/* Data flow analysis for GNU compiler. Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000 Free Software Foundation, Inc. This file is part of GNU CC. GNU CC 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. GNU CC 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 GNU CC; 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 "insn-flags.h" #include "expr.h" #include "ssa.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 /* The obstack on which the flow graph components are allocated. */ struct obstack flow_obstack; static char *flow_firstobj; /* Number of basic blocks in the current function. */ int n_basic_blocks; /* Number of edges in the current function. */ int n_edges; /* The basic block array. */ varray_type basic_block_info; /* The special entry and exit blocks. */ struct basic_block_def entry_exit_blocks[2] = {{NULL, /* head */ NULL, /* end */ NULL, /* pred */ NULL, /* succ */ NULL, /* local_set */ NULL, /* cond_local_set */ NULL, /* global_live_at_start */ NULL, /* global_live_at_end */ NULL, /* aux */ ENTRY_BLOCK, /* index */ 0, /* loop_depth */ -1, -1, /* eh_beg, eh_end */ 0 /* count */ }, { NULL, /* head */ NULL, /* end */ NULL, /* pred */ NULL, /* succ */ NULL, /* local_set */ NULL, /* cond_local_set */ NULL, /* global_live_at_start */ NULL, /* global_live_at_end */ NULL, /* aux */ EXIT_BLOCK, /* index */ 0, /* loop_depth */ -1, -1, /* eh_beg, eh_end */ 0 /* count */ } }; /* 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; /* Set of registers that may be eliminable. These are handled specially in updating regs_ever_live. */ static HARD_REG_SET elim_reg_set; /* The basic block structure for every insn, indexed by uid. */ varray_type basic_block_for_insn; /* The labels mentioned in non-jump rtl. Valid during find_basic_blocks. */ /* ??? Should probably be using LABEL_NUSES instead. It would take a bit of surgery to be able to use or co-opt the routines in jump. */ static rtx label_value_list; static rtx tail_recursion_label_list; /* Holds information for tracking conditional register life information. */ struct reg_cond_life_info { /* An EXPR_LIST of conditions under which a register is dead. */ rtx condition; /* ??? 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 /* Non-zero if the value of CC0 is live. */ int cc0_live; /* Flags controling the set of information propagate_block collects. */ int flags; }; /* Store the data structures necessary for depth-first search. */ struct depth_first_search_dsS { /* stack for backtracking during the algorithm */ basic_block *stack; /* number of edges in the stack. That is, positions 0, ..., sp-1 have edges. */ unsigned int sp; /* record of basic blocks already seen by depth-first search */ sbitmap visited_blocks; }; typedef struct depth_first_search_dsS *depth_first_search_ds; /* Forward declarations */ static int count_basic_blocks PARAMS ((rtx)); static void find_basic_blocks_1 PARAMS ((rtx)); static rtx find_label_refs PARAMS ((rtx, rtx)); static void clear_edges PARAMS ((void)); static void make_edges PARAMS ((rtx)); static void make_label_edge PARAMS ((sbitmap *, basic_block, rtx, int)); static void make_eh_edge PARAMS ((sbitmap *, eh_nesting_info *, basic_block, rtx, int)); static void mark_critical_edges PARAMS ((void)); static void move_stray_eh_region_notes PARAMS ((void)); static void record_active_eh_regions PARAMS ((rtx)); static void commit_one_edge_insertion PARAMS ((edge)); static void delete_unreachable_blocks PARAMS ((void)); static void delete_eh_regions PARAMS ((void)); static int can_delete_note_p PARAMS ((rtx)); static void expunge_block PARAMS ((basic_block)); static int can_delete_label_p PARAMS ((rtx)); static int tail_recursion_label_p PARAMS ((rtx)); static int merge_blocks_move_predecessor_nojumps PARAMS ((basic_block, basic_block)); static int merge_blocks_move_successor_nojumps PARAMS ((basic_block, basic_block)); static int merge_blocks PARAMS ((edge,basic_block,basic_block)); static void try_merge_blocks PARAMS ((void)); static void tidy_fallthru_edges PARAMS ((void)); 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 int set_noop_p PARAMS ((rtx)); static int noop_move_p PARAMS ((rtx)); static void delete_noop_moves PARAMS ((rtx)); 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 ((basic_block, 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 ior_reg_cond PARAMS ((rtx, rtx)); static rtx not_reg_cond PARAMS ((rtx)); static rtx nand_reg_cond PARAMS ((rtx, rtx)); #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 dump_edge_info PARAMS ((FILE *, edge, int)); static void print_rtl_and_abort PARAMS ((void)); 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 remove_fake_successors PARAMS ((basic_block)); static void flow_nodes_print PARAMS ((const char *, const sbitmap, FILE *)); static void flow_edge_list_print PARAMS ((const char *, const edge *, int, FILE *)); static void flow_loops_cfg_dump PARAMS ((const struct loops *, FILE *)); static int flow_loop_nested_p PARAMS ((struct loop *, struct loop *)); static int flow_loop_entry_edges_find PARAMS ((basic_block, const sbitmap, edge **)); static int flow_loop_exit_edges_find PARAMS ((const sbitmap, edge **)); static int flow_loop_nodes_find PARAMS ((basic_block, basic_block, sbitmap)); static int flow_depth_first_order_compute PARAMS ((int *, int *)); static void flow_dfs_compute_reverse_init PARAMS ((depth_first_search_ds)); static void flow_dfs_compute_reverse_add_bb PARAMS ((depth_first_search_ds, basic_block)); static basic_block flow_dfs_compute_reverse_execute PARAMS ((depth_first_search_ds)); static void flow_dfs_compute_reverse_finish PARAMS ((depth_first_search_ds)); static void flow_loop_pre_header_scan PARAMS ((struct loop *)); static basic_block flow_loop_pre_header_find PARAMS ((basic_block, const sbitmap *)); static void flow_loop_tree_node_add PARAMS ((struct loop *, struct loop *)); static void flow_loops_tree_build PARAMS ((struct loops *)); static int flow_loop_level_compute PARAMS ((struct loop *, int)); static int flow_loops_level_compute PARAMS ((struct loops *)); static void allocate_bb_life_data PARAMS ((void)); /* Find basic blocks of the current function. F is the first insn of the function and NREGS the number of register numbers in use. */ void find_basic_blocks (f, nregs, file) rtx f; int nregs ATTRIBUTE_UNUSED; FILE *file ATTRIBUTE_UNUSED; { int max_uid; /* Flush out existing data. */ if (basic_block_info != NULL) { int i; clear_edges (); /* Clear bb->aux on all extant basic blocks. We'll use this as a tag for reuse during create_basic_block, just in case some pass copies around basic block notes improperly. */ for (i = 0; i < n_basic_blocks; ++i) BASIC_BLOCK (i)->aux = NULL; VARRAY_FREE (basic_block_info); } n_basic_blocks = count_basic_blocks (f); /* Size the basic block table. The actual structures will be allocated by find_basic_blocks_1, since we want to keep the structure pointers stable across calls to find_basic_blocks. */ /* ??? This whole issue would be much simpler if we called find_basic_blocks exactly once, and thereafter we don't have a single long chain of instructions at all until close to the end of compilation when we actually lay them out. */ VARRAY_BB_INIT (basic_block_info, n_basic_blocks, "basic_block_info"); find_basic_blocks_1 (f); /* Record the block to which an insn belongs. */ /* ??? This should be done another way, by which (perhaps) a label is tagged directly with the basic block that it starts. It is used for more than that currently, but IMO that is the only valid use. */ max_uid = get_max_uid (); #ifdef AUTO_INC_DEC /* Leave space for insns life_analysis makes in some cases for auto-inc. These cases are rare, so we don't need too much space. */ max_uid += max_uid / 10; #endif compute_bb_for_insn (max_uid); /* Discover the edges of our cfg. */ record_active_eh_regions (f); make_edges (label_value_list); /* Do very simple cleanup now, for the benefit of code that runs between here and cleanup_cfg, e.g. thread_prologue_and_epilogue_insns. */ tidy_fallthru_edges (); mark_critical_edges (); #ifdef ENABLE_CHECKING verify_flow_info (); #endif } void check_function_return_warnings () { if (warn_missing_noreturn && !TREE_THIS_VOLATILE (cfun->decl) && EXIT_BLOCK_PTR->pred == NULL) 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. */ compute_bb_for_insn (max_uid); if (BLOCK_FOR_INSN (cfun->x_clobber_return_insn) != NULL) warning ("control reaches end of non-void function"); } } } /* Count the basic blocks of the function. */ static int count_basic_blocks (f) rtx f; { register rtx insn; register RTX_CODE prev_code; register int count = 0; int eh_region = 0; int call_had_abnormal_edge = 0; prev_code = JUMP_INSN; for (insn = f; insn; insn = NEXT_INSN (insn)) { register RTX_CODE code = GET_CODE (insn); if (code == CODE_LABEL || (GET_RTX_CLASS (code) == 'i' && (prev_code == JUMP_INSN || prev_code == BARRIER || (prev_code == CALL_INSN && call_had_abnormal_edge)))) count++; /* Record whether this call created an edge. */ if (code == CALL_INSN) { rtx note = find_reg_note (insn, REG_EH_REGION, NULL_RTX); int region = (note ? INTVAL (XEXP (note, 0)) : 1); call_had_abnormal_edge = 0; /* If there is an EH region or rethrow, we have an edge. */ if ((eh_region && region > 0) || find_reg_note (insn, REG_EH_RETHROW, NULL_RTX)) call_had_abnormal_edge = 1; else if (nonlocal_goto_handler_labels && region >= 0) /* If there is a nonlocal goto label and the specified region number isn't -1, we have an edge. (0 means no throw, but might have a nonlocal goto). */ call_had_abnormal_edge = 1; } if (code != NOTE) prev_code = code; else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG) ++eh_region; else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END) --eh_region; } /* The rest of the compiler works a bit smoother when we don't have to check for the edge case of do-nothing functions with no basic blocks. */ if (count == 0) { emit_insn (gen_rtx_USE (VOIDmode, const0_rtx)); count = 1; } return count; } /* Scan a list of insns for labels referred to other than by jumps. This is used to scan the alternatives of a call placeholder. */ static rtx find_label_refs (f, lvl) rtx f; rtx lvl; { rtx insn; for (insn = f; insn; insn = NEXT_INSN (insn)) if (INSN_P (insn)) { rtx note; /* Make a list of all labels referred to other than by jumps (which just don't have the REG_LABEL notes). Make a special exception for labels followed by an ADDR*VEC, as this would be a part of the tablejump setup code. Make a special exception for the eh_return_stub_label, which we know isn't part of any otherwise visible control flow. */ for (note = REG_NOTES (insn); note; note = XEXP (note, 1)) if (REG_NOTE_KIND (note) == REG_LABEL) { rtx lab = XEXP (note, 0), next; if (lab == eh_return_stub_label) ; else if ((next = next_nonnote_insn (lab)) != NULL && GET_CODE (next) == JUMP_INSN && (GET_CODE (PATTERN (next)) == ADDR_VEC || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC)) ; else if (GET_CODE (lab) == NOTE) ; else lvl = alloc_EXPR_LIST (0, XEXP (note, 0), lvl); } } return lvl; } /* Find all basic blocks of the function whose first insn is F. Collect and return a list of labels whose addresses are taken. This will be used in make_edges for use with computed gotos. */ static void find_basic_blocks_1 (f) rtx f; { register rtx insn, next; int i = 0; rtx bb_note = NULL_RTX; rtx eh_list = NULL_RTX; rtx lvl = NULL_RTX; rtx trll = NULL_RTX; rtx head = NULL_RTX; rtx end = NULL_RTX; /* We process the instructions in a slightly different way than we did previously. This is so that we see a NOTE_BASIC_BLOCK after we have closed out the previous block, so that it gets attached at the proper place. Since this form should be equivalent to the previous, count_basic_blocks continues to use the old form as a check. */ for (insn = f; insn; insn = next) { enum rtx_code code = GET_CODE (insn); next = NEXT_INSN (insn); switch (code) { case NOTE: { int kind = NOTE_LINE_NUMBER (insn); /* Keep a LIFO list of the currently active exception notes. */ if (kind == NOTE_INSN_EH_REGION_BEG) eh_list = alloc_INSN_LIST (insn, eh_list); else if (kind == NOTE_INSN_EH_REGION_END) { rtx t = eh_list; eh_list = XEXP (eh_list, 1); free_INSN_LIST_node (t); } /* Look for basic block notes with which to keep the basic_block_info pointers stable. Unthread the note now; we'll put it back at the right place in create_basic_block. Or not at all if we've already found a note in this block. */ else if (kind == NOTE_INSN_BASIC_BLOCK) { if (bb_note == NULL_RTX) bb_note = insn; else next = flow_delete_insn (insn); } break; } case CODE_LABEL: /* A basic block starts at a label. If we've closed one off due to a barrier or some such, no need to do it again. */ if (head != NULL_RTX) { /* While we now have edge lists with which other portions of the compiler might determine a call ending a basic block does not imply an abnormal edge, it will be a bit before everything can be updated. So continue to emit a noop at the end of such a block. */ if (GET_CODE (end) == CALL_INSN && ! SIBLING_CALL_P (end)) { rtx nop = gen_rtx_USE (VOIDmode, const0_rtx); end = emit_insn_after (nop, end); } create_basic_block (i++, head, end, bb_note); bb_note = NULL_RTX; } head = end = insn; break; case JUMP_INSN: /* A basic block ends at a jump. */ if (head == NULL_RTX) head = insn; else { /* ??? Make a special check for table jumps. The way this happens is truly and amazingly gross. We are about to create a basic block that contains just a code label and an addr*vec jump insn. Worse, an addr_diff_vec creates its own natural loop. Prevent this bit of brain damage, pasting things together correctly in make_edges. The correct solution involves emitting the table directly on the tablejump instruction as a note, or JUMP_LABEL. */ if (GET_CODE (PATTERN (insn)) == ADDR_VEC || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC) { head = end = NULL; n_basic_blocks--; break; } } end = insn; goto new_bb_inclusive; case BARRIER: /* A basic block ends at a barrier. It may be that an unconditional jump already closed the basic block -- no need to do it again. */ if (head == NULL_RTX) break; /* While we now have edge lists with which other portions of the compiler might determine a call ending a basic block does not imply an abnormal edge, it will be a bit before everything can be updated. So continue to emit a noop at the end of such a block. */ if (GET_CODE (end) == CALL_INSN && ! SIBLING_CALL_P (end)) { rtx nop = gen_rtx_USE (VOIDmode, const0_rtx); end = emit_insn_after (nop, end); } goto new_bb_exclusive; case CALL_INSN: { /* Record whether this call created an edge. */ rtx note = find_reg_note (insn, REG_EH_REGION, NULL_RTX); int region = (note ? INTVAL (XEXP (note, 0)) : 1); int call_has_abnormal_edge = 0; if (GET_CODE (PATTERN (insn)) == CALL_PLACEHOLDER) { /* Scan each of the alternatives for label refs. */ lvl = find_label_refs (XEXP (PATTERN (insn), 0), lvl); lvl = find_label_refs (XEXP (PATTERN (insn), 1), lvl); lvl = find_label_refs (XEXP (PATTERN (insn), 2), lvl); /* Record its tail recursion label, if any. */ if (XEXP (PATTERN (insn), 3) != NULL_RTX) trll = alloc_EXPR_LIST (0, XEXP (PATTERN (insn), 3), trll); } /* If there is an EH region or rethrow, we have an edge. */ if ((eh_list && region > 0) || find_reg_note (insn, REG_EH_RETHROW, NULL_RTX)) call_has_abnormal_edge = 1; else if (nonlocal_goto_handler_labels && region >= 0) /* If there is a nonlocal goto label and the specified region number isn't -1, we have an edge. (0 means no throw, but might have a nonlocal goto). */ call_has_abnormal_edge = 1; /* A basic block ends at a call that can either throw or do a non-local goto. */ if (call_has_abnormal_edge) { new_bb_inclusive: if (head == NULL_RTX) head = insn; end = insn; new_bb_exclusive: create_basic_block (i++, head, end, bb_note); head = end = NULL_RTX; bb_note = NULL_RTX; break; } } /* Fall through. */ default: if (GET_RTX_CLASS (code) == 'i') { if (head == NULL_RTX) head = insn; end = insn; } break; } if (GET_RTX_CLASS (code) == 'i') { rtx note; /* Make a list of all labels referred to other than by jumps (which just don't have the REG_LABEL notes). Make a special exception for labels followed by an ADDR*VEC, as this would be a part of the tablejump setup code. Make a special exception for the eh_return_stub_label, which we know isn't part of any otherwise visible control flow. */ for (note = REG_NOTES (insn); note; note = XEXP (note, 1)) if (REG_NOTE_KIND (note) == REG_LABEL) { rtx lab = XEXP (note, 0), next; if (lab == eh_return_stub_label) ; else if ((next = next_nonnote_insn (lab)) != NULL && GET_CODE (next) == JUMP_INSN && (GET_CODE (PATTERN (next)) == ADDR_VEC || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC)) ; else if (GET_CODE (lab) == NOTE) ; else lvl = alloc_EXPR_LIST (0, XEXP (note, 0), lvl); } } } if (head != NULL_RTX) create_basic_block (i++, head, end, bb_note); else if (bb_note) flow_delete_insn (bb_note); if (i != n_basic_blocks) abort (); label_value_list = lvl; tail_recursion_label_list = trll; } /* Tidy the CFG by deleting unreachable code and whatnot. */ void cleanup_cfg (f) rtx f; { delete_unreachable_blocks (); move_stray_eh_region_notes (); record_active_eh_regions (f); try_merge_blocks (); mark_critical_edges (); /* Kill the data we won't maintain. */ free_EXPR_LIST_list (&label_value_list); free_EXPR_LIST_list (&tail_recursion_label_list); } /* Create a new basic block consisting of the instructions between HEAD and END inclusive. Reuses the note and basic block struct in BB_NOTE, if any. */ void create_basic_block (index, head, end, bb_note) int index; rtx head, end, bb_note; { basic_block bb; if (bb_note && ! RTX_INTEGRATED_P (bb_note) && (bb = NOTE_BASIC_BLOCK (bb_note)) != NULL && bb->aux == NULL) { /* If we found an existing note, thread it back onto the chain. */ rtx after; if (GET_CODE (head) == CODE_LABEL) after = head; else { after = PREV_INSN (head); head = bb_note; } if (after != bb_note && NEXT_INSN (after) != bb_note) reorder_insns (bb_note, bb_note, after); } else { /* Otherwise we must create a note and a basic block structure. Since we allow basic block structs in rtl, give the struct the same lifetime by allocating it off the function obstack rather than using malloc. */ bb = (basic_block) obstack_alloc (&flow_obstack, sizeof (*bb)); memset (bb, 0, sizeof (*bb)); if (GET_CODE (head) == CODE_LABEL) bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, head); else { bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, head); head = bb_note; } NOTE_BASIC_BLOCK (bb_note) = bb; } /* Always include the bb note in the block. */ if (NEXT_INSN (end) == bb_note) end = bb_note; bb->head = head; bb->end = end; bb->index = index; BASIC_BLOCK (index) = bb; /* Tag the block so that we know it has been used when considering other basic block notes. */ bb->aux = bb; } /* Records the basic block struct in BB_FOR_INSN, for every instruction indexed by INSN_UID. MAX is the size of the array. */ void compute_bb_for_insn (max) int max; { int i; if (basic_block_for_insn) VARRAY_FREE (basic_block_for_insn); VARRAY_BB_INIT (basic_block_for_insn, max, "basic_block_for_insn"); for (i = 0; i < n_basic_blocks; ++i) { basic_block bb = BASIC_BLOCK (i); rtx insn, end; end = bb->end; insn = bb->head; while (1) { int uid = INSN_UID (insn); if (uid < max) VARRAY_BB (basic_block_for_insn, uid) = bb; if (insn == end) break; insn = NEXT_INSN (insn); } } } /* Free the memory associated with the edge structures. */ static void clear_edges () { int i; edge n, e; for (i = 0; i < n_basic_blocks; ++i) { basic_block bb = BASIC_BLOCK (i); for (e = bb->succ; e; e = n) { n = e->succ_next; free (e); } bb->succ = 0; bb->pred = 0; } for (e = ENTRY_BLOCK_PTR->succ; e; e = n) { n = e->succ_next; free (e); } ENTRY_BLOCK_PTR->succ = 0; EXIT_BLOCK_PTR->pred = 0; n_edges = 0; } /* Identify the edges between basic blocks. NONLOCAL_LABEL_LIST is a list of non-local labels in the function. Blocks that are otherwise unreachable may be reachable with a non-local goto. BB_EH_END is an array indexed by basic block number in which we record the list of exception regions active at the end of the basic block. */ static void make_edges (label_value_list) rtx label_value_list; { int i; eh_nesting_info *eh_nest_info = init_eh_nesting_info (); sbitmap *edge_cache = NULL; /* Assume no computed jump; revise as we create edges. */ current_function_has_computed_jump = 0; /* Heavy use of computed goto in machine-generated code can lead to nearly fully-connected CFGs. In that case we spend a significant amount of time searching the edge lists for duplicates. */ if (forced_labels || label_value_list) { edge_cache = sbitmap_vector_alloc (n_basic_blocks, n_basic_blocks); sbitmap_vector_zero (edge_cache, n_basic_blocks); } /* By nature of the way these get numbered, block 0 is always the entry. */ make_edge (edge_cache, ENTRY_BLOCK_PTR, BASIC_BLOCK (0), EDGE_FALLTHRU); for (i = 0; i < n_basic_blocks; ++i) { basic_block bb = BASIC_BLOCK (i); rtx insn, x; enum rtx_code code; int force_fallthru = 0; /* Examine the last instruction of the block, and discover the ways we can leave the block. */ insn = bb->end; code = GET_CODE (insn); /* A branch. */ if (code == JUMP_INSN) { rtx tmp; /* ??? Recognize a tablejump and do the right thing. */ if ((tmp = JUMP_LABEL (insn)) != NULL_RTX && (tmp = NEXT_INSN (tmp)) != NULL_RTX && GET_CODE (tmp) == JUMP_INSN && (GET_CODE (PATTERN (tmp)) == ADDR_VEC || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC)) { rtvec vec; int j; if (GET_CODE (PATTERN (tmp)) == ADDR_VEC) vec = XVEC (PATTERN (tmp), 0); else vec = XVEC (PATTERN (tmp), 1); for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j) make_label_edge (edge_cache, bb, XEXP (RTVEC_ELT (vec, j), 0), 0); /* Some targets (eg, ARM) emit a conditional jump that also contains the out-of-range target. Scan for these and add an edge if necessary. */ if ((tmp = single_set (insn)) != NULL && SET_DEST (tmp) == pc_rtx && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF) make_label_edge (edge_cache, bb, XEXP (XEXP (SET_SRC (tmp), 2), 0), 0); #ifdef CASE_DROPS_THROUGH /* Silly VAXen. The ADDR_VEC is going to be in the way of us naturally detecting fallthru into the next block. */ force_fallthru = 1; #endif } /* If this is a computed jump, then mark it as reaching everything on the label_value_list and forced_labels list. */ else if (computed_jump_p (insn)) { current_function_has_computed_jump = 1; for (x = label_value_list; x; x = XEXP (x, 1)) make_label_edge (edge_cache, bb, XEXP (x, 0), EDGE_ABNORMAL); for (x = forced_labels; x; x = XEXP (x, 1)) make_label_edge (edge_cache, bb, XEXP (x, 0), EDGE_ABNORMAL); } /* Returns create an exit out. */ else if (returnjump_p (insn)) make_edge (edge_cache, bb, EXIT_BLOCK_PTR, 0); /* Otherwise, we have a plain conditional or unconditional jump. */ else { if (! JUMP_LABEL (insn)) abort (); make_label_edge (edge_cache, bb, JUMP_LABEL (insn), 0); } } /* If this is a sibling call insn, then this is in effect a combined call and return, and so we need an edge to the exit block. No need to worry about EH edges, since we wouldn't have created the sibling call in the first place. */ if (code == CALL_INSN && SIBLING_CALL_P (insn)) make_edge (edge_cache, bb, EXIT_BLOCK_PTR, EDGE_ABNORMAL | EDGE_ABNORMAL_CALL); /* If this is a CALL_INSN, then mark it as reaching the active EH handler for this CALL_INSN. If we're handling asynchronous exceptions then any insn can reach any of the active handlers. Also mark the CALL_INSN as reaching any nonlocal goto handler. */ else if (code == CALL_INSN || asynchronous_exceptions) { /* Add any appropriate EH edges. We do this unconditionally since there may be a REG_EH_REGION or REG_EH_RETHROW note on the call, and this needn't be within an EH region. */ make_eh_edge (edge_cache, eh_nest_info, bb, insn, bb->eh_end); /* If we have asynchronous exceptions, do the same for *all* exception regions active in the block. */ if (asynchronous_exceptions && bb->eh_beg != bb->eh_end) { if (bb->eh_beg >= 0) make_eh_edge (edge_cache, eh_nest_info, bb, NULL_RTX, bb->eh_beg); for (x = bb->head; x != bb->end; x = NEXT_INSN (x)) if (GET_CODE (x) == NOTE && (NOTE_LINE_NUMBER (x) == NOTE_INSN_EH_REGION_BEG || NOTE_LINE_NUMBER (x) == NOTE_INSN_EH_REGION_END)) { int region = NOTE_EH_HANDLER (x); make_eh_edge (edge_cache, eh_nest_info, bb, NULL_RTX, region); } } if (code == CALL_INSN && nonlocal_goto_handler_labels) { /* ??? This could be made smarter: in some cases it's possible to tell that certain calls will not do a nonlocal goto. For example, if the nested functions that do the nonlocal gotos do not have their addresses taken, then only calls to those functions or to other nested functions that use them could possibly do nonlocal gotos. */ /* We do know that a REG_EH_REGION note with a value less than 0 is guaranteed not to perform a non-local goto. */ rtx note = find_reg_note (insn, REG_EH_REGION, NULL_RTX); if (!note || INTVAL (XEXP (note, 0)) >= 0) for (x = nonlocal_goto_handler_labels; x; x = XEXP (x, 1)) make_label_edge (edge_cache, bb, XEXP (x, 0), EDGE_ABNORMAL | EDGE_ABNORMAL_CALL); } } /* We know something about the structure of the function __throw in libgcc2.c. It is the only function that ever contains eh_stub labels. It modifies its return address so that the last block returns to one of the eh_stub labels within it. So we have to make additional edges in the flow graph. */ if (i + 1 == n_basic_blocks && eh_return_stub_label != 0) make_label_edge (edge_cache, bb, eh_return_stub_label, EDGE_EH); /* Find out if we can drop through to the next block. */ insn = next_nonnote_insn (insn); if (!insn || (i + 1 == n_basic_blocks && force_fallthru)) make_edge (edge_cache, bb, EXIT_BLOCK_PTR, EDGE_FALLTHRU); else if (i + 1 < n_basic_blocks) { rtx tmp = BLOCK_HEAD (i + 1); if (GET_CODE (tmp) == NOTE) tmp = next_nonnote_insn (tmp); if (force_fallthru || insn == tmp) make_edge (edge_cache, bb, BASIC_BLOCK (i + 1), EDGE_FALLTHRU); } } free_eh_nesting_info (eh_nest_info); if (edge_cache) sbitmap_vector_free (edge_cache); } /* Create an edge between two basic blocks. FLAGS are auxiliary information about the edge that is accumulated between calls. */ void make_edge (edge_cache, src, dst, flags) sbitmap *edge_cache; basic_block src, dst; int flags; { int use_edge_cache; edge e; /* Don't bother with edge cache for ENTRY or EXIT; there aren't that many edges to them, and we didn't allocate memory for it. */ use_edge_cache = (edge_cache && src != ENTRY_BLOCK_PTR && dst != EXIT_BLOCK_PTR); /* Make sure we don't add duplicate edges. */ switch (use_edge_cache) { default: /* Quick test for non-existance of the edge. */ if (! TEST_BIT (edge_cache[src->index], dst->index)) break; /* The edge exists; early exit if no work to do. */ if (flags == 0) return; /* FALLTHRU */ case 0: for (e = src->succ; e; e = e->succ_next) if (e->dest == dst) { e->flags |= flags; return; } break; } e = (edge) xcalloc (1, sizeof (*e)); n_edges++; e->succ_next = src->succ; e->pred_next = dst->pred; e->src = src; e->dest = dst; e->flags = flags; src->succ = e; dst->pred = e; if (use_edge_cache) SET_BIT (edge_cache[src->index], dst->index); } /* Create an edge from a basic block to a label. */ static void make_label_edge (edge_cache, src, label, flags) sbitmap *edge_cache; basic_block src; rtx label; int flags; { if (GET_CODE (label) != CODE_LABEL) abort (); /* If the label was never emitted, this insn is junk, but avoid a crash trying to refer to BLOCK_FOR_INSN (label). This can happen as a result of a syntax error and a diagnostic has already been printed. */ if (INSN_UID (label) == 0) return; make_edge (edge_cache, src, BLOCK_FOR_INSN (label), flags); } /* Create the edges generated by INSN in REGION. */ static void make_eh_edge (edge_cache, eh_nest_info, src, insn, region) sbitmap *edge_cache; eh_nesting_info *eh_nest_info; basic_block src; rtx insn; int region; { handler_info **handler_list; int num, is_call; is_call = (insn && GET_CODE (insn) == CALL_INSN ? EDGE_ABNORMAL_CALL : 0); num = reachable_handlers (region, eh_nest_info, insn, &handler_list); while (--num >= 0) { make_label_edge (edge_cache, src, handler_list[num]->handler_label, EDGE_ABNORMAL | EDGE_EH | is_call); } } /* EH_REGION notes appearing between basic blocks is ambiguous, and even dangerous if we intend to move basic blocks around. Move such notes into the following block. */ static void move_stray_eh_region_notes () { int i; basic_block b1, b2; if (n_basic_blocks < 2) return; b2 = BASIC_BLOCK (n_basic_blocks - 1); for (i = n_basic_blocks - 2; i >= 0; --i, b2 = b1) { rtx insn, next, list = NULL_RTX; b1 = BASIC_BLOCK (i); for (insn = NEXT_INSN (b1->end); insn != b2->head; insn = next) { next = NEXT_INSN (insn); if (GET_CODE (insn) == NOTE && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG || NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END)) { /* Unlink from the insn chain. */ NEXT_INSN (PREV_INSN (insn)) = next; PREV_INSN (next) = PREV_INSN (insn); /* Queue it. */ NEXT_INSN (insn) = list; list = insn; } } if (list == NULL_RTX) continue; /* Find where to insert these things. */ insn = b2->head; if (GET_CODE (insn) == CODE_LABEL) insn = NEXT_INSN (insn); while (list) { next = NEXT_INSN (list); add_insn_after (list, insn); list = next; } } } /* Recompute eh_beg/eh_end for each basic block. */ static void record_active_eh_regions (f) rtx f; { rtx insn, eh_list = NULL_RTX; int i = 0; basic_block bb = BASIC_BLOCK (0); for (insn = f; insn; insn = NEXT_INSN (insn)) { if (bb->head == insn) bb->eh_beg = (eh_list ? NOTE_EH_HANDLER (XEXP (eh_list, 0)) : -1); if (GET_CODE (insn) == NOTE) { int kind = NOTE_LINE_NUMBER (insn); if (kind == NOTE_INSN_EH_REGION_BEG) eh_list = alloc_INSN_LIST (insn, eh_list); else if (kind == NOTE_INSN_EH_REGION_END) { rtx t = XEXP (eh_list, 1); free_INSN_LIST_node (eh_list); eh_list = t; } } if (bb->end == insn) { bb->eh_end = (eh_list ? NOTE_EH_HANDLER (XEXP (eh_list, 0)) : -1); i += 1; if (i == n_basic_blocks) break; bb = BASIC_BLOCK (i); } } } /* Identify critical edges and set the bits appropriately. */ static void mark_critical_edges () { int i, n = n_basic_blocks; basic_block bb; /* We begin with the entry block. This is not terribly important now, but could be if a front end (Fortran) implemented alternate entry points. */ bb = ENTRY_BLOCK_PTR; i = -1; while (1) { edge e; /* (1) Critical edges must have a source with multiple successors. */ if (bb->succ && bb->succ->succ_next) { for (e = bb->succ; e; e = e->succ_next) { /* (2) Critical edges must have a destination with multiple predecessors. Note that we know there is at least one predecessor -- the edge we followed to get here. */ if (e->dest->pred->pred_next) e->flags |= EDGE_CRITICAL; else e->flags &= ~EDGE_CRITICAL; } } else { for (e = bb->succ; e; e = e->succ_next) e->flags &= ~EDGE_CRITICAL; } if (++i >= n) break; bb = BASIC_BLOCK (i); } } /* Split a block BB after insn INSN creating a new fallthru edge. Return the new edge. Note that to keep other parts of the compiler happy, this function renumbers all the basic blocks so that the new one has a number one greater than the block split. */ edge split_block (bb, insn) basic_block bb; rtx insn; { basic_block new_bb; edge new_edge; edge e; rtx bb_note; int i, j; /* There is no point splitting the block after its end. */ if (bb->end == insn) return 0; /* Create the new structures. */ new_bb = (basic_block) obstack_alloc (&flow_obstack, sizeof (*new_bb)); new_edge = (edge) xcalloc (1, sizeof (*new_edge)); n_edges++; memset (new_bb, 0, sizeof (*new_bb)); new_bb->head = NEXT_INSN (insn); new_bb->end = bb->end; bb->end = insn; new_bb->succ = bb->succ; bb->succ = new_edge; new_bb->pred = new_edge; new_bb->count = bb->count; new_bb->loop_depth = bb->loop_depth; new_edge->src = bb; new_edge->dest = new_bb; new_edge->flags = EDGE_FALLTHRU; new_edge->probability = REG_BR_PROB_BASE; new_edge->count = bb->count; /* Redirect the src of the successor edges of bb to point to new_bb. */ for (e = new_bb->succ; e; e = e->succ_next) e->src = new_bb; /* Place the new block just after the block being split. */ VARRAY_GROW (basic_block_info, ++n_basic_blocks); /* Some parts of the compiler expect blocks to be number in sequential order so insert the new block immediately after the block being split.. */ j = bb->index; for (i = n_basic_blocks - 1; i > j + 1; --i) { basic_block tmp = BASIC_BLOCK (i - 1); BASIC_BLOCK (i) = tmp; tmp->index = i; } BASIC_BLOCK (i) = new_bb; new_bb->index = i; /* Create the basic block note. */ bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, new_bb->head); NOTE_BASIC_BLOCK (bb_note) = new_bb; new_bb->head = bb_note; update_bb_for_insn (new_bb); if (bb->global_live_at_start) { new_bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack); new_bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack); COPY_REG_SET (new_bb->global_live_at_end, bb->global_live_at_end); /* We now have to calculate which registers are live at the end of the split basic block and at the start of the new basic block. Start with those registers that are known to be live at the end of the original basic block and get propagate_block to determine which registers are live. */ COPY_REG_SET (new_bb->global_live_at_start, bb->global_live_at_end); propagate_block (new_bb, new_bb->global_live_at_start, NULL, NULL, 0); COPY_REG_SET (bb->global_live_at_end, new_bb->global_live_at_start); } return new_edge; } /* Split a (typically critical) edge. Return the new block. Abort on abnormal edges. ??? The code generally expects to be called on critical edges. The case of a block ending in an unconditional jump to a block with multiple predecessors is not handled optimally. */ basic_block split_edge (edge_in) edge edge_in; { basic_block old_pred, bb, old_succ; edge edge_out; rtx bb_note; int i, j; /* Abnormal edges cannot be split. */ if ((edge_in->flags & EDGE_ABNORMAL) != 0) abort (); old_pred = edge_in->src; old_succ = edge_in->dest; /* Remove the existing edge from the destination's pred list. */ { edge *pp; for (pp = &old_succ->pred; *pp != edge_in; pp = &(*pp)->pred_next) continue; *pp = edge_in->pred_next; edge_in->pred_next = NULL; } /* Create the new structures. */ bb = (basic_block) obstack_alloc (&flow_obstack, sizeof (*bb)); edge_out = (edge) xcalloc (1, sizeof (*edge_out)); n_edges++; memset (bb, 0, sizeof (*bb)); /* ??? This info is likely going to be out of date very soon. */ if (old_succ->global_live_at_start) { bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack); bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack); COPY_REG_SET (bb->global_live_at_start, old_succ->global_live_at_start); COPY_REG_SET (bb->global_live_at_end, old_succ->global_live_at_start); } /* Wire them up. */ bb->pred = edge_in; bb->succ = edge_out; bb->count = edge_in->count; edge_in->dest = bb; edge_in->flags &= ~EDGE_CRITICAL; edge_out->pred_next = old_succ->pred; edge_out->succ_next = NULL; edge_out->src = bb; edge_out->dest = old_succ; edge_out->flags = EDGE_FALLTHRU; edge_out->probability = REG_BR_PROB_BASE; edge_out->count = edge_in->count; old_succ->pred = edge_out; /* Tricky case -- if there existed a fallthru into the successor (and we're not it) we must add a new unconditional jump around the new block we're actually interested in. Further, if that edge is critical, this means a second new basic block must be created to hold it. In order to simplify correct insn placement, do this before we touch the existing basic block ordering for the block we were really wanting. */ if ((edge_in->flags & EDGE_FALLTHRU) == 0) { edge e; for (e = edge_out->pred_next; e; e = e->pred_next) if (e->flags & EDGE_FALLTHRU) break; if (e) { basic_block jump_block; rtx pos; if ((e->flags & EDGE_CRITICAL) == 0 && e->src != ENTRY_BLOCK_PTR) { /* Non critical -- we can simply add a jump to the end of the existing predecessor. */ jump_block = e->src; } else { /* We need a new block to hold the jump. The simplest way to do the bulk of the work here is to recursively call ourselves. */ jump_block = split_edge (e); e = jump_block->succ; } /* Now add the jump insn ... */ pos = emit_jump_insn_after (gen_jump (old_succ->head), jump_block->end); jump_block->end = pos; if (basic_block_for_insn) set_block_for_insn (pos, jump_block); emit_barrier_after (pos); /* ... let jump know that label is in use, ... */ JUMP_LABEL (pos) = old_succ->head; ++LABEL_NUSES (old_succ->head); /* ... and clear fallthru on the outgoing edge. */ e->flags &= ~EDGE_FALLTHRU; /* Continue splitting the interesting edge. */ } } /* Place the new block just in front of the successor. */ VARRAY_GROW (basic_block_info, ++n_basic_blocks); if (old_succ == EXIT_BLOCK_PTR) j = n_basic_blocks - 1; else j = old_succ->index; for (i = n_basic_blocks - 1; i > j; --i) { basic_block tmp = BASIC_BLOCK (i - 1); BASIC_BLOCK (i) = tmp; tmp->index = i; } BASIC_BLOCK (i) = bb; bb->index = i; /* Create the basic block note. Where we place the note can have a noticable impact on the generated code. Consider this cfg: E | 0 / \ +->1-->2--->E | | +--+ If we need to insert an insn on the edge from block 0 to block 1, we want to ensure the instructions we insert are outside of any loop notes that physically sit between block 0 and block 1. Otherwise we confuse the loop optimizer into thinking the loop is a phony. */ if (old_succ != EXIT_BLOCK_PTR && PREV_INSN (old_succ->head) && GET_CODE (PREV_INSN (old_succ->head)) == NOTE && NOTE_LINE_NUMBER (PREV_INSN (old_succ->head)) == NOTE_INSN_LOOP_BEG) bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, PREV_INSN (old_succ->head)); else if (old_succ != EXIT_BLOCK_PTR) bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, old_succ->head); else bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, get_last_insn ()); NOTE_BASIC_BLOCK (bb_note) = bb; bb->head = bb->end = bb_note; /* Not quite simple -- for non-fallthru edges, we must adjust the predecessor's jump instruction to target our new block. */ if ((edge_in->flags & EDGE_FALLTHRU) == 0) { rtx tmp, insn = old_pred->end; rtx old_label = old_succ->head; rtx new_label = gen_label_rtx (); if (GET_CODE (insn) != JUMP_INSN) abort (); /* ??? Recognize a tablejump and adjust all matching cases. */ if ((tmp = JUMP_LABEL (insn)) != NULL_RTX && (tmp = NEXT_INSN (tmp)) != NULL_RTX && GET_CODE (tmp) == JUMP_INSN && (GET_CODE (PATTERN (tmp)) == ADDR_VEC || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC)) { rtvec vec; int j; if (GET_CODE (PATTERN (tmp)) == ADDR_VEC) vec = XVEC (PATTERN (tmp), 0); else vec = XVEC (PATTERN (tmp), 1); for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j) if (XEXP (RTVEC_ELT (vec, j), 0) == old_label) { RTVEC_ELT (vec, j) = gen_rtx_LABEL_REF (VOIDmode, new_label); --LABEL_NUSES (old_label); ++LABEL_NUSES (new_label); } /* Handle casesi dispatch insns */ if ((tmp = single_set (insn)) != NULL && SET_DEST (tmp) == pc_rtx && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF && XEXP (XEXP (SET_SRC (tmp), 2), 0) == old_label) { XEXP (SET_SRC (tmp), 2) = gen_rtx_LABEL_REF (VOIDmode, new_label); --LABEL_NUSES (old_label); ++LABEL_NUSES (new_label); } } else { /* This would have indicated an abnormal edge. */ if (computed_jump_p (insn)) abort (); /* A return instruction can't be redirected. */ if (returnjump_p (insn)) abort (); /* If the insn doesn't go where we think, we're confused. */ if (JUMP_LABEL (insn) != old_label) abort (); redirect_jump (insn, new_label, 0); } emit_label_before (new_label, bb_note); bb->head = new_label; } return bb; } /* Queue instructions for insertion on an edge between two basic blocks. The new instructions and basic blocks (if any) will not appear in the CFG until commit_edge_insertions is called. */ void insert_insn_on_edge (pattern, e) rtx pattern; edge e; { /* We cannot insert instructions on an abnormal critical edge. It will be easier to find the culprit if we die now. */ if ((e->flags & (EDGE_ABNORMAL|EDGE_CRITICAL)) == (EDGE_ABNORMAL|EDGE_CRITICAL)) abort (); if (e->insns == NULL_RTX) start_sequence (); else push_to_sequence (e->insns); emit_insn (pattern); e->insns = get_insns (); end_sequence (); } /* Update the CFG for the instructions queued on edge E. */ static void commit_one_edge_insertion (e) edge e; { rtx before = NULL_RTX, after = NULL_RTX, insns, tmp, last; basic_block bb; /* Pull the insns off the edge now since the edge might go away. */ insns = e->insns; e->insns = NULL_RTX; /* Figure out where to put these things. If the destination has one predecessor, insert there. Except for the exit block. */ if (e->dest->pred->pred_next == NULL && e->dest != EXIT_BLOCK_PTR) { bb = e->dest; /* Get the location correct wrt a code label, and "nice" wrt a basic block note, and before everything else. */ tmp = bb->head; if (GET_CODE (tmp) == CODE_LABEL) tmp = NEXT_INSN (tmp); if (NOTE_INSN_BASIC_BLOCK_P (tmp)) tmp = NEXT_INSN (tmp); if (tmp == bb->head) before = tmp; else after = PREV_INSN (tmp); } /* If the source has one successor and the edge is not abnormal, insert there. Except for the entry block. */ else if ((e->flags & EDGE_ABNORMAL) == 0 && e->src->succ->succ_next == NULL && e->src != ENTRY_BLOCK_PTR) { bb = e->src; /* It is possible to have a non-simple jump here. Consider a target where some forms of unconditional jumps clobber a register. This happens on the fr30 for example. We know this block has a single successor, so we can just emit the queued insns before the jump. */ if (GET_CODE (bb->end) == JUMP_INSN) { before = bb->end; } else { /* We'd better be fallthru, or we've lost track of what's what. */ if ((e->flags & EDGE_FALLTHRU) == 0) abort (); after = bb->end; } } /* Otherwise we must split the edge. */ else { bb = split_edge (e); after = bb->end; } /* Now that we've found the spot, do the insertion. */ /* Set the new block number for these insns, if structure is allocated. */ if (basic_block_for_insn) { rtx i; for (i = insns; i != NULL_RTX; i = NEXT_INSN (i)) set_block_for_insn (i, bb); } if (before) { emit_insns_before (insns, before); if (before == bb->head) bb->head = insns; last = prev_nonnote_insn (before); } else { last = emit_insns_after (insns, after); if (after == bb->end) bb->end = last; } if (returnjump_p (last)) { /* ??? Remove all outgoing edges from BB and add one for EXIT. This is not currently a problem because this only happens for the (single) epilogue, which already has a fallthru edge to EXIT. */ e = bb->succ; if (e->dest != EXIT_BLOCK_PTR || e->succ_next != NULL || (e->flags & EDGE_FALLTHRU) == 0) abort (); e->flags &= ~EDGE_FALLTHRU; emit_barrier_after (last); bb->end = last; if (before) flow_delete_insn (before); } else if (GET_CODE (last) == JUMP_INSN) abort (); } /* Update the CFG for all queued instructions. */ void commit_edge_insertions () { int i; basic_block bb; #ifdef ENABLE_CHECKING verify_flow_info (); #endif i = -1; bb = ENTRY_BLOCK_PTR; while (1) { edge e, next; for (e = bb->succ; e; e = next) { next = e->succ_next; if (e->insns) commit_one_edge_insertion (e); } if (++i >= n_basic_blocks) break; bb = BASIC_BLOCK (i); } } /* Delete all unreachable basic blocks. */ static void delete_unreachable_blocks () { basic_block *worklist, *tos; int deleted_handler; edge e; int i, n; n = n_basic_blocks; tos = worklist = (basic_block *) xmalloc (sizeof (basic_block) * n); /* Use basic_block->aux as a marker. Clear them all. */ for (i = 0; i < n; ++i) BASIC_BLOCK (i)->aux = NULL; /* Add our starting points to the worklist. Almost always there will be only one. It isn't inconcievable that we might one day directly support Fortran alternate entry points. */ for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next) { *tos++ = e->dest; /* Mark the block with a handy non-null value. */ e->dest->aux = e; } /* Iterate: find everything reachable from what we've already seen. */ while (tos != worklist) { basic_block b = *--tos; for (e = b->succ; e; e = e->succ_next) if (!e->dest->aux) { *tos++ = e->dest; e->dest->aux = e; } } /* Delete all unreachable basic blocks. Count down so that we don't interfere with the block renumbering that happens in flow_delete_block. */ deleted_handler = 0; for (i = n - 1; i >= 0; --i) { basic_block b = BASIC_BLOCK (i); if (b->aux != NULL) /* This block was found. Tidy up the mark. */ b->aux = NULL; else deleted_handler |= flow_delete_block (b); } tidy_fallthru_edges (); /* If we deleted an exception handler, we may have EH region begin/end blocks to remove as well. */ if (deleted_handler) delete_eh_regions (); free (worklist); } /* Find EH regions for which there is no longer a handler, and delete them. */ static void delete_eh_regions () { rtx insn; update_rethrow_references (); for (insn = get_insns (); insn; insn = NEXT_INSN (insn)) if (GET_CODE (insn) == NOTE) { if ((NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG) || (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END)) { int num = NOTE_EH_HANDLER (insn); /* A NULL handler indicates a region is no longer needed, as long as its rethrow label isn't used. */ if (get_first_handler (num) == NULL && ! rethrow_used (num)) { NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED; NOTE_SOURCE_FILE (insn) = 0; } } } } /* Return true if NOTE is not one of the ones that must be kept paired, so that we may simply delete them. */ static int can_delete_note_p (note) rtx note; { return (NOTE_LINE_NUMBER (note) == NOTE_INSN_DELETED || NOTE_LINE_NUMBER (note) == NOTE_INSN_BASIC_BLOCK); } /* Unlink a chain of insns between START and FINISH, leaving notes that must be paired. */ void flow_delete_insn_chain (start, finish) rtx start, finish; { /* Unchain the insns one by one. It would be quicker to delete all of these with a single unchaining, rather than one at a time, but we need to keep the NOTE's. */ rtx next; while (1) { next = NEXT_INSN (start); if (GET_CODE (start) == NOTE && !can_delete_note_p (start)) ; else if (GET_CODE (start) == CODE_LABEL && ! can_delete_label_p (start)) { const char *name = LABEL_NAME (start); PUT_CODE (start, NOTE); NOTE_LINE_NUMBER (start) = NOTE_INSN_DELETED_LABEL; NOTE_SOURCE_FILE (start) = name; } else next = flow_delete_insn (start); if (start == finish) break; start = next; } } /* Delete the insns in a (non-live) block. We physically delete every non-deleted-note insn, and update the flow graph appropriately. Return nonzero if we deleted an exception handler. */ /* ??? Preserving all such notes strikes me as wrong. It would be nice to post-process the stream to remove empty blocks, loops, ranges, etc. */ int flow_delete_block (b) basic_block b; { int deleted_handler = 0; rtx insn, end, tmp; /* If the head of this block is a CODE_LABEL, then it might be the label for an exception handler which can't be reached. We need to remove the label from the exception_handler_label list and remove the associated NOTE_INSN_EH_REGION_BEG and NOTE_INSN_EH_REGION_END notes. */ insn = b->head; never_reached_warning (insn); if (GET_CODE (insn) == CODE_LABEL) { rtx x, *prev = &exception_handler_labels; for (x = exception_handler_labels; x; x = XEXP (x, 1)) { if (XEXP (x, 0) == insn) { /* Found a match, splice this label out of the EH label list. */ *prev = XEXP (x, 1); XEXP (x, 1) = NULL_RTX; XEXP (x, 0) = NULL_RTX; /* Remove the handler from all regions */ remove_handler (insn); deleted_handler = 1; break; } prev = &XEXP (x, 1); } } /* Include any jump table following the basic block. */ end = b->end; if (GET_CODE (end) == JUMP_INSN && (tmp = JUMP_LABEL (end)) != NULL_RTX && (tmp = NEXT_INSN (tmp)) != NULL_RTX && GET_CODE (tmp) == JUMP_INSN && (GET_CODE (PATTERN (tmp)) == ADDR_VEC || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC)) end = tmp; /* Include any barrier that may follow the basic block. */ tmp = next_nonnote_insn (end); if (tmp && GET_CODE (tmp) == BARRIER) end = tmp; /* Selectively delete the entire chain. */ flow_delete_insn_chain (insn, end); /* Remove the edges into and out of this block. Note that there may indeed be edges in, if we are removing an unreachable loop. */ { edge e, next, *q; for (e = b->pred; e; e = next) { for (q = &e->src->succ; *q != e; q = &(*q)->succ_next) continue; *q = e->succ_next; next = e->pred_next; n_edges--; free (e); } for (e = b->succ; e; e = next) { for (q = &e->dest->pred; *q != e; q = &(*q)->pred_next) continue; *q = e->pred_next; next = e->succ_next; n_edges--; free (e); } b->pred = NULL; b->succ = NULL; } /* Remove the basic block from the array, and compact behind it. */ expunge_block (b); return deleted_handler; } /* Remove block B from the basic block array and compact behind it. */ static void expunge_block (b) basic_block b; { int i, n = n_basic_blocks; for (i = b->index; i + 1 < n; ++i) { basic_block x = BASIC_BLOCK (i + 1); BASIC_BLOCK (i) = x; x->index = i; } basic_block_info->num_elements--; n_basic_blocks--; } /* Delete INSN by patching it out. Return the next insn. */ rtx flow_delete_insn (insn) rtx insn; { rtx prev = PREV_INSN (insn); rtx next = NEXT_INSN (insn); rtx note; PREV_INSN (insn) = NULL_RTX; NEXT_INSN (insn) = NULL_RTX; INSN_DELETED_P (insn) = 1; if (prev) NEXT_INSN (prev) = next; if (next) PREV_INSN (next) = prev; else set_last_insn (prev); if (GET_CODE (insn) == CODE_LABEL) remove_node_from_expr_list (insn, &nonlocal_goto_handler_labels); /* If deleting a jump, decrement the use count of the label. Deleting the label itself should happen in the normal course of block merging. */ if (GET_CODE (insn) == JUMP_INSN && JUMP_LABEL (insn) && GET_CODE (JUMP_LABEL (insn)) == CODE_LABEL) LABEL_NUSES (JUMP_LABEL (insn))--; /* Also if deleting an insn that references a label. */ else if ((note = find_reg_note (insn, REG_LABEL, NULL_RTX)) != NULL_RTX && GET_CODE (XEXP (note, 0)) == CODE_LABEL) LABEL_NUSES (XEXP (note, 0))--; return next; } /* True if a given label can be deleted. */ static int can_delete_label_p (label) rtx label; { rtx x; if (LABEL_PRESERVE_P (label)) return 0; for (x = forced_labels; x; x = XEXP (x, 1)) if (label == XEXP (x, 0)) return 0; for (x = label_value_list; x; x = XEXP (x, 1)) if (label == XEXP (x, 0)) return 0; for (x = exception_handler_labels; x; x = XEXP (x, 1)) if (label == XEXP (x, 0)) return 0; /* User declared labels must be preserved. */ if (LABEL_NAME (label) != 0) return 0; return 1; } static int tail_recursion_label_p (label) rtx label; { rtx x; for (x = tail_recursion_label_list; x; x = XEXP (x, 1)) if (label == XEXP (x, 0)) return 1; return 0; } /* Blocks A and B are to be merged into a single block A. The insns are already contiguous, hence `nomove'. */ void merge_blocks_nomove (a, b) basic_block a, b; { edge e; rtx b_head, b_end, a_end; rtx del_first = NULL_RTX, del_last = NULL_RTX; int b_empty = 0; /* If there was a CODE_LABEL beginning B, delete it. */ b_head = b->head; b_end = b->end; if (GET_CODE (b_head) == CODE_LABEL) { /* Detect basic blocks with nothing but a label. This can happen in particular at the end of a function. */ if (b_head == b_end) b_empty = 1; del_first = del_last = b_head; b_head = NEXT_INSN (b_head); } /* Delete the basic block note. */ if (NOTE_INSN_BASIC_BLOCK_P (b_head)) { if (b_head == b_end) b_empty = 1; if (! del_last) del_first = b_head; del_last = b_head; b_head = NEXT_INSN (b_head); } /* If there was a jump out of A, delete it. */ a_end = a->end; if (GET_CODE (a_end) == JUMP_INSN) { rtx prev; for (prev = PREV_INSN (a_end); ; prev = PREV_INSN (prev)) if (GET_CODE (prev) != NOTE || NOTE_LINE_NUMBER (prev) == NOTE_INSN_BASIC_BLOCK || prev == a->head) break; del_first = a_end; #ifdef HAVE_cc0 /* If this was a conditional jump, we need to also delete the insn that set cc0. */ if (prev && sets_cc0_p (prev)) { rtx tmp = prev; prev = prev_nonnote_insn (prev); if (!prev) prev = a->head; del_first = tmp; } #endif a_end = prev; } else if (GET_CODE (NEXT_INSN (a_end)) == BARRIER) del_first = NEXT_INSN (a_end); /* Delete everything marked above as well as crap that might be hanging out between the two blocks. */ flow_delete_insn_chain (del_first, del_last); /* Normally there should only be one successor of A and that is B, but partway though the merge of blocks for conditional_execution we'll be merging a TEST block with THEN and ELSE successors. Free the whole lot of them and hope the caller knows what they're doing. */ while (a->succ) remove_edge (a->succ); /* Adjust the edges out of B for the new owner. */ for (e = b->succ; e; e = e->succ_next) e->src = a; a->succ = b->succ; /* B hasn't quite yet ceased to exist. Attempt to prevent mishap. */ b->pred = b->succ = NULL; /* Reassociate the insns of B with A. */ if (!b_empty) { if (basic_block_for_insn) { BLOCK_FOR_INSN (b_head) = a; while (b_head != b_end) { b_head = NEXT_INSN (b_head); BLOCK_FOR_INSN (b_head) = a; } } a_end = b_end; } a->end = a_end; expunge_block (b); } /* Blocks A and B are to be merged into a single block. A has no incoming fallthru edge, so it can be moved before B without adding or modifying any jumps (aside from the jump from A to B). */ static int merge_blocks_move_predecessor_nojumps (a, b) basic_block a, b; { rtx start, end, barrier; int index; start = a->head; end = a->end; barrier = next_nonnote_insn (end); if (GET_CODE (barrier) != BARRIER) abort (); flow_delete_insn (barrier); /* Move block and loop notes out of the chain so that we do not disturb their order. ??? A better solution would be to squeeze out all the non-nested notes and adjust the block trees appropriately. Even better would be to have a tighter connection between block trees and rtl so that this is not necessary. */ start = squeeze_notes (start, end); /* Scramble the insn chain. */ if (end != PREV_INSN (b->head)) reorder_insns (start, end, PREV_INSN (b->head)); if (rtl_dump_file) { fprintf (rtl_dump_file, "Moved block %d before %d and merged.\n", a->index, b->index); } /* Swap the records for the two blocks around. Although we are deleting B, A is now where B was and we want to compact the BB array from where A used to be. */ BASIC_BLOCK (a->index) = b; BASIC_BLOCK (b->index) = a; index = a->index; a->index = b->index; b->index = index; /* Now blocks A and B are contiguous. Merge them. */ merge_blocks_nomove (a, b); return 1; } /* Blocks A and B are to be merged into a single block. B has no outgoing fallthru edge, so it can be moved after A without adding or modifying any jumps (aside from the jump from A to B). */ static int merge_blocks_move_successor_nojumps (a, b) basic_block a, b; { rtx start, end, barrier; start = b->head; end = b->end; barrier = NEXT_INSN (end); /* Recognize a jump table following block B. */ if (GET_CODE (barrier) == CODE_LABEL && NEXT_INSN (barrier) && GET_CODE (NEXT_INSN (barrier)) == JUMP_INSN && (GET_CODE (PATTERN (NEXT_INSN (barrier))) == ADDR_VEC || GET_CODE (PATTERN (NEXT_INSN (barrier))) == ADDR_DIFF_VEC)) { end = NEXT_INSN (barrier); barrier = NEXT_INSN (end); } /* There had better have been a barrier there. Delete it. */ if (GET_CODE (barrier) != BARRIER) abort (); flow_delete_insn (barrier); /* Move block and loop notes out of the chain so that we do not disturb their order. ??? A better solution would be to squeeze out all the non-nested notes and adjust the block trees appropriately. Even better would be to have a tighter connection between block trees and rtl so that this is not necessary. */ start = squeeze_notes (start, end); /* Scramble the insn chain. */ reorder_insns (start, end, a->end); /* Now blocks A and B are contiguous. Merge them. */ merge_blocks_nomove (a, b); if (rtl_dump_file) { fprintf (rtl_dump_file, "Moved block %d after %d and merged.\n", b->index, a->index); } return 1; } /* Attempt to merge basic blocks that are potentially non-adjacent. Return true iff the attempt succeeded. */ static int merge_blocks (e, b, c) edge e; basic_block b, c; { /* If C has a tail recursion label, do not merge. There is no edge recorded from the call_placeholder back to this label, as that would make optimize_sibling_and_tail_recursive_calls more complex for no gain. */ if (GET_CODE (c->head) == CODE_LABEL && tail_recursion_label_p (c->head)) return 0; /* If B has a fallthru edge to C, no need to move anything. */ if (e->flags & EDGE_FALLTHRU) { merge_blocks_nomove (b, c); if (rtl_dump_file) { fprintf (rtl_dump_file, "Merged %d and %d without moving.\n", b->index, c->index); } return 1; } else { edge tmp_edge; basic_block d; int c_has_outgoing_fallthru; int b_has_incoming_fallthru; /* We must make sure to not munge nesting of exception regions, lexical blocks, and loop notes. The first is taken care of by requiring that the active eh region at the end of one block always matches the active eh region at the beginning of the next block. The later two are taken care of by squeezing out all the notes. */ /* ??? A throw/catch edge (or any abnormal edge) should be rarely executed and we may want to treat blocks which have two out edges, one normal, one abnormal as only having one edge for block merging purposes. */ for (tmp_edge = c->succ; tmp_edge; tmp_edge = tmp_edge->succ_next) if (tmp_edge->flags & EDGE_FALLTHRU) break; c_has_outgoing_fallthru = (tmp_edge != NULL); for (tmp_edge = b->pred; tmp_edge; tmp_edge = tmp_edge->pred_next) if (tmp_edge->flags & EDGE_FALLTHRU) break; b_has_incoming_fallthru = (tmp_edge != NULL); /* If B does not have an incoming fallthru, and the exception regions match, then it can be moved immediately before C without introducing or modifying jumps. C can not be the first block, so we do not have to worry about accessing a non-existent block. */ d = BASIC_BLOCK (c->index - 1); if (! b_has_incoming_fallthru && d->eh_end == b->eh_beg && b->eh_end == c->eh_beg) return merge_blocks_move_predecessor_nojumps (b, c); /* Otherwise, we're going to try to move C after B. Make sure the exception regions match. If B is the last basic block, then we must not try to access the block structure for block B + 1. Luckily in that case we do not need to worry about matching exception regions. */ d = (b->index + 1 < n_basic_blocks ? BASIC_BLOCK (b->index + 1) : NULL); if (b->eh_end == c->eh_beg && (d == NULL || c->eh_end == d->eh_beg)) { /* If C does not have an outgoing fallthru, then it can be moved immediately after B without introducing or modifying jumps. */ if (! c_has_outgoing_fallthru) return merge_blocks_move_successor_nojumps (b, c); /* Otherwise, we'll need to insert an extra jump, and possibly a new block to contain it. */ /* ??? Not implemented yet. */ } return 0; } } /* Top level driver for merge_blocks. */ static void try_merge_blocks () { int i; /* Attempt to merge blocks as made possible by edge removal. If a block has only one successor, and the successor has only one predecessor, they may be combined. */ for (i = 0; i < n_basic_blocks;) { basic_block c, b = BASIC_BLOCK (i); edge s; /* A loop because chains of blocks might be combineable. */ while ((s = b->succ) != NULL && s->succ_next == NULL && (s->flags & EDGE_EH) == 0 && (c = s->dest) != EXIT_BLOCK_PTR && c->pred->pred_next == NULL /* If the jump insn has side effects, we can't kill the edge. */ && (GET_CODE (b->end) != JUMP_INSN || onlyjump_p (b->end)) && merge_blocks (s, b, c)) continue; /* Don't get confused by the index shift caused by deleting blocks. */ i = b->index + 1; } } /* The given edge should potentially be a fallthru edge. If that is in fact true, delete the jump and barriers that are in the way. */ void tidy_fallthru_edge (e, b, c) edge e; basic_block b, c; { rtx q; /* ??? In a late-running flow pass, other folks may have deleted basic blocks by nopping out blocks, leaving multiple BARRIERs between here and the target label. They ought to be chastized and fixed. We can also wind up with a sequence of undeletable labels between one block and the next. So search through a sequence of barriers, labels, and notes for the head of block C and assert that we really do fall through. */ if (next_real_insn (b->end) != next_real_insn (PREV_INSN (c->head))) return; /* Remove what will soon cease being the jump insn from the source block. If block B consisted only of this single jump, turn it into a deleted note. */ q = b->end; if (GET_CODE (q) == JUMP_INSN && onlyjump_p (q) && (any_uncondjump_p (q) || (b->succ == e && e->succ_next == NULL))) { #ifdef HAVE_cc0 /* If this was a conditional jump, we need to also delete the insn that set cc0. */ if (any_condjump_p (q) && sets_cc0_p (PREV_INSN (q))) q = PREV_INSN (q); #endif if (b->head == q) { PUT_CODE (q, NOTE); NOTE_LINE_NUMBER (q) = NOTE_INSN_DELETED; NOTE_SOURCE_FILE (q) = 0; } else q = PREV_INSN (q); b->end = q; } /* Selectively unlink the sequence. */ if (q != PREV_INSN (c->head)) flow_delete_insn_chain (NEXT_INSN (q), PREV_INSN (c->head)); e->flags |= EDGE_FALLTHRU; } /* Fix up edges that now fall through, or rather should now fall through but previously required a jump around now deleted blocks. Simplify the search by only examining blocks numerically adjacent, since this is how find_basic_blocks created them. */ static void tidy_fallthru_edges () { int i; for (i = 1; i < n_basic_blocks; ++i) { basic_block b = BASIC_BLOCK (i - 1); basic_block c = BASIC_BLOCK (i); edge s; /* We care about simple conditional or unconditional jumps with a single successor. If we had a conditional branch to the next instruction when find_basic_blocks was called, then there will only be one out edge for the block which ended with the conditional branch (since we do not create duplicate edges). Furthermore, the edge will be marked as a fallthru because we merge the flags for the duplicate edges. So we do not want to check that the edge is not a FALLTHRU edge. */ if ((s = b->succ) != NULL && s->succ_next == NULL && s->dest == c /* If the jump insn has side effects, we can't tidy the edge. */ && (GET_CODE (b->end) != JUMP_INSN || onlyjump_p (b->end))) tidy_fallthru_edge (s, b, c); } } /* 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 struct {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); /* 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); } /* 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); /* For a global update, we go through the relaxation process again. */ if (extent != UPDATE_LIFE_LOCAL) { calculate_global_regs_live (blocks, blocks, prop_flags & PROP_SCAN_DEAD_CODE); /* 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 (basic_block_for_insn) { VARRAY_FREE (basic_block_for_insn); basic_block_for_insn = NULL; } if (! keep_head_end_p) { 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; } } /* Return nonzero if the destination of SET equals the source. */ static int set_noop_p (set) rtx set; { rtx src = SET_SRC (set); rtx dst = SET_DEST (set); if (GET_CODE (src) == SUBREG && GET_CODE (dst) == SUBREG) { if (SUBREG_WORD (src) != SUBREG_WORD (dst)) return 0; src = SUBREG_REG (src); dst = SUBREG_REG (dst); } return (GET_CODE (src) == REG && GET_CODE (dst) == REG && REGNO (src) == REGNO (dst)); } /* Return nonzero if an insn consists only of SETs, each of which only sets a value to itself. */ static int noop_move_p (insn) rtx insn; { rtx pat = PATTERN (insn); /* Insns carrying these notes are useful later on. */ if (find_reg_note (insn, REG_EQUAL, NULL_RTX)) return 0; if (GET_CODE (pat) == SET && set_noop_p (pat)) return 1; if (GET_CODE (pat) == PARALLEL) { int i; /* If nothing but SETs of registers to themselves, this insn can also be deleted. */ for (i = 0; i < XVECLEN (pat, 0); i++) { rtx tem = XVECEXP (pat, 0, i); if (GET_CODE (tem) == USE || GET_CODE (tem) == CLOBBER) continue; if (GET_CODE (tem) != SET || ! set_noop_p (tem)) return 0; } return 1; } return 0; } /* Delete any insns that copy a register to itself. */ static void delete_noop_moves (f) rtx f; { rtx insn; for (insn = f; insn; insn = NEXT_INSN (insn)) { if (GET_CODE (insn) == INSN && noop_move_p (insn)) { PUT_CODE (insn, NOTE); NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED; NOTE_SOURCE_FILE (insn) = 0; } } } /* 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_CODE (XEXP (x, 0)) == PRE_DEC || GET_CODE (XEXP (x, 0)) == PRE_INC || GET_CODE (XEXP (x, 0)) == POST_DEC || GET_CODE (XEXP (x, 0)) == POST_INC) && 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; { 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 } #ifdef PIC_OFFSET_TABLE_REGNUM #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 (fixed_regs[PIC_OFFSET_TABLE_REGNUM]) SET_REGNO_REG_SET (set, PIC_OFFSET_TABLE_REGNUM); #endif #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); /* Mark all call-saved registers that we actaully used. */ if (HAVE_epilogue && reload_completed) { for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) if (regs_ever_live[i] && ! call_used_regs[i] && ! LOCAL_REGNO (i)) SET_REGNO_REG_SET (set, i); } /* 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; regset_head tmp_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); /* 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); while (qhead != qtail) { int rescan, changed; basic_block bb; edge e; bb = *qhead++; if (qhead == qend) qhead = queue; bb->aux = NULL; /* Begin by propogating 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; IOR_REG_SET (new_live_at_end, sb->global_live_at_start); } /* Force the stack pointer to be live -- which might not already be the case for blocks within infinite loops. */ SET_REGNO_REG_SET (new_live_at_end, STACK_POINTER_REGNUM); /* Similarly for the frame pointer before reload. Any reference to any pseudo before reload is a potential reference of the frame pointer. */ if (! reload_completed) SET_REGNO_REG_SET (new_live_at_end, FRAME_POINTER_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); 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. */ static 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); /* 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. */ if (inote) { rtx label = XEXP (inote, 0); rtx next; if (LABEL_NUSES (label) == 1 && (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))--; flow_delete_insn (next); } } if (bb->end == insn) bb->end = PREV_INSN (insn); flow_delete_insn (insn); } /* Delete dead libcalls for propagate_block. Return the insn before the libcall. */ static rtx propagate_block_delete_libcall (bb, insn, note) basic_block bb; rtx insn, note; { rtx first = XEXP (note, 0); rtx before = PREV_INSN (first); if (insn == bb->end) bb->end = before; flow_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)); } /* We almost certainly don't want to delete prologue or epilogue instructions. Warn about probable compiler losage. */ if (insn_is_dead && reload_completed && (((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) { if (flags & PROP_KILL_DEAD_CODE) { warning ("ICE: would have deleted prologue/epilogue insn"); if (!inhibit_warnings) debug_rtx (insn); } libcall_is_dead = insn_is_dead = 0; } /* If an instruction consists of just dead store(s) on final pass, delete it. */ if ((flags & PROP_KILL_DEAD_CODE) && insn_is_dead) { /* 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 (pbi->bb, insn, note); insn = NEXT_INSN (prev); } 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_CALL_P (insn)) free_EXPR_LIST_list (&pbi->mem_set_list); /* 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 (call_used_regs[i] && ! global_regs[i] && ! fixed_regs[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->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 ((flags & (PROP_DEATH_NOTES | PROP_SCAN_DEAD_CODE)) && 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 = alloc_EXPR_LIST (0, cond, NULL_RTX); 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))) { rtx insn; for (insn = bb->end; insn != bb->head; insn = PREV_INSN (insn)) if (GET_CODE (insn) == INSN && GET_CODE (PATTERN (insn)) == SET && GET_CODE (SET_DEST (PATTERN (insn))) == MEM) { rtx mem = SET_DEST (PATTERN (insn)); if (XEXP (mem, 0) == frame_pointer_rtx || (GET_CODE (XEXP (mem, 0)) == PLUS && XEXP (XEXP (mem, 0), 0) == frame_pointer_rtx && GET_CODE (XEXP (XEXP (mem, 0), 1)) == CONST_INT)) { #ifdef AUTO_INC_DEC /* Store a copy of mem, otherwise the address may be scrogged by find_auto_inc. This matters because insn_dead_p uses an rtx_equal_p check to determine if two addresses are the same. This works before find_auto_inc, but fails after find_auto_inc, causing discrepencies between the set of live registers calculated during the calculate_global_regs_live phase and what actually exists after flow completes, leading to aborts. */ if (flags & PROP_AUTOINC) mem = shallow_copy_rtx (mem); #endif pbi->mem_set_list = alloc_EXPR_LIST (0, mem, pbi->mem_set_list); } } } 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. */ void 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; 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. */ 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) == NOTE && NOTE_LINE_NUMBER (insn) == NOTE_INSN_SETJMP) IOR_REG_SET (regs_live_at_setjmp, pbi->reg_live); prev = propagate_one_insn (pbi, insn); if (insn == bb->head) break; } free_propagate_block_info (pbi); } /* 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; if (MEM_VOLATILE_P (r)) return 0; /* 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). */ temp = pbi->mem_set_list; while (temp) { rtx mem = XEXP (temp, 0); if (rtx_equal_p (mem, r)) 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 temp = XEXP (temp, 1); } } 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; /* 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 #ifdef PIC_OFFSET_TABLE_REGNUM /* Before reload, do not allow sets of the pic register to be deleted. Reload can insert references to constant pool memory anywhere in the function, making the PIC register live where it wasn't before. */ if (regno == PIC_OFFSET_TABLE_REGNUM && fixed_regs[regno] && ! reload_completed) 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)); } /* 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) { rtx temp = pbi->mem_set_list; rtx prev = NULL_RTX; rtx next; while (temp) { next = XEXP (temp, 1); if (reg_overlap_mentioned_p (XEXP (note, 0), XEXP (temp, 0))) { /* Splice temp out of list. */ if (prev) XEXP (prev, 1) = next; else pbi->mem_set_list = next; free_EXPR_LIST_node (temp); } else prev = temp; temp = next; } } } } /* EXP is either a MEM or 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 ((GET_CODE (exp) == MEM && output_dependence (XEXP (temp, 0), exp)) || (GET_CODE (exp) == REG && 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); } 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 rtx, X. */ 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; int not_dead = 0; int i; /* 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. */ if (GET_CODE (reg) == PARALLEL && GET_MODE (reg) == BLKmode) { for (i = XVECLEN (reg, 0) - 1; i >= 0; i--) mark_set_1 (pbi, code, XVECEXP (reg, 0, i), cond, insn, flags); return; } /* 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 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 = 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) { #ifdef ALTER_HARD_SUBREG regno_first = ALTER_HARD_SUBREG (outer_mode, SUBREG_WORD (reg), inner_mode, regno_first); #else regno_first += SUBREG_WORD (reg); #endif 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 = 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) == MEM || 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 /* We do not know the size of a BLKmode store, so we do not track them for redundant store elimination. */ && GET_MODE (reg) != BLKmode /* 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)) { #ifdef AUTO_INC_DEC /* Store a copy of mem, otherwise the address may be scrogged by find_auto_inc. */ if (flags & PROP_AUTOINC) reg = shallow_copy_rtx (reg); #endif pbi->mem_set_list = alloc_EXPR_LIST (0, reg, pbi->mem_set_list); } } 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 = 1; } #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) += (optimize_size ? 1 : pbi->bb->loop_depth + 1); /* 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 && ! 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) 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 = alloc_EXPR_LIST (0, cond, NULL_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); /* If the register is now unconditionally dead, remove the entry in the splay_tree. */ if (ncond == 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_EXPR_LIST_list (&rcli->condition); 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]; rtx c, *prev; /* 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; c = *(prev = &rcli->condition); while (c) { if (regno == REGNO (XEXP (XEXP (c, 0), 0))) { rtx next = XEXP (c, 1); free_EXPR_LIST_node (c); c = *prev = next; } else c = *(prev = &XEXP (c, 1)); } /* If the entire condition is now NULL, signal the node to be removed. */ if (! rcli->condition) { xdata[1] = node->key; return -1; } else 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 NAND. We actually use EXPR_LIST to chain the sub-expressions together instead of IOR because it's easier to manipulate and we have the lists.c functions to reuse nodes. Return a new rtl expression as appropriate. */ static rtx ior_reg_cond (old, x) rtx old, x; { enum rtx_code x_code; rtx x_reg; rtx c; /* We expect these conditions to be of the form (eq reg 0). */ x_code = GET_CODE (x); if (GET_RTX_CLASS (x_code) != '<' || GET_CODE (x_reg = XEXP (x, 0)) != REG || XEXP (x, 1) != const0_rtx) abort (); /* Search the expression for an existing sub-expression of X_REG. */ for (c = old; c; c = XEXP (c, 1)) { rtx y = XEXP (c, 0); if (REGNO (XEXP (y, 0)) == REGNO (x_reg)) { /* If we find X already present in OLD, we need do nothing. */ if (GET_CODE (y) == x_code) return old; /* If we find X being a compliment of a condition in OLD, then the entire condition is true. */ if (GET_CODE (y) == reverse_condition (x_code)) return const1_rtx; } } /* Otherwise just add to the chain. */ return alloc_EXPR_LIST (0, x, old); } static rtx not_reg_cond (x) rtx x; { enum rtx_code x_code; rtx x_reg; /* We expect these conditions to be of the form (eq reg 0). */ x_code = GET_CODE (x); if (GET_RTX_CLASS (x_code) != '<' || GET_CODE (x_reg = XEXP (x, 0)) != REG || XEXP (x, 1) != const0_rtx) abort (); return alloc_EXPR_LIST (0, gen_rtx_fmt_ee (reverse_condition (x_code), VOIDmode, x_reg, const0_rtx), NULL_RTX); } static rtx nand_reg_cond (old, x) rtx old, x; { enum rtx_code x_code; rtx x_reg; rtx c, *prev; /* We expect these conditions to be of the form (eq reg 0). */ x_code = GET_CODE (x); if (GET_RTX_CLASS (x_code) != '<' || GET_CODE (x_reg = XEXP (x, 0)) != REG || XEXP (x, 1) != const0_rtx) abort (); /* Search the expression for an existing sub-expression of X_REG. */ for (c = *(prev = &old); c; c = *(prev = &XEXP (c, 1))) { rtx y = XEXP (c, 0); if (REGNO (XEXP (y, 0)) == REGNO (x_reg)) { /* If we find X already present in OLD, then we need to splice it out. */ if (GET_CODE (y) == x_code) { *prev = XEXP (c, 1); free_EXPR_LIST_node (c); return old ? old : const0_rtx; } /* If we find X being a compliment of a condition in OLD, then we need do nothing. */ if (GET_CODE (y) == reverse_condition (x_code)) return old; } } /* Otherwise, by implication, the register in question is now live for the inverse of the condition X. */ return alloc_EXPR_LIST (0, gen_rtx_fmt_ee (reverse_condition (x_code), VOIDmode, x_reg, const0_rtx), old); } #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 (basic_block_for_insn) for (temp = insns; temp; temp = NEXT_INSN (temp)) set_block_for_insn (temp, pbi->bb); /* 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)++; } 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_N_REFS (regno) += (optimize_size ? 1 : pbi->bb->loop_depth + 1); /* 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; { int regno = REGNO (reg); int some_was_live = REGNO_REG_SET_P (pbi->reg_live, regno); int some_was_dead = ! some_was_live; int some_not_set; int n; /* A hard reg in a wide mode may really be multiple registers. If so, mark all of them just like the first. */ if (regno < FIRST_PSEUDO_REGISTER) { n = HARD_REGNO_NREGS (regno, GET_MODE (reg)); while (--n > 0) { int needed_regno = REGNO_REG_SET_P (pbi->reg_live, regno + n); some_was_live |= needed_regno; some_was_dead |= ! needed_regno; } } 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] = insn; } if (pbi->flags & PROP_REG_INFO) { if (regno < 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) && (regno == FRAME_POINTER_REGNUM || regno == ARG_POINTER_REGNUM))) { int n = HARD_REGNO_NREGS (regno, GET_MODE (reg)); do regs_ever_live[regno + --n] = 1; while (n > 0); } } else { /* Keep track of which basic block each reg appears in. */ register int blocknum = pbi->bb->index; if (REG_BASIC_BLOCK (regno) == REG_BLOCK_UNKNOWN) REG_BASIC_BLOCK (regno) = blocknum; else if (REG_BASIC_BLOCK (regno) != blocknum) REG_BASIC_BLOCK (regno) = REG_BLOCK_GLOBAL; /* Count (weighted) number of uses of each reg. */ REG_N_REFS (regno) += (optimize_size ? 1 : pbi->bb->loop_depth + 1); } } /* Find out if any of the register was set this insn. */ some_not_set = ! REGNO_REG_SET_P (pbi->new_set, regno); if (regno < FIRST_PSEUDO_REGISTER) { n = HARD_REGNO_NREGS (regno, GET_MODE (reg)); while (--n > 0) some_not_set |= ! REGNO_REG_SET_P (pbi->new_set, regno + n); } /* 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_PSEUDO_REGISTER && HARD_REGNO_NREGS (regno, GET_MODE (reg)) > 1) { n = HARD_REGNO_NREGS (regno, GET_MODE (reg)); while (--n >= 0) some_was_live |= REGNO_REG_SET_P (pbi->new_set, regno + n); } /* 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)) REG_NOTES (insn) = alloc_EXPR_LIST (REG_DEAD, reg, REG_NOTES (insn)); if (pbi->flags & PROP_REG_INFO) REG_N_DEATHS (regno)++; } else { /* Don't make a REG_DEAD note for a part of a register that is set in the insn. */ n = regno + HARD_REGNO_NREGS (regno, GET_MODE (reg)) - 1; for (; n >= regno; n--) if (! REGNO_REG_SET_P (pbi->reg_live, n) && ! dead_or_set_regno_p (insn, n)) REG_NOTES (insn) = alloc_EXPR_LIST (REG_DEAD, gen_rtx_REG (reg_raw_mode[n], n), REG_NOTES (insn)); } } SET_REGNO_REG_SET (pbi->reg_live, regno); if (regno < FIRST_PSEUDO_REGISTER) { n = HARD_REGNO_NREGS (regno, GET_MODE (reg)); while (--n > 0) SET_REGNO_REG_SET (pbi->reg_live, regno + n); } #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, regno); 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 = nand_reg_cond (ncond, cond); /* If the register is now unconditionally live, remove the entry in the splay_tree. */ if (ncond == const0_rtx) { rcli->condition = NULL_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))); } } } 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); splay_tree_insert (pbi->reg_cond_dead, regno, (splay_tree_value) rcli); SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0))); } } else if (some_was_live) { splay_tree_node node; struct reg_cond_life_info *rcli; node = splay_tree_lookup (pbi->reg_cond_dead, regno); if (node != NULL) { /* The register was conditionally live previously, but is now unconditionally so. Remove it from the conditionally dead list, so that a conditional set won't cause us to think it dead. */ rcli = (struct reg_cond_life_info *) node->value; rcli->condition = NULL_RTX; splay_tree_remove (pbi->reg_cond_dead, regno); } } #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); } 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, 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); /* 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 *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_N_REFS (regno) += (optimize_size ? 