/* Data flow analysis for GNU compiler. Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001 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 file contains the data flow analysis pass of the compiler. It computes data flow information which tells combine_instructions which insns to consider combining and controls register allocation. Additional data flow information that is too bulky to record is generated during the analysis, and is used at that time to create autoincrement and autodecrement addressing. The first step is dividing the function into basic blocks. find_basic_blocks does this. Then life_analysis determines where each register is live and where it is dead. ** find_basic_blocks ** find_basic_blocks divides the current function's rtl into basic blocks and constructs the CFG. The blocks are recorded in the basic_block_info array; the CFG exists in the edge structures referenced by the blocks. find_basic_blocks also finds any unreachable loops and deletes them. ** life_analysis ** life_analysis is called immediately after find_basic_blocks. It uses the basic block information to determine where each hard or pseudo register is live. ** live-register info ** The information about where each register is live is in two parts: the REG_NOTES of insns, and the vector basic_block->global_live_at_start. basic_block->global_live_at_start has an element for each basic block, and the element is a bit-vector with a bit for each hard or pseudo register. The bit is 1 if the register is live at the beginning of the basic block. Two types of elements can be added to an insn's REG_NOTES. A REG_DEAD note is added to an insn's REG_NOTES for any register that meets both of two conditions: The value in the register is not needed in subsequent insns and the insn does not replace the value in the register (in the case of multi-word hard registers, the value in each register must be replaced by the insn to avoid a REG_DEAD note). In the vast majority of cases, an object in a REG_DEAD note will be used somewhere in the insn. The (rare) exception to this is if an insn uses a multi-word hard register and only some of the registers are needed in subsequent insns. In that case, REG_DEAD notes will be provided for those hard registers that are not subsequently needed. Partial REG_DEAD notes of this type do not occur when an insn sets only some of the hard registers used in such a multi-word operand; omitting REG_DEAD notes for objects stored in an insn is optional and the desire to do so does not justify the complexity of the partial REG_DEAD notes. REG_UNUSED notes are added for each register that is set by the insn but is unused subsequently (if every register set by the insn is unused and the insn does not reference memory or have some other side-effect, the insn is deleted instead). If only part of a multi-word hard register is used in a subsequent insn, REG_UNUSED notes are made for the parts that will not be used. To determine which registers are live after any insn, one can start from the beginning of the basic block and scan insns, noting which registers are set by each insn and which die there. ** Other actions of life_analysis ** life_analysis sets up the LOG_LINKS fields of insns because the information needed to do so is readily available. life_analysis deletes insns whose only effect is to store a value that is never used. life_analysis notices cases where a reference to a register as a memory address can be combined with a preceding or following incrementation or decrementation of the register. The separate instruction to increment or decrement is deleted and the address is changed to a POST_INC or similar rtx. Each time an incrementing or decrementing address is created, a REG_INC element is added to the insn's REG_NOTES list. life_analysis fills in certain vectors containing information about register usage: REG_N_REFS, REG_N_DEATHS, REG_N_SETS, REG_LIVE_LENGTH, REG_N_CALLS_CROSSED and REG_BASIC_BLOCK. life_analysis sets current_function_sp_is_unchanging if the function doesn't modify the stack pointer. */ /* TODO: Split out from life_analysis: - local property discovery (bb->local_live, bb->local_set) - global property computation - log links creation - pre/post modify transformation */ #include "config.h" #include "system.h" #include "tree.h" #include "rtl.h" #include "tm_p.h" #include "hard-reg-set.h" #include "basic-block.h" #include "insn-config.h" #include "regs.h" #include "flags.h" #include "output.h" #include "function.h" #include "except.h" #include "toplev.h" #include "recog.h" #include "expr.h" #include "ssa.h" #include "timevar.h" #include "obstack.h" #include "splay-tree.h" #define obstack_chunk_alloc xmalloc #define obstack_chunk_free free /* EXIT_IGNORE_STACK should be nonzero if, when returning from a function, the stack pointer does not matter. The value is tested only in functions that have frame pointers. No definition is equivalent to always zero. */ #ifndef EXIT_IGNORE_STACK #define EXIT_IGNORE_STACK 0 #endif #ifndef HAVE_epilogue #define HAVE_epilogue 0 #endif #ifndef HAVE_prologue #define HAVE_prologue 0 #endif #ifndef HAVE_sibcall_epilogue #define HAVE_sibcall_epilogue 0 #endif #ifndef LOCAL_REGNO #define LOCAL_REGNO(REGNO) 0 #endif #ifndef EPILOGUE_USES #define EPILOGUE_USES(REGNO) 0 #endif #ifdef HAVE_conditional_execution #ifndef REVERSE_CONDEXEC_PREDICATES_P #define REVERSE_CONDEXEC_PREDICATES_P(x, y) ((x) == reverse_condition (y)) #endif #endif /* Nonzero if the second flow pass has completed. */ int flow2_completed; /* Maximum register number used in this function, plus one. */ int max_regno; /* Indexed by n, giving various register information */ varray_type reg_n_info; /* Size of a regset for the current function, in (1) bytes and (2) elements. */ int regset_bytes; int regset_size; /* Regset of regs live when calls to `setjmp'-like functions happen. */ /* ??? Does this exist only for the setjmp-clobbered warning message? */ regset regs_live_at_setjmp; /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers that have to go in the same hard reg. The first two regs in the list are a pair, and the next two are another pair, etc. */ rtx regs_may_share; /* Callback that determines if it's ok for a function to have no noreturn attribute. */ int (*lang_missing_noreturn_ok_p) PARAMS ((tree)); /* Set of registers that may be eliminable. These are handled specially in updating regs_ever_live. */ static HARD_REG_SET elim_reg_set; /* Holds information for tracking conditional register life information. */ struct reg_cond_life_info { /* A boolean expression of conditions under which a register is dead. */ rtx condition; /* Conditions under which a register is dead at the basic block end. */ rtx orig_condition; /* A boolean expression of conditions under which a register has been stored into. */ rtx stores; /* ??? Could store mask of bytes that are dead, so that we could finally track lifetimes of multi-word registers accessed via subregs. */ }; /* For use in communicating between propagate_block and its subroutines. Holds all information needed to compute life and def-use information. */ struct propagate_block_info { /* The basic block we're considering. */ basic_block bb; /* Bit N is set if register N is conditionally or unconditionally live. */ regset reg_live; /* Bit N is set if register N is set this insn. */ regset new_set; /* Element N is the next insn that uses (hard or pseudo) register N within the current basic block; or zero, if there is no such insn. */ rtx *reg_next_use; /* Contains a list of all the MEMs we are tracking for dead store elimination. */ rtx mem_set_list; /* If non-null, record the set of registers set unconditionally in the basic block. */ regset local_set; /* If non-null, record the set of registers set conditionally in the basic block. */ regset cond_local_set; #ifdef HAVE_conditional_execution /* Indexed by register number, holds a reg_cond_life_info for each register that is not unconditionally live or dead. */ splay_tree reg_cond_dead; /* Bit N is set if register N is in an expression in reg_cond_dead. */ regset reg_cond_reg; #endif /* The length of mem_set_list. */ int mem_set_list_len; /* Non-zero if the value of CC0 is live. */ int cc0_live; /* Flags controling the set of information propagate_block collects. */ int flags; }; /* Maximum length of pbi->mem_set_list before we start dropping new elements on the floor. */ #define MAX_MEM_SET_LIST_LEN 100 /* Have print_rtl_and_abort give the same information that fancy_abort does. */ #define print_rtl_and_abort() \ print_rtl_and_abort_fcn (__FILE__, __LINE__, __FUNCTION__) /* Forward declarations */ static int verify_wide_reg_1 PARAMS ((rtx *, void *)); static void verify_wide_reg PARAMS ((int, rtx, rtx)); static void verify_local_live_at_start PARAMS ((regset, basic_block)); static void notice_stack_pointer_modification_1 PARAMS ((rtx, rtx, void *)); static void notice_stack_pointer_modification PARAMS ((rtx)); static void mark_reg PARAMS ((rtx, void *)); static void mark_regs_live_at_end PARAMS ((regset)); static int set_phi_alternative_reg PARAMS ((rtx, int, int, void *)); static void calculate_global_regs_live PARAMS ((sbitmap, sbitmap, int)); static void propagate_block_delete_insn PARAMS ((basic_block, rtx)); static rtx propagate_block_delete_libcall PARAMS ((rtx, rtx)); static int insn_dead_p PARAMS ((struct propagate_block_info *, rtx, int, rtx)); static int libcall_dead_p PARAMS ((struct propagate_block_info *, rtx, rtx)); static void mark_set_regs PARAMS ((struct propagate_block_info *, rtx, rtx)); static void mark_set_1 PARAMS ((struct propagate_block_info *, enum rtx_code, rtx, rtx, rtx, int)); #ifdef HAVE_conditional_execution static int mark_regno_cond_dead PARAMS ((struct propagate_block_info *, int, rtx)); static void free_reg_cond_life_info PARAMS ((splay_tree_value)); static int flush_reg_cond_reg_1 PARAMS ((splay_tree_node, void *)); static void flush_reg_cond_reg PARAMS ((struct propagate_block_info *, int)); static rtx elim_reg_cond PARAMS ((rtx, unsigned int)); static rtx ior_reg_cond PARAMS ((rtx, rtx, int)); static rtx not_reg_cond PARAMS ((rtx)); static rtx and_reg_cond PARAMS ((rtx, rtx, int)); #endif #ifdef AUTO_INC_DEC static void attempt_auto_inc PARAMS ((struct propagate_block_info *, rtx, rtx, rtx, rtx, rtx)); static void find_auto_inc PARAMS ((struct propagate_block_info *, rtx, rtx)); static int try_pre_increment_1 PARAMS ((struct propagate_block_info *, rtx)); static int try_pre_increment PARAMS ((rtx, rtx, HOST_WIDE_INT)); #endif static void mark_used_reg PARAMS ((struct propagate_block_info *, rtx, rtx, rtx)); static void mark_used_regs PARAMS ((struct propagate_block_info *, rtx, rtx, rtx)); void dump_flow_info PARAMS ((FILE *)); void debug_flow_info PARAMS ((void)); static void print_rtl_and_abort_fcn PARAMS ((const char *, int, const char *)) ATTRIBUTE_NORETURN; static void add_to_mem_set_list PARAMS ((struct propagate_block_info *, rtx)); static void invalidate_mems_from_autoinc PARAMS ((struct propagate_block_info *, rtx)); static void invalidate_mems_from_set PARAMS ((struct propagate_block_info *, rtx)); static void delete_dead_jumptables PARAMS ((void)); void check_function_return_warnings () { if (warn_missing_noreturn && !TREE_THIS_VOLATILE (cfun->decl) && EXIT_BLOCK_PTR->pred == NULL && (lang_missing_noreturn_ok_p && !lang_missing_noreturn_ok_p (cfun->decl))) warning ("function might be possible candidate for attribute `noreturn'"); /* If we have a path to EXIT, then we do return. */ if (TREE_THIS_VOLATILE (cfun->decl) && EXIT_BLOCK_PTR->pred != NULL) warning ("`noreturn' function does return"); /* If the clobber_return_insn appears in some basic block, then we do reach the end without returning a value. */ else if (warn_return_type && cfun->x_clobber_return_insn != NULL && EXIT_BLOCK_PTR->pred != NULL) { int max_uid = get_max_uid (); /* If clobber_return_insn was excised by jump1, then renumber_insns can make max_uid smaller than the number still recorded in our rtx. That's fine, since this is a quick way of verifying that the insn is no longer in the chain. */ if (INSN_UID (cfun->x_clobber_return_insn) < max_uid) { /* Recompute insn->block mapping, since the initial mapping is set before we delete unreachable blocks. */ if (BLOCK_FOR_INSN (cfun->x_clobber_return_insn) != NULL) warning ("control reaches end of non-void function"); } } } /* Return the INSN immediately following the NOTE_INSN_BASIC_BLOCK note associated with the BLOCK. */ rtx first_insn_after_basic_block_note (block) basic_block block; { rtx insn; /* Get the first instruction in the block. */ insn = block->head; if (insn == NULL_RTX) return NULL_RTX; if (GET_CODE (insn) == CODE_LABEL) insn = NEXT_INSN (insn); if (!NOTE_INSN_BASIC_BLOCK_P (insn)) abort (); return NEXT_INSN (insn); } /* Perform data flow analysis. F is the first insn of the function; FLAGS is a set of PROP_* flags to be used in accumulating flow info. */ void life_analysis (f, file, flags) rtx f; FILE *file; int flags; { #ifdef ELIMINABLE_REGS register int i; static const struct {const int from, to; } eliminables[] = ELIMINABLE_REGS; #endif /* Record which registers will be eliminated. We use this in mark_used_regs. */ CLEAR_HARD_REG_SET (elim_reg_set); #ifdef ELIMINABLE_REGS for (i = 0; i < (int) ARRAY_SIZE (eliminables); i++) SET_HARD_REG_BIT (elim_reg_set, eliminables[i].from); #else SET_HARD_REG_BIT (elim_reg_set, FRAME_POINTER_REGNUM); #endif if (! optimize) flags &= ~(PROP_LOG_LINKS | PROP_AUTOINC | PROP_ALLOW_CFG_CHANGES); /* The post-reload life analysis have (on a global basis) the same registers live as was computed by reload itself. elimination Otherwise offsets and such may be incorrect. Reload will make some registers as live even though they do not appear in the rtl. We don't want to create new auto-incs after reload, since they are unlikely to be useful and can cause problems with shared stack slots. */ if (reload_completed) flags &= ~(PROP_REG_INFO | PROP_AUTOINC); /* We want alias analysis information for local dead store elimination. */ if (optimize && (flags & PROP_SCAN_DEAD_CODE)) init_alias_analysis (); /* Always remove no-op moves. Do this before other processing so that we don't have to keep re-scanning them. */ delete_noop_moves (f); /* Some targets can emit simpler epilogues if they know that sp was not ever modified during the function. After reload, of course, we've already emitted the epilogue so there's no sense searching. */ if (! reload_completed) notice_stack_pointer_modification (f); /* Allocate and zero out data structures that will record the data from lifetime analysis. */ allocate_reg_life_data (); allocate_bb_life_data (); /* Find the set of registers live on function exit. */ mark_regs_live_at_end (EXIT_BLOCK_PTR->global_live_at_start); /* "Update" life info from zero. It'd be nice to begin the relaxation with just the exit and noreturn blocks, but that set is not immediately handy. */ if (flags & PROP_REG_INFO) memset (regs_ever_live, 0, sizeof (regs_ever_live)); update_life_info (NULL, UPDATE_LIFE_GLOBAL, flags); /* Clean up. */ if (optimize && (flags & PROP_SCAN_DEAD_CODE)) end_alias_analysis (); if (file) dump_flow_info (file); free_basic_block_vars (1); #ifdef ENABLE_CHECKING { rtx insn; /* Search for any REG_LABEL notes which reference deleted labels. */ for (insn = get_insns (); insn; insn = NEXT_INSN (insn)) { rtx inote = find_reg_note (insn, REG_LABEL, NULL_RTX); if (inote && GET_CODE (inote) == NOTE_INSN_DELETED_LABEL) abort (); } } #endif /* Removing dead insns should've made jumptables really dead. */ delete_dead_jumptables (); } /* A subroutine of verify_wide_reg, called through for_each_rtx. Search for REGNO. If found, abort if it is not wider than word_mode. */ static int verify_wide_reg_1 (px, pregno) rtx *px; void *pregno; { rtx x = *px; unsigned int regno = *(int *) pregno; if (GET_CODE (x) == REG && REGNO (x) == regno) { if (GET_MODE_BITSIZE (GET_MODE (x)) <= BITS_PER_WORD) abort (); return 1; } return 0; } /* A subroutine of verify_local_live_at_start. Search through insns between HEAD and END looking for register REGNO. */ static void verify_wide_reg (regno, head, end) int regno; rtx head, end; { while (1) { if (INSN_P (head) && for_each_rtx (&PATTERN (head), verify_wide_reg_1, ®no)) return; if (head == end) break; head = NEXT_INSN (head); } /* We didn't find the register at all. Something's way screwy. */ if (rtl_dump_file) fprintf (rtl_dump_file, "Aborting in verify_wide_reg; reg %d\n", regno); print_rtl_and_abort (); } /* A subroutine of update_life_info. Verify that there are no untoward changes in live_at_start during a local update. */ static void verify_local_live_at_start (new_live_at_start, bb) regset new_live_at_start; basic_block bb; { if (reload_completed) { /* After reload, there are no pseudos, nor subregs of multi-word registers. The regsets should exactly match. */ if (! REG_SET_EQUAL_P (new_live_at_start, bb->global_live_at_start)) { if (rtl_dump_file) { fprintf (rtl_dump_file, "live_at_start mismatch in bb %d, aborting\n", bb->index); debug_bitmap_file (rtl_dump_file, bb->global_live_at_start); debug_bitmap_file (rtl_dump_file, new_live_at_start); } print_rtl_and_abort (); } } else { int i; /* Find the set of changed registers. */ XOR_REG_SET (new_live_at_start, bb->global_live_at_start); EXECUTE_IF_SET_IN_REG_SET (new_live_at_start, 0, i, { /* No registers should die. */ if (REGNO_REG_SET_P (bb->global_live_at_start, i)) { if (rtl_dump_file) fprintf (rtl_dump_file, "Register %d died unexpectedly in block %d\n", i, bb->index); print_rtl_and_abort (); } /* Verify that the now-live register is wider than word_mode. */ verify_wide_reg (i, bb->head, bb->end); }); } } /* Updates life information starting with the basic blocks set in BLOCKS. If BLOCKS is null, consider it to be the universal set. If EXTENT is UPDATE_LIFE_LOCAL, such as after splitting or peepholeing, we are only expecting local modifications to basic blocks. If we find extra registers live at the beginning of a block, then we either killed useful data, or we have a broken split that wants data not provided. If we find registers removed from live_at_start, that means we have a broken peephole that is killing a register it shouldn't. ??? This is not true in one situation -- when a pre-reload splitter generates subregs of a multi-word pseudo, current life analysis will lose the kill. So we _can_ have a pseudo go live. How irritating. Including PROP_REG_INFO does not properly refresh regs_ever_live unless the caller resets it to zero. */ void update_life_info (blocks, extent, prop_flags) sbitmap blocks; enum update_life_extent extent; int prop_flags; { regset tmp; regset_head tmp_head; int i; tmp = INITIALIZE_REG_SET (tmp_head); /* Changes to the CFG are only allowed when doing a global update for the entire CFG. */ if ((prop_flags & PROP_ALLOW_CFG_CHANGES) && (extent == UPDATE_LIFE_LOCAL || blocks)) abort (); /* For a global update, we go through the relaxation process again. */ if (extent != UPDATE_LIFE_LOCAL) { for ( ; ; ) { int changed = 0; calculate_global_regs_live (blocks, blocks, prop_flags & (PROP_SCAN_DEAD_CODE | PROP_ALLOW_CFG_CHANGES)); if ((prop_flags & (PROP_KILL_DEAD_CODE | PROP_ALLOW_CFG_CHANGES)) != (PROP_KILL_DEAD_CODE | PROP_ALLOW_CFG_CHANGES)) break; /* Removing dead code may allow the CFG to be simplified which in turn may allow for further dead code detection / removal. */ for (i = n_basic_blocks - 1; i >= 0; --i) { basic_block bb = BASIC_BLOCK (i); COPY_REG_SET (tmp, bb->global_live_at_end); changed |= propagate_block (bb, tmp, NULL, NULL, prop_flags & (PROP_SCAN_DEAD_CODE | PROP_KILL_DEAD_CODE)); } if (! changed || ! cleanup_cfg (CLEANUP_EXPENSIVE)) break; } /* If asked, remove notes from the blocks we'll update. */ if (extent == UPDATE_LIFE_GLOBAL_RM_NOTES) count_or_remove_death_notes (blocks, 1); } if (blocks) { EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i, { basic_block bb = BASIC_BLOCK (i); COPY_REG_SET (tmp, bb->global_live_at_end); propagate_block (bb, tmp, NULL, NULL, prop_flags); if (extent == UPDATE_LIFE_LOCAL) verify_local_live_at_start (tmp, bb); }); } else { for (i = n_basic_blocks - 1; i >= 0; --i) { basic_block bb = BASIC_BLOCK (i); COPY_REG_SET (tmp, bb->global_live_at_end); propagate_block (bb, tmp, NULL, NULL, prop_flags); if (extent == UPDATE_LIFE_LOCAL) verify_local_live_at_start (tmp, bb); } } FREE_REG_SET (tmp); if (prop_flags & PROP_REG_INFO) { /* The only pseudos that are live at the beginning of the function are those that were not set anywhere in the function. local-alloc doesn't know how to handle these correctly, so mark them as not local to any one basic block. */ EXECUTE_IF_SET_IN_REG_SET (ENTRY_BLOCK_PTR->global_live_at_end, FIRST_PSEUDO_REGISTER, i, { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; }); /* We have a problem with any pseudoreg that lives across the setjmp. ANSI says that if a user variable does not change in value between the setjmp and the longjmp, then the longjmp preserves it. This includes longjmp from a place where the pseudo appears dead. (In principle, the value still exists if it is in scope.) If the pseudo goes in a hard reg, some other value may occupy that hard reg where this pseudo is dead, thus clobbering the pseudo. Conclusion: such a pseudo must not go in a hard reg. */ EXECUTE_IF_SET_IN_REG_SET (regs_live_at_setjmp, FIRST_PSEUDO_REGISTER, i, { if (regno_reg_rtx[i] != 0) { REG_LIVE_LENGTH (i) = -1; REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN; } }); } } /* Free the variables allocated by find_basic_blocks. KEEP_HEAD_END_P is non-zero if basic_block_info is not to be freed. */ void free_basic_block_vars (keep_head_end_p) int keep_head_end_p; { if (! keep_head_end_p) { if (basic_block_info) { clear_edges (); VARRAY_FREE (basic_block_info); } n_basic_blocks = 0; ENTRY_BLOCK_PTR->aux = NULL; ENTRY_BLOCK_PTR->global_live_at_end = NULL; EXIT_BLOCK_PTR->aux = NULL; EXIT_BLOCK_PTR->global_live_at_start = NULL; } } /* Delete any insns that copy a register to itself. */ void delete_noop_moves (f) rtx f ATTRIBUTE_UNUSED; { int i; rtx insn, next; basic_block bb; for (i = 0; i < n_basic_blocks; i++) { bb = BASIC_BLOCK (i); for (insn = bb->head; insn != NEXT_INSN (bb->end); insn = next) { next = NEXT_INSN (insn); if (INSN_P (insn) && noop_move_p (insn)) { /* Do not call delete_insn here to not confuse backward pointers of LIBCALL block. */ PUT_CODE (insn, NOTE); NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED; NOTE_SOURCE_FILE (insn) = 0; if (insn == bb->end) purge_dead_edges (bb); } } } } /* Delete any jump tables never referenced. We can't delete them at the time of removing tablejump insn as they are referenced by the preceeding insns computing the destination, so we delay deleting and garbagecollect them once life information is computed. */ static void delete_dead_jumptables () { rtx insn, next; for (insn = get_insns (); insn; insn = next) { next = NEXT_INSN (insn); if (GET_CODE (insn) == CODE_LABEL && LABEL_NUSES (insn) == LABEL_PRESERVE_P (insn) && GET_CODE (next) == JUMP_INSN && (GET_CODE (PATTERN (next)) == ADDR_VEC || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC)) { if (rtl_dump_file) fprintf (rtl_dump_file, "Dead jumptable %i removed\n", INSN_UID (insn)); delete_insn (NEXT_INSN (insn)); delete_insn (insn); next = NEXT_INSN (next); } } } /* Determine if the stack pointer is constant over the life of the function. Only useful before prologues have been emitted. */ static void notice_stack_pointer_modification_1 (x, pat, data) rtx x; rtx pat ATTRIBUTE_UNUSED; void *data ATTRIBUTE_UNUSED; { if (x == stack_pointer_rtx /* The stack pointer is only modified indirectly as the result of a push until later in flow. See the comments in rtl.texi regarding Embedded Side-Effects on Addresses. */ || (GET_CODE (x) == MEM && GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) == 'a' && XEXP (XEXP (x, 0), 0) == stack_pointer_rtx)) current_function_sp_is_unchanging = 0; } static void notice_stack_pointer_modification (f) rtx f; { rtx insn; /* Assume that the stack pointer is unchanging if alloca hasn't been used. */ current_function_sp_is_unchanging = !current_function_calls_alloca; if (! current_function_sp_is_unchanging) return; for (insn = f; insn; insn = NEXT_INSN (insn)) { if (INSN_P (insn)) { /* Check if insn modifies the stack pointer. */ note_stores (PATTERN (insn), notice_stack_pointer_modification_1, NULL); if (! current_function_sp_is_unchanging) return; } } } /* Mark a register in SET. Hard registers in large modes get all of their component registers set as well. */ static void mark_reg (reg, xset) rtx reg; void *xset; { regset set = (regset) xset; int regno = REGNO (reg); if (GET_MODE (reg) == BLKmode) abort (); SET_REGNO_REG_SET (set, regno); if (regno < FIRST_PSEUDO_REGISTER) { int n = HARD_REGNO_NREGS (regno, GET_MODE (reg)); while (--n > 0) SET_REGNO_REG_SET (set, regno + n); } } /* Mark those regs which are needed at the end of the function as live at the end of the last basic block. */ static void mark_regs_live_at_end (set) regset set; { unsigned int i; /* If exiting needs the right stack value, consider the stack pointer live at the end of the function. */ if ((HAVE_epilogue && reload_completed) || ! EXIT_IGNORE_STACK || (! FRAME_POINTER_REQUIRED && ! current_function_calls_alloca && flag_omit_frame_pointer) || current_function_sp_is_unchanging) { SET_REGNO_REG_SET (set, STACK_POINTER_REGNUM); } /* Mark the frame pointer if needed at the end of the function. If we end up eliminating it, it will be removed from the live list of each basic block by reload. */ if (! reload_completed || frame_pointer_needed) { SET_REGNO_REG_SET (set, FRAME_POINTER_REGNUM); #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM /* If they are different, also mark the hard frame pointer as live. */ if (! LOCAL_REGNO (HARD_FRAME_POINTER_REGNUM)) SET_REGNO_REG_SET (set, HARD_FRAME_POINTER_REGNUM); #endif } #ifndef PIC_OFFSET_TABLE_REG_CALL_CLOBBERED /* Many architectures have a GP register even without flag_pic. Assume the pic register is not in use, or will be handled by other means, if it is not fixed. */ if (PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM && fixed_regs[PIC_OFFSET_TABLE_REGNUM]) SET_REGNO_REG_SET (set, PIC_OFFSET_TABLE_REGNUM); #endif /* Mark all global registers, and all registers used by the epilogue as being live at the end of the function since they may be referenced by our caller. */ for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) if (global_regs[i] || EPILOGUE_USES (i)) SET_REGNO_REG_SET (set, i); if (HAVE_epilogue && reload_completed) { /* Mark all call-saved registers that we actually used. */ for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) if (regs_ever_live[i] && ! LOCAL_REGNO (i) && ! TEST_HARD_REG_BIT (regs_invalidated_by_call, i)) SET_REGNO_REG_SET (set, i); } #ifdef EH_RETURN_DATA_REGNO /* Mark the registers that will contain data for the handler. */ if (reload_completed && current_function_calls_eh_return) for (i = 0; ; ++i) { unsigned regno = EH_RETURN_DATA_REGNO(i); if (regno == INVALID_REGNUM) break; SET_REGNO_REG_SET (set, regno); } #endif #ifdef EH_RETURN_STACKADJ_RTX if ((! HAVE_epilogue || ! reload_completed) && current_function_calls_eh_return) { rtx tmp = EH_RETURN_STACKADJ_RTX; if (tmp && REG_P (tmp)) mark_reg (tmp, set); } #endif #ifdef EH_RETURN_HANDLER_RTX if ((! HAVE_epilogue || ! reload_completed) && current_function_calls_eh_return) { rtx tmp = EH_RETURN_HANDLER_RTX; if (tmp && REG_P (tmp)) mark_reg (tmp, set); } #endif /* Mark function return value. */ diddle_return_value (mark_reg, set); } /* Callback function for for_each_successor_phi. DATA is a regset. Sets the SRC_REGNO, the regno of the phi alternative for phi node INSN, in the regset. */ static int set_phi_alternative_reg (insn, dest_regno, src_regno, data) rtx insn ATTRIBUTE_UNUSED; int dest_regno ATTRIBUTE_UNUSED; int src_regno; void *data; { regset live = (regset) data; SET_REGNO_REG_SET (live, src_regno); return 0; } /* Propagate global life info around the graph of basic blocks. Begin considering blocks with their corresponding bit set in BLOCKS_IN. If BLOCKS_IN is null, consider it the universal set. BLOCKS_OUT is set for every block that was changed. */ static void calculate_global_regs_live (blocks_in, blocks_out, flags) sbitmap blocks_in, blocks_out; int flags; { basic_block *queue, *qhead, *qtail, *qend; regset tmp, new_live_at_end, call_used; regset_head tmp_head, call_used_head; regset_head new_live_at_end_head; int i; tmp = INITIALIZE_REG_SET (tmp_head); new_live_at_end = INITIALIZE_REG_SET (new_live_at_end_head); call_used = INITIALIZE_REG_SET (call_used_head); /* Inconveniently, this is only redily available in hard reg set form. */ for (i = 0; i < FIRST_PSEUDO_REGISTER; ++i) if (call_used_regs[i]) SET_REGNO_REG_SET (call_used, i); /* Create a worklist. Allocate an extra slot for ENTRY_BLOCK, and one because the `head == tail' style test for an empty queue doesn't work with a full queue. */ queue = (basic_block *) xmalloc ((n_basic_blocks + 2) * sizeof (*queue)); qtail = queue; qhead = qend = queue + n_basic_blocks + 2; /* Queue the blocks set in the initial mask. Do this in reverse block number order so that we are more likely for the first round to do useful work. We use AUX non-null to flag that the block is queued. */ if (blocks_in) { /* Clear out the garbage that might be hanging out in bb->aux. */ for (i = n_basic_blocks - 1; i >= 0; --i) BASIC_BLOCK (i)->aux = NULL; EXECUTE_IF_SET_IN_SBITMAP (blocks_in, 0, i, { basic_block bb = BASIC_BLOCK (i); *--qhead = bb; bb->aux = bb; }); } else { for (i = 0; i < n_basic_blocks; ++i) { basic_block bb = BASIC_BLOCK (i); *--qhead = bb; bb->aux = bb; } } if (blocks_out) sbitmap_zero (blocks_out); /* We work through the queue until there are no more blocks. What is live at the end of this block is precisely the union of what is live at the beginning of all its successors. So, we set its GLOBAL_LIVE_AT_END field based on the GLOBAL_LIVE_AT_START field for its successors. Then, we compute GLOBAL_LIVE_AT_START for this block by walking through the instructions in this block in reverse order and updating as we go. If that changed GLOBAL_LIVE_AT_START, we add the predecessors of the block to the queue; they will now need to recalculate GLOBAL_LIVE_AT_END. We are guaranteed to terminate, because GLOBAL_LIVE_AT_START never shrinks. If a register appears in GLOBAL_LIVE_AT_START, it must either be live at the end of the block, or used within the block. In the latter case, it will certainly never disappear from GLOBAL_LIVE_AT_START. In the former case, the register could go away only if it disappeared from GLOBAL_LIVE_AT_START for one of the successor blocks. By induction, that cannot occur. */ while (qhead != qtail) { int rescan, changed; basic_block bb; edge e; bb = *qhead++; if (qhead == qend) qhead = queue; bb->aux = NULL; /* Begin by propagating live_at_start from the successor blocks. */ CLEAR_REG_SET (new_live_at_end); for (e = bb->succ; e; e = e->succ_next) { basic_block sb = e->dest; /* Call-clobbered registers die across exception and call edges. */ /* ??? Abnormal call edges ignored for the moment, as this gets confused by sibling call edges, which crashes reg-stack. */ if (e->flags & EDGE_EH) { bitmap_operation (tmp, sb->global_live_at_start, call_used, BITMAP_AND_COMPL); IOR_REG_SET (new_live_at_end, tmp); } else IOR_REG_SET (new_live_at_end, sb->global_live_at_start); } /* The all-important stack pointer must always be live. */ SET_REGNO_REG_SET (new_live_at_end, STACK_POINTER_REGNUM); /* Before reload, there are a few registers that must be forced live everywhere -- which might not already be the case for blocks within infinite loops. */ if (! reload_completed) { /* Any reference to any pseudo before reload is a potential reference of the frame pointer. */ SET_REGNO_REG_SET (new_live_at_end, FRAME_POINTER_REGNUM); #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM /* Pseudos with argument area equivalences may require reloading via the argument pointer. */ if (fixed_regs[ARG_POINTER_REGNUM]) SET_REGNO_REG_SET (new_live_at_end, ARG_POINTER_REGNUM); #endif /* Any constant, or pseudo with constant equivalences, may require reloading from memory using the pic register. */ if (PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM && fixed_regs[PIC_OFFSET_TABLE_REGNUM]) SET_REGNO_REG_SET (new_live_at_end, PIC_OFFSET_TABLE_REGNUM); } /* Regs used in phi nodes are not included in global_live_at_start, since they are live only along a particular edge. Set those regs that are live because of a phi node alternative corresponding to this particular block. */ if (in_ssa_form) for_each_successor_phi (bb, &set_phi_alternative_reg, new_live_at_end); if (bb == ENTRY_BLOCK_PTR) { COPY_REG_SET (bb->global_live_at_end, new_live_at_end); continue; } /* On our first pass through this block, we'll go ahead and continue. Recognize first pass by local_set NULL. On subsequent passes, we get to skip out early if live_at_end wouldn't have changed. */ if (bb->local_set == NULL) { bb->local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack); bb->cond_local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack); rescan = 1; } else { /* If any bits were removed from live_at_end, we'll have to rescan the block. This wouldn't be necessary if we had precalculated local_live, however with PROP_SCAN_DEAD_CODE local_live is really dependent on live_at_end. */ CLEAR_REG_SET (tmp); rescan = bitmap_operation (tmp, bb->global_live_at_end, new_live_at_end, BITMAP_AND_COMPL); if (! rescan) { /* If any of the registers in the new live_at_end set are conditionally set in this basic block, we must rescan. This is because conditional lifetimes at the end of the block do not just take the live_at_end set into account, but also the liveness at the start of each successor block. We can miss changes in those sets if we only compare the new live_at_end against the previous one. */ CLEAR_REG_SET (tmp); rescan = bitmap_operation (tmp, new_live_at_end, bb->cond_local_set, BITMAP_AND); } if (! rescan) { /* Find the set of changed bits. Take this opportunity to notice that this set is empty and early out. */ CLEAR_REG_SET (tmp); changed = bitmap_operation (tmp, bb->global_live_at_end, new_live_at_end, BITMAP_XOR); if (! changed) continue; /* If any of the changed bits overlap with local_set, we'll have to rescan the block. Detect overlap by the AND with ~local_set turning off bits. */ rescan = bitmap_operation (tmp, tmp, bb->local_set, BITMAP_AND_COMPL); } } /* Let our caller know that BB changed enough to require its death notes updated. */ if (blocks_out) SET_BIT (blocks_out, bb->index); if (! rescan) { /* Add to live_at_start the set of all registers in new_live_at_end that aren't in the old live_at_end. */ bitmap_operation (tmp, new_live_at_end, bb->global_live_at_end, BITMAP_AND_COMPL); COPY_REG_SET (bb->global_live_at_end, new_live_at_end); changed = bitmap_operation (bb->global_live_at_start, bb->global_live_at_start, tmp, BITMAP_IOR); if (! changed) continue; } else { COPY_REG_SET (bb->global_live_at_end, new_live_at_end); /* Rescan the block insn by insn to turn (a copy of) live_at_end into live_at_start. */ propagate_block (bb, new_live_at_end, bb->local_set, bb->cond_local_set, flags); /* If live_at start didn't change, no need to go farther. */ if (REG_SET_EQUAL_P (bb->global_live_at_start, new_live_at_end)) continue; COPY_REG_SET (bb->global_live_at_start, new_live_at_end); } /* Queue all predecessors of BB so that we may re-examine their live_at_end. */ for (e = bb->pred; e; e = e->pred_next) { basic_block pb = e->src; if (pb->aux == NULL) { *qtail++ = pb; if (qtail == qend) qtail = queue; pb->aux = pb; } } } FREE_REG_SET (tmp); FREE_REG_SET (new_live_at_end); FREE_REG_SET (call_used); if (blocks_out) { EXECUTE_IF_SET_IN_SBITMAP (blocks_out, 0, i, { basic_block bb = BASIC_BLOCK (i); FREE_REG_SET (bb->local_set); FREE_REG_SET (bb->cond_local_set); }); } else { for (i = n_basic_blocks - 1; i >= 0; --i) { basic_block bb = BASIC_BLOCK (i); FREE_REG_SET (bb->local_set); FREE_REG_SET (bb->cond_local_set); } } free (queue); } /* Subroutines of life analysis. */ /* Allocate the permanent data structures that represent the results of life analysis. Not static since used also for stupid life analysis. */ void allocate_bb_life_data () { register int i; for (i = 0; i < n_basic_blocks; i++) { basic_block bb = BASIC_BLOCK (i); bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack); bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack); } ENTRY_BLOCK_PTR->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack); EXIT_BLOCK_PTR->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack); regs_live_at_setjmp = OBSTACK_ALLOC_REG_SET (&flow_obstack); } void allocate_reg_life_data () { int i; max_regno = max_reg_num (); /* Recalculate the register space, in case it has grown. Old style vector oriented regsets would set regset_{size,bytes} here also. */ allocate_reg_info (max_regno, FALSE, FALSE); /* Reset all the data we'll collect in propagate_block and its subroutines. */ for (i = 0; i < max_regno; i++) { REG_N_SETS (i) = 0; REG_N_REFS (i) = 0; REG_N_DEATHS (i) = 0; REG_N_CALLS_CROSSED (i) = 0; REG_LIVE_LENGTH (i) = 0; REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN; } } /* Delete dead instructions for propagate_block. */ static void propagate_block_delete_insn (bb, insn) basic_block bb; rtx insn; { rtx inote = find_reg_note (insn, REG_LABEL, NULL_RTX); bool purge = false; /* If the insn referred to a label, and that label was attached to an ADDR_VEC, it's safe to delete the ADDR_VEC. In fact, it's pretty much mandatory to delete it, because the ADDR_VEC may be referencing labels that no longer exist. INSN may reference a deleted label, particularly when a jump table has been optimized into a direct jump. There's no real good way to fix up the reference to the deleted label when the label is deleted, so we just allow it here. After dead code elimination is complete, we do search for any REG_LABEL notes which reference deleted labels as a sanity check. */ if (inote && GET_CODE (inote) == CODE_LABEL) { rtx label = XEXP (inote, 0); rtx next; /* The label may be forced if it has been put in the constant pool. If that is the only use we must discard the table jump following it, but not the label itself. */ if (LABEL_NUSES (label) == 1 + LABEL_PRESERVE_P (label) && (next = next_nonnote_insn (label)) != NULL && GET_CODE (next) == JUMP_INSN && (GET_CODE (PATTERN (next)) == ADDR_VEC || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC)) { rtx pat = PATTERN (next); int diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC; int len = XVECLEN (pat, diff_vec_p); int i; for (i = 0; i < len; i++) LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))--; delete_insn (next); } } if (bb->end == insn) purge = true; delete_insn (insn); if (purge) purge_dead_edges (bb); } /* Delete dead libcalls for propagate_block. Return the insn before the libcall. */ static rtx propagate_block_delete_libcall ( insn, note) rtx insn, note; { rtx first = XEXP (note, 0); rtx before = PREV_INSN (first); delete_insn_chain (first, insn); return before; } /* Update the life-status of regs for one insn. Return the previous insn. */ rtx propagate_one_insn (pbi, insn) struct propagate_block_info *pbi; rtx insn; { rtx prev = PREV_INSN (insn); int flags = pbi->flags; int insn_is_dead = 0; int libcall_is_dead = 0; rtx note; int i; if (! INSN_P (insn)) return prev; note = find_reg_note (insn, REG_RETVAL, NULL_RTX); if (flags & PROP_SCAN_DEAD_CODE) { insn_is_dead = insn_dead_p (pbi, PATTERN (insn), 0, REG_NOTES (insn)); libcall_is_dead = (insn_is_dead && note != 0 && libcall_dead_p (pbi, note, insn)); } /* If an instruction consists of just dead store(s) on final pass, delete it. */ if ((flags & PROP_KILL_DEAD_CODE) && insn_is_dead) { /* If we're trying to delete a prologue or epilogue instruction that isn't flagged as possibly being dead, something is wrong. But if we are keeping the stack pointer depressed, we might well be deleting insns that are used to compute the amount to update it by, so they are fine. */ if (reload_completed && !(TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE && (TYPE_RETURNS_STACK_DEPRESSED (TREE_TYPE (current_function_decl)))) && (((HAVE_epilogue || HAVE_prologue) && prologue_epilogue_contains (insn)) || (HAVE_sibcall_epilogue && sibcall_epilogue_contains (insn))) && find_reg_note (insn, REG_MAYBE_DEAD, NULL_RTX) == 0) abort (); /* Record sets. Do this even for dead instructions, since they would have killed the values if they hadn't been deleted. */ mark_set_regs (pbi, PATTERN (insn), insn); /* CC0 is now known to be dead. Either this insn used it, in which case it doesn't anymore, or clobbered it, so the next insn can't use it. */ pbi->cc0_live = 0; if (libcall_is_dead) prev = propagate_block_delete_libcall ( insn, note); else propagate_block_delete_insn (pbi->bb, insn); return prev; } /* See if this is an increment or decrement that can be merged into a following memory address. */ #ifdef AUTO_INC_DEC { register rtx x = single_set (insn); /* Does this instruction increment or decrement a register? */ if ((flags & PROP_AUTOINC) && x != 0 && GET_CODE (SET_DEST (x)) == REG && (GET_CODE (SET_SRC (x)) == PLUS || GET_CODE (SET_SRC (x)) == MINUS) && XEXP (SET_SRC (x), 0) == SET_DEST (x) && GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT /* Ok, look for a following memory ref we can combine with. If one is found, change the memory ref to a PRE_INC or PRE_DEC, cancel this insn, and return 1. Return 0 if nothing has been done. */ && try_pre_increment_1 (pbi, insn)) return prev; } #endif /* AUTO_INC_DEC */ CLEAR_REG_SET (pbi->new_set); /* If this is not the final pass, and this insn is copying the value of a library call and it's dead, don't scan the insns that perform the library call, so that the call's arguments are not marked live. */ if (libcall_is_dead) { /* Record the death of the dest reg. */ mark_set_regs (pbi, PATTERN (insn), insn); insn = XEXP (note, 0); return PREV_INSN (insn); } else if (GET_CODE (PATTERN (insn)) == SET && SET_DEST (PATTERN (insn)) == stack_pointer_rtx && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx && GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == CONST_INT) /* We have an insn to pop a constant amount off the stack. (Such insns use PLUS regardless of the direction of the stack, and any insn to adjust the stack by a constant is always a pop.) These insns, if not dead stores, have no effect on life. */ ; else { /* Any regs live at the time of a call instruction must not go in a register clobbered by calls. Find all regs now live and record this for them. */ if (GET_CODE (insn) == CALL_INSN && (flags & PROP_REG_INFO)) EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i, { REG_N_CALLS_CROSSED (i)++; }); /* Record sets. Do this even for dead instructions, since they would have killed the values if they hadn't been deleted. */ mark_set_regs (pbi, PATTERN (insn), insn); if (GET_CODE (insn) == CALL_INSN) { register int i; rtx note, cond; cond = NULL_RTX; if (GET_CODE (PATTERN (insn)) == COND_EXEC) cond = COND_EXEC_TEST (PATTERN (insn)); /* Non-constant calls clobber memory. */ if (! CONST_OR_PURE_CALL_P (insn)) { free_EXPR_LIST_list (&pbi->mem_set_list); pbi->mem_set_list_len = 0; } /* There may be extra registers to be clobbered. */ for (note = CALL_INSN_FUNCTION_USAGE (insn); note; note = XEXP (note, 1)) if (GET_CODE (XEXP (note, 0)) == CLOBBER) mark_set_1 (pbi, CLOBBER, XEXP (XEXP (note, 0), 0), cond, insn, pbi->flags); /* Calls change all call-used and global registers. */ for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) if (TEST_HARD_REG_BIT (regs_invalidated_by_call, i)) { /* We do not want REG_UNUSED notes for these registers. */ mark_set_1 (pbi, CLOBBER, gen_rtx_REG (reg_raw_mode[i], i), cond, insn, pbi->flags & ~(PROP_DEATH_NOTES | PROP_REG_INFO)); } } /* If an insn doesn't use CC0, it becomes dead since we assume that every insn clobbers it. So show it dead here; mark_used_regs will set it live if it is referenced. */ pbi->cc0_live = 0; /* Record uses. */ if (! insn_is_dead) mark_used_regs (pbi, PATTERN (insn), NULL_RTX, insn); /* Sometimes we may have inserted something before INSN (such as a move) when we make an auto-inc. So ensure we will scan those insns. */ #ifdef AUTO_INC_DEC prev = PREV_INSN (insn); #endif if (! insn_is_dead && GET_CODE (insn) == CALL_INSN) { register int i; rtx note, cond; cond = NULL_RTX; if (GET_CODE (PATTERN (insn)) == COND_EXEC) cond = COND_EXEC_TEST (PATTERN (insn)); /* Calls use their arguments. */ for (note = CALL_INSN_FUNCTION_USAGE (insn); note; note = XEXP (note, 1)) if (GET_CODE (XEXP (note, 0)) == USE) mark_used_regs (pbi, XEXP (XEXP (note, 0), 0), cond, insn); /* The stack ptr is used (honorarily) by a CALL insn. */ SET_REGNO_REG_SET (pbi->reg_live, STACK_POINTER_REGNUM); /* Calls may also reference any of the global registers, so they are made live. */ for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) if (global_regs[i]) mark_used_reg (pbi, gen_rtx_REG (reg_raw_mode[i], i), cond, insn); } } /* On final pass, update counts of how many insns in which each reg is live. */ if (flags & PROP_REG_INFO) EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i, { REG_LIVE_LENGTH (i)++; }); return prev; } /* Initialize a propagate_block_info struct for public consumption. Note that the structure itself is opaque to this file, but that the user can use the regsets provided here. */ struct propagate_block_info * init_propagate_block_info (bb, live, local_set, cond_local_set, flags) basic_block bb; regset live, local_set, cond_local_set; int flags; { struct propagate_block_info *pbi = xmalloc (sizeof (*pbi)); pbi->bb = bb; pbi->reg_live = live; pbi->mem_set_list = NULL_RTX; pbi->mem_set_list_len = 0; pbi->local_set = local_set; pbi->cond_local_set = cond_local_set; pbi->cc0_live = 0; pbi->flags = flags; if (flags & (PROP_LOG_LINKS | PROP_AUTOINC)) pbi->reg_next_use = (rtx *) xcalloc (max_reg_num (), sizeof (rtx)); else pbi->reg_next_use = NULL; pbi->new_set = BITMAP_XMALLOC (); #ifdef HAVE_conditional_execution pbi->reg_cond_dead = splay_tree_new (splay_tree_compare_ints, NULL, free_reg_cond_life_info); pbi->reg_cond_reg = BITMAP_XMALLOC (); /* If this block ends in a conditional branch, for each register live from one side of the branch and not the other, record the register as conditionally dead. */ if (GET_CODE (bb->end) == JUMP_INSN && any_condjump_p (bb->end)) { regset_head diff_head; regset diff = INITIALIZE_REG_SET (diff_head); basic_block bb_true, bb_false; rtx cond_true, cond_false, set_src; int i; /* Identify the successor blocks. */ bb_true = bb->succ->dest; if (bb->succ->succ_next != NULL) { bb_false = bb->succ->succ_next->dest; if (bb->succ->flags & EDGE_FALLTHRU) { basic_block t = bb_false; bb_false = bb_true; bb_true = t; } else if (! (bb->succ->succ_next->flags & EDGE_FALLTHRU)) abort (); } else { /* This can happen with a conditional jump to the next insn. */ if (JUMP_LABEL (bb->end) != bb_true->head) abort (); /* Simplest way to do nothing. */ bb_false = bb_true; } /* Extract the condition from the branch. */ set_src = SET_SRC (pc_set (bb->end)); cond_true = XEXP (set_src, 0); cond_false = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond_true)), GET_MODE (cond_true), XEXP (cond_true, 0), XEXP (cond_true, 1)); if (GET_CODE (XEXP (set_src, 1)) == PC) { rtx t = cond_false; cond_false = cond_true; cond_true = t; } /* Compute which register lead different lives in the successors. */ if (bitmap_operation (diff, bb_true->global_live_at_start, bb_false->global_live_at_start, BITMAP_XOR)) { rtx reg = XEXP (cond_true, 0); if (GET_CODE (reg) == SUBREG) reg = SUBREG_REG (reg); if (GET_CODE (reg) != REG) abort (); SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (reg)); /* For each such register, mark it conditionally dead. */ EXECUTE_IF_SET_IN_REG_SET (diff, 0, i, { struct reg_cond_life_info *rcli; rtx cond; rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli)); if (REGNO_REG_SET_P (bb_true->global_live_at_start, i)) cond = cond_false; else cond = cond_true; rcli->condition = cond; rcli->stores = const0_rtx; rcli->orig_condition = cond; splay_tree_insert (pbi->reg_cond_dead, i, (splay_tree_value) rcli); }); } FREE_REG_SET (diff); } #endif /* If this block has no successors, any stores to the frame that aren't used later in the block are dead. So make a pass over the block recording any such that are made and show them dead at the end. We do a very conservative and simple job here. */ if (optimize && ! (TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE && (TYPE_RETURNS_STACK_DEPRESSED (TREE_TYPE (current_function_decl)))) && (flags & PROP_SCAN_DEAD_CODE) && (bb->succ == NULL || (bb->succ->succ_next == NULL && bb->succ->dest == EXIT_BLOCK_PTR && ! current_function_calls_eh_return))) { rtx insn, set; for (insn = bb->end; insn != bb->head; insn = PREV_INSN (insn)) if (GET_CODE (insn) == INSN && (set = single_set (insn)) && GET_CODE (SET_DEST (set)) == MEM) { rtx mem = SET_DEST (set); rtx canon_mem = canon_rtx (mem); /* This optimization is performed by faking a store to the memory at the end of the block. This doesn't work for unchanging memories because multiple stores to unchanging memory is illegal and alias analysis doesn't consider it. */ if (RTX_UNCHANGING_P (canon_mem)) continue; if (XEXP (canon_mem, 0) == frame_pointer_rtx || (GET_CODE (XEXP (canon_mem, 0)) == PLUS && XEXP (XEXP (canon_mem, 0), 0) == frame_pointer_rtx && GET_CODE (XEXP (XEXP (canon_mem, 0), 1)) == CONST_INT)) add_to_mem_set_list (pbi, canon_mem); } } return pbi; } /* Release a propagate_block_info struct. */ void free_propagate_block_info (pbi) struct propagate_block_info *pbi; { free_EXPR_LIST_list (&pbi->mem_set_list); BITMAP_XFREE (pbi->new_set); #ifdef HAVE_conditional_execution splay_tree_delete (pbi->reg_cond_dead); BITMAP_XFREE (pbi->reg_cond_reg); #endif if (pbi->reg_next_use) free (pbi->reg_next_use); free (pbi); } /* Compute the registers live at the beginning of a basic block BB from those live at the end. When called, REG_LIVE contains those live at the end. On return, it contains those live at the beginning. LOCAL_SET, if non-null, will be set with all registers killed unconditionally by this basic block. Likewise, COND_LOCAL_SET, if non-null, will be set with all registers killed conditionally by this basic block. If there is any unconditional set of a register, then the corresponding bit will be set in LOCAL_SET and cleared in COND_LOCAL_SET. It is valid for LOCAL_SET and COND_LOCAL_SET to be the same set. In this case, the resulting set will be equal to the union of the two sets that would otherwise be computed. Return non-zero if an INSN is deleted (i.e. by dead code removal). */ int propagate_block (bb, live, local_set, cond_local_set, flags) basic_block bb; regset live; regset local_set; regset cond_local_set; int flags; { struct propagate_block_info *pbi; rtx insn, prev; int changed; pbi = init_propagate_block_info (bb, live, local_set, cond_local_set, flags); if (flags & PROP_REG_INFO) { register int i; /* Process the regs live at the end of the block. Mark them as not local to any one basic block. */ EXECUTE_IF_SET_IN_REG_SET (live, 0, i, { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; }); } /* Scan the block an insn at a time from end to beginning. */ changed = 0; for (insn = bb->end;; insn = prev) { /* If this is a call to `setjmp' et al, warn if any non-volatile datum is live. */ if ((flags & PROP_REG_INFO) && GET_CODE (insn) == CALL_INSN && find_reg_note (insn, REG_SETJMP, NULL)) IOR_REG_SET (regs_live_at_setjmp, pbi->reg_live); prev = propagate_one_insn (pbi, insn); changed |= NEXT_INSN (prev) != insn; if (insn == bb->head) break; } free_propagate_block_info (pbi); return changed; } /* Return 1 if X (the body of an insn, or part of it) is just dead stores (SET expressions whose destinations are registers dead after the insn). NEEDED is the regset that says which regs are alive after the insn. Unless CALL_OK is non-zero, an insn is needed if it contains a CALL. If X is the entire body of an insn, NOTES contains the reg notes pertaining to the insn. */ static int insn_dead_p (pbi, x, call_ok, notes) struct propagate_block_info *pbi; rtx x; int call_ok; rtx notes ATTRIBUTE_UNUSED; { enum rtx_code code = GET_CODE (x); #ifdef AUTO_INC_DEC /* If flow is invoked after reload, we must take existing AUTO_INC expresions into account. */ if (reload_completed) { for (; notes; notes = XEXP (notes, 1)) { if (REG_NOTE_KIND (notes) == REG_INC) { int regno = REGNO (XEXP (notes, 0)); /* Don't delete insns to set global regs. */ if ((regno < FIRST_PSEUDO_REGISTER && global_regs[regno]) || REGNO_REG_SET_P (pbi->reg_live, regno)) return 0; } } } #endif /* If setting something that's a reg or part of one, see if that register's altered value will be live. */ if (code == SET) { rtx r = SET_DEST (x); #ifdef HAVE_cc0 if (GET_CODE (r) == CC0) return ! pbi->cc0_live; #endif /* A SET that is a subroutine call cannot be dead. */ if (GET_CODE (SET_SRC (x)) == CALL) { if (! call_ok) return 0; } /* Don't eliminate loads from volatile memory or volatile asms. */ else if (volatile_refs_p (SET_SRC (x))) return 0; if (GET_CODE (r) == MEM) { rtx temp, canon_r; if (MEM_VOLATILE_P (r) || GET_MODE (r) == BLKmode) return 0; canon_r = canon_rtx (r); /* Walk the set of memory locations we are currently tracking and see if one is an identical match to this memory location. If so, this memory write is dead (remember, we're walking backwards from the end of the block to the start). Since rtx_equal_p does not check the alias set or flags, we also must have the potential for them to conflict (anti_dependence). */ for (temp = pbi->mem_set_list; temp != 0; temp = XEXP (temp, 1)) if (anti_dependence (r, XEXP (temp, 0))) { rtx mem = XEXP (temp, 0); if (rtx_equal_p (XEXP (canon_r, 0), XEXP (mem, 0)) && (GET_MODE_SIZE (GET_MODE (canon_r)) <= GET_MODE_SIZE (GET_MODE (mem)))) return 1; #ifdef AUTO_INC_DEC /* Check if memory reference matches an auto increment. Only post increment/decrement or modify are valid. */ if (GET_MODE (mem) == GET_MODE (r) && (GET_CODE (XEXP (mem, 0)) == POST_DEC || GET_CODE (XEXP (mem, 0)) == POST_INC || GET_CODE (XEXP (mem, 0)) == POST_MODIFY) && GET_MODE (XEXP (mem, 0)) == GET_MODE (r) && rtx_equal_p (XEXP (XEXP (mem, 0), 0), XEXP (r, 0))) return 1; #endif } } else { while (GET_CODE (r) == SUBREG || GET_CODE (r) == STRICT_LOW_PART || GET_CODE (r) == ZERO_EXTRACT) r = XEXP (r, 0); if (GET_CODE (r) == REG) { int regno = REGNO (r); /* Obvious. */ if (REGNO_REG_SET_P (pbi->reg_live, regno)) return 0; /* If this is a hard register, verify that subsequent words are not needed. */ if (regno < FIRST_PSEUDO_REGISTER) { int n = HARD_REGNO_NREGS (regno, GET_MODE (r)); while (--n > 0) if (REGNO_REG_SET_P (pbi->reg_live, regno+n)) return 0; } /* Don't delete insns to set global regs. */ if (regno < FIRST_PSEUDO_REGISTER && global_regs[regno]) return 0; /* Make sure insns to set the stack pointer aren't deleted. */ if (regno == STACK_POINTER_REGNUM) return 0; /* ??? These bits might be redundant with the force live bits in calculate_global_regs_live. We would delete from sequential sets; whether this actually affects real code for anything but the stack pointer I don't know. */ /* Make sure insns to set the frame pointer aren't deleted. */ if (regno == FRAME_POINTER_REGNUM && (! reload_completed || frame_pointer_needed)) return 0; #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM if (regno == HARD_FRAME_POINTER_REGNUM && (! reload_completed || frame_pointer_needed)) return 0; #endif #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM /* Make sure insns to set arg pointer are never deleted (if the arg pointer isn't fixed, there will be a USE for it, so we can treat it normally). */ if (regno == ARG_POINTER_REGNUM && fixed_regs[regno]) return 0; #endif /* Otherwise, the set is dead. */ return 1; } } } /* If performing several activities, insn is dead if each activity is individually dead. Also, CLOBBERs and USEs can be ignored; a CLOBBER or USE that's inside a PARALLEL doesn't make the insn worth keeping. */ else if (code == PARALLEL) { int i = XVECLEN (x, 0); for (i--; i >= 0; i--) if (GET_CODE (XVECEXP (x, 0, i)) != CLOBBER && GET_CODE (XVECEXP (x, 0, i)) != USE && ! insn_dead_p (pbi, XVECEXP (x, 0, i), call_ok, NULL_RTX)) return 0; return 1; } /* A CLOBBER of a pseudo-register that is dead serves no purpose. That is not necessarily true for hard registers. */ else if (code == CLOBBER && GET_CODE (XEXP (x, 0)) == REG && REGNO (XEXP (x, 0)) >= FIRST_PSEUDO_REGISTER && ! REGNO_REG_SET_P (pbi->reg_live, REGNO (XEXP (x, 0)))) return 1; /* We do not check other CLOBBER or USE here. An insn consisting of just a CLOBBER or just a USE should not be deleted. */ return 0; } /* If INSN is the last insn in a libcall, and assuming INSN is dead, return 1 if the entire library call is dead. This is true if INSN copies a register (hard or pseudo) and if the hard return reg of the call insn is dead. (The caller should have tested the destination of the SET inside INSN already for death.) If this insn doesn't just copy a register, then we don't have an ordinary libcall. In that case, cse could not have managed to substitute the source for the dest later on, so we can assume the libcall is dead. PBI is the block info giving pseudoregs live before this insn. NOTE is the REG_RETVAL note of the insn. */ static int libcall_dead_p (pbi, note, insn) struct propagate_block_info *pbi; rtx note; rtx insn; { rtx x = single_set (insn); if (x) { register rtx r = SET_SRC (x); if (GET_CODE (r) == REG) { rtx call = XEXP (note, 0); rtx call_pat; register int i; /* Find the call insn. */ while (call != insn && GET_CODE (call) != CALL_INSN) call = NEXT_INSN (call); /* If there is none, do nothing special, since ordinary death handling can understand these insns. */ if (call == insn) return 0; /* See if the hard reg holding the value is dead. If this is a PARALLEL, find the call within it. */ call_pat = PATTERN (call); if (GET_CODE (call_pat) == PARALLEL) { for (i = XVECLEN (call_pat, 0) - 1; i >= 0; i--) if (GET_CODE (XVECEXP (call_pat, 0, i)) == SET && GET_CODE (SET_SRC (XVECEXP (call_pat, 0, i))) == CALL) break; /* This may be a library call that is returning a value via invisible pointer. Do nothing special, since ordinary death handling can understand these insns. */ if (i < 0) return 0; call_pat = XVECEXP (call_pat, 0, i); } return insn_dead_p (pbi, call_pat, 1, REG_NOTES (call)); } } return 1; } /* Return 1 if register REGNO was used before it was set, i.e. if it is live at function entry. Don't count global register variables, variables in registers that can be used for function arg passing, or variables in fixed hard registers. */ int regno_uninitialized (regno) int regno; { if (n_basic_blocks == 0 || (regno < FIRST_PSEUDO_REGISTER && (global_regs[regno] || fixed_regs[regno] || FUNCTION_ARG_REGNO_P (regno)))) return 0; return REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno); } /* 1 if register REGNO was alive at a place where `setjmp' was called and was set more than once or is an argument. Such regs may be clobbered by `longjmp'. */ int regno_clobbered_at_setjmp (regno) int regno; { if (n_basic_blocks == 0) return 0; return ((REG_N_SETS (regno) > 1 || REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno)) && REGNO_REG_SET_P (regs_live_at_setjmp, regno)); } /* Add MEM to PBI->MEM_SET_LIST. MEM should be canonical. Respect the maximal list size; look for overlaps in mode and select the largest. */ static void add_to_mem_set_list (pbi, mem) struct propagate_block_info *pbi; rtx mem; { rtx i; /* We don't know how large a BLKmode store is, so we must not take them into consideration. */ if (GET_MODE (mem) == BLKmode) return; for (i = pbi->mem_set_list; i ; i = XEXP (i, 1)) { rtx e = XEXP (i, 0); if (rtx_equal_p (XEXP (mem, 0), XEXP (e, 0))) { if (GET_MODE_SIZE (GET_MODE (mem)) > GET_MODE_SIZE (GET_MODE (e))) { #ifdef AUTO_INC_DEC /* If we must store a copy of the mem, we can just modify the mode of the stored copy. */ if (pbi->flags & PROP_AUTOINC) PUT_MODE (e, GET_MODE (mem)); else #endif XEXP (i, 0) = mem; } return; } } if (pbi->mem_set_list_len < MAX_MEM_SET_LIST_LEN) { #ifdef AUTO_INC_DEC /* Store a copy of mem, otherwise the address may be scrogged by find_auto_inc. */ if (pbi->flags & PROP_AUTOINC) mem = shallow_copy_rtx (mem); #endif pbi->mem_set_list = alloc_EXPR_LIST (0, mem, pbi->mem_set_list); pbi->mem_set_list_len++; } } /* INSN references memory, possibly using autoincrement addressing modes. Find any entries on the mem_set_list that need to be invalidated due to an address change. */ static void invalidate_mems_from_autoinc (pbi, insn) struct propagate_block_info *pbi; rtx insn; { rtx note = REG_NOTES (insn); for (note = REG_NOTES (insn); note; note = XEXP (note, 1)) if (REG_NOTE_KIND (note) == REG_INC) invalidate_mems_from_set (pbi, XEXP (note, 0)); } /* EXP is a REG. Remove any dependant entries from pbi->mem_set_list. */ static void invalidate_mems_from_set (pbi, exp) struct propagate_block_info *pbi; rtx exp; { rtx temp = pbi->mem_set_list; rtx prev = NULL_RTX; rtx next; while (temp) { next = XEXP (temp, 1); if (reg_overlap_mentioned_p (exp, XEXP (temp, 0))) { /* Splice this entry out of the list. */ if (prev) XEXP (prev, 1) = next; else pbi->mem_set_list = next; free_EXPR_LIST_node (temp); pbi->mem_set_list_len--; } else prev = temp; temp = next; } } /* Process the registers that are set within X. Their bits are set to 1 in the regset DEAD, because they are dead prior to this insn. If INSN is nonzero, it is the insn being processed. FLAGS is the set of operations to perform. */ static void mark_set_regs (pbi, x, insn) struct propagate_block_info *pbi; rtx x, insn; { rtx cond = NULL_RTX; rtx link; enum rtx_code code; if (insn) for (link = REG_NOTES (insn); link; link = XEXP (link, 1)) { if (REG_NOTE_KIND (link) == REG_INC) mark_set_1 (pbi, SET, XEXP (link, 0), (GET_CODE (x) == COND_EXEC ? COND_EXEC_TEST (x) : NULL_RTX), insn, pbi->flags); } retry: switch (code = GET_CODE (x)) { case SET: case CLOBBER: mark_set_1 (pbi, code, SET_DEST (x), cond, insn, pbi->flags); return; case COND_EXEC: cond = COND_EXEC_TEST (x); x = COND_EXEC_CODE (x); goto retry; case PARALLEL: { register int i; for (i = XVECLEN (x, 0) - 1; i >= 0; i--) { rtx sub = XVECEXP (x, 0, i); switch (code = GET_CODE (sub)) { case COND_EXEC: if (cond != NULL_RTX) abort (); cond = COND_EXEC_TEST (sub); sub = COND_EXEC_CODE (sub); if (GET_CODE (sub) != SET && GET_CODE (sub) != CLOBBER) break; /* Fall through. */ case SET: case CLOBBER: mark_set_1 (pbi, code, SET_DEST (sub), cond, insn, pbi->flags); break; default: break; } } break; } default: break; } } /* Process a single set, which appears in INSN. REG (which may not actually be a REG, it may also be a SUBREG, PARALLEL, etc.) is being set using the CODE (which may be SET, CLOBBER, or COND_EXEC). If the set is conditional (because it appear in a COND_EXEC), COND will be the condition. */ static void mark_set_1 (pbi, code, reg, cond, insn, flags) struct propagate_block_info *pbi; enum rtx_code code; rtx reg, cond, insn; int flags; { int regno_first = -1, regno_last = -1; unsigned long not_dead = 0; int i; /* Modifying just one hardware register of a multi-reg value or just a byte field of a register does not mean the value from before this insn is now dead. Of course, if it was dead after it's unused now. */ switch (GET_CODE (reg)) { case PARALLEL: /* Some targets place small structures in registers for return values of functions. We have to detect this case specially here to get correct flow information. */ for (i = XVECLEN (reg, 0) - 1; i >= 0; i--) if (XEXP (XVECEXP (reg, 0, i), 0) != 0) mark_set_1 (pbi, code, XEXP (XVECEXP (reg, 0, i), 0), cond, insn, flags); return; case ZERO_EXTRACT: case SIGN_EXTRACT: case STRICT_LOW_PART: /* ??? Assumes STRICT_LOW_PART not used on multi-word registers. */ do reg = XEXP (reg, 0); while (GET_CODE (reg) == SUBREG || GET_CODE (reg) == ZERO_EXTRACT || GET_CODE (reg) == SIGN_EXTRACT || GET_CODE (reg) == STRICT_LOW_PART); if (GET_CODE (reg) == MEM) break; not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live, REGNO (reg)); /* Fall through. */ case REG: regno_last = regno_first = REGNO (reg); if (regno_first < FIRST_PSEUDO_REGISTER) regno_last += HARD_REGNO_NREGS (regno_first, GET_MODE (reg)) - 1; break; case SUBREG: if (GET_CODE (SUBREG_REG (reg)) == REG) { enum machine_mode outer_mode = GET_MODE (reg); enum machine_mode inner_mode = GET_MODE (SUBREG_REG (reg)); /* Identify the range of registers affected. This is moderately tricky for hard registers. See alter_subreg. */ regno_last = regno_first = REGNO (SUBREG_REG (reg)); if (regno_first < FIRST_PSEUDO_REGISTER) { regno_first += subreg_regno_offset (regno_first, inner_mode, SUBREG_BYTE (reg), outer_mode); regno_last = (regno_first + HARD_REGNO_NREGS (regno_first, outer_mode) - 1); /* Since we've just adjusted the register number ranges, make sure REG matches. Otherwise some_was_live will be clear when it shouldn't have been, and we'll create incorrect REG_UNUSED notes. */ reg = gen_rtx_REG (outer_mode, regno_first); } else { /* If the number of words in the subreg is less than the number of words in the full register, we have a well-defined partial set. Otherwise the high bits are undefined. This is only really applicable to pseudos, since we just took care of multi-word hard registers. */ if (((GET_MODE_SIZE (outer_mode) + UNITS_PER_WORD - 1) / UNITS_PER_WORD) < ((GET_MODE_SIZE (inner_mode) + UNITS_PER_WORD - 1) / UNITS_PER_WORD)) not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live, regno_first); reg = SUBREG_REG (reg); } } else reg = SUBREG_REG (reg); break; default: break; } /* If this set is a MEM, then it kills any aliased writes. If this set is a REG, then it kills any MEMs which use the reg. */ if (optimize && (flags & PROP_SCAN_DEAD_CODE)) { if (GET_CODE (reg) == REG) invalidate_mems_from_set (pbi, reg); /* If the memory reference had embedded side effects (autoincrement address modes. Then we may need to kill some entries on the memory set list. */ if (insn && GET_CODE (reg) == MEM) invalidate_mems_from_autoinc (pbi, insn); if (GET_CODE (reg) == MEM && ! side_effects_p (reg) /* ??? With more effort we could track conditional memory life. */ && ! cond /* There are no REG_INC notes for SP, so we can't assume we'll see everything that invalidates it. To be safe, don't eliminate any stores though SP; none of them should be redundant anyway. */ && ! reg_mentioned_p (stack_pointer_rtx, reg)) add_to_mem_set_list (pbi, canon_rtx (reg)); } if (GET_CODE (reg) == REG && ! (regno_first == FRAME_POINTER_REGNUM && (! reload_completed || frame_pointer_needed)) #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM && ! (regno_first == HARD_FRAME_POINTER_REGNUM && (! reload_completed || frame_pointer_needed)) #endif #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM && ! (regno_first == ARG_POINTER_REGNUM && fixed_regs[regno_first]) #endif ) { int some_was_live = 0, some_was_dead = 0; for (i = regno_first; i <= regno_last; ++i) { int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i); if (pbi->local_set) { /* Order of the set operation matters here since both sets may be the same. */ CLEAR_REGNO_REG_SET (pbi->cond_local_set, i); if (cond != NULL_RTX && ! REGNO_REG_SET_P (pbi->local_set, i)) SET_REGNO_REG_SET (pbi->cond_local_set, i); else SET_REGNO_REG_SET (pbi->local_set, i); } if (code != CLOBBER) SET_REGNO_REG_SET (pbi->new_set, i); some_was_live |= needed_regno; some_was_dead |= ! needed_regno; } #ifdef HAVE_conditional_execution /* Consider conditional death in deciding that the register needs a death note. */ if (some_was_live && ! not_dead /* The stack pointer is never dead. Well, not strictly true, but it's very difficult to tell from here. Hopefully combine_stack_adjustments will fix up the most egregious errors. */ && regno_first != STACK_POINTER_REGNUM) { for (i = regno_first; i <= regno_last; ++i) if (! mark_regno_cond_dead (pbi, i, cond)) not_dead |= ((unsigned long) 1) << (i - regno_first); } #endif /* Additional data to record if this is the final pass. */ if (flags & (PROP_LOG_LINKS | PROP_REG_INFO | PROP_DEATH_NOTES | PROP_AUTOINC)) { register rtx y; register int blocknum = pbi->bb->index; y = NULL_RTX; if (flags & (PROP_LOG_LINKS | PROP_AUTOINC)) { y = pbi->reg_next_use[regno_first]; /* The next use is no longer next, since a store intervenes. */ for (i = regno_first; i <= regno_last; ++i) pbi->reg_next_use[i] = 0; } if (flags & PROP_REG_INFO) { for (i = regno_first; i <= regno_last; ++i) { /* Count (weighted) references, stores, etc. This counts a register twice if it is modified, but that is correct. */ REG_N_SETS (i) += 1; REG_N_REFS (i) += 1; REG_FREQ (i) += REG_FREQ_FROM_BB (pbi->bb); /* The insns where a reg is live are normally counted elsewhere, but we want the count to include the insn where the reg is set, and the normal counting mechanism would not count it. */ REG_LIVE_LENGTH (i) += 1; } /* If this is a hard reg, record this function uses the reg. */ if (regno_first < FIRST_PSEUDO_REGISTER) { for (i = regno_first; i <= regno_last; i++) regs_ever_live[i] = 1; } else { /* Keep track of which basic blocks each reg appears in. */ if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN) REG_BASIC_BLOCK (regno_first) = blocknum; else if (REG_BASIC_BLOCK (regno_first) != blocknum) REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL; } } if (! some_was_dead) { if (flags & PROP_LOG_LINKS) { /* Make a logical link from the next following insn that uses this register, back to this insn. The following insns have already been processed. We don't build a LOG_LINK for hard registers containing in ASM_OPERANDs. If these registers get replaced, we might wind up changing the semantics of the insn, even if reload can make what appear to be valid assignments later. */ if (y && (BLOCK_NUM (y) == blocknum) && (regno_first >= FIRST_PSEUDO_REGISTER || asm_noperands (PATTERN (y)) < 0)) LOG_LINKS (y) = alloc_INSN_LIST (insn, LOG_LINKS (y)); } } else if (not_dead) ; else if (! some_was_live) { if (flags & PROP_REG_INFO) REG_N_DEATHS (regno_first) += 1; if (flags & PROP_DEATH_NOTES) { /* Note that dead stores have already been deleted when possible. If we get here, we have found a dead store that cannot be eliminated (because the same insn does something useful). Indicate this by marking the reg being set as dying here. */ REG_NOTES (insn) = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn)); } } else { if (flags & PROP_DEATH_NOTES) { /* This is a case where we have a multi-word hard register and some, but not all, of the words of the register are needed in subsequent insns. Write REG_UNUSED notes for those parts that were not needed. This case should be rare. */ for (i = regno_first; i <= regno_last; ++i) if (! REGNO_REG_SET_P (pbi->reg_live, i)) REG_NOTES (insn) = alloc_EXPR_LIST (REG_UNUSED, gen_rtx_REG (reg_raw_mode[i], i), REG_NOTES (insn)); } } } /* Mark the register as being dead. */ if (some_was_live /* The stack pointer is never dead. Well, not strictly true, but it's very difficult to tell from here. Hopefully combine_stack_adjustments will fix up the most egregious errors. */ && regno_first != STACK_POINTER_REGNUM) { for (i = regno_first; i <= regno_last; ++i) if (!(not_dead & (((unsigned long) 1) << (i - regno_first)))) CLEAR_REGNO_REG_SET (pbi->reg_live, i); } } else if (GET_CODE (reg) == REG) { if (flags & (PROP_LOG_LINKS | PROP_AUTOINC)) pbi->reg_next_use[regno_first] = 0; } /* If this is the last pass and this is a SCRATCH, show it will be dying here and count it. */ else if (GET_CODE (reg) == SCRATCH) { if (flags & PROP_DEATH_NOTES) REG_NOTES (insn) = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn)); } } #ifdef HAVE_conditional_execution /* Mark REGNO conditionally dead. Return true if the register is now unconditionally dead. */ static int mark_regno_cond_dead (pbi, regno, cond) struct propagate_block_info *pbi; int regno; rtx cond; { /* If this is a store to a predicate register, the value of the predicate is changing, we don't know that the predicate as seen before is the same as that seen after. Flush all dependent conditions from reg_cond_dead. This will make all such conditionally live registers unconditionally live. */ if (REGNO_REG_SET_P (pbi->reg_cond_reg, regno)) flush_reg_cond_reg (pbi, regno); /* If this is an unconditional store, remove any conditional life that may have existed. */ if (cond == NULL_RTX) splay_tree_remove (pbi->reg_cond_dead, regno); else { splay_tree_node node; struct reg_cond_life_info *rcli; rtx ncond; /* Otherwise this is a conditional set. Record that fact. It may have been conditionally used, or there may be a subsequent set with a complimentary condition. */ node = splay_tree_lookup (pbi->reg_cond_dead, regno); if (node == NULL) { /* The register was unconditionally live previously. Record the current condition as the condition under which it is dead. */ rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli)); rcli->condition = cond; rcli->stores = cond; rcli->orig_condition = const0_rtx; splay_tree_insert (pbi->reg_cond_dead, regno, (splay_tree_value) rcli); SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0))); /* Not unconditionaly dead. */ return 0; } else { /* The register was conditionally live previously. Add the new condition to the old. */ rcli = (struct reg_cond_life_info *) node->value; ncond = rcli->condition; ncond = ior_reg_cond (ncond, cond, 1); if (rcli->stores == const0_rtx) rcli->stores = cond; else if (rcli->stores != const1_rtx) rcli->stores = ior_reg_cond (rcli->stores, cond, 1); /* If the register is now unconditionally dead, remove the entry in the splay_tree. A register is unconditionally dead if the dead condition ncond is true. A register is also unconditionally dead if the sum of all conditional stores is an unconditional store (stores is true), and the dead condition is identically the same as the original dead condition initialized at the end of the block. This is a pointer compare, not an rtx_equal_p compare. */ if (ncond == const1_rtx || (ncond == rcli->orig_condition && rcli->stores == const1_rtx)) splay_tree_remove (pbi->reg_cond_dead, regno); else { rcli->condition = ncond; SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0))); /* Not unconditionaly dead. */ return 0; } } } return 1; } /* Called from splay_tree_delete for pbi->reg_cond_life. */ static void free_reg_cond_life_info (value) splay_tree_value value; { struct reg_cond_life_info *rcli = (struct reg_cond_life_info *) value; free (rcli); } /* Helper function for flush_reg_cond_reg. */ static int flush_reg_cond_reg_1 (node, data) splay_tree_node node; void *data; { struct reg_cond_life_info *rcli; int *xdata = (int *) data; unsigned int regno = xdata[0]; /* Don't need to search if last flushed value was farther on in the in-order traversal. */ if (xdata[1] >= (int) node->key) return 0; /* Splice out portions of the expression that refer to regno. */ rcli = (struct reg_cond_life_info *) node->value; rcli->condition = elim_reg_cond (rcli->condition, regno); if (rcli->stores != const0_rtx && rcli->stores != const1_rtx) rcli->stores = elim_reg_cond (rcli->stores, regno); /* If the entire condition is now false, signal the node to be removed. */ if (rcli->condition == const0_rtx) { xdata[1] = node->key; return -1; } else if (rcli->condition == const1_rtx) abort (); return 0; } /* Flush all (sub) expressions referring to REGNO from REG_COND_LIVE. */ static void flush_reg_cond_reg (pbi, regno) struct propagate_block_info *pbi; int regno; { int pair[2]; pair[0] = regno; pair[1] = -1; while (splay_tree_foreach (pbi->reg_cond_dead, flush_reg_cond_reg_1, pair) == -1) splay_tree_remove (pbi->reg_cond_dead, pair[1]); CLEAR_REGNO_REG_SET (pbi->reg_cond_reg, regno); } /* Logical arithmetic on predicate conditions. IOR, NOT and AND. For ior/and, the ADD flag determines whether we want to add the new condition X to the old one unconditionally. If it is zero, we will only return a new expression if X allows us to simplify part of OLD, otherwise we return OLD unchanged to the caller. If ADD is nonzero, we will return a new condition in all cases. The toplevel caller of one of these functions should always pass 1 for ADD. */ static rtx ior_reg_cond (old, x, add) rtx old, x; int add; { rtx op0, op1; if (GET_RTX_CLASS (GET_CODE (old)) == '<') { if (GET_RTX_CLASS (GET_CODE (x)) == '<' && REVERSE_CONDEXEC_PREDICATES_P (GET_CODE (x), GET_CODE (old)) && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0))) return const1_rtx; if (GET_CODE (x) == GET_CODE (old) && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0))) return old; if (! add) return old; return gen_rtx_IOR (0, old, x); } switch (GET_CODE (old)) { case IOR: op0 = ior_reg_cond (XEXP (old, 0), x, 0); op1 = ior_reg_cond (XEXP (old, 1), x, 0); if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1)) { if (op0 == const0_rtx) return op1; if (op1 == const0_rtx) return op0; if (op0 == const1_rtx || op1 == const1_rtx) return const1_rtx; if (op0 == XEXP (old, 0)) op0 = gen_rtx_IOR (0, op0, x); else op1 = gen_rtx_IOR (0, op1, x); return gen_rtx_IOR (0, op0, op1); } if (! add) return old; return gen_rtx_IOR (0, old, x); case AND: op0 = ior_reg_cond (XEXP (old, 0), x, 0); op1 = ior_reg_cond (XEXP (old, 1), x, 0); if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1)) { if (op0 == const1_rtx) return op1; if (op1 == const1_rtx) return op0; if (op0 == const0_rtx || op1 == const0_rtx) return const0_rtx; if (op0 == XEXP (old, 0)) op0 = gen_rtx_IOR (0, op0, x); else op1 = gen_rtx_IOR (0, op1, x); return gen_rtx_AND (0, op0, op1); } if (! add) return old; return gen_rtx_IOR (0, old, x); case NOT: op0 = and_reg_cond (XEXP (old, 0), not_reg_cond (x), 0); if (op0 != XEXP (old, 0)) return not_reg_cond (op0); if (! add) return old; return gen_rtx_IOR (0, old, x); default: abort (); } } static rtx not_reg_cond (x) rtx x; { enum rtx_code x_code; if (x == const0_rtx) return const1_rtx; else if (x == const1_rtx) return const0_rtx; x_code = GET_CODE (x); if (x_code == NOT) return XEXP (x, 0); if (GET_RTX_CLASS (x_code) == '<' && GET_CODE (XEXP (x, 0)) == REG) { if (XEXP (x, 1) != const0_rtx) abort (); return gen_rtx_fmt_ee (reverse_condition (x_code), VOIDmode, XEXP (x, 0), const0_rtx); } return gen_rtx_NOT (0, x); } static rtx and_reg_cond (old, x, add) rtx old, x; int add; { rtx op0, op1; if (GET_RTX_CLASS (GET_CODE (old)) == '<') { if (GET_RTX_CLASS (GET_CODE (x)) == '<' && GET_CODE (x) == reverse_condition (GET_CODE (old)) && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0))) return const0_rtx; if (GET_CODE (x) == GET_CODE (old) && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0))) return old; if (! add) return old; return gen_rtx_AND (0, old, x); } switch (GET_CODE (old)) { case IOR: op0 = and_reg_cond (XEXP (old, 0), x, 0); op1 = and_reg_cond (XEXP (old, 1), x, 0); if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1)) { if (op0 == const0_rtx) return op1; if (op1 == const0_rtx) return op0; if (op0 == const1_rtx || op1 == const1_rtx) return const1_rtx; if (op0 == XEXP (old, 0)) op0 = gen_rtx_AND (0, op0, x); else op1 = gen_rtx_AND (0, op1, x); return gen_rtx_IOR (0, op0, op1); } if (! add) return old; return gen_rtx_AND (0, old, x); case AND: op0 = and_reg_cond (XEXP (old, 0), x, 0); op1 = and_reg_cond (XEXP (old, 1), x, 0); if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1)) { if (op0 == const1_rtx) return op1; if (op1 == const1_rtx) return op0; if (op0 == const0_rtx || op1 == const0_rtx) return const0_rtx; if (op0 == XEXP (old, 0)) op0 = gen_rtx_AND (0, op0, x); else op1 = gen_rtx_AND (0, op1, x); return gen_rtx_AND (0, op0, op1); } if (! add) return old; /* If X is identical to one of the existing terms of the AND, then just return what we already have. */ /* ??? There really should be some sort of recursive check here in case there are nested ANDs. */ if ((GET_CODE (XEXP (old, 0)) == GET_CODE (x) && REGNO (XEXP (XEXP (old, 0), 0)) == REGNO (XEXP (x, 0))) || (GET_CODE (XEXP (old, 1)) == GET_CODE (x) && REGNO (XEXP (XEXP (old, 1), 0)) == REGNO (XEXP (x, 0)))) return old; return gen_rtx_AND (0, old, x); case NOT: op0 = ior_reg_cond (XEXP (old, 0), not_reg_cond (x), 0); if (op0 != XEXP (old, 0)) return not_reg_cond (op0); if (! add) return old; return gen_rtx_AND (0, old, x); default: abort (); } } /* Given a condition X, remove references to reg REGNO and return the new condition. The removal will be done so that all conditions involving REGNO are considered to evaluate to false. This function is used when the value of REGNO changes. */ static rtx elim_reg_cond (x, regno) rtx x; unsigned int regno; { rtx op0, op1; if (GET_RTX_CLASS (GET_CODE (x)) == '<') { if (REGNO (XEXP (x, 0)) == regno) return const0_rtx; return x; } switch (GET_CODE (x)) { case AND: op0 = elim_reg_cond (XEXP (x, 0), regno); op1 = elim_reg_cond (XEXP (x, 1), regno); if (op0 == const0_rtx || op1 == const0_rtx) return const0_rtx; if (op0 == const1_rtx) return op1; if (op1 == const1_rtx) return op0; if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1)) return x; return gen_rtx_AND (0, op0, op1); case IOR: op0 = elim_reg_cond (XEXP (x, 0), regno); op1 = elim_reg_cond (XEXP (x, 1), regno); if (op0 == const1_rtx || op1 == const1_rtx) return const1_rtx; if (op0 == const0_rtx) return op1; if (op1 == const0_rtx) return op0; if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1)) return x; return gen_rtx_IOR (0, op0, op1); case NOT: op0 = elim_reg_cond (XEXP (x, 0), regno); if (op0 == const0_rtx) return const1_rtx; if (op0 == const1_rtx) return const0_rtx; if (op0 != XEXP (x, 0)) return not_reg_cond (op0); return x; default: abort (); } } #endif /* HAVE_conditional_execution */ #ifdef AUTO_INC_DEC /* Try to substitute the auto-inc expression INC as the address inside MEM which occurs in INSN. Currently, the address of MEM is an expression involving INCR_REG, and INCR is the next use of INCR_REG; it is an insn that has a single set whose source is a PLUS of INCR_REG and something else. */ static void attempt_auto_inc (pbi, inc, insn, mem, incr, incr_reg) struct propagate_block_info *pbi; rtx inc, insn, mem, incr, incr_reg; { int regno = REGNO (incr_reg); rtx set = single_set (incr); rtx q = SET_DEST (set); rtx y = SET_SRC (set); int opnum = XEXP (y, 0) == incr_reg ? 0 : 1; /* Make sure this reg appears only once in this insn. */ if (count_occurrences (PATTERN (insn), incr_reg, 1) != 1) return; if (dead_or_set_p (incr, incr_reg) /* Mustn't autoinc an eliminable register. */ && (regno >= FIRST_PSEUDO_REGISTER || ! TEST_HARD_REG_BIT (elim_reg_set, regno))) { /* This is the simple case. Try to make the auto-inc. If we can't, we are done. Otherwise, we will do any needed updates below. */ if (! validate_change (insn, &XEXP (mem, 0), inc, 0)) return; } else if (GET_CODE (q) == REG /* PREV_INSN used here to check the semi-open interval [insn,incr). */ && ! reg_used_between_p (q, PREV_INSN (insn), incr) /* We must also check for sets of q as q may be a call clobbered hard register and there may be a call between PREV_INSN (insn) and incr. */ && ! reg_set_between_p (q, PREV_INSN (insn), incr)) { /* We have *p followed sometime later by q = p+size. Both p and q must be live afterward, and q is not used between INSN and its assignment. Change it to q = p, ...*q..., q = q+size. Then fall into the usual case. */ rtx insns, temp; start_sequence (); emit_move_insn (q, incr_reg); insns = get_insns (); end_sequence (); /* If we can't make the auto-inc, or can't make the replacement into Y, exit. There's no point in making the change below if we can't do the auto-inc and doing so is not correct in the pre-inc case. */ XEXP (inc, 0) = q; validate_change (insn, &XEXP (mem, 0), inc, 1); validate_change (incr, &XEXP (y, opnum), q, 1); if (! apply_change_group ()) return; /* We now know we'll be doing this change, so emit the new insn(s) and do the updates. */ emit_insns_before (insns, insn); if (pbi->bb->head == insn) pbi->bb->head = insns; /* INCR will become a NOTE and INSN won't contain a use of INCR_REG. If a use of INCR_REG was just placed in the insn before INSN, make that the next use. Otherwise, invalidate it. */ if (GET_CODE (PREV_INSN (insn)) == INSN && GET_CODE (PATTERN (PREV_INSN (insn))) == SET && SET_SRC (PATTERN (PREV_INSN (insn))) == incr_reg) pbi->reg_next_use[regno] = PREV_INSN (insn); else pbi->reg_next_use[regno] = 0; incr_reg = q; regno = REGNO (q); /* REGNO is now used in INCR which is below INSN, but it previously wasn't live here. If we don't mark it as live, we'll put a REG_DEAD note for it on this insn, which is incorrect. */ SET_REGNO_REG_SET (pbi->reg_live, regno); /* If there are any calls between INSN and INCR, show that REGNO now crosses them. */ for (temp = insn; temp != incr; temp = NEXT_INSN (temp)) if (GET_CODE (temp) == CALL_INSN) REG_N_CALLS_CROSSED (regno)++; /* Invalidate alias info for Q since we just changed its value. */ clear_reg_alias_info (q); } else return; /* If we haven't returned, it means we were able to make the auto-inc, so update the status. First, record that this insn has an implicit side effect. */ REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, incr_reg, REG_NOTES (insn)); /* Modify the old increment-insn to simply copy the already-incremented value of our register. */ if (! validate_change (incr, &SET_SRC (set), incr_reg, 0)) abort (); /* If that makes it a no-op (copying the register into itself) delete it so it won't appear to be a "use" and a "set" of this register. */ if (REGNO (SET_DEST (set)) == REGNO (incr_reg)) { /* If the original source was dead, it's dead now. */ rtx note; while ((note = find_reg_note (incr, REG_DEAD, NULL_RTX)) != NULL_RTX) { remove_note (incr, note); if (XEXP (note, 0) != incr_reg) CLEAR_REGNO_REG_SET (pbi->reg_live, REGNO (XEXP (note, 0))); } PUT_CODE (incr, NOTE); NOTE_LINE_NUMBER (incr) = NOTE_INSN_DELETED; NOTE_SOURCE_FILE (incr) = 0; } if (regno >= FIRST_PSEUDO_REGISTER) { /* Count an extra reference to the reg. When a reg is incremented, spilling it is worse, so we want to make that less likely. */ REG_FREQ (regno) += REG_FREQ_FROM_BB (pbi->bb); /* Count the increment as a setting of the register, even though it isn't a SET in rtl. */ REG_N_SETS (regno)++; } } /* X is a MEM found in INSN. See if we can convert it into an auto-increment reference. */ static void find_auto_inc (pbi, x, insn) struct propagate_block_info *pbi; rtx x; rtx insn; { rtx addr = XEXP (x, 0); HOST_WIDE_INT offset = 0; rtx set, y, incr, inc_val; int regno; int size = GET_MODE_SIZE (GET_MODE (x)); if (GET_CODE (insn) == JUMP_INSN) return; /* Here we detect use of an index register which might be good for postincrement, postdecrement, preincrement, or predecrement. */ if (GET_CODE (addr) == PLUS && GET_CODE (XEXP (addr, 1)) == CONST_INT) offset = INTVAL (XEXP (addr, 1)), addr = XEXP (addr, 0); if (GET_CODE (addr) != REG) return; regno = REGNO (addr); /* Is the next use an increment that might make auto-increment? */ incr = pbi->reg_next_use[regno]; if (incr == 0 || BLOCK_NUM (incr) != BLOCK_NUM (insn)) return; set = single_set (incr); if (set == 0 || GET_CODE (set) != SET) return; y = SET_SRC (set); if (GET_CODE (y) != PLUS) return; if (REG_P (XEXP (y, 0)) && REGNO (XEXP (y, 0)) == REGNO (addr)) inc_val = XEXP (y, 1); else if (REG_P (XEXP (y, 1)) && REGNO (XEXP (y, 1)) == REGNO (addr)) inc_val = XEXP (y, 0); else return; if (GET_CODE (inc_val) == CONST_INT) { if (HAVE_POST_INCREMENT && (INTVAL (inc_val) == size && offset == 0)) attempt_auto_inc (pbi, gen_rtx_POST_INC (Pmode, addr), insn, x, incr, addr); else if (HAVE_POST_DECREMENT && (INTVAL (inc_val) == -size && offset == 0)) attempt_auto_inc (pbi, gen_rtx_POST_DEC (Pmode, addr), insn, x, incr, addr); else if (HAVE_PRE_INCREMENT && (INTVAL (inc_val) == size && offset == size)) attempt_auto_inc (pbi, gen_rtx_PRE_INC (Pmode, addr), insn, x, incr, addr); else if (HAVE_PRE_DECREMENT && (INTVAL (inc_val) == -size && offset == -size)) attempt_auto_inc (pbi, gen_rtx_PRE_DEC (Pmode, addr), insn, x, incr, addr); else if (HAVE_POST_MODIFY_DISP && offset == 0) attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr, gen_rtx_PLUS (Pmode, addr, inc_val)), insn, x, incr, addr); } else if (GET_CODE (inc_val) == REG && ! reg_set_between_p (inc_val, PREV_INSN (insn), NEXT_INSN (incr))) { if (HAVE_POST_MODIFY_REG && offset == 0) attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr, gen_rtx_PLUS (Pmode, addr, inc_val)), insn, x, incr, addr); } } #endif /* AUTO_INC_DEC */ static void mark_used_reg (pbi, reg, cond, insn) struct propagate_block_info *pbi; rtx reg; rtx cond ATTRIBUTE_UNUSED; rtx insn; { unsigned int regno_first, regno_last, i; int some_was_live, some_was_dead, some_not_set; regno_last = regno_first = REGNO (reg); if (regno_first < FIRST_PSEUDO_REGISTER) regno_last += HARD_REGNO_NREGS (regno_first, GET_MODE (reg)) - 1; /* Find out if any of this register is live after this instruction. */ some_was_live = some_was_dead = 0; for (i = regno_first; i <= regno_last; ++i) { int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i); some_was_live |= needed_regno; some_was_dead |= ! needed_regno; } /* Find out if any of the register was set this insn. */ some_not_set = 0; for (i = regno_first; i <= regno_last; ++i) some_not_set |= ! REGNO_REG_SET_P (pbi->new_set, i); if (pbi->flags & (PROP_LOG_LINKS | PROP_AUTOINC)) { /* Record where each reg is used, so when the reg is set we know the next insn that uses it. */ pbi->reg_next_use[regno_first] = insn; } if (pbi->flags & PROP_REG_INFO) { if (regno_first < FIRST_PSEUDO_REGISTER) { /* If this is a register we are going to try to eliminate, don't mark it live here. If we are successful in eliminating it, it need not be live unless it is used for pseudos, in which case it will have been set live when it was allocated to the pseudos. If the register will not be eliminated, reload will set it live at that point. Otherwise, record that this function uses this register. */ /* ??? The PPC backend tries to "eliminate" on the pic register to itself. This should be fixed. In the mean time, hack around it. */ if (! (TEST_HARD_REG_BIT (elim_reg_set, regno_first) && (regno_first == FRAME_POINTER_REGNUM || regno_first == ARG_POINTER_REGNUM))) for (i = regno_first; i <= regno_last; ++i) regs_ever_live[i] = 1; } else { /* Keep track of which basic block each reg appears in. */ register int blocknum = pbi->bb->index; if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN) REG_BASIC_BLOCK (regno_first) = blocknum; else if (REG_BASIC_BLOCK (regno_first) != blocknum) REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL; /* Count (weighted) number of uses of each reg. */ REG_FREQ (regno_first) += REG_FREQ_FROM_BB (pbi->bb); REG_N_REFS (regno_first)++; } } /* Record and count the insns in which a reg dies. If it is used in this insn and was dead below the insn then it dies in this insn. If it was set in this insn, we do not make a REG_DEAD note; likewise if we already made such a note. */ if ((pbi->flags & (PROP_DEATH_NOTES | PROP_REG_INFO)) && some_was_dead && some_not_set) { /* Check for the case where the register dying partially overlaps the register set by this insn. */ if (regno_first != regno_last) for (i = regno_first; i <= regno_last; ++i) some_was_live |= REGNO_REG_SET_P (pbi->new_set, i); /* If none of the words in X is needed, make a REG_DEAD note. Otherwise, we must make partial REG_DEAD notes. */ if (! some_was_live) { if ((pbi->flags & PROP_DEATH_NOTES) && ! find_regno_note (insn, REG_DEAD, regno_first)) REG_NOTES (insn) = alloc_EXPR_LIST (REG_DEAD, reg, REG_NOTES (insn)); if (pbi->flags & PROP_REG_INFO) REG_N_DEATHS (regno_first)++; } else { /* Don't make a REG_DEAD note for a part of a register that is set in the insn. */ for (i = regno_first; i <= regno_last; ++i) if (! REGNO_REG_SET_P (pbi->reg_live, i) && ! dead_or_set_regno_p (insn, i)) REG_NOTES (insn) = alloc_EXPR_LIST (REG_DEAD, gen_rtx_REG (reg_raw_mode[i], i), REG_NOTES (insn)); } } /* Mark the register as being live. */ for (i = regno_first; i <= regno_last; ++i) { SET_REGNO_REG_SET (pbi->reg_live, i); #ifdef HAVE_conditional_execution /* If this is a conditional use, record that fact. If it is later conditionally set, we'll know to kill the register. */ if (cond != NULL_RTX) { splay_tree_node node; struct reg_cond_life_info *rcli; rtx ncond; if (some_was_live) { node = splay_tree_lookup (pbi->reg_cond_dead, i); if (node == NULL) { /* The register was unconditionally live previously. No need to do anything. */ } else { /* The register was conditionally live previously. Subtract the new life cond from the old death cond. */ rcli = (struct reg_cond_life_info *) node->value; ncond = rcli->condition; ncond = and_reg_cond (ncond, not_reg_cond (cond), 1); /* If the register is now unconditionally live, remove the entry in the splay_tree. */ if (ncond == const0_rtx) splay_tree_remove (pbi->reg_cond_dead, i); else { rcli->condition = ncond; SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0))); } } } else { /* The register was not previously live at all. Record the condition under which it is still dead. */ rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli)); rcli->condition = not_reg_cond (cond); rcli->stores = const0_rtx; rcli->orig_condition = const0_rtx; splay_tree_insert (pbi->reg_cond_dead, i, (splay_tree_value) rcli); SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0))); } } else if (some_was_live) { /* The register may have been conditionally live previously, but is now unconditionally live. Remove it from the conditionally dead list, so that a conditional set won't cause us to think it dead. */ splay_tree_remove (pbi->reg_cond_dead, i); } #endif } } /* Scan expression X and store a 1-bit in NEW_LIVE for each reg it uses. This is done assuming the registers needed from X are those that have 1-bits in PBI->REG_LIVE. INSN is the containing instruction. If INSN is dead, this function is not called. */ static void mark_used_regs (pbi, x, cond, insn) struct propagate_block_info *pbi; rtx x, cond, insn; { register RTX_CODE code; register int regno; int flags = pbi->flags; retry: code = GET_CODE (x); switch (code) { case LABEL_REF: case SYMBOL_REF: case CONST_INT: case CONST: case CONST_DOUBLE: case PC: case ADDR_VEC: case ADDR_DIFF_VEC: return; #ifdef HAVE_cc0 case CC0: pbi->cc0_live = 1; return; #endif case CLOBBER: /* If we are clobbering a MEM, mark any registers inside the address as being used. */ if (GET_CODE (XEXP (x, 0)) == MEM) mark_used_regs (pbi, XEXP (XEXP (x, 0), 0), cond, insn); return; case MEM: /* Don't bother watching stores to mems if this is not the final pass. We'll not be deleting dead stores this round. */ if (optimize && (flags & PROP_SCAN_DEAD_CODE)) { /* Invalidate the data for the last MEM stored, but only if MEM is something that can be stored into. */ if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0))) /* Needn't clear the memory set list. */ ; else { rtx temp = pbi->mem_set_list; rtx prev = NULL_RTX; rtx next; while (temp) { next = XEXP (temp, 1); if (anti_dependence (XEXP (temp, 0), x)) { /* Splice temp out of the list. */ if (prev) XEXP (prev, 1) = next; else pbi->mem_set_list = next; free_EXPR_LIST_node (temp); pbi->mem_set_list_len--; } else prev = temp; temp = next; } } /* If the memory reference had embedded side effects (autoincrement address modes. Then we may need to kill some entries on the memory set list. */ if (insn) invalidate_mems_from_autoinc (pbi, insn); } #ifdef AUTO_INC_DEC if (flags & PROP_AUTOINC) find_auto_inc (pbi, x, insn); #endif break; case SUBREG: #ifdef CLASS_CANNOT_CHANGE_MODE if (GET_CODE (SUBREG_REG (x)) == REG && REGNO (SUBREG_REG (x)) >= FIRST_PSEUDO_REGISTER && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (x), GET_MODE (SUBREG_REG (x)))) REG_CHANGES_MODE (REGNO (SUBREG_REG (x))) = 1; #endif /* While we're here, optimize this case. */ x = SUBREG_REG (x); if (GET_CODE (x) != REG) goto retry; /* Fall through. */ case REG: /* See a register other than being set => mark it as needed. */ mark_used_reg (pbi, x, cond, insn); return; case SET: { register rtx testreg = SET_DEST (x); int mark_dest = 0; /* If storing into MEM, don't show it as being used. But do show the address as being used. */ if (GET_CODE (testreg) == MEM) { #ifdef AUTO_INC_DEC if (flags & PROP_AUTOINC) find_auto_inc (pbi, testreg, insn); #endif mark_used_regs (pbi, XEXP (testreg, 0), cond, insn); mark_used_regs (pbi, SET_SRC (x), cond, insn); return; } /* Storing in STRICT_LOW_PART is like storing in a reg in that this SET might be dead, so ignore it in TESTREG. but in some other ways it is like using the reg. Storing in a SUBREG or a bit field is like storing the entire register in that if the register's value is not used then this SET is not needed. */ while (GET_CODE (testreg) == STRICT_LOW_PART || GET_CODE (testreg) == ZERO_EXTRACT || GET_CODE (testreg) == SIGN_EXTRACT || GET_CODE (testreg) == SUBREG) { #ifdef CLASS_CANNOT_CHANGE_MODE if (GET_CODE (testreg) == SUBREG && GET_CODE (SUBREG_REG (testreg)) == REG && REGNO (SUBREG_REG (testreg)) >= FIRST_PSEUDO_REGISTER && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (SUBREG_REG (testreg)), GET_MODE (testreg))) REG_CHANGES_MODE (REGNO (SUBREG_REG (testreg))) = 1; #endif /* Modifying a single register in an alternate mode does not use any of the old value. But these other ways of storing in a register do use the old value. */ if (GET_CODE (testreg) == SUBREG && !