral mode, to avoid creating something like (AND:SF ...). */ if (SCALAR_INT_MODE_P (tmode) /* It is unsafe to commute the AND into the SUBREG if the SUBREG is paradoxical and WORD_REGISTER_OPERATIONS is not defined. As originally written the upper bits have a defined value due to the AND operation. However, if we commute the AND inside the SUBREG then they no longer have defined values and the meaning of the code has been changed. */ && (0 #ifdef WORD_REGISTER_OPERATIONS || (mode_width > GET_MODE_BITSIZE (tmode) && mode_width <= BITS_PER_WORD) #endif || (mode_width <= GET_MODE_BITSIZE (tmode) && subreg_lowpart_p (XEXP (op0, 0)))) && GET_CODE (XEXP (op0, 1)) == CONST_INT && mode_width <= HOST_BITS_PER_WIDE_INT && GET_MODE_BITSIZE (tmode) <= HOST_BITS_PER_WIDE_INT && ((c1 = INTVAL (XEXP (op0, 1))) & ~mask) == 0 && (c1 & ~GET_MODE_MASK (tmode)) == 0 && c1 != mask && c1 != GET_MODE_MASK (tmode)) { op0 = gen_binary (AND, tmode, SUBREG_REG (XEXP (op0, 0)), gen_int_mode (c1, tmode)); op0 = gen_lowpart_for_combine (mode, op0); continue; } } /* Convert (ne (and (lshiftrt (not X)) 1) 0) to (eq (and (lshiftrt X) 1) 0). */ if (const_op == 0 && equality_comparison_p && XEXP (op0, 1) == const1_rtx && GET_CODE (XEXP (op0, 0)) == LSHIFTRT && GET_CODE (XEXP (XEXP (op0, 0), 0)) == NOT) { op0 = simplify_and_const_int (op0, mode, gen_rtx_LSHIFTRT (mode, XEXP (XEXP (XEXP (op0, 0), 0), 0), XEXP (XEXP (op0, 0), 1)), (HOST_WIDE_INT) 1); code = (code == NE ? EQ : NE); continue; } break; case ASHIFT: /* If we have (compare (ashift FOO N) (const_int C)) and the high order N bits of FOO (N+1 if an inequality comparison) are known to be zero, we can do this by comparing FOO with C shifted right N bits so long as the low-order N bits of C are zero. */ if (GET_CODE (XEXP (op0, 1)) == CONST_INT && INTVAL (XEXP (op0, 1)) >= 0 && ((INTVAL (XEXP (op0, 1)) + ! equality_comparison_p) < HOST_BITS_PER_WIDE_INT) && ((const_op & (((HOST_WIDE_INT) 1 << INTVAL (XEXP (op0, 1))) - 1)) == 0) && mode_width <= HOST_BITS_PER_WIDE_INT && (nonzero_bits (XEXP (op0, 0), mode) & ~(mask >> (INTVAL (XEXP (op0, 1)) + ! equality_comparison_p))) == 0) { /* We must perform a logical shift, not an arithmetic one, as we want the top N bits of C to be zero. */ unsigned HOST_WIDE_INT temp = const_op & GET_MODE_MASK (mode); temp >>= INTVAL (XEXP (op0, 1)); op1 = gen_int_mode (temp, mode); op0 = XEXP (op0, 0); continue; } /* If we are doing a sign bit comparison, it means we are testing a particular bit. Convert it to the appropriate AND. */ if (sign_bit_comparison_p && GET_CODE (XEXP (op0, 1)) == CONST_INT && mode_width <= HOST_BITS_PER_WIDE_INT) { op0 = simplify_and_const_int (NULL_RTX, mode, XEXP (op0, 0), ((HOST_WIDE_INT) 1 << (mode_width - 1 - INTVAL (XEXP (op0, 1))))); code = (code == LT ? NE : EQ); continue; } /* If this an equality comparison with zero and we are shifting the low bit to the sign bit, we can convert this to an AND of the low-order bit. */ if (const_op == 0 && equality_comparison_p && GET_CODE (XEXP (op0, 1)) == CONST_INT && (unsigned HOST_WIDE_INT) INTVAL (XEXP (op0, 1)) == mode_width - 1) { op0 = simplify_and_const_int (NULL_RTX, mode, XEXP (op0, 0), (HOST_WIDE_INT) 1); continue; } break; case ASHIFTRT: /* If this is an equality comparison with zero, we can do this as a logical shift, which might be much simpler. */ if (equality_comparison_p && const_op == 0 && GET_CODE (XEXP (op0, 1)) == CONST_INT) { op0 = simplify_shift_const (NULL_RTX, LSHIFTRT, mode, XEXP (op0, 0), INTVAL (XEXP (op0, 1))); continue; } /* If OP0 is a sign extension and CODE is not an unsigned comparison, do the comparison in a narrower mode. */ if (! unsigned_comparison_p && GET_CODE (XEXP (op0, 1)) == CONST_INT && GET_CODE (XEXP (op0, 0)) == ASHIFT && XEXP (op0, 1) == XEXP (XEXP (op0, 0), 1) && (tmode = mode_for_size (mode_width - INTVAL (XEXP (op0, 1)), MODE_INT, 1)) != BLKmode && (((unsigned HOST_WIDE_INT) const_op + (GET_MODE_MASK (tmode) >> 1) + 1) <= GET_MODE_MASK (tmode))) { op0 = gen_lowpart_for_combine (tmode, XEXP (XEXP (op0, 0), 0)); continue; } /* Likewise if OP0 is a PLUS of a sign extension with a constant, which is usually represented with the PLUS between the shifts. */ if (! unsigned_comparison_p && GET_CODE (XEXP (op0, 1)) == CONST_INT && GET_CODE (XEXP (op0, 0)) == PLUS && GET_CODE (XEXP (XEXP (op0, 0), 1)) == CONST_INT && GET_CODE (XEXP (XEXP (op0, 0), 0)) == ASHIFT && XEXP (op0, 1) == XEXP (XEXP (XEXP (op0, 0), 0), 1) && (tmode = mode_for_size (mode_width - INTVAL (XEXP (op0, 1)), MODE_INT, 1)) != BLKmode && (((unsigned HOST_WIDE_INT) const_op + (GET_MODE_MASK (tmode) >> 1) + 1) <= GET_MODE_MASK (tmode))) { rtx inner = XEXP (XEXP (XEXP (op0, 0), 0), 0); rtx add_const = XEXP (XEXP (op0, 0), 1); rtx new_const = gen_binary (ASHIFTRT, GET_MODE (op0), add_const, XEXP (op0, 1)); op0 = gen_binary (PLUS, tmode, gen_lowpart_for_combine (tmode, inner), new_const); continue; } /* ... fall through ... */ case LSHIFTRT: /* If we have (compare (xshiftrt FOO N) (const_int C)) and the low order N bits of FOO are known to be zero, we can do this by comparing FOO with C shifted left N bits so long as no overflow occurs. */ if (GET_CODE (XEXP (op0, 1)) == CONST_INT && INTVAL (XEXP (op0, 1)) >= 0 && INTVAL (XEXP (op0, 1)) < HOST_BITS_PER_WIDE_INT && mode_width <= HOST_BITS_PER_WIDE_INT && (nonzero_bits (XEXP (op0, 0), mode) & (((HOST_WIDE_INT) 1 << INTVAL (XEXP (op0, 1))) - 1)) == 0 && (((unsigned HOST_WIDE_INT) const_op + (GET_CODE (op0) != LSHIFTRT ? ((GET_MODE_MASK (mode) >> INTVAL (XEXP (op0, 1)) >> 1) + 1) : 0)) <= GET_MODE_MASK (mode) >> INTVAL (XEXP (op0, 1)))) { /* If the shift was logical, then we must make the condition unsigned. */ if (GET_CODE (op0) == LSHIFTRT) code = unsigned_condition (code); const_op <<= INTVAL (XEXP (op0, 1)); op1 = GEN_INT (const_op); op0 = XEXP (op0, 0); continue; } /* If we are using this shift to extract just the sign bit, we can replace this with an LT or GE comparison. */ if (const_op == 0 && (equality_comparison_p || sign_bit_comparison_p) && GET_CODE (XEXP (op0, 1)) == CONST_INT && (unsigned HOST_WIDE_INT) INTVAL (XEXP (op0, 1)) == mode_width - 1) { op0 = XEXP (op0, 0); code = (code == NE || code == GT ? LT : GE); continue; } break; default: break; } break; } /* Now make any compound operations involved in this comparison. Then, check for an outmost SUBREG on OP0 that is not doing anything or is paradoxical. The latter transformation must only be performed when it is known that the "extra" bits will be the same in op0 and op1 or that they don't matter. There are three cases to consider: 1. SUBREG_REG (op0) is a register. In this case the bits are don't care bits and we can assume they have any convenient value. So making the transformation is safe. 2. SUBREG_REG (op0) is a memory and LOAD_EXTEND_OP is not defined. In this case the upper bits of op0 are undefined. We should not make the simplification in that case as we do not know the contents of those bits. 3. SUBREG_REG (op0) is a memory and LOAD_EXTEND_OP is defined and not NIL. In that case we know those bits are zeros or ones. We must also be sure that they are the same as the upper bits of op1. We can never remove a SUBREG for a non-equality comparison because the sign bit is in a different place in the underlying object. */ op0 = make_compound_operation (op0, op1 == const0_rtx ? COMPARE : SET); op1 = make_compound_operation (op1, SET); if (GET_CODE (op0) == SUBREG && subreg_lowpart_p (op0) /* Case 3 above, to sometimes allow (subreg (mem x)), isn't implemented. */ && GET_CODE (SUBREG_REG (op0)) == REG && GET_MODE_CLASS (GET_MODE (op0)) == MODE_INT && GET_MODE_CLASS (GET_MODE (SUBREG_REG (op0))) == MODE_INT && (code == NE || code == EQ)) { if (GET_MODE_SIZE (GET_MODE (op0)) > GET_MODE_SIZE (GET_MODE (SUBREG_REG (op0)))) { op0 = SUBREG_REG (op0); op1 = gen_lowpart_for_combine (GET_MODE (op0), op1); } else if ((GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (op0))) <= HOST_BITS_PER_WIDE_INT) && (nonzero_bits (SUBREG_REG (op0), GET_MODE (SUBREG_REG (op0))) & ~GET_MODE_MASK (GET_MODE (op0))) == 0) { tem = gen_lowpart_for_combine (GET_MODE (SUBREG_REG (op0)), op1); if ((nonzero_bits (tem, GET_MODE (SUBREG_REG (op0))) & ~GET_MODE_MASK (GET_MODE (op0))) == 0) op0 = SUBREG_REG (op0), op1 = tem; } } /* We now do the opposite procedure: Some machines don't have compare insns in all modes. If OP0's mode is an integer mode smaller than a word and we can't do a compare in that mode, see if there is a larger mode for which we can do the compare. There are a number of cases in which we can use the wider mode. */ mode = GET_MODE (op0); if (mode != VOIDmode && GET_MODE_CLASS (mode) == MODE_INT && GET_MODE_SIZE (mode) < UNITS_PER_WORD && ! have_insn_for (COMPARE, mode)) for (tmode = GET_MODE_WIDER_MODE (mode); (tmode != VOIDmode && GET_MODE_BITSIZE (tmode) <= HOST_BITS_PER_WIDE_INT); tmode = GET_MODE_WIDER_MODE (tmode)) if (have_insn_for (COMPARE, tmode)) { int zero_extended; /* If the only nonzero bits in OP0 and OP1 are those in the narrower mode and this is an equality or unsigned comparison, we can use the wider mode. Similarly for sign-extended values, in which case it is true for all comparisons. */ zero_extended = ((code == EQ || code == NE || code == GEU || code == GTU || code == LEU || code == LTU) && (nonzero_bits (op0, tmode) & ~GET_MODE_MASK (mode)) == 0 && ((GET_CODE (op1) == CONST_INT || (nonzero_bits (op1, tmode) & ~GET_MODE_MASK (mode)) == 0))); if (zero_extended || ((num_sign_bit_copies (op0, tmode) > (unsigned int) (GET_MODE_BITSIZE (tmode) - GET_MODE_BITSIZE (mode))) && (num_sign_bit_copies (op1, tmode) > (unsigned int) (GET_MODE_BITSIZE (tmode) - GET_MODE_BITSIZE (mode))))) { /* If OP0 is an AND and we don't have an AND in MODE either, make a new AND in the proper mode. */ if (GET_CODE (op0) == AND && !have_insn_for (AND, mode)) op0 = gen_binary (AND, tmode, gen_lowpart_for_combine (tmode, XEXP (op0, 0)), gen_lowpart_for_combine (tmode, XEXP (op0, 1))); op0 = gen_lowpart_for_combine (tmode, op0); if (zero_extended && GET_CODE (op1) == CONST_INT) op1 = GEN_INT (INTVAL (op1) & GET_MODE_MASK (mode)); op1 = gen_lowpart_for_combine (tmode, op1); break; } /* If this is a test for negative, we can make an explicit test of the sign bit. */ if (op1 == const0_rtx && (code == LT || code == GE) && GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT) { op0 = gen_binary (AND, tmode, gen_lowpart_for_combine (tmode, op0), GEN_INT ((HOST_WIDE_INT) 1 << (GET_MODE_BITSIZE (mode) - 1))); code = (code == LT) ? NE : EQ; break; } } #ifdef CANONICALIZE_COMPARISON /* If this machine only supports a subset of valid comparisons, see if we can convert an unsupported one into a supported one. */ CANONICALIZE_COMPARISON (code, op0, op1); #endif *pop0 = op0; *pop1 = op1; return code; } /* Like jump.c' reversed_comparison_code, but use combine infrastructure for searching backward. */ static enum rtx_code combine_reversed_comparison_code (exp) rtx exp; { enum rtx_code code1 = reversed_comparison_code (exp, NULL); rtx x; if (code1 != UNKNOWN || GET_MODE_CLASS (GET_MODE (XEXP (exp, 0))) != MODE_CC) return code1; /* Otherwise try and find where the condition codes were last set and use that. */ x = get_last_value (XEXP (exp, 0)); if (!x || GET_CODE (x) != COMPARE) return UNKNOWN; return reversed_comparison_code_parts (GET_CODE (exp), XEXP (x, 0), XEXP (x, 1), NULL); } /* Return comparison with reversed code of EXP and operands OP0 and OP1. Return NULL_RTX in case we fail to do the reversal. */ static rtx reversed_comparison (exp, mode, op0, op1) rtx exp, op0, op1; enum machine_mode mode; { enum rtx_code reversed_code = combine_reversed_comparison_code (exp); if (reversed_code == UNKNOWN) return NULL_RTX; else return gen_binary (reversed_code, mode, op0, op1); } /* Utility function for following routine. Called when X is part of a value being stored into reg_last_set_value. Sets reg_last_set_table_tick for each register mentioned. Similar to mention_regs in cse.c */ static void update_table_tick (x) rtx x; { enum rtx_code code = GET_CODE (x); const char *fmt = GET_RTX_FORMAT (code); int i; if (code == REG) { unsigned int regno = REGNO (x); unsigned int endregno = regno + (regno < FIRST_PSEUDO_REGISTER ? HARD_REGNO_NREGS (regno, GET_MODE (x)) : 1); unsigned int r; for (r = regno; r < endregno; r++) reg_last_set_table_tick[r] = label_tick; return; } for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) /* Note that we can't have an "E" in values stored; see get_last_value_validate. */ if (fmt[i] == 'e') { /* Check for identical subexpressions. If x contains identical subexpression we only have to traverse one of them. */ if (i == 0 && (GET_RTX_CLASS (code) == '2' || GET_RTX_CLASS (code) == 'c')) { /* Note that at this point x1 has already been processed. */ rtx x0 = XEXP (x, 0); rtx x1 = XEXP (x, 1); /* If x0 and x1 are identical then there is no need to process x0. */ if (x0 == x1) break; /* If x0 is identical to a subexpression of x1 then while processing x1, x0 has already been processed. Thus we are done with x. */ if ((GET_RTX_CLASS (GET_CODE (x1)) == '2' || GET_RTX_CLASS (GET_CODE (x1)) == 'c') && (x0 == XEXP (x1, 0) || x0 == XEXP (x1, 1))) break; /* If x1 is identical to a subexpression of x0 then we still have to process the rest of x0. */ if ((GET_RTX_CLASS (GET_CODE (x0)) == '2' || GET_RTX_CLASS (GET_CODE (x0)) == 'c') && (x1 == XEXP (x0, 0) || x1 == XEXP (x0, 1))) { update_table_tick (XEXP (x0, x1 == XEXP (x0, 0) ? 1 : 0)); break; } } update_table_tick (XEXP (x, i)); } } /* Record that REG is set to VALUE in insn INSN. If VALUE is zero, we are saying that the register is clobbered and we no longer know its value. If INSN is zero, don't update reg_last_set; this is only permitted with VALUE also zero and is used to invalidate the register. */ static void record_value_for_reg (reg, insn, value) rtx reg; rtx insn; rtx value; { unsigned int regno = REGNO (reg); unsigned int endregno = regno + (regno < FIRST_PSEUDO_REGISTER ? HARD_REGNO_NREGS (regno, GET_MODE (reg)) : 1); unsigned int i; /* If VALUE contains REG and we have a previous value for REG, substitute the previous value. */ if (value && insn && reg_overlap_mentioned_p (reg, value)) { rtx tem; /* Set things up so get_last_value is allowed to see anything set up to our insn. */ subst_low_cuid = INSN_CUID (insn); tem = get_last_value (reg); /* If TEM is simply a binary operation with two CLOBBERs as operands, it isn't going to be useful and will take a lot of time to process, so just use the CLOBBER. */ if (tem) { if ((GET_RTX_CLASS (GET_CODE (tem)) == '2' || GET_RTX_CLASS (GET_CODE (tem)) == 'c') && GET_CODE (XEXP (tem, 0)) == CLOBBER && GET_CODE (XEXP (tem, 1)) == CLOBBER) tem = XEXP (tem, 0); value = replace_rtx (copy_rtx (value), reg, tem); } } /* For each register modified, show we don't know its value, that we don't know about its bitwise content, that its value has been updated, and that we don't know the location of the death of the register. */ for (i = regno; i < endregno; i++) { if (insn) reg_last_set[i] = insn; reg_last_set_value[i] = 0; reg_last_set_mode[i] = 0; reg_last_set_nonzero_bits[i] = 0; reg_last_set_sign_bit_copies[i] = 0; reg_last_death[i] = 0; } /* Mark registers that are being referenced in this value. */ if (value) update_table_tick (value); /* Now update the status of each register being set. If someone is using this register in this block, set this register to invalid since we will get confused between the two lives in this basic block. This makes using this register always invalid. In cse, we scan the table to invalidate all entries using this register, but this is too much work for us. */ for (i = regno; i < endregno; i++) { reg_last_set_label[i] = label_tick; if (value && reg_last_set_table_tick[i] == label_tick) reg_last_set_invalid[i] = 1; else reg_last_set_invalid[i] = 0; } /* The value being assigned might refer to X (like in "x++;"). In that case, we must replace it with (clobber (const_int 0)) to prevent infinite loops. */ if (value && ! get_last_value_validate (&value, insn, reg_last_set_label[regno], 0)) { value = copy_rtx (value); if (! get_last_value_validate (&value, insn, reg_last_set_label[regno], 1)) value = 0; } /* For the main register being modified, update the value, the mode, the nonzero bits, and the number of sign bit copies. */ reg_last_set_value[regno] = value; if (value) { enum machine_mode mode = GET_MODE (reg); subst_low_cuid = INSN_CUID (insn); reg_last_set_mode[regno] = mode; if (GET_MODE_CLASS (mode) == MODE_INT && GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT) mode = nonzero_bits_mode; reg_last_set_nonzero_bits[regno] = nonzero_bits (value, mode); reg_last_set_sign_bit_copies[regno] = num_sign_bit_copies (value, GET_MODE (reg)); } } /* Called via note_stores from record_dead_and_set_regs to handle one SET or CLOBBER in an insn. DATA is the instruction in which the set is occurring. */ static void record_dead_and_set_regs_1 (dest, setter, data) rtx dest, setter; void *data; { rtx record_dead_insn = (rtx) data; if (GET_CODE (dest) == SUBREG) dest = SUBREG_REG (dest); if (GET_CODE (dest) == REG) { /* If we are setting the whole register, we know its value. Otherwise show that we don't know the value. We can handle SUBREG in some cases. */ if (GET_CODE (setter) == SET && dest == SET_DEST (setter)) record_value_for_reg (dest, record_dead_insn, SET_SRC (setter)); else if (GET_CODE (setter) == SET && GET_CODE (SET_DEST (setter)) == SUBREG && SUBREG_REG (SET_DEST (setter)) == dest && GET_MODE_BITSIZE (GET_MODE (dest)) <= BITS_PER_WORD && subreg_lowpart_p (SET_DEST (setter))) record_value_for_reg (dest, record_dead_insn, gen_lowpart_for_combine (GET_MODE (dest), SET_SRC (setter))); else record_value_for_reg (dest, record_dead_insn, NULL_RTX); } else if (GET_CODE (dest) == MEM /* Ignore pushes, they clobber nothing. */ && ! push_operand (dest, GET_MODE (dest))) mem_last_set = INSN_CUID (record_dead_insn); } /* Update the records of when each REG was most recently set or killed for the things done by INSN. This is the last thing done in processing INSN in the combiner loop. We update reg_last_set, reg_last_set_value, reg_last_set_mode, reg_last_set_nonzero_bits, reg_last_set_sign_bit_copies, reg_last_death, and also the similar information mem_last_set (which insn most recently modified memory) and last_call_cuid (which insn was the most recent subroutine call). */ static void record_dead_and_set_regs (insn) rtx insn; { rtx link; unsigned int i; for (link = REG_NOTES (insn); link; link = XEXP (link, 1)) { if (REG_NOTE_KIND (link) == REG_DEAD && GET_CODE (XEXP (link, 0)) == REG) { unsigned int regno = REGNO (XEXP (link, 0)); unsigned int endregno = regno + (regno < FIRST_PSEUDO_REGISTER ? HARD_REGNO_NREGS (regno, GET_MODE (XEXP (link, 0))) : 1); for (i = regno; i < endregno; i++) reg_last_death[i] = insn; } else if (REG_NOTE_KIND (link) == REG_INC) record_value_for_reg (XEXP (link, 0), insn, NULL_RTX); } if (GET_CODE (insn) == CALL_INSN) { for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) if (TEST_HARD_REG_BIT (regs_invalidated_by_call, i)) { reg_last_set_value[i] = 0; reg_last_set_mode[i] = 0; reg_last_set_nonzero_bits[i] = 0; reg_last_set_sign_bit_copies[i] = 0; reg_last_death[i] = 0; } last_call_cuid = mem_last_set = INSN_CUID (insn); /* Don't bother recording what this insn does. It might set the return value register, but we can't combine into a call pattern anyway, so there's no point trying (and it may cause a crash, if e.g. we wind up asking for last_set_value of a SUBREG of the return value register). */ return; } note_stores (PATTERN (insn), record_dead_and_set_regs_1, insn); } /* If a SUBREG has the promoted bit set, it is in fact a property of the register present in the SUBREG, so for each such SUBREG go back and adjust nonzero and sign bit information of the registers that are known to have some zero/sign bits set. This is needed because when combine blows the SUBREGs away, the information on zero/sign bits is lost and further combines can be missed because of that. */ static void record_promoted_value (insn, subreg) rtx insn; rtx subreg; { rtx links, set; unsigned int regno = REGNO (SUBREG_REG (subreg)); enum machine_mode mode = GET_MODE (subreg); if (GET_MODE_BITSIZE (mode) > HOST_BITS_PER_WIDE_INT) return; for (links = LOG_LINKS (insn); links;) { insn = XEXP (links, 0); set = single_set (insn); if (! set || GET_CODE (SET_DEST (set)) != REG || REGNO (SET_DEST (set)) != regno || GET_MODE (SET_DEST (set)) != GET_MODE (SUBREG_REG (subreg))) { links = XEXP (links, 1); continue; } if (reg_last_set[regno] == insn) { if (SUBREG_PROMOTED_UNSIGNED_P (subreg) > 0) reg_last_set_nonzero_bits[regno] &= GET_MODE_MASK (mode); } if (GET_CODE (SET_SRC (set)) == REG) { regno = REGNO (SET_SRC (set)); links = LOG_LINKS (insn); } else break; } } /* Scan X for promoted SUBREGs. For each one found, note what it implies to the registers used in it. */ static void check_promoted_subreg (insn, x) rtx insn; rtx x; { if (GET_CODE (x) == SUBREG && SUBREG_PROMOTED_VAR_P (x) && GET_CODE (SUBREG_REG (x)) == REG) record_promoted_value (insn, x); else { const char *format = GET_RTX_FORMAT (GET_CODE (x)); int i, j; for (i = 0; i < GET_RTX_LENGTH (GET_CODE (x)); i++) switch (format[i]) { case 'e': check_promoted_subreg (insn, XEXP (x, i)); break; case 'V': case 'E': if (XVEC (x, i) != 0) for (j = 0; j < XVECLEN (x, i); j++) check_promoted_subreg (insn, XVECEXP (x, i, j)); break; } } } /* Utility routine for the following function. Verify that all the registers mentioned in *LOC are valid when *LOC was part of a value set when label_tick == TICK. Return 0 if some are not. If REPLACE is nonzero, replace the invalid reference with (clobber (const_int 0)) and return 1. This replacement is useful because we often can get useful information about the form of a value (e.g., if it was produced by a shift that always produces -1 or 0) even though we don't know exactly what registers it was produced from. */ static int get_last_value_validate (loc, insn, tick, replace) rtx *loc; rtx insn; int tick; int replace; { rtx x = *loc; const char *fmt = GET_RTX_FORMAT (GET_CODE (x)); int len = GET_RTX_LENGTH (GET_CODE (x)); int i; if (GET_CODE (x) == REG) { unsigned int regno = REGNO (x); unsigned int endregno = regno + (regno < FIRST_PSEUDO_REGISTER ? HARD_REGNO_NREGS (regno, GET_MODE (x)) : 1); unsigned int j; for (j = regno; j < endregno; j++) if (reg_last_set_invalid[j] /* If this is a pseudo-register that was only set once and not live at the beginning of the function, it is always valid. */ || (! (regno >= FIRST_PSEUDO_REGISTER && REG_N_SETS (regno) == 1 && (! REGNO_REG_SET_P (ENTRY_BLOCK_PTR->next_bb->global_live_at_start, regno))) && reg_last_set_label[j] > tick)) { if (replace) *loc = gen_rtx_CLOBBER (GET_MODE (x), const0_rtx); return replace; } return 1; } /* If this is a memory reference, make sure that there were no stores after it that might have clobbered the value. We don't have alias info, so we assume any store invalidates it. */ else if (GET_CODE (x) == MEM && ! RTX_UNCHANGING_P (x) && INSN_CUID (insn) <= mem_last_set) { if (replace) *loc = gen_rtx_CLOBBER (GET_MODE (x), const0_rtx); return replace; } for (i = 0; i < len; i++) { if (fmt[i] == 'e') { /* Check for identical subexpressions. If x contains identical subexpression we only have to traverse one of them. */ if (i == 1 && (GET_RTX_CLASS (GET_CODE (x)) == '2' || GET_RTX_CLASS (GET_CODE (x)) == 'c')) { /* Note that at this point x0 has already been checked and found valid. */ rtx x0 = XEXP (x, 0); rtx x1 = XEXP (x, 1); /* If x0 and x1 are identical then x is also valid. */ if (x0 == x1) return 1; /* If x1 is identical to a subexpression of x0 then while checking x0, x1 has already been checked. Thus it is valid and so as x. */ if ((GET_RTX_CLASS (GET_CODE (x0)) == '2' || GET_RTX_CLASS (GET_CODE (x0)) == 'c') && (x1 == XEXP (x0, 0) || x1 == XEXP (x0, 1))) return 1; /* If x0 is identical to a subexpression of x1 then x is valid iff the rest of x1 is valid. */ if ((GET_RTX_CLASS (GET_CODE (x1)) == '2' || GET_RTX_CLASS (GET_CODE (x1)) == 'c') && (x0 == XEXP (x1, 0) || x0 == XEXP (x1, 1))) return get_last_value_validate (&XEXP (x1, x0 == XEXP (x1, 0) ? 1 : 0), insn, tick, replace); } if (get_last_value_validate (&XEXP (x, i), insn, tick, replace) == 0) return 0; } /* Don't bother with these. They shouldn't occur anyway. */ else if (fmt[i] == 'E') return 0; } /* If we haven't found a reason for it to be invalid, it is valid. */ return 1; } /* Get the last value assigned to X, if known. Some registers in the value may be replaced with (clobber (const_int 0)) if their value is known longer known reliably. */ static rtx get_last_value (x) rtx x; { unsigned int regno; rtx value; /* If this is a non-paradoxical SUBREG, get the value of its operand and then convert it to the desired mode. If this is a paradoxical SUBREG, we cannot predict what values the "extra" bits might have. */ if (GET_CODE (x) == SUBREG && subreg_lowpart_p (x) && (GET_MODE_SIZE (GET_MODE (x)) <= GET_MODE_SIZE (GET_MODE (SUBREG_REG (x)))) && (value = get_last_value (SUBREG_REG (x))) != 0) return gen_lowpart_for_combine (GET_MODE (x), value); if (GET_CODE (x) != REG) return 0; regno = REGNO (x); value = reg_last_set_value[regno]; /* If we don't have a value, or if it isn't for this basic block and it's either a hard register, set more than once, or it's a live at the beginning of the function, return 0. Because if it's not live at the beginning of the function then the reg is always set before being used (is never used without being set). And, if it's set only once, and it's always set before use, then all uses must have the same last value, even if it's not from this basic block. */ if (value == 0 || (reg_last_set_label[regno] != label_tick && (regno < FIRST_PSEUDO_REGISTER || REG_N_SETS (regno) != 1 || (REGNO_REG_SET_P (ENTRY_BLOCK_PTR->next_bb->global_live_at_start, regno))))) return 0; /* If the value was set in a later insn than the ones we are processing, we can't use it even if the register was only set once. */ if (INSN_CUID (reg_last_set[regno]) >= subst_low_cuid) return 0; /* If the value has all its registers valid, return it. */ if (get_last_value_validate (&value, reg_last_set[regno], reg_last_set_label[regno], 0)) return value; /* Otherwise, make a copy and replace any invalid register with (clobber (const_int 0)). If that fails for some reason, return 0. */ value = copy_rtx (value); if (get_last_value_validate (&value, reg_last_set[regno], reg_last_set_label[regno], 1)) return value; return 0; } /* Return nonzero if expression X refers to a REG or to memory that is set in an instruction more recent than FROM_CUID. */ static int use_crosses_set_p (x, from_cuid) rtx x; int from_cuid; { const char *fmt; int i; enum rtx_code code = GET_CODE (x); if (code == REG) { unsigned int regno = REGNO (x); unsigned endreg = regno + (regno < FIRST_PSEUDO_REGISTER ? HARD_REGNO_NREGS (regno, GET_MODE (x)) : 1); #ifdef PUSH_ROUNDING /* Don't allow uses of the stack pointer to be moved, because we don't know whether the move crosses a push insn. */ if (regno == STACK_POINTER_REGNUM && PUSH_ARGS) return 1; #endif for (; regno < endreg; regno++) if (reg_last_set[regno] && INSN_CUID (reg_last_set[regno]) > from_cuid) return 1; return 0; } if (code == MEM && mem_last_set > from_cuid) return 1; fmt = GET_RTX_FORMAT (code); for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) { if (fmt[i] == 'E') { int j; for (j = XVECLEN (x, i) - 1; j >= 0; j--) if (use_crosses_set_p (XVECEXP (x, i, j), from_cuid)) return 1; } else if (fmt[i] == 'e' && use_crosses_set_p (XEXP (x, i), from_cuid)) return 1; } return 0; } /* Define three variables used for communication between the following routines. */ static unsigned int reg_dead_regno, reg_dead_endregno; static int reg_dead_flag; /* Function called via note_stores from reg_dead_at_p. If DEST is within [reg_dead_regno, reg_dead_endregno), set reg_dead_flag to 1 if X is a CLOBBER and to -1 it is a SET. */ static void reg_dead_at_p_1 (dest, x, data) rtx dest; rtx x; void *data ATTRIBUTE_UNUSED; { unsigned int regno, endregno; if (GET_CODE (dest) != REG) return; regno = REGNO (dest); endregno = regno + (regno < FIRST_PSEUDO_REGISTER ? HARD_REGNO_NREGS (regno, GET_MODE (dest)) : 1); if (reg_dead_endregno > regno && reg_dead_regno < endregno) reg_dead_flag = (GET_CODE (x) == CLOBBER) ? 