1 : pbi->bb->loop_depth + 1); 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 *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]); }); } void debug_regset (r) regset r; { dump_regset (r, stderr); putc ('\n', stderr); } void dump_flow_info (file) FILE *file; { register int i; static const char * const reg_class_names[] = REG_CLASS_NAMES; fprintf (file, "%d registers.\n", max_regno); for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++) if (REG_N_REFS (i)) { enum reg_class class, altclass; fprintf (file, "\nRegister %d used %d times across %d insns", i, REG_N_REFS (i), REG_LIVE_LENGTH (i)); if (REG_BASIC_BLOCK (i) >= 0) fprintf (file, " in block %d", REG_BASIC_BLOCK (i)); if (REG_N_SETS (i)) fprintf (file, "; set %d time%s", REG_N_SETS (i), (REG_N_SETS (i) == 1) ? "" : "s"); if (REG_USERVAR_P (regno_reg_rtx[i])) fprintf (file, "; user var"); if (REG_N_DEATHS (i) != 1) fprintf (file, "; dies in %d places", REG_N_DEATHS (i)); if (REG_N_CALLS_CROSSED (i) == 1) fprintf (file, "; crosses 1 call"); else if (REG_N_CALLS_CROSSED (i)) fprintf (file, "; crosses %d calls", REG_N_CALLS_CROSSED (i)); if (PSEUDO_REGNO_BYTES (i) != UNITS_PER_WORD) fprintf (file, "; %d bytes", PSEUDO_REGNO_BYTES (i)); class = reg_preferred_class (i); altclass = reg_alternate_class (i); if (class != GENERAL_REGS || altclass != ALL_REGS) { if (altclass == ALL_REGS || class == ALL_REGS) fprintf (file, "; pref %s", reg_class_names[(int) class]); else if (altclass == NO_REGS) fprintf (file, "; %s or none", reg_class_names[(int) class]); else fprintf (file, "; pref %s, else %s", reg_class_names[(int) class], reg_class_names[(int) altclass]); } if (REG_POINTER (regno_reg_rtx[i])) fprintf (file, "; pointer"); fprintf (file, ".\n"); } fprintf (file, "\n%d basic blocks, %d edges.\n", n_basic_blocks, n_edges); for (i = 0; i < n_basic_blocks; i++) { register basic_block bb = BASIC_BLOCK (i); register edge e; fprintf (file, "\nBasic block %d: first insn %d, last %d, loop_depth %d, count %d.\n", i, INSN_UID (bb->head), INSN_UID (bb->end), bb->loop_depth, bb->count); fprintf (file, "Predecessors: "); for (e = bb->pred; e; e = e->pred_next) dump_edge_info (file, e, 0); fprintf (file, "\nSuccessors: "); for (e = bb->succ; e; e = e->succ_next) dump_edge_info (file, e, 1); fprintf (file, "\nRegisters live at start:"); dump_regset (bb->global_live_at_start, file); fprintf (file, "\nRegisters live at end:"); dump_regset (bb->global_live_at_end, file); putc ('\n', file); } putc ('\n', file); } void debug_flow_info () { dump_flow_info (stderr); } static void dump_edge_info (file, e, do_succ) FILE *file; edge e; int do_succ; { basic_block side = (do_succ ? e->dest : e->src); if (side == ENTRY_BLOCK_PTR) fputs (" ENTRY", file); else if (side == EXIT_BLOCK_PTR) fputs (" EXIT", file); else fprintf (file, " %d", side->index); if (e->count) fprintf (file, " count:%d", e->count); if (e->flags) { static const char * const bitnames[] = { "fallthru", "crit", "ab", "abcall", "eh", "fake" }; int comma = 0; int i, flags = e->flags; fputc (' ', file); fputc ('(', file); for (i = 0; flags; i++) if (flags & (1 << i)) { flags &= ~(1 << i); if (comma) fputc (',', file); if (i < (int) ARRAY_SIZE (bitnames)) fputs (bitnames[i], file); else fprintf (file, "%d", i); comma = 1; } fputc (')', file); } } /* Print out one basic block with live information at start and end. */ void dump_bb (bb, outf) basic_block bb; FILE *outf; { rtx insn; rtx last; edge e; fprintf (outf, ";; Basic block %d, loop depth %d, count %d", bb->index, bb->loop_depth, bb->count); if (bb->eh_beg != -1 || bb->eh_end != -1) fprintf (outf, ", eh regions %d/%d", bb->eh_beg, bb->eh_end); putc ('\n', outf); fputs (";; Predecessors: ", outf); for (e = bb->pred; e; e = e->pred_next) dump_edge_info (outf, e, 0); putc ('\n', outf); fputs (";; Registers live at start:", outf); dump_regset (bb->global_live_at_start, outf); putc ('\n', outf); for (insn = bb->head, last = NEXT_INSN (bb->end); insn != last; insn = NEXT_INSN (insn)) print_rtl_single (outf, insn); fputs (";; Registers live at end:", outf); dump_regset (bb->global_live_at_end, outf); putc ('\n', outf); fputs (";; Successors: ", outf); for (e = bb->succ; e; e = e->succ_next) dump_edge_info (outf, e, 1); putc ('\n', outf); } void debug_bb (bb) basic_block bb; { dump_bb (bb, stderr); } void debug_bb_n (n) int n; { dump_bb (BASIC_BLOCK (n), stderr); } /* Like print_rtl, but also print out live information for the start of each basic block. */ void print_rtl_with_bb (outf, rtx_first) FILE *outf; rtx rtx_first; { register rtx tmp_rtx; if (rtx_first == 0) fprintf (outf, "(nil)\n"); else { int i; enum bb_state { NOT_IN_BB, IN_ONE_BB, IN_MULTIPLE_BB }; int max_uid = get_max_uid (); basic_block *start = (basic_block *) xcalloc (max_uid, sizeof (basic_block)); basic_block *end = (basic_block *) xcalloc (max_uid, sizeof (basic_block)); enum bb_state *in_bb_p = (enum bb_state *) xcalloc (max_uid, sizeof (enum bb_state)); for (i = n_basic_blocks - 1; i >= 0; i--) { basic_block bb = BASIC_BLOCK (i); rtx x; start[INSN_UID (bb->head)] = bb; end[INSN_UID (bb->end)] = bb; for (x = bb->head; x != NULL_RTX; x = NEXT_INSN (x)) { enum bb_state state = IN_MULTIPLE_BB; if (in_bb_p[INSN_UID (x)] == NOT_IN_BB) state = IN_ONE_BB; in_bb_p[INSN_UID (x)] = state; if (x == bb->end) break; } } for (tmp_rtx = rtx_first; NULL != tmp_rtx; tmp_rtx = NEXT_INSN (tmp_rtx)) { int did_output; basic_block bb; if ((bb = start[INSN_UID (tmp_rtx)]) != NULL) { fprintf (outf, ";; Start of basic block %d, registers live:", bb->index); dump_regset (bb->global_live_at_start, outf); putc ('\n', outf); } if (in_bb_p[INSN_UID (tmp_rtx)] == NOT_IN_BB && GET_CODE (tmp_rtx) != NOTE && GET_CODE (tmp_rtx) != BARRIER) fprintf (outf, ";; Insn is not within a basic block\n"); else if (in_bb_p[INSN_UID (tmp_rtx)] == IN_MULTIPLE_BB) fprintf (outf, ";; Insn is in multiple basic blocks\n"); did_output = print_rtl_single (outf, tmp_rtx); if ((bb = end[INSN_UID (tmp_rtx)]) != NULL) { fprintf (outf, ";; End of basic block %d, registers live:\n", bb->index); dump_regset (bb->global_live_at_end, outf); putc ('\n', outf); } if (did_output) putc ('\n', outf); } free (start); free (end); free (in_bb_p); } if (current_function_epilogue_delay_list != 0) { fprintf (outf, "\n;; Insns in epilogue delay list:\n\n"); for (tmp_rtx = current_function_epilogue_delay_list; tmp_rtx != 0; tmp_rtx = XEXP (tmp_rtx, 1)) print_rtl_single (outf, XEXP (tmp_rtx, 0)); } } /* Dump the rtl into the current debugging dump file, then abort. */ static void print_rtl_and_abort () { if (rtl_dump_file) { print_rtl_with_bb (rtl_dump_file, get_insns ()); fclose (rtl_dump_file); } abort (); } /* 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; } /* Update insns block within BB. */ void update_bb_for_insn (bb) basic_block bb; { rtx insn; if (! basic_block_for_insn) return; for (insn = bb->head; ; insn = NEXT_INSN (insn)) { set_block_for_insn (insn, bb); if (insn == bb->end) break; } } /* Record INSN's block as BB. */ void set_block_for_insn (insn, bb) rtx insn; basic_block bb; { size_t uid = INSN_UID (insn); if (uid >= basic_block_for_insn->num_elements) { int new_size; /* Add one-eighth the size so we don't keep calling xrealloc. */ new_size = uid + (uid + 7) / 8; VARRAY_GROW (basic_block_for_insn, new_size); } VARRAY_BB (basic_block_for_insn, uid) = bb; } /* Record INSN's block number as BB. */ /* ??? This has got to go. */ void set_block_num (insn, bb) rtx insn; int bb; { set_block_for_insn (insn, BASIC_BLOCK (bb)); } /* Verify the CFG consistency. This function check some CFG invariants and aborts when something is wrong. Hope that this function will help to convert many optimization passes to preserve CFG consistent. Currently it does following checks: - test head/end pointers - overlapping of basic blocks - edge list corectness - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note) - tails of basic blocks (ensure that boundary is necesary) - scans body of the basic block for JUMP_INSN, CODE_LABEL and NOTE_INSN_BASIC_BLOCK - check that all insns are in the basic blocks (except the switch handling code, barriers and notes) - check that all returns are followed by barriers In future it can be extended check a lot of other stuff as well (reachability of basic blocks, life information, etc. etc.). */ void verify_flow_info () { const int max_uid = get_max_uid (); const rtx rtx_first = get_insns (); rtx last_head = get_last_insn (); basic_block *bb_info; rtx x; int i, last_bb_num_seen, num_bb_notes, err = 0; bb_info = (basic_block *) xcalloc (max_uid, sizeof (basic_block)); for (i = n_basic_blocks - 1; i >= 0; i--) { basic_block bb = BASIC_BLOCK (i); rtx head = bb->head; rtx end = bb->end; /* Verify the end of the basic block is in the INSN chain. */ for (x = last_head; x != NULL_RTX; x = PREV_INSN (x)) if (x == end) break; if (!x) { error ("End insn %d for block %d not found in the insn stream.", INSN_UID (end), bb->index); err = 1; } /* Work backwards from the end to the head of the basic block to verify the head is in the RTL chain. */ for (; x != NULL_RTX; x = PREV_INSN (x)) { /* While walking over the insn chain, verify insns appear in only one basic block and initialize the BB_INFO array used by other passes. */ if (bb_info[INSN_UID (x)] != NULL) { error ("Insn %d is in multiple basic blocks (%d and %d)", INSN_UID (x), bb->index, bb_info[INSN_UID (x)]->index); err = 1; } bb_info[INSN_UID (x)] = bb; if (x == head) break; } if (!x) { error ("Head insn %d for block %d not found in the insn stream.", INSN_UID (head), bb->index); err = 1; } last_head = x; } /* Now check the basic blocks (boundaries etc.) */ for (i = n_basic_blocks - 1; i >= 0; i--) { basic_block bb = BASIC_BLOCK (i); /* Check corectness of edge lists */ edge e; e = bb->succ; while (e) { if (e->src != bb) { fprintf (stderr, "verify_flow_info: Basic block %d succ edge is corrupted\n", bb->index); fprintf (stderr, "Predecessor: "); dump_edge_info (stderr, e, 0); fprintf (stderr, "\nSuccessor: "); dump_edge_info (stderr, e, 1); fflush (stderr); err = 1; } if (e->dest != EXIT_BLOCK_PTR) { edge e2 = e->dest->pred; while (e2 && e2 != e) e2 = e2->pred_next; if (!e2) { error ("Basic block %i edge lists are corrupted", bb->index); err = 1; } } e = e->succ_next; } e = bb->pred; while (e) { if (e->dest != bb) { error ("Basic block %d pred edge is corrupted", bb->index); fputs ("Predecessor: ", stderr); dump_edge_info (stderr, e, 0); fputs ("\nSuccessor: ", stderr); dump_edge_info (stderr, e, 1); fputc ('\n', stderr); err = 1; } if (e->src != ENTRY_BLOCK_PTR) { edge e2 = e->src->succ; while (e2 && e2 != e) e2 = e2->succ_next; if (!e2) { error ("Basic block %i edge lists are corrupted", bb->index); err = 1; } } e = e->pred_next; } /* OK pointers are correct. Now check the header of basic block. It ought to contain optional CODE_LABEL followed by NOTE_BASIC_BLOCK. */ x = bb->head; if (GET_CODE (x) == CODE_LABEL) { if (bb->end == x) { error ("NOTE_INSN_BASIC_BLOCK is missing for block %d", bb->index); err = 1; } x = NEXT_INSN (x); } if (!NOTE_INSN_BASIC_BLOCK_P (x) || NOTE_BASIC_BLOCK (x) != bb) { error ("NOTE_INSN_BASIC_BLOCK is missing for block %d\n", bb->index); err = 1; } if (bb->end == x) { /* Do checks for empty blocks here */ } else { x = NEXT_INSN (x); while (x) { if (NOTE_INSN_BASIC_BLOCK_P (x)) { error ("NOTE_INSN_BASIC_BLOCK %d in the middle of basic block %d", INSN_UID (x), bb->index); err = 1; } if (x == bb->end) break; if (GET_CODE (x) == JUMP_INSN || GET_CODE (x) == CODE_LABEL || GET_CODE (x) == BARRIER) { error ("In basic block %d:", bb->index); fatal_insn ("Flow control insn inside a basic block", x); } x = NEXT_INSN (x); } } } last_bb_num_seen = -1; num_bb_notes = 0; x = rtx_first; while (x) { if (NOTE_INSN_BASIC_BLOCK_P (x)) { basic_block bb = NOTE_BASIC_BLOCK (x); num_bb_notes++; if (bb->index != last_bb_num_seen + 1) fatal ("Basic blocks not numbered consecutively"); last_bb_num_seen = bb->index; } if (!bb_info[INSN_UID (x)]) { switch (GET_CODE (x)) { case BARRIER: case NOTE: break; case CODE_LABEL: /* An addr_vec is placed outside any block block. */ if (NEXT_INSN (x) && GET_CODE (NEXT_INSN (x)) == JUMP_INSN && (GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_DIFF_VEC || GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_VEC)) { x = NEXT_INSN (x); } /* But in any case, non-deletable labels can appear anywhere. */ break; default: fatal_insn ("Insn outside basic block", x); } } if (INSN_P (x) && GET_CODE (x) == JUMP_INSN && returnjump_p (x) && ! condjump_p (x) && ! (NEXT_INSN (x) && GET_CODE (NEXT_INSN (x)) == BARRIER)) fatal_insn ("Return not followed by barrier", x); x = NEXT_INSN (x); } if (num_bb_notes != n_basic_blocks) fatal ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)", num_bb_notes, n_basic_blocks); if (err) abort (); /* Clean up. */ free (bb_info); } /* Functions to access an edge list with a vector representation. Enough data is kept such that given an index number, the pred and succ that edge represents can be determined, or given a pred and a succ, its index number can be returned. This allows algorithms which consume a lot of memory to represent the normally full matrix of edge (pred,succ) with a single indexed vector, edge (EDGE_INDEX (pred, succ)), with no wasted space in the client code due to sparse flow graphs. */ /* This functions initializes the edge list. Basically the entire flowgraph is processed, and all edges are assigned a number, and the data structure is filled in. */ struct edge_list * create_edge_list () { struct edge_list *elist; edge e; int num_edges; int x; int block_count; block_count = n_basic_blocks + 2; /* Include the entry and exit blocks. */ num_edges = 0; /* Determine the number of edges in the flow graph by counting successor edges on each basic block. */ for (x = 0; x < n_basic_blocks; x++) { basic_block bb = BASIC_BLOCK (x); for (e = bb->succ; e; e = e->succ_next) num_edges++; } /* Don't forget successors of the entry block. */ for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next) num_edges++; elist = (struct edge_list *) xmalloc (sizeof (struct edge_list)); elist->num_blocks = block_count; elist->num_edges = num_edges; elist->index_to_edge = (edge *) xmalloc (sizeof (edge) * num_edges); num_edges = 0; /* Follow successors of the entry block, and register these edges. */ for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next) { elist->index_to_edge[num_edges] = e; num_edges++; } for (x = 0; x < n_basic_blocks; x++) { basic_block bb = BASIC_BLOCK (x); /* Follow all successors of blocks, and register these edges. */ for (e = bb->succ; e; e = e->succ_next) { elist->index_to_edge[num_edges] = e; num_edges++; } } return elist; } /* This function free's memory associated with an edge list. */ void free_edge_list (elist) struct edge_list *elist; { if (elist) { free (elist->index_to_edge); free (elist); } } /* This function provides debug output showing an edge list. */ void print_edge_list (f, elist) FILE *f; struct edge_list *elist; { int x; fprintf (f, "Compressed edge list, %d BBs + entry & exit, and %d edges\n", elist->num_blocks - 2, elist->num_edges); for (x = 0; x < elist->num_edges; x++) { fprintf (f, " %-4d - edge(", x); if (INDEX_EDGE_PRED_BB (elist, x) == ENTRY_BLOCK_PTR) fprintf (f, "entry,"); else fprintf (f, "%d,", INDEX_EDGE_PRED_BB (elist, x)->index); if (INDEX_EDGE_SUCC_BB (elist, x) == EXIT_BLOCK_PTR) fprintf (f, "exit)\n"); else fprintf (f, "%d)\n", INDEX_EDGE_SUCC_BB (elist, x)->index); } } /* This function provides an internal consistency check of an edge list, verifying that all edges are present, and that there are no extra edges. */ void verify_edge_list (f, elist) FILE *f; struct edge_list *elist; { int x, pred, succ, index; edge e; for (x = 0; x < n_basic_blocks; x++) { basic_block bb = BASIC_BLOCK (x); for (e = bb->succ; e; e = e->succ_next) { pred = e->src->index; succ = e->dest->index; index = EDGE_INDEX (elist, e->src, e->dest); if (index == EDGE_INDEX_NO_EDGE) { fprintf (f, "*p* No index for edge from %d to %d\n", pred, succ); continue; } if (INDEX_EDGE_PRED_BB (elist, index)->index != pred) fprintf (f, "*p* Pred for index %d should be %d not %d\n", index, pred, INDEX_EDGE_PRED_BB (elist, index)->index); if (INDEX_EDGE_SUCC_BB (elist, index)->index != succ) fprintf (f, "*p* Succ for index %d should be %d not %d\n", index, succ, INDEX_EDGE_SUCC_BB (elist, index)->index); } } for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next) { pred = e->src->index; succ = e->dest->index; index = EDGE_INDEX (elist, e->src, e->dest); if (index == EDGE_INDEX_NO_EDGE) { fprintf (f, "*p* No index for edge from %d to %d\n", pred, succ); continue; } if (INDEX_EDGE_PRED_BB (elist, index)->index != pred) fprintf (f, "*p* Pred for index %d should be %d not %d\n", index, pred, INDEX_EDGE_PRED_BB (elist, index)->index); if (INDEX_EDGE_SUCC_BB (elist, index)->index != succ) fprintf (f, "*p* Succ for index %d should be %d not %d\n", index, succ, INDEX_EDGE_SUCC_BB (elist, index)->index); } /* We've verified that all the edges are in the list, no lets make sure there are no spurious edges in the list. */ for (pred = 0; pred < n_basic_blocks; pred++) for (succ = 0; succ < n_basic_blocks; succ++) { basic_block p = BASIC_BLOCK (pred); basic_block s = BASIC_BLOCK (succ); int found_edge = 0; for (e = p->succ; e; e = e->succ_next) if (e->dest == s) { found_edge = 1; break; } for (e = s->pred; e; e = e->pred_next) if (e->src == p) { found_edge = 1; break; } if (EDGE_INDEX (elist, BASIC_BLOCK (pred), BASIC_BLOCK (succ)) == EDGE_INDEX_NO_EDGE && found_edge != 0) fprintf (f, "*** Edge (%d, %d) appears to not have an index\n", pred, succ); if (EDGE_INDEX (elist, BASIC_BLOCK (pred), BASIC_BLOCK (succ)) != EDGE_INDEX_NO_EDGE && found_edge == 0) fprintf (f, "*** Edge (%d, %d) has index %d, but there is no edge\n", pred, succ, EDGE_INDEX (elist, BASIC_BLOCK (pred), BASIC_BLOCK (succ))); } for (succ = 0; succ < n_basic_blocks; succ++) { basic_block p = ENTRY_BLOCK_PTR; basic_block s = BASIC_BLOCK (succ); int found_edge = 0; for (e = p->succ; e; e = e->succ_next) if (e->dest == s) { found_edge = 1; break; } for (e = s->pred; e; e = e->pred_next) if (e->src == p) { found_edge = 1; break; } if (EDGE_INDEX (elist, ENTRY_BLOCK_PTR, BASIC_BLOCK (succ)) == EDGE_INDEX_NO_EDGE && found_edge != 0) fprintf (f, "*** Edge (entry, %d) appears to not have an index\n", succ); if (EDGE_INDEX (elist, ENTRY_BLOCK_PTR, BASIC_BLOCK (succ)) != EDGE_INDEX_NO_EDGE && found_edge == 0) fprintf (f, "*** Edge (entry, %d) has index %d, but no edge exists\n", succ, EDGE_INDEX (elist, ENTRY_BLOCK_PTR, BASIC_BLOCK (succ))); } for (pred = 0; pred < n_basic_blocks; pred++) { basic_block p = BASIC_BLOCK (pred); basic_block s = EXIT_BLOCK_PTR; int found_edge = 0; for (e = p->succ; e; e = e->succ_next) if (e->dest == s) { found_edge = 1; break; } for (e = s->pred; e; e = e->pred_next) if (e->src == p) { found_edge = 1; break; } if (EDGE_INDEX (elist, BASIC_BLOCK (pred), EXIT_BLOCK_PTR) == EDGE_INDEX_NO_EDGE && found_edge != 0) fprintf (f, "*** Edge (%d, exit) appears to not have an index\n", pred); if (EDGE_INDEX (elist, BASIC_BLOCK (pred), EXIT_BLOCK_PTR) != EDGE_INDEX_NO_EDGE && found_edge == 0) fprintf (f, "*** Edge (%d, exit) has index %d, but no edge exists\n", pred, EDGE_INDEX (elist, BASIC_BLOCK (pred), EXIT_BLOCK_PTR)); } } /* This routine will determine what, if any, edge there is between a specified predecessor and successor. */ int find_edge_index (edge_list, pred, succ) struct edge_list *edge_list; basic_block pred, succ; { int x; for (x = 0; x < NUM_EDGES (edge_list); x++) { if (INDEX_EDGE_PRED_BB (edge_list, x) == pred && INDEX_EDGE_SUCC_BB (edge_list, x) == succ) return x; } return (EDGE_INDEX_NO_EDGE); } /* This function will remove an edge from the flow graph. */ void remove_edge (e) edge e; { edge last_pred = NULL; edge last_succ = NULL; edge tmp; basic_block src, dest; src = e->src; dest = e->dest; for (tmp = src->succ; tmp && tmp != e; tmp = tmp->succ_next) last_succ = tmp; if (!tmp) abort (); if (last_succ) last_succ->succ_next = e->succ_next; else src->succ = e->succ_next; for (tmp = dest->pred; tmp && tmp != e; tmp = tmp->pred_next) last_pred = tmp; if (!tmp) abort (); if (last_pred) last_pred->pred_next = e->pred_next; else dest->pred = e->pred_next; n_edges--; free (e); } /* This routine will remove any fake successor edges for a basic block. When the edge is removed, it is also removed from whatever predecessor list it is in. */ static void remove_fake_successors (bb) basic_block bb; { edge e; for (e = bb->succ; e;) { edge tmp = e; e = e->succ_next; if ((tmp->flags & EDGE_FAKE) == EDGE_FAKE) remove_edge (tmp); } } /* This routine will remove all fake edges from the flow graph. If we remove all fake successors, it will automatically remove all fake predecessors. */ void remove_fake_edges () { int x; for (x = 0; x < n_basic_blocks; x++) remove_fake_successors (BASIC_BLOCK (x)); /* We've handled all successors except the entry block's. */ remove_fake_successors (ENTRY_BLOCK_PTR); } /* This function will add a fake edge between any block which has no successors, and the exit block. Some data flow equations require these edges to exist. */ void add_noreturn_fake_exit_edges () { int x; for (x = 0; x < n_basic_blocks; x++) if (BASIC_BLOCK (x)->succ == NULL) make_edge (NULL, BASIC_BLOCK (x), EXIT_BLOCK_PTR, EDGE_FAKE); } /* This function adds a fake edge between any infinite loops to the exit block. Some optimizations require a path from each node to the exit node. See also Morgan, Figure 3.10, pp. 82-83. The current implementation is ugly, not attempting to minimize the number of inserted fake edges. To reduce the number of fake edges to insert, add fake edges from _innermost_ loops containing only nodes not reachable from the exit block. */ void connect_infinite_loops_to_exit () { basic_block unvisited_block; /* Perform depth-first search in the reverse graph to find nodes reachable from the exit block. */ struct depth_first_search_dsS dfs_ds; flow_dfs_compute_reverse_init (&dfs_ds); flow_dfs_compute_reverse_add_bb (&dfs_ds, EXIT_BLOCK_PTR); /* Repeatedly add fake edges, updating the unreachable nodes. */ while (1) { unvisited_block = flow_dfs_compute_reverse_execute (&dfs_ds); if (!unvisited_block) break; make_edge (NULL, unvisited_block, EXIT_BLOCK_PTR, EDGE_FAKE); flow_dfs_compute_reverse_add_bb (&dfs_ds, unvisited_block); } flow_dfs_compute_reverse_finish (&dfs_ds); return; } /* Redirect an edge's successor from one block to another. */ void redirect_edge_succ (e, new_succ) edge e; basic_block new_succ; { edge *pe; /* Disconnect the edge from the old successor block. */ for (pe = &e->dest->pred; *pe != e; pe = &(*pe)->pred_next) continue; *pe = (*pe)->pred_next; /* Reconnect the edge to the new successor block. */ e->pred_next = new_succ->pred; new_succ->pred = e; e->dest = new_succ; } /* Redirect an edge's predecessor from one block to another. */ void redirect_edge_pred (e, new_pred) edge e; basic_block new_pred; { edge *pe; /* Disconnect the edge from the old predecessor block. */ for (pe = &e->src->succ; *pe != e; pe = &(*pe)->succ_next) continue; *pe = (*pe)->succ_next; /* Reconnect the edge to the new predecessor block. */ e->succ_next = new_pred->succ; new_pred->succ = e; e->src = new_pred; } /* Dump the list of basic blocks in the bitmap NODES. */ static void flow_nodes_print (str, nodes, file) const char *str; const sbitmap nodes; FILE *file; { int node; if (! nodes) return; fprintf (file, "%s { ", str); EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, {fprintf (file, "%d ", node);}); fputs ("}\n", file); } /* Dump the list of edges in the array EDGE_LIST. */ static void flow_edge_list_print (str, edge_list, num_edges, file) const char *str; const edge *edge_list; int num_edges; FILE *file; { int i; if (! edge_list) return; fprintf (file, "%s { ", str); for (i = 0; i < num_edges; i++) fprintf (file, "%d->%d ", edge_list[i]->src->index, edge_list[i]->dest->index); fputs ("}\n", file); } /* Dump loop related CFG information. */ static void flow_loops_cfg_dump (loops, file) const struct loops *loops; FILE *file; { int i; if (! loops->num || ! file || ! loops->cfg.dom) return; for (i = 0; i < n_basic_blocks; i++) { edge succ; fprintf (file, ";; %d succs { ", i); for (succ = BASIC_BLOCK (i)->succ; succ; succ = succ->succ_next) fprintf (file, "%d ", succ->dest->index); flow_nodes_print ("} dom", loops->cfg.dom[i], file); } /* Dump the DFS node order. */ if (loops->cfg.dfs_order) { fputs (";; DFS order: ", file); for (i = 0; i < n_basic_blocks; i++) fprintf (file, "%d ", loops->cfg.dfs_order[i]); fputs ("\n", file); } /* Dump the reverse completion node order. */ if (loops->cfg.rc_order) { fputs (";; RC order: ", file); for (i = 0; i < n_basic_blocks; i++) fprintf (file, "%d ", loops->cfg.rc_order[i]); fputs ("\n", file); } } /* Return non-zero if the nodes of LOOP are a subset of OUTER. */ static int flow_loop_nested_p (outer, loop) struct loop *outer; struct loop *loop; { return sbitmap_a_subset_b_p (loop->nodes, outer->nodes); } /* Dump the loop information specified by LOOP to the stream FILE using auxiliary dump callback function LOOP_DUMP_AUX if non null. */ void flow_loop_dump (loop, file, loop_dump_aux, verbose) const struct loop *loop; FILE *file; void (*loop_dump_aux) PARAMS((const struct loop *, FILE *, int)); int verbose; { if (! loop || ! loop->header) return; fprintf (file, ";;\n;; Loop %d (%d to %d):%s%s\n", loop->num, INSN_UID (loop->first->head), INSN_UID (loop->last->end), loop->shared ? " shared" : "", loop->invalid ? " invalid" : ""); fprintf (file, ";; header %d, latch %d, pre-header %d, first %d, last %d\n", loop->header->index, loop->latch->index, loop->pre_header ? loop->pre_header->index : -1, loop->first->index, loop->last->index); fprintf (file, ";; depth %d, level %d, outer %ld\n", loop->depth, loop->level, (long) (loop->outer ? loop->outer->num : -1)); if (loop->pre_header_edges) flow_edge_list_print (";; pre-header edges", loop->pre_header_edges, loop->num_pre_header_edges, file); flow_edge_list_print (";; entry edges", loop->entry_edges, loop->num_entries, file); fprintf (file, ";; %d", loop->num_nodes); flow_nodes_print (" nodes", loop->nodes, file); flow_edge_list_print (";; exit edges", loop->exit_edges, loop->num_exits, file); if (loop->exits_doms) flow_nodes_print (";; exit doms", loop->exits_doms, file); if (loop_dump_aux) loop_dump_aux (loop, file, verbose); } /* Dump the loop information specified by LOOPS to the stream FILE, using auxiliary dump callback function LOOP_DUMP_AUX if non null. */ void flow_loops_dump (loops, file, loop_dump_aux, verbose) const struct loops *loops; FILE *file; void (*loop_dump_aux) PARAMS((const struct loop *, FILE *, int)); int verbose; { int i; int num_loops; num_loops = loops->num; if (! num_loops || ! file) return; fprintf (file, ";; %d loops found, %d levels\n", num_loops, loops->levels); for (i = 0; i < num_loops; i++) { struct loop *loop = &loops->array[i]; flow_loop_dump (loop, file, loop_dump_aux, verbose); if (loop->shared) { int j; for (j = 0; j < i; j++) { struct loop *oloop = &loops->array[j]; if (loop->header == oloop->header) { int disjoint; int smaller; smaller = loop->num_nodes < oloop->num_nodes; /* If the union of LOOP and OLOOP is different than the larger of LOOP and OLOOP then LOOP and OLOOP must be disjoint. */ disjoint = ! flow_loop_nested_p (smaller ? loop : oloop, smaller ? oloop : loop); fprintf (file, ";; loop header %d shared by loops %d, %d %s\n", loop->header->index, i, j, disjoint ? "disjoint" : "nested"); } } } } if (verbose) flow_loops_cfg_dump (loops, file); } /* Free all the memory allocated for LOOPS. */ void flow_loops_free (loops) struct loops *loops; { if (loops->array) { int i; if (! loops->num) abort (); /* Free the loop descriptors. */ for (i = 0; i < loops->num; i++) { struct loop *loop = &loops->array[i]; if (loop->pre_header_edges) free (loop->pre_header_edges); if (loop->nodes) sbitmap_free (loop->nodes); if (loop->entry_edges) free (loop->entry_edges); if (loop->exit_edges) free (loop->exit_edges); if (loop->exits_doms) sbitmap_free (loop->exits_doms); } free (loops->array); loops->array = NULL; if (loops->cfg.dom) sbitmap_vector_free (loops->cfg.dom); if (loops->cfg.dfs_order) free (loops->cfg.dfs_order); if (loops->shared_headers) sbitmap_free (loops->shared_headers); } } /* Find the entry edges into the loop with header HEADER and nodes NODES and store in ENTRY_EDGES array. Return the number of entry edges from the loop. */ static int flow_loop_entry_edges_find (header, nodes, entry_edges) basic_block header; const sbitmap nodes; edge **entry_edges; { edge e; int num_entries; *entry_edges = NULL; num_entries = 0; for (e = header->pred; e; e = e->pred_next) { basic_block src = e->src; if (src == ENTRY_BLOCK_PTR || ! TEST_BIT (nodes, src->index)) num_entries++; } if (! num_entries) abort (); *entry_edges = (edge *) xmalloc (num_entries * sizeof (edge *)); num_entries = 0; for (e = header->pred; e; e = e->pred_next) { basic_block src = e->src; if (src == ENTRY_BLOCK_PTR || ! TEST_BIT (nodes, src->index)) (*entry_edges)[num_entries++] = e; } return num_entries; } /* Find the exit edges from the loop using the bitmap of loop nodes NODES and store in EXIT_EDGES array. Return the number of exit edges from the loop. */ static int flow_loop_exit_edges_find (nodes, exit_edges) const sbitmap nodes; edge **exit_edges; { edge e; int node; int num_exits; *exit_edges = NULL; /* Check all nodes within the loop to see if there are any successors not in the loop. Note that a node may have multiple exiting edges ????? A node can have one jumping edge and one fallthru edge so only one of these can exit the loop. */ num_exits = 0; EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, { for (e = BASIC_BLOCK (node)->succ; e; e = e->succ_next) { basic_block dest = e->dest; if (dest == EXIT_BLOCK_PTR || ! TEST_BIT (nodes, dest->index)) num_exits++; } }); if (! num_exits) return 0; *exit_edges = (edge *) xmalloc (num_exits * sizeof (edge *)); /* Store all exiting edges into an array. */ num_exits = 0; EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, { for (e = BASIC_BLOCK (node)->succ; e; e = e->succ_next) { basic_block dest = e->dest; if (dest == EXIT_BLOCK_PTR || ! TEST_BIT (nodes, dest->index)) (*exit_edges)[num_exits++] = e; } }); return num_exits; } /* Find the nodes contained within the loop with header HEADER and latch LATCH and store in NODES. Return the number of nodes within the loop. */ static int flow_loop_nodes_find (header, latch, nodes) basic_block header; basic_block latch; sbitmap nodes; { basic_block *stack; int sp; int num_nodes = 0; stack = (basic_block *) xmalloc (n_basic_blocks * sizeof (basic_block)); sp = 0; /* Start with only the loop header in the set of loop nodes. */ sbitmap_zero (nodes); SET_BIT (nodes, header->index); num_nodes++; header->loop_depth++; /* Push the loop latch on to the stack. */ if (! TEST_BIT (nodes, latch->index)) { SET_BIT (nodes, latch->index); latch->loop_depth++; num_nodes++; stack[sp++] = latch; } while (sp) { basic_block node; edge e; node = stack[--sp]; for (e = node->pred; e; e = e->pred_next) { basic_block ancestor = e->src; /* If each ancestor not marked as part of loop, add to set of loop nodes and push on to stack. */ if (ancestor != ENTRY_BLOCK_PTR && ! TEST_BIT (nodes, ancestor->index)) { SET_BIT (nodes, ancestor->index); ancestor->loop_depth++; num_nodes++; stack[sp++] = ancestor; } } } free (stack); return num_nodes; } /* Compute the depth first search order and store in the array DFS_ORDER if non-zero, marking the nodes visited in VISITED. If RC_ORDER is non-zero, return the reverse completion number for each node. Returns the number of nodes visited. A depth first search tries to get as far away from the starting point as quickly as possible. */ static int flow_depth_first_order_compute (dfs_order, rc_order) int *dfs_order; int *rc_order; { edge *stack; int sp; int dfsnum = 0; int rcnum = n_basic_blocks - 1; sbitmap visited; /* Allocate stack for back-tracking up CFG. */ stack = (edge *) xmalloc ((n_basic_blocks + 1) * sizeof (edge)); sp = 0; /* Allocate bitmap to track nodes that have been visited. */ visited = sbitmap_alloc (n_basic_blocks); /* None of the nodes in the CFG have been visited yet. */ sbitmap_zero (visited); /* Push the first edge on to the stack. */ stack[sp++] = ENTRY_BLOCK_PTR->succ; while (sp) { edge e; basic_block src; basic_block dest; /* Look at the edge on the top of the stack. */ e = stack[sp - 1]; src = e->src; dest = e->dest; /* Check if the edge destination has been visited yet. */ if (dest != EXIT_BLOCK_PTR && ! TEST_BIT (visited, dest->index)) { /* Mark that we have visited the destination. */ SET_BIT (visited, dest->index); if (dfs_order) dfs_order[dfsnum++] = dest->index; if (dest->succ) { /* Since the DEST node has been visited for the first time, check its successors. */ stack[sp++] = dest->succ; } else { /* There are no successors for the DEST node so assign its reverse completion number. */ if (rc_order) rc_order[rcnum--] = dest->index; } } else { if (! e->succ_next && src != ENTRY_BLOCK_PTR) { /* There are no more successors for the SRC node so assign its reverse completion number. */ if (rc_order) rc_order[rcnum--] = src->index; } if (e->succ_next) stack[sp - 1] = e->succ_next; else sp--; } } free (stack); sbitmap_free (visited); /* The number of nodes visited should not be greater than n_basic_blocks. */ if (dfsnum > n_basic_blocks) abort (); /* There are some nodes left in the CFG that are unreachable. */ if (dfsnum < n_basic_blocks) abort (); return dfsnum; } /* Compute the depth first search order on the _reverse_ graph and store in the array DFS_ORDER, marking the nodes visited in VISITED. Returns the number of nodes visited. The computation is split into three pieces: flow_dfs_compute_reverse_init () creates the necessary data structures. flow_dfs_compute_reverse_add_bb () adds a basic block to the data structures. The block will start the search. flow_dfs_compute_reverse_execute () continues (or starts) the search using the block on the top of the stack, stopping when the stack is empty. flow_dfs_compute_reverse_finish () destroys the necessary data structures. Thus, the user will probably call ..._init(), call ..._add_bb() to add a beginning basic block to the stack, call ..._execute(), possibly add another bb to the stack and again call ..._execute(), ..., and finally call _finish(). */ /* Initialize the data structures used for depth-first search on the reverse graph. If INITIALIZE_STACK is nonzero, the exit block is added to the basic block stack. DATA is the current depth-first search context. If INITIALIZE_STACK is non-zero, there is an element on the stack. */ static void flow_dfs_compute_reverse_init (data) depth_first_search_ds data; { /* Allocate stack for back-tracking up CFG. */ data->stack = (basic_block *) xmalloc ((n_basic_blocks - (INVALID_BLOCK + 1)) * sizeof (basic_block)); data->sp = 0; /* Allocate bitmap to track nodes that have been visited. */ data->visited_blocks = sbitmap_alloc (n_basic_blocks - (INVALID_BLOCK + 1)); /* None of the nodes in the CFG have been visited yet. */ sbitmap_zero (data->visited_blocks); return; } /* Add the specified basic block to the top of the dfs data structures. When the search continues, it will start at the block. */ static void flow_dfs_compute_reverse_add_bb (data, bb) depth_first_search_ds data; basic_block bb; { data->stack[data->sp++] = bb; return; } /* Continue the depth-first search through the reverse graph starting with the block at the stack's top and ending when the stack is empty. Visited nodes are marked. Returns an unvisited basic block, or NULL if there is none available. */ static basic_block flow_dfs_compute_reverse_execute (data) depth_first_search_ds data; { basic_block bb; edge e; int i; while (data->sp > 0) { bb = data->stack[--data->sp]; /* Mark that we have visited this node. */ if (!TEST_BIT (data->visited_blocks, bb->index - (INVALID_BLOCK + 1))) { SET_BIT (data->visited_blocks, bb->index - (INVALID_BLOCK + 1)); /* Perform depth-first search on adjacent vertices. */ for (e = bb->pred; e; e = e->pred_next) flow_dfs_compute_reverse_add_bb (data, e->src); } } /* Determine if there are unvisited basic blocks. */ for (i = n_basic_blocks - (INVALID_BLOCK + 1); --i >= 0;) if (!TEST_BIT (data->visited_blocks, i)) return BASIC_BLOCK (i + (INVALID_BLOCK + 1)); return NULL; } /* Destroy the data structures needed for depth-first search on the reverse graph. */ static void flow_dfs_compute_reverse_finish (data) depth_first_search_ds data; { free (data->stack); sbitmap_free (data->visited_blocks); return; } /* Find the root node of the loop pre-header extended basic block and the edges along the trace from the root node to the loop header. */ static void flow_loop_pre_header_scan (loop) struct loop *loop; { int num = 0; basic_block ebb; loop->num_pre_header_edges = 0; if (loop->num_entries != 1) return; ebb = loop->entry_edges[0]->src; if (ebb != ENTRY_BLOCK_PTR) { edge e; /* Count number of edges along trace from loop header to root of pre-header extended basic block. Usually this is only one or two edges. */ num++; while (ebb->pred->src != ENTRY_BLOCK_PTR && ! ebb->pred->pred_next) { ebb = ebb->pred->src; num++; } loop->pre_header_edges = (edge *) xmalloc (num * sizeof (edge *)); loop->num_pre_header_edges = num; /* Store edges in order that they are followed. The source of the first edge is the root node of the pre-header extended basic block and the destination of the last last edge is the loop header. */ for (e = loop->entry_edges[0]; num; e = e->src->pred) { loop->pre_header_edges[--num] = e; } } } /* Return the block for the pre-header of the loop with header HEADER where DOM specifies the dominator information. Return NULL if there is no pre-header. */ static basic_block flow_loop_pre_header_find (header, dom) basic_block header; const sbitmap *dom; { basic_block pre_header; edge e; /* If block p is a predecessor of the header and is the only block that the header does not dominate, then it is the pre-header. */ pre_header = NULL; for (e = header->pred; e; e = e->pred_next) { basic_block node = e->src; if (node != ENTRY_BLOCK_PTR && ! TEST_BIT (dom[node->index], header->index)) { if (pre_header == NULL) pre_header = node; else { /* There are multiple edges into the header from outside the loop so there is no pre-header block. */ pre_header = NULL; break; } } } return pre_header; } /* Add LOOP to the loop hierarchy tree where PREVLOOP was the loop previously added. The insertion algorithm assumes that the loops are added in the order found by a depth first search of the CFG. */ static void flow_loop_tree_node_add (prevloop, loop) struct loop *prevloop; struct loop *loop; { if (flow_loop_nested_p (prevloop, loop)) { prevloop->inner = loop; loop->outer = prevloop; return; } while (prevloop->outer) { if (flow_loop_nested_p (prevloop->outer, loop)) { prevloop->next = loop; loop->outer = prevloop->outer; return; } prevloop = prevloop->outer; } prevloop->next = loop; loop->outer = NULL; } /* Build the loop hierarchy tree for LOOPS. */ static void flow_loops_tree_build (loops) struct loops *loops; { int i; int num_loops; num_loops = loops->num; if (! num_loops) return; /* Root the loop hierarchy tree with the first loop found. Since we used a depth first search this should be the outermost loop. */ loops->tree = &loops->array[0]; loops->tree->outer = loops->tree->inner = loops->tree->next = NULL; /* Add the remaining loops to the tree. */ for (i = 1; i < num_loops; i++) flow_loop_tree_node_add (&loops->array[i - 1], &loops->array[i]); } /* Helper function to compute loop nesting depth and enclosed loop level for the natural loop specified by LOOP at the loop depth DEPTH. Returns the loop level. */ static int flow_loop_level_compute (loop, depth) struct loop *loop; int depth; { struct loop *inner; int level = 1; if (! loop) return 0; /* Traverse loop tree assigning depth and computing level as the maximum level of all the inner loops of this loop. The loop level is equivalent to the height of the loop in the loop tree and corresponds to the number of enclosed loop levels (including itself). */ for (inner = loop->inner; inner; inner = inner->next) { int ilevel; ilevel = flow_loop_level_compute (inner, depth + 1) + 1; if (ilevel > level) level = ilevel; } loop->level = level; loop->depth = depth; return level; } /* Compute the loop nesting depth and enclosed loop level for the loop hierarchy tree specfied by LOOPS. Return the maximum enclosed loop level. */ static int flow_loops_level_compute (loops) struct loops *loops; { struct loop *loop; int level; int levels = 0; /* Traverse all the outer level loops. */ for (loop = loops->tree; loop; loop = loop->next) { level = flow_loop_level_compute (loop, 1); if (level > levels) levels = level; } return levels; } /* Find all the natural loops in the function and save in LOOPS structure and recalculate loop_depth information in basic block structures. FLAGS controls which loop information is collected. Return the number of natural loops found. */ int flow_loops_find (loops, flags) struct loops *loops; int flags; { int i; int b; int num_loops; edge e; sbitmap headers; sbitmap *dom; int *dfs_order; int *rc_order; /* This function cannot be repeatedly called with different flags to build up the loop information. The loop tree must always be built if this function is called. */ if (! (flags & LOOP_TREE)) abort (); memset (loops, 0, sizeof (*loops)); /* Taking care of this degenerate case makes the rest of this code simpler. */ if (n_basic_blocks == 0) return 0; dfs_order = NULL; rc_order = NULL; /* Compute the dominators. */ dom = sbitmap_vector_alloc (n_basic_blocks, n_basic_blocks); calculate_dominance_info (NULL, dom, CDI_DOMINATORS); /* Count the number of loop edges (back edges). This should be the same as the number of natural loops. */ num_loops = 0; for (b = 0; b < n_basic_blocks; b++) { basic_block header; header = BASIC_BLOCK (b); header->loop_depth = 0; for (e = header->pred; e; e = e->pred_next) { basic_block latch = e->src; /* Look for back edges where a predecessor is dominated by this block. A natural loop has a single entry node (header) that dominates all the nodes in the loop. It also has single back edge to the header from a latch node. Note that multiple natural loops may share the same header. */ if (b != header->index) abort (); if (latch != ENTRY_BLOCK_PTR && TEST_BIT (dom[latch->index], b)) num_loops++; } } if (num_loops) { /* Compute depth first search order of the CFG so that outer natural loops will be found before inner natural loops. */ dfs_order = (int *) xmalloc (n_basic_blocks * sizeof (int)); rc_order = (int *) xmalloc (n_basic_blocks * sizeof (int)); flow_depth_first_order_compute (dfs_order, rc_order); /* Allocate loop structures. */ loops->array = (struct loop *) xcalloc (num_loops, sizeof (struct loop)); headers = sbitmap_alloc (n_basic_blocks); sbitmap_zero (headers); loops->shared_headers = sbitmap_alloc (n_basic_blocks); sbitmap_zero (loops->shared_headers); /* Find and record information about all the natural loops in the CFG. */ num_loops = 0; for (b = 0; b < n_basic_blocks; b++) { basic_block header; /* Search the nodes of the CFG in reverse completion order so that we can find outer loops first. */ header = BASIC_BLOCK (rc_order[b]); /* Look for all the possible latch blocks for this header. */ for (e = header->pred; e; e = e->pred_next) { basic_block latch = e->src; /* Look for back edges where a predecessor is dominated by this block. A natural loop has a single entry node (header) that dominates all the nodes in the loop. It also has single back edge to the header from a latch node. Note that multiple natural loops may share the same header. */ if (latch != ENTRY_BLOCK_PTR && TEST_BIT (dom[latch->index], header->index)) { struct loop *loop; loop = loops->array + num_loops; loop->header = header; loop->latch = latch; loop->num = num_loops; num_loops++; } } } for (i = 0; i < num_loops; i++) { struct loop *loop = &loops->array[i]; int j; /* Keep track of blocks that are loop headers so that we can tell which loops should be merged. */ if (TEST_BIT (headers, loop->header->index)) SET_BIT (loops->shared_headers, loop->header->index); SET_BIT (headers, loop->header->index); /* Find nodes contained within the loop. */ loop->nodes = sbitmap_alloc (n_basic_blocks); loop->num_nodes = flow_loop_nodes_find (loop->header, loop->latch, loop->nodes); /* Compute first and last blocks within the loop. These are often the same as the loop header and loop latch respectively, but this is not always the case. */ loop->first = BASIC_BLOCK (sbitmap_first_set_bit (loop->nodes)); loop->last = BASIC_BLOCK (sbitmap_last_set_bit (loop->nodes)); if (flags & LOOP_EDGES) { /* Find edges which enter the loop header. Note that the entry edges should only enter the header of a natural loop. */ loop->num_entries = flow_loop_entry_edges_find (loop->header, loop->nodes, &loop->entry_edges); /* Find edges which exit the loop. */ loop->num_exits = flow_loop_exit_edges_find (loop->nodes, &loop->exit_edges); /* Determine which loop nodes dominate all the exits of the loop. */ loop->exits_doms = sbitmap_alloc (n_basic_blocks); sbitmap_copy (loop->exits_doms, loop->nodes); for (j = 0; j < loop->num_exits; j++) sbitmap_a_and_b (loop->exits_doms, loop->exits_doms, dom[loop->exit_edges[j]->src->index]); /* The header of a natural loop must dominate all exits. */ if (! TEST_BIT (loop->exits_doms, loop->header->index)) abort (); } if (flags & LOOP_PRE_HEADER) { /* Look to see if the loop has a pre-header node. */ loop->pre_header = flow_loop_pre_header_find (loop->header, dom); flow_loop_pre_header_scan (loop); } } /* Natural loops with shared headers may either be disjoint or nested. Disjoint loops with shared headers cannot be inner loops and should be merged. For now just mark loops that share headers. */ for (i = 0; i < num_loops; i++) if (TEST_BIT (loops->shared_headers, loops->array[i].header->index)) loops->array[i].shared = 1; sbitmap_free (headers); } loops->num = num_loops; /* Save CFG derived information to avoid recomputing it. */ loops->cfg.dom = dom; loops->cfg.dfs_order = dfs_order; loops->cfg.rc_order = rc_order; /* Build the loop hierarchy tree. */ flow_loops_tree_build (loops); /* Assign the loop nesting depth and enclosed loop level for each loop. */ loops->levels = flow_loops_level_compute (loops); return num_loops; } /* Update the information regarding the loops in the CFG specified by LOOPS. */ int flow_loops_update (loops, flags) struct loops *loops; int flags; { /* One day we may want to update the current loop data. For now throw away the old stuff and rebuild what we need. */ if (loops->array) flow_loops_free (loops); return flow_loops_find (loops, flags); } /* Return non-zero if edge E enters header of LOOP from outside of LOOP. */ int flow_loop_outside_edge_p (loop, e) const struct loop *loop; edge e; { if (e->dest != loop->header) abort (); return (e->src == ENTRY_BLOCK_PTR) || ! TEST_BIT (loop->nodes, e->src->index); } /* 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); }); } /* Called once at intialization time. */ void init_flow () { static int initialized; if (!initialized) { gcc_obstack_init (&flow_obstack); flow_firstobj = (char *) obstack_alloc (&flow_obstack, 0); initialized = 1; } else { obstack_free (&flow_obstack, flow_firstobj); flow_firstobj = (char *) obstack_alloc (&flow_obstack, 0); } }