(REG_SIZE (SUBREG_REG (testreg)) > REG_SIZE (testreg))) ; else mark_dest = 1; testreg = XEXP (testreg, 0); } /* If this is a store into a register or group of registers, recursively scan the value being stored. */ if ((GET_CODE (testreg) == PARALLEL && GET_MODE (testreg) == BLKmode) || (GET_CODE (testreg) == REG && (regno = REGNO (testreg), ! (regno == FRAME_POINTER_REGNUM && (! reload_completed || frame_pointer_needed))) #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM && ! (regno == HARD_FRAME_POINTER_REGNUM && (! reload_completed || frame_pointer_needed)) #endif #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno]) #endif )) { if (mark_dest) mark_used_regs (pbi, SET_DEST (x), cond, insn); mark_used_regs (pbi, SET_SRC (x), cond, insn); return; } } break; case ASM_OPERANDS: case UNSPEC_VOLATILE: case TRAP_IF: case ASM_INPUT: { /* Traditional and volatile asm instructions must be considered to use and clobber all hard registers, all pseudo-registers and all of memory. So must TRAP_IF and UNSPEC_VOLATILE operations. Consider for instance a volatile asm that changes the fpu rounding mode. An insn should not be moved across this even if it only uses pseudo-regs because it might give an incorrectly rounded result. ?!? Unfortunately, marking all hard registers as live causes massive problems for the register allocator and marking all pseudos as live creates mountains of uninitialized variable warnings. So for now, just clear the memory set list and mark any regs we can find in ASM_OPERANDS as used. */ if (code != ASM_OPERANDS || MEM_VOLATILE_P (x)) { free_EXPR_LIST_list (&pbi->mem_set_list); pbi->mem_set_list_len = 0; } /* For all ASM_OPERANDS, we must traverse the vector of input operands. We can not just fall through here since then we would be confused by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate traditional asms unlike their normal usage. */ if (code == ASM_OPERANDS) { int j; for (j = 0; j < ASM_OPERANDS_INPUT_LENGTH (x); j++) mark_used_regs (pbi, ASM_OPERANDS_INPUT (x, j), cond, insn); } break; } case COND_EXEC: if (cond != NULL_RTX) abort (); mark_used_regs (pbi, COND_EXEC_TEST (x), NULL_RTX, insn); cond = COND_EXEC_TEST (x); x = COND_EXEC_CODE (x); goto retry; case PHI: /* We _do_not_ want to scan operands of phi nodes. Operands of a phi function are evaluated only when control reaches this block along a particular edge. Therefore, regs that appear as arguments to phi should not be added to the global live at start. */ return; default: break; } /* Recursively scan the operands of this expression. */ { register const char * const fmt = GET_RTX_FORMAT (code); register int i; for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) { if (fmt[i] == 'e') { /* Tail recursive case: save a function call level. */ if (i == 0) { x = XEXP (x, 0); goto retry; } mark_used_regs (pbi, XEXP (x, i), cond, insn); } else if (fmt[i] == 'E') { register int j; for (j = 0; j < XVECLEN (x, i); j++) mark_used_regs (pbi, XVECEXP (x, i, j), cond, insn); } } } } #ifdef AUTO_INC_DEC static int try_pre_increment_1 (pbi, insn) struct propagate_block_info *pbi; rtx insn; { /* Find the next use of this reg. If in same basic block, make it do pre-increment or pre-decrement if appropriate. */ rtx x = single_set (insn); HOST_WIDE_INT amount = ((GET_CODE (SET_SRC (x)) == PLUS ? 1 : -1) * INTVAL (XEXP (SET_SRC (x), 1))); int regno = REGNO (SET_DEST (x)); rtx y = pbi->reg_next_use[regno]; if (y != 0 && SET_DEST (x) != stack_pointer_rtx && BLOCK_NUM (y) == BLOCK_NUM (insn) /* Don't do this if the reg dies, or gets set in y; a standard addressing mode would be better. */ && ! dead_or_set_p (y, SET_DEST (x)) && try_pre_increment (y, SET_DEST (x), amount)) { /* We have found a suitable auto-increment and already changed insn Y to do it. So flush this increment instruction. */ propagate_block_delete_insn (pbi->bb, insn); /* Count a reference to this reg for the increment insn we are deleting. When a reg is incremented, spilling it is worse, so we want to make that less likely. */ if (regno >= FIRST_PSEUDO_REGISTER) { REG_FREQ (regno) += REG_FREQ_FROM_BB (pbi->bb); REG_N_SETS (regno)++; } /* Flush any remembered memories depending on the value of the incremented register. */ invalidate_mems_from_set (pbi, SET_DEST (x)); return 1; } return 0; } /* Try to change INSN so that it does pre-increment or pre-decrement addressing on register REG in order to add AMOUNT to REG. AMOUNT is negative for pre-decrement. Returns 1 if the change could be made. This checks all about the validity of the result of modifying INSN. */ static int try_pre_increment (insn, reg, amount) rtx insn, reg; HOST_WIDE_INT amount; { register rtx use; /* Nonzero if we can try to make a pre-increment or pre-decrement. For example, addl $4,r1; movl (r1),... can become movl +(r1),... */ int pre_ok = 0; /* Nonzero if we can try to make a post-increment or post-decrement. For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,... It is possible for both PRE_OK and POST_OK to be nonzero if the machine supports both pre-inc and post-inc, or both pre-dec and post-dec. */ int post_ok = 0; /* Nonzero if the opportunity actually requires post-inc or post-dec. */ int do_post = 0; /* From the sign of increment, see which possibilities are conceivable on this target machine. */ if (HAVE_PRE_INCREMENT && amount > 0) pre_ok = 1; if (HAVE_POST_INCREMENT && amount > 0) post_ok = 1; if (HAVE_PRE_DECREMENT && amount < 0) pre_ok = 1; if (HAVE_POST_DECREMENT && amount < 0) post_ok = 1; if (! (pre_ok || post_ok)) return 0; /* It is not safe to add a side effect to a jump insn because if the incremented register is spilled and must be reloaded there would be no way to store the incremented value back in memory. */ if (GET_CODE (insn) == JUMP_INSN) return 0; use = 0; if (pre_ok) use = find_use_as_address (PATTERN (insn), reg, 0); if (post_ok && (use == 0 || use == (rtx) 1)) { use = find_use_as_address (PATTERN (insn), reg, -amount); do_post = 1; } if (use == 0 || use == (rtx) 1) return 0; if (GET_MODE_SIZE (GET_MODE (use)) != (amount > 0 ? amount : - amount)) return 0; /* See if this combination of instruction and addressing mode exists. */ if (! validate_change (insn, &XEXP (use, 0), gen_rtx_fmt_e (amount > 0 ? (do_post ? POST_INC : PRE_INC) : (do_post ? POST_DEC : PRE_DEC), Pmode, reg), 0)) return 0; /* Record that this insn now has an implicit side effect on X. */ REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, reg, REG_NOTES (insn)); return 1; } #endif /* AUTO_INC_DEC */ /* Find the place in the rtx X where REG is used as a memory address. Return the MEM rtx that so uses it. If PLUSCONST is nonzero, search instead for a memory address equivalent to (plus REG (const_int PLUSCONST)). If such an address does not appear, return 0. If REG appears more than once, or is used other than in such an address, return (rtx)1. */ rtx find_use_as_address (x, reg, plusconst) register rtx x; rtx reg; HOST_WIDE_INT plusconst; { enum rtx_code code = GET_CODE (x); const char * const fmt = GET_RTX_FORMAT (code); register int i; register rtx value = 0; register rtx tem; if (code == MEM && XEXP (x, 0) == reg && plusconst == 0) return x; if (code == MEM && GET_CODE (XEXP (x, 0)) == PLUS && XEXP (XEXP (x, 0), 0) == reg && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT && INTVAL (XEXP (XEXP (x, 0), 1)) == plusconst) return x; if (code == SIGN_EXTRACT || code == ZERO_EXTRACT) { /* If REG occurs inside a MEM used in a bit-field reference, that is unacceptable. */ if (find_use_as_address (XEXP (x, 0), reg, 0) != 0) return (rtx) (HOST_WIDE_INT) 1; } if (x == reg) return (rtx) (HOST_WIDE_INT) 1; for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) { if (fmt[i] == 'e') { tem = find_use_as_address (XEXP (x, i), reg, plusconst); if (value == 0) value = tem; else if (tem != 0) return (rtx) (HOST_WIDE_INT) 1; } else if (fmt[i] == 'E') { register int j; for (j = XVECLEN (x, i) - 1; j >= 0; j--) { tem = find_use_as_address (XVECEXP (x, i, j), reg, plusconst); if (value == 0) value = tem; else if (tem != 0) return (rtx) (HOST_WIDE_INT) 1; } } } return value; } /* Write information about registers and basic blocks into FILE. This is part of making a debugging dump. */ void dump_regset (r, outf) regset r; FILE *outf; { int i; if (r == NULL) { fputs (" (nil)", outf); return; } EXECUTE_IF_SET_IN_REG_SET (r, 0, i, { fprintf (outf, " %d", i); if (i < FIRST_PSEUDO_REGISTER) fprintf (outf, " [%s]", reg_names[i]); }); } /* Print a human-reaable representation of R on the standard error stream. This function is designed to be used from within the debugger. */ void debug_regset (r) regset r; { dump_regset (r, stderr); putc ('\n', stderr); } /* Dump the rtl into the current debugging dump file, then abort. */ static void print_rtl_and_abort_fcn (file, line, function) const char *file; int line; const char *function; { if (rtl_dump_file) { print_rtl_with_bb (rtl_dump_file, get_insns ()); fclose (rtl_dump_file); } fancy_abort (file, line, function); } /* Recompute register set/reference counts immediately prior to register allocation. This avoids problems with set/reference counts changing to/from values which have special meanings to the register allocators. Additionally, the reference counts are the primary component used by the register allocators to prioritize pseudos for allocation to hard regs. More accurate reference counts generally lead to better register allocation. F is the first insn to be scanned. LOOP_STEP denotes how much loop_depth should be incremented per loop nesting level in order to increase the ref count more for references in a loop. It might be worthwhile to update REG_LIVE_LENGTH, REG_BASIC_BLOCK and possibly other information which is used by the register allocators. */ void recompute_reg_usage (f, loop_step) rtx f ATTRIBUTE_UNUSED; int loop_step ATTRIBUTE_UNUSED; { allocate_reg_life_data (); update_life_info (NULL, UPDATE_LIFE_LOCAL, PROP_REG_INFO); } /* Optionally removes all the REG_DEAD and REG_UNUSED notes from a set of blocks. If BLOCKS is NULL, assume the universal set. Returns a count of the number of registers that died. */ int count_or_remove_death_notes (blocks, kill) sbitmap blocks; int kill; { int i, count = 0; for (i = n_basic_blocks - 1; i >= 0; --i) { basic_block bb; rtx insn; if (blocks && ! TEST_BIT (blocks, i)) continue; bb = BASIC_BLOCK (i); for (insn = bb->head;; insn = NEXT_INSN (insn)) { if (INSN_P (insn)) { rtx *pprev = ®_NOTES (insn); rtx link = *pprev; while (link) { switch (REG_NOTE_KIND (link)) { case REG_DEAD: if (GET_CODE (XEXP (link, 0)) == REG) { rtx reg = XEXP (link, 0); int n; if (REGNO (reg) >= FIRST_PSEUDO_REGISTER) n = 1; else n = HARD_REGNO_NREGS (REGNO (reg), GET_MODE (reg)); count += n; } /* Fall through. */ case REG_UNUSED: if (kill) { rtx next = XEXP (link, 1); free_EXPR_LIST_node (link); *pprev = link = next; break; } /* Fall through. */ default: pprev = &XEXP (link, 1); link = *pprev; break; } } } if (insn == bb->end) break; } } return count; } /* Clear LOG_LINKS fields of insns in a chain. Also clear the global_live_at_{start,end} fields of the basic block structures. */ void clear_log_links (insns) rtx insns; { rtx i; int b; for (i = insns; i; i = NEXT_INSN (i)) if (INSN_P (i)) LOG_LINKS (i) = 0; for (b = 0; b < n_basic_blocks; b++) { basic_block bb = BASIC_BLOCK (b); bb->global_live_at_start = NULL; bb->global_live_at_end = NULL; } ENTRY_BLOCK_PTR->global_live_at_end = NULL; EXIT_BLOCK_PTR->global_live_at_start = NULL; } /* Given a register bitmap, turn on the bits in a HARD_REG_SET that correspond to the hard registers, if any, set in that map. This could be done far more efficiently by having all sorts of special-cases with moving single words, but probably isn't worth the trouble. */ void reg_set_to_hard_reg_set (to, from) HARD_REG_SET *to; bitmap from; { int i; EXECUTE_IF_SET_IN_BITMAP (from, 0, i, { if (i >= FIRST_PSEUDO_REGISTER) return; SET_HARD_REG_BIT (*to, i); }); }