1 : -1; } /* Return nonzero if REG is known to be dead at INSN. We scan backwards from INSN. If we hit a REG_DEAD note or a CLOBBER referencing REG, it is dead. If we hit a SET referencing REG, it is live. Otherwise, see if it is live or dead at the start of the basic block we are in. Hard regs marked as being live in NEWPAT_USED_REGS must be assumed to be always live. */ static int reg_dead_at_p (reg, insn) rtx reg; rtx insn; { basic_block block; unsigned int i; /* Set variables for reg_dead_at_p_1. */ reg_dead_regno = REGNO (reg); reg_dead_endregno = reg_dead_regno + (reg_dead_regno < FIRST_PSEUDO_REGISTER ? HARD_REGNO_NREGS (reg_dead_regno, GET_MODE (reg)) : 1); reg_dead_flag = 0; /* Check that reg isn't mentioned in NEWPAT_USED_REGS. */ if (reg_dead_regno < FIRST_PSEUDO_REGISTER) { for (i = reg_dead_regno; i < reg_dead_endregno; i++) if (TEST_HARD_REG_BIT (newpat_used_regs, i)) return 0; } /* Scan backwards until we find a REG_DEAD note, SET, CLOBBER, label, or beginning of function. */ for (; insn && GET_CODE (insn) != CODE_LABEL && GET_CODE (insn) != BARRIER; insn = prev_nonnote_insn (insn)) { note_stores (PATTERN (insn), reg_dead_at_p_1, NULL); if (reg_dead_flag) return reg_dead_flag == 1 ? 1 : 0; if (find_regno_note (insn, REG_DEAD, reg_dead_regno)) return 1; } /* Get the basic block that we were in. */ if (insn == 0) block = ENTRY_BLOCK_PTR->next_bb; else { FOR_EACH_BB (block) if (insn == block->head) break; if (block == EXIT_BLOCK_PTR) return 0; } for (i = reg_dead_regno; i < reg_dead_endregno; i++) if (REGNO_REG_SET_P (block->global_live_at_start, i)) return 0; return 1; } /* Note hard registers in X that are used. This code is similar to that in flow.c, but much simpler since we don't care about pseudos. */ static void mark_used_regs_combine (x) rtx x; { RTX_CODE code = GET_CODE (x); unsigned int regno; int i; switch (code) { case LABEL_REF: case SYMBOL_REF: case CONST_INT: case CONST: case CONST_DOUBLE: case CONST_VECTOR: case PC: case ADDR_VEC: case ADDR_DIFF_VEC: case ASM_INPUT: #ifdef HAVE_cc0 /* CC0 must die in the insn after it is set, so we don't need to take special note of it here. */ case CC0: #endif return; case CLOBBER: /* If we are clobbering a MEM, mark any hard registers inside the address as used. */ if (GET_CODE (XEXP (x, 0)) == MEM) mark_used_regs_combine (XEXP (XEXP (x, 0), 0)); return; case REG: regno = REGNO (x); /* A hard reg in a wide mode may really be multiple registers. If so, mark all of them just like the first. */ if (regno < FIRST_PSEUDO_REGISTER) { unsigned int endregno, r; /* None of this applies to the stack, frame or arg pointers. */ if (regno == STACK_POINTER_REGNUM #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM || regno == HARD_FRAME_POINTER_REGNUM #endif #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM || (regno == ARG_POINTER_REGNUM && fixed_regs[regno]) #endif || regno == FRAME_POINTER_REGNUM) return; endregno = regno + HARD_REGNO_NREGS (regno, GET_MODE (x)); for (r = regno; r < endregno; r++) SET_HARD_REG_BIT (newpat_used_regs, r); } return; case SET: { /* If setting a MEM, or a SUBREG of a MEM, then note any hard regs in the address. */ rtx testreg = SET_DEST (x); while (GET_CODE (testreg) == SUBREG || GET_CODE (testreg) == ZERO_EXTRACT || GET_CODE (testreg) == SIGN_EXTRACT || GET_CODE (testreg) == STRICT_LOW_PART) testreg = XEXP (testreg, 0); if (GET_CODE (testreg) == MEM) mark_used_regs_combine (XEXP (testreg, 0)); mark_used_regs_combine (SET_SRC (x)); } return; default: break; } /* Recursively scan the operands of this expression. */ { const char *fmt = GET_RTX_FORMAT (code); for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) { if (fmt[i] == 'e') mark_used_regs_combine (XEXP (x, i)); else if (fmt[i] == 'E') { int j; for (j = 0; j < XVECLEN (x, i); j++) mark_used_regs_combine (XVECEXP (x, i, j)); } } } } /* Remove register number REGNO from the dead registers list of INSN. Return the note used to record the death, if there was one. */ rtx remove_death (regno, insn) unsigned int regno; rtx insn; { rtx note = find_regno_note (insn, REG_DEAD, regno); if (note) { REG_N_DEATHS (regno)--; remove_note (insn, note); } return note; } /* For each register (hardware or pseudo) used within expression X, if its death is in an instruction with cuid between FROM_CUID (inclusive) and TO_INSN (exclusive), put a REG_DEAD note for that register in the list headed by PNOTES. That said, don't move registers killed by maybe_kill_insn. This is done when X is being merged by combination into TO_INSN. These notes will then be distributed as needed. */ static void move_deaths (x, maybe_kill_insn, from_cuid, to_insn, pnotes) rtx x; rtx maybe_kill_insn; int from_cuid; rtx to_insn; rtx *pnotes; { const char *fmt; int len, i; enum rtx_code code = GET_CODE (x); if (code == REG) { unsigned int regno = REGNO (x); rtx where_dead = reg_last_death[regno]; rtx before_dead, after_dead; /* Don't move the register if it gets killed in between from and to. */ if (maybe_kill_insn && reg_set_p (x, maybe_kill_insn) && ! reg_referenced_p (x, maybe_kill_insn)) return; /* WHERE_DEAD could be a USE insn made by combine, so first we make sure that we have insns with valid INSN_CUID values. */ before_dead = where_dead; while (before_dead && INSN_UID (before_dead) > max_uid_cuid) before_dead = PREV_INSN (before_dead); after_dead = where_dead; while (after_dead && INSN_UID (after_dead) > max_uid_cuid) after_dead = NEXT_INSN (after_dead); if (before_dead && after_dead && INSN_CUID (before_dead) >= from_cuid && (INSN_CUID (after_dead) < INSN_CUID (to_insn) || (where_dead != after_dead && INSN_CUID (after_dead) == INSN_CUID (to_insn)))) { rtx note = remove_death (regno, where_dead); /* It is possible for the call above to return 0. This can occur when reg_last_death points to I2 or I1 that we combined with. In that case make a new note. We must also check for the case where X is a hard register and NOTE is a death note for a range of hard registers including X. In that case, we must put REG_DEAD notes for the remaining registers in place of NOTE. */ if (note != 0 && regno < FIRST_PSEUDO_REGISTER && (GET_MODE_SIZE (GET_MODE (XEXP (note, 0))) > GET_MODE_SIZE (GET_MODE (x)))) { unsigned int deadregno = REGNO (XEXP (note, 0)); unsigned int deadend = (deadregno + HARD_REGNO_NREGS (deadregno, GET_MODE (XEXP (note, 0)))); unsigned int ourend = regno + HARD_REGNO_NREGS (regno, GET_MODE (x)); unsigned int i; for (i = deadregno; i < deadend; i++) if (i < regno || i >= ourend) REG_NOTES (where_dead) = gen_rtx_EXPR_LIST (REG_DEAD, regno_reg_rtx[i], REG_NOTES (where_dead)); } /* If we didn't find any note, or if we found a REG_DEAD note that covers only part of the given reg, and we have a multi-reg hard register, then to be safe we must check for REG_DEAD notes for each register other than the first. They could have their own REG_DEAD notes lying around. */ else if ((note == 0 || (note != 0 && (GET_MODE_SIZE (GET_MODE (XEXP (note, 0))) < GET_MODE_SIZE (GET_MODE (x))))) && regno < FIRST_PSEUDO_REGISTER && HARD_REGNO_NREGS (regno, GET_MODE (x)) > 1) { unsigned int ourend = regno + HARD_REGNO_NREGS (regno, GET_MODE (x)); unsigned int i, offset; rtx oldnotes = 0; if (note) offset = HARD_REGNO_NREGS (regno, GET_MODE (XEXP (note, 0))); else offset = 1; for (i = regno + offset; i < ourend; i++) move_deaths (regno_reg_rtx[i], maybe_kill_insn, from_cuid, to_insn, &oldnotes); } if (note != 0 && GET_MODE (XEXP (note, 0)) == GET_MODE (x)) { XEXP (note, 1) = *pnotes; *pnotes = note; } else *pnotes = gen_rtx_EXPR_LIST (REG_DEAD, x, *pnotes); REG_N_DEATHS (regno)++; } return; } else if (GET_CODE (x) == SET) { rtx dest = SET_DEST (x); move_deaths (SET_SRC (x), maybe_kill_insn, from_cuid, to_insn, pnotes); /* In the case of a ZERO_EXTRACT, a STRICT_LOW_PART, or a SUBREG that accesses one word of a multi-word item, some piece of everything register in the expression is used by this insn, so remove any old death. */ /* ??? So why do we test for equality of the sizes? */ if (GET_CODE (dest) == ZERO_EXTRACT || GET_CODE (dest) == STRICT_LOW_PART || (GET_CODE (dest) == SUBREG && (((GET_MODE_SIZE (GET_MODE (dest)) + UNITS_PER_WORD - 1) / UNITS_PER_WORD) == ((GET_MODE_SIZE (GET_MODE (SUBREG_REG (dest))) + UNITS_PER_WORD - 1) / UNITS_PER_WORD)))) { move_deaths (dest, maybe_kill_insn, from_cuid, to_insn, pnotes); return; } /* If this is some other SUBREG, we know it replaces the entire value, so use that as the destination. */ if (GET_CODE (dest) == SUBREG) dest = SUBREG_REG (dest); /* If this is a MEM, adjust deaths of anything used in the address. For a REG (the only other possibility), the entire value is being replaced so the old value is not used in this insn. */ if (GET_CODE (dest) == MEM) move_deaths (XEXP (dest, 0), maybe_kill_insn, from_cuid, to_insn, pnotes); return; } else if (GET_CODE (x) == CLOBBER) return; len = GET_RTX_LENGTH (code); fmt = GET_RTX_FORMAT (code); for (i = 0; i < len; i++) { if (fmt[i] == 'E') { int j; for (j = XVECLEN (x, i) - 1; j >= 0; j--) move_deaths (XVECEXP (x, i, j), maybe_kill_insn, from_cuid, to_insn, pnotes); } else if (fmt[i] == 'e') move_deaths (XEXP (x, i), maybe_kill_insn, from_cuid, to_insn, pnotes); } } /* Return 1 if X is the target of a bit-field assignment in BODY, the pattern of an insn. X must be a REG. */ static int reg_bitfield_target_p (x, body) rtx x; rtx body; { int i; if (GET_CODE (body) == SET) { rtx dest = SET_DEST (body); rtx target; unsigned int regno, tregno, endregno, endtregno; if (GET_CODE (dest) == ZERO_EXTRACT) target = XEXP (dest, 0); else if (GET_CODE (dest) == STRICT_LOW_PART) target = SUBREG_REG (XEXP (dest, 0)); else return 0; if (GET_CODE (target) == SUBREG) target = SUBREG_REG (target); if (GET_CODE (target) != REG) return 0; tregno = REGNO (target), regno = REGNO (x); if (tregno >= FIRST_PSEUDO_REGISTER || regno >= FIRST_PSEUDO_REGISTER) return target == x; endtregno = tregno + HARD_REGNO_NREGS (tregno, GET_MODE (target)); endregno = regno + HARD_REGNO_NREGS (regno, GET_MODE (x)); return endregno > tregno && regno < endtregno; } else if (GET_CODE (body) == PARALLEL) for (i = XVECLEN (body, 0) - 1; i >= 0; i--) if (reg_bitfield_target_p (x, XVECEXP (body, 0, i))) return 1; return 0; } /* Given a chain of REG_NOTES originally from FROM_INSN, try to place them as appropriate. I3 and I2 are the insns resulting from the combination insns including FROM (I2 may be zero). Each note in the list is either ignored or placed on some insns, depending on the type of note. */ static void distribute_notes (notes, from_insn, i3, i2) rtx notes; rtx from_insn; rtx i3, i2; { rtx note, next_note; rtx tem; for (note = notes; note; note = next_note) { rtx place = 0, place2 = 0; /* If this NOTE references a pseudo register, ensure it references the latest copy of that register. */ if (XEXP (note, 0) && GET_CODE (XEXP (note, 0)) == REG && REGNO (XEXP (note, 0)) >= FIRST_PSEUDO_REGISTER) XEXP (note, 0) = regno_reg_rtx[REGNO (XEXP (note, 0))]; next_note = XEXP (note, 1); switch (REG_NOTE_KIND (note)) { case REG_BR_PROB: case REG_BR_PRED: /* Doesn't matter much where we put this, as long as it's somewhere. It is preferable to keep these notes on branches, which is most likely to be i3. */ place = i3; break; case REG_VTABLE_REF: /* ??? Should remain with *a particular* memory load. Given the nature of vtable data, the last insn seems relatively safe. */ place = i3; break; case REG_NON_LOCAL_GOTO: if (GET_CODE (i3) == JUMP_INSN) place = i3; else if (i2 && GET_CODE (i2) == JUMP_INSN) place = i2; else abort (); break; case REG_EH_REGION: /* These notes must remain with the call or trapping instruction. */ if (GET_CODE (i3) == CALL_INSN) place = i3; else if (i2 && GET_CODE (i2) == CALL_INSN) place = i2; else if (flag_non_call_exceptions) { if (may_trap_p (i3)) place = i3; else if (i2 && may_trap_p (i2)) place = i2; /* ??? Otherwise assume we've combined things such that we can now prove that the instructions can't trap. Drop the note in this case. */ } else abort (); break; case REG_NORETURN: case REG_SETJMP: /* These notes must remain with the call. It should not be possible for both I2 and I3 to be a call. */ if (GET_CODE (i3) == CALL_INSN) place = i3; else if (i2 && GET_CODE (i2) == CALL_INSN) place = i2; else abort (); break; case REG_UNUSED: /* Any clobbers for i3 may still exist, and so we must process REG_UNUSED notes from that insn. Any clobbers from i2 or i1 can only exist if they were added by recog_for_combine. In that case, recog_for_combine created the necessary REG_UNUSED notes. Trying to keep any original REG_UNUSED notes from these insns can cause incorrect output if it is for the same register as the original i3 dest. In that case, we will notice that the register is set in i3, and then add a REG_UNUSED note for the destination of i3, which is wrong. However, it is possible to have REG_UNUSED notes from i2 or i1 for register which were both used and clobbered, so we keep notes from i2 or i1 if they will turn into REG_DEAD notes. */ /* If this register is set or clobbered in I3, put the note there unless there is one already. */ if (reg_set_p (XEXP (note, 0), PATTERN (i3))) { if (from_insn != i3) break; if (! (GET_CODE (XEXP (note, 0)) == REG ? find_regno_note (i3, REG_UNUSED, REGNO (XEXP (note, 0))) : find_reg_note (i3, REG_UNUSED, XEXP (note, 0)))) place = i3; } /* Otherwise, if this register is used by I3, then this register now dies here, so we must put a REG_DEAD note here unless there is one already. */ else if (reg_referenced_p (XEXP (note, 0), PATTERN (i3)) && ! (GET_CODE (XEXP (note, 0)) == REG ? find_regno_note (i3, REG_DEAD, REGNO (XEXP (note, 0))) : find_reg_note (i3, REG_DEAD, XEXP (note, 0)))) { PUT_REG_NOTE_KIND (note, REG_DEAD); place = i3; } break; case REG_EQUAL: case REG_EQUIV: case REG_NOALIAS: /* These notes say something about results of an insn. We can only support them if they used to be on I3 in which case they remain on I3. Otherwise they are ignored. If the note refers to an expression that is not a constant, we must also ignore the note since we cannot tell whether the equivalence is still true. It might be possible to do slightly better than this (we only have a problem if I2DEST or I1DEST is present in the expression), but it doesn't seem worth the trouble. */ if (from_insn == i3 && (XEXP (note, 0) == 0 || CONSTANT_P (XEXP (note, 0)))) place = i3; break; case REG_INC: case REG_NO_CONFLICT: /* These notes say something about how a register is used. They must be present on any use of the register in I2 or I3. */ if (reg_mentioned_p (XEXP (note, 0), PATTERN (i3))) place = i3; if (i2 && reg_mentioned_p (XEXP (note, 0), PATTERN (i2))) { if (place) place2 = i2; else place = i2; } break; case REG_LABEL: /* This can show up in several ways -- either directly in the pattern, or hidden off in the constant pool with (or without?) a REG_EQUAL note. */ /* ??? Ignore the without-reg_equal-note problem for now. */ if (reg_mentioned_p (XEXP (note, 0), PATTERN (i3)) || ((tem = find_reg_note (i3, REG_EQUAL, NULL_RTX)) && GET_CODE (XEXP (tem, 0)) == LABEL_REF && XEXP (XEXP (tem, 0), 0) == XEXP (note, 0))) place = i3; if (i2 && (reg_mentioned_p (XEXP (note, 0), PATTERN (i2)) || ((tem = find_reg_note (i2, REG_EQUAL, NULL_RTX)) && GET_CODE (XEXP (tem, 0)) == LABEL_REF && XEXP (XEXP (tem, 0), 0) == XEXP (note, 0)))) { if (place) place2 = i2; else place = i2; } /* Don't attach REG_LABEL note to a JUMP_INSN which has JUMP_LABEL already. Instead, decrement LABEL_NUSES. */ if (place && GET_CODE (place) == JUMP_INSN && JUMP_LABEL (place)) { if (JUMP_LABEL (place) != XEXP (note, 0)) abort (); if (GET_CODE (JUMP_LABEL (place)) == CODE_LABEL) LABEL_NUSES (JUMP_LABEL (place))--; place = 0; } if (place2 && GET_CODE (place2) == JUMP_INSN && JUMP_LABEL (place2)) { if (JUMP_LABEL (place2) != XEXP (note, 0)) abort (); if (GET_CODE (JUMP_LABEL (place2)) == CODE_LABEL) LABEL_NUSES (JUMP_LABEL (place2))--; place2 = 0; } break; case REG_NONNEG: case REG_WAS_0: /* These notes say something about the value of a register prior to the execution of an insn. It is too much trouble to see if the note is still correct in all situations. It is better to simply delete it. */ break; case REG_RETVAL: /* If the insn previously containing this note still exists, put it back where it was. Otherwise move it to the previous insn. Adjust the corresponding REG_LIBCALL note. */ if (GET_CODE (from_insn) != NOTE) place = from_insn; else { tem = find_reg_note (XEXP (note, 0), REG_LIBCALL, NULL_RTX); place = prev_real_insn (from_insn); if (tem && place) XEXP (tem, 0) = place; /* If we're deleting the last remaining instruction of a libcall sequence, don't add the notes. */ else if (XEXP (note, 0) == from_insn) tem = place = 0; } break; case REG_LIBCALL: /* This is handled similarly to REG_RETVAL. */ if (GET_CODE (from_insn) != NOTE) place = from_insn; else { tem = find_reg_note (XEXP (note, 0), REG_RETVAL, NULL_RTX); place = next_real_insn (from_insn); if (tem && place) XEXP (tem, 0) = place; /* If we're deleting the last remaining instruction of a libcall sequence, don't add the notes. */ else if (XEXP (note, 0) == from_insn) tem = place = 0; } break; case REG_DEAD: /* If the register is used as an input in I3, it dies there. Similarly for I2, if it is nonzero and adjacent to I3. If the register is not used as an input in either I3 or I2 and it is not one of the registers we were supposed to eliminate, there are two possibilities. We might have a non-adjacent I2 or we might have somehow eliminated an additional register from a computation. For example, we might have had A & B where we discover that B will always be zero. In this case we will eliminate the reference to A. In both cases, we must search to see if we can find a previous use of A and put the death note there. */ if (from_insn && GET_CODE (from_insn) == CALL_INSN && find_reg_fusage (from_insn, USE, XEXP (note, 0))) place = from_insn; else if (reg_referenced_p (XEXP (note, 0), PATTERN (i3))) place = i3; else if (i2 != 0 && next_nonnote_insn (i2) == i3 && reg_referenced_p (XEXP (note, 0), PATTERN (i2))) place = i2; if (place == 0) { basic_block bb = this_basic_block; for (tem = PREV_INSN (i3); place == 0; tem = PREV_INSN (tem)) { if (! INSN_P (tem)) { if (tem == bb->head) break; continue; } /* If the register is being set at TEM, see if that is all TEM is doing. If so, delete TEM. Otherwise, make this into a REG_UNUSED note instead. */ if (reg_set_p (XEXP (note, 0), PATTERN (tem))) { rtx set = single_set (tem); rtx inner_dest = 0; #ifdef HAVE_cc0 rtx cc0_setter = NULL_RTX; #endif if (set != 0) for (inner_dest = SET_DEST (set); (GET_CODE (inner_dest) == STRICT_LOW_PART || GET_CODE (inner_dest) == SUBREG || GET_CODE (inner_dest) == ZERO_EXTRACT); inner_dest = XEXP (inner_dest, 0)) ; /* Verify that it was the set, and not a clobber that modified the register. CC0 targets must be careful to maintain setter/user pairs. If we cannot delete the setter due to side effects, mark the user with an UNUSED note instead of deleting it. */ if (set != 0 && ! side_effects_p (SET_SRC (set)) && rtx_equal_p (XEXP (note, 0), inner_dest) #ifdef HAVE_cc0 && (! reg_mentioned_p (cc0_rtx, SET_SRC (set)) || ((cc0_setter = prev_cc0_setter (tem)) != NULL && sets_cc0_p (PATTERN (cc0_setter)) > 0)) #endif ) { /* Move the notes and links of TEM elsewhere. This might delete other dead insns recursively. First set the pattern to something that won't use any register. */ PATTERN (tem) = pc_rtx; distribute_notes (REG_NOTES (tem), tem, tem, NULL_RTX); distribute_links (LOG_LINKS (tem)); PUT_CODE (tem, NOTE); NOTE_LINE_NUMBER (tem) = NOTE_INSN_DELETED; NOTE_SOURCE_FILE (tem) = 0; #ifdef HAVE_cc0 /* Delete the setter too. */ if (cc0_setter) { PATTERN (cc0_setter) = pc_rtx; distribute_notes (REG_NOTES (cc0_setter), cc0_setter, cc0_setter, NULL_RTX); distribute_links (LOG_LINKS (cc0_setter)); PUT_CODE (cc0_setter, NOTE); NOTE_LINE_NUMBER (cc0_setter) = NOTE_INSN_DELETED; NOTE_SOURCE_FILE (cc0_setter) = 0; } #endif } /* If the register is both set and used here, put the REG_DEAD note here, but place a REG_UNUSED note here too unless there already is one. */ else if (reg_referenced_p (XEXP (note, 0), PATTERN (tem))) { place = tem; if (! find_regno_note (tem, REG_UNUSED, REGNO (XEXP (note, 0)))) REG_NOTES (tem) = gen_rtx_EXPR_LIST (REG_UNUSED, XEXP (note, 0), REG_NOTES (tem)); } else { PUT_REG_NOTE_KIND (note, REG_UNUSED); /* If there isn't already a REG_UNUSED note, put one here. */ if (! find_regno_note (tem, REG_UNUSED, REGNO (XEXP (note, 0)))) place = tem; break; } } else if (reg_referenced_p (XEXP (note, 0), PATTERN (tem)) || (GET_CODE (tem) == CALL_INSN && find_reg_fusage (tem, USE, XEXP (note, 0)))) { place = tem; /* If we are doing a 3->2 combination, and we have a register which formerly died in i3 and was not used by i2, which now no longer dies in i3 and is used in i2 but does not die in i2, and place is between i2 and i3, then we may need to move a link from place to i2. */ if (i2 && INSN_UID (place) <= max_uid_cuid && INSN_CUID (place) > INSN_CUID (i2) && from_insn && INSN_CUID (from_insn) > INSN_CUID (i2) && reg_referenced_p (XEXP (note, 0), PATTERN (i2))) { rtx links = LOG_LINKS (place); LOG_LINKS (place) = 0; distribute_links (links); } break; } if (tem == bb->head) break; } /* We haven't found an insn for the death note and it is still a REG_DEAD note, but we have hit the beginning of the block. If the existing life info says the reg was dead, there's nothing left to do. Otherwise, we'll need to do a global life update after combine. */ if (REG_NOTE_KIND (note) == REG_DEAD && place == 0 && REGNO_REG_SET_P (bb->global_live_at_start, REGNO (XEXP (note, 0)))) SET_BIT (refresh_blocks, this_basic_block->index); } /* If the register is set or already dead at PLACE, we needn't do anything with this note if it is still a REG_DEAD note. We can here if it is set at all, not if is it totally replace, which is what `dead_or_set_p' checks, so also check for it being set partially. */ if (place && REG_NOTE_KIND (note) == REG_DEAD) { unsigned int regno = REGNO (XEXP (note, 0)); /* Similarly, if the instruction on which we want to place the note is a noop, we'll need do a global live update after we remove them in delete_noop_moves. */ if (noop_move_p (place)) SET_BIT (refresh_blocks, this_basic_block->index); if (dead_or_set_p (place, XEXP (note, 0)) || reg_bitfield_target_p (XEXP (note, 0), PATTERN (place))) { /* Unless the register previously died in PLACE, clear reg_last_death. [I no longer understand why this is being done.] */ if (reg_last_death[regno] != place) reg_last_death[regno] = 0; place = 0; } else reg_last_death[regno] = place; /* If this is a death note for a hard reg that is occupying multiple registers, ensure that we are still using all parts of the object. If we find a piece of the object that is unused, we must arrange for an appropriate REG_DEAD note to be added for it. However, we can't just emit a USE and tag the note to it, since the register might actually be dead; so we recourse, and the recursive call then finds the previous insn that used this register. */ if (place && regno < FIRST_PSEUDO_REGISTER && HARD_REGNO_NREGS (regno, GET_MODE (XEXP (note, 0))) > 1) { unsigned int endregno = regno + HARD_REGNO_NREGS (regno, GET_MODE (XEXP (note, 0))); int all_used = 1; unsigned int i; for (i = regno; i < endregno; i++) if ((! refers_to_regno_p (i, i + 1, PATTERN (place), 0) && ! find_regno_fusage (place, USE, i)) || dead_or_set_regno_p (place, i)) all_used = 0; if (! all_used) { /* Put only REG_DEAD notes for pieces that are not already dead or set. */ for (i = regno; i < endregno; i += HARD_REGNO_NREGS (i, reg_raw_mode[i])) { rtx piece = regno_reg_rtx[i]; basic_block bb = this_basic_block; if (! dead_or_set_p (place, piece) && ! reg_bitfield_target_p (piece, PATTERN (place))) { rtx new_note = gen_rtx_EXPR_LIST (REG_DEAD, piece, NULL_RTX); distribute_notes (new_note, place, place, NULL_RTX); } else if (! refers_to_regno_p (i, i + 1, PATTERN (place), 0) && ! find_regno_fusage (place, USE, i)) for (tem = PREV_INSN (place); ; tem = PREV_INSN (tem)) { if (! INSN_P (tem)) { if (tem == bb->head) { SET_BIT (refresh_blocks, this_basic_block->index); break; } continue; } if (dead_or_set_p (tem, piece) || reg_bitfield_target_p (piece, PATTERN (tem))) { REG_NOTES (tem) = gen_rtx_EXPR_LIST (REG_UNUSED, piece, REG_NOTES (tem)); break; } } } place = 0; } } } break; default: /* Any other notes should not be present at this point in the compilation. */ abort (); } if (place) { XEXP (note, 1) = REG_NOTES (place); REG_NOTES (place) = note; } else if ((REG_NOTE_KIND (note) == REG_DEAD || REG_NOTE_KIND (note) == REG_UNUSED) && GET_CODE (XEXP (note, 0)) == REG) REG_N_DEATHS (REGNO (XEXP (note, 0)))--; if (place2) { if ((REG_NOTE_KIND (note) == REG_DEAD || REG_NOTE_KIND (note) == REG_UNUSED) && GET_CODE (XEXP (note, 0)) == REG) REG_N_DEATHS (REGNO (XEXP (note, 0)))++; REG_NOTES (place2) = gen_rtx_fmt_ee (GET_CODE (note), REG_NOTE_KIND (note), XEXP (note, 0), REG_NOTES (place2)); } } } /* Similarly to above, distribute the LOG_LINKS that used to be present on I3, I2, and I1 to new locations. This is also called in one case to add a link pointing at I3 when I3's destination is changed. */ static void distribute_links (links) rtx links; { rtx link, next_link; for (link = links; link; link = next_link) { rtx place = 0; rtx insn; rtx set, reg; next_link = XEXP (link, 1); /* If the insn that this link points to is a NOTE or isn't a single set, ignore it. In the latter case, it isn't clear what we can do other than ignore the link, since we can't tell which register it was for. Such links wouldn't be used by combine anyway. It is not possible for the destination of the target of the link to have been changed by combine. The only potential of this is if we replace I3, I2, and I1 by I3 and I2. But in that case the destination of I2 also remains unchanged. */ if (GET_CODE (XEXP (link, 0)) == NOTE || (set = single_set (XEXP (link, 0))) == 0) continue; reg = SET_DEST (set); while (GET_CODE (reg) == SUBREG || GET_CODE (reg) == ZERO_EXTRACT || GET_CODE (reg) == SIGN_EXTRACT || GET_CODE (reg) == STRICT_LOW_PART) reg = XEXP (reg, 0); /* A LOG_LINK is defined as being placed on the first insn that uses a register and points to the insn that sets the register. Start searching at the next insn after the target of the link and stop when we reach a set of the register or the end of the basic block. Note that this correctly handles the link that used to point from I3 to I2. Also note that not much searching is typically done here since most links don't point very far away. */ for (insn = NEXT_INSN (XEXP (link, 0)); (insn && (this_basic_block->next_bb == EXIT_BLOCK_PTR || this_basic_block->next_bb->head != insn)); insn = NEXT_INSN (insn)) if (INSN_P (insn) && reg_overlap_mentioned_p (reg, PATTERN (insn))) { if (reg_referenced_p (reg, PATTERN (insn))) place = insn; break; } else if (GET_CODE (insn) == CALL_INSN && find_reg_fusage (insn, USE, reg)) { place = insn; break; } /* If we found a place to put the link, place it there unless there is already a link to the same insn as LINK at that point. */ if (place) { rtx link2; for (link2 = LOG_LINKS (place); link2; link2 = XEXP (link2, 1)) if (XEXP (link2, 0) == XEXP (link, 0)) break; if (link2 == 0) { XEXP (link, 1) = LOG_LINKS (place); LOG_LINKS (place) = link; /* Set added_links_insn to the earliest insn we added a link to. */ if (added_links_insn == 0 || INSN_CUID (added_links_insn) > INSN_CUID (place)) added_links_insn = place; } } } } /* Compute INSN_CUID for INSN, which is an insn made by combine. */ static int insn_cuid (insn) rtx insn; { while (insn != 0 && INSN_UID (insn) > max_uid_cuid && GET_CODE (insn) == INSN && GET_CODE (PATTERN (insn)) == USE) insn = NEXT_INSN (insn); if (INSN_UID (insn) > max_uid_cuid) abort (); return INSN_CUID (insn); } void dump_combine_stats (file) FILE *file; { fnotice (file, ";; Combiner statistics: %d attempts, %d substitutions (%d requiring new space),\n;; %d successes.\n\n", combine_attempts, combine_merges, combine_extras, combine_successes); } void dump_combine_total_stats (file) FILE *file; { fnotice (file, "\n;; Combiner totals: %d attempts, %d substitutions (%d requiring new space),\n;; %d successes.\n", total_attempts, total_merges, total_extras, total_successes); }