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Diffstat (limited to 'gcc-4.2.1-5666.3/gcc/cfgcleanup.c')
| -rw-r--r-- | gcc-4.2.1-5666.3/gcc/cfgcleanup.c | 2347 |
1 files changed, 0 insertions, 2347 deletions
diff --git a/gcc-4.2.1-5666.3/gcc/cfgcleanup.c b/gcc-4.2.1-5666.3/gcc/cfgcleanup.c deleted file mode 100644 index 0e13f7a07..000000000 --- a/gcc-4.2.1-5666.3/gcc/cfgcleanup.c +++ /dev/null @@ -1,2347 +0,0 @@ -/* Control flow optimization code for GNU compiler. - Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998, - 1999, 2000, 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc. - -This file is part of GCC. - -GCC is free software; you can redistribute it and/or modify it under -the terms of the GNU General Public License as published by the Free -Software Foundation; either version 2, or (at your option) any later -version. - -GCC is distributed in the hope that it will be useful, but WITHOUT ANY -WARRANTY; without even the implied warranty of MERCHANTABILITY or -FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -for more details. - -You should have received a copy of the GNU General Public License -along with GCC; see the file COPYING. If not, write to the Free -Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA -02110-1301, USA. */ - -/* This file contains optimizer of the control flow. The main entry point is - cleanup_cfg. Following optimizations are performed: - - - Unreachable blocks removal - - Edge forwarding (edge to the forwarder block is forwarded to its - successor. Simplification of the branch instruction is performed by - underlying infrastructure so branch can be converted to simplejump or - eliminated). - - Cross jumping (tail merging) - - Conditional jump-around-simplejump simplification - - Basic block merging. */ - -#include "config.h" -#include "system.h" -#include "coretypes.h" -#include "tm.h" -#include "rtl.h" -#include "hard-reg-set.h" -#include "regs.h" -#include "timevar.h" -#include "output.h" -#include "insn-config.h" -#include "flags.h" -#include "recog.h" -#include "toplev.h" -#include "cselib.h" -#include "params.h" -#include "tm_p.h" -#include "target.h" -#include "cfglayout.h" -#include "emit-rtl.h" -#include "tree-pass.h" -#include "cfgloop.h" -#include "expr.h" - -#define FORWARDER_BLOCK_P(BB) ((BB)->flags & BB_FORWARDER_BLOCK) - -/* Set to true when we are running first pass of try_optimize_cfg loop. */ -static bool first_pass; -static bool try_crossjump_to_edge (int, edge, edge); -static bool try_crossjump_bb (int, basic_block); -static bool outgoing_edges_match (int, basic_block, basic_block); -static int flow_find_cross_jump (int, basic_block, basic_block, rtx *, rtx *); -static bool old_insns_match_p (int, rtx, rtx); - -static void merge_blocks_move_predecessor_nojumps (basic_block, basic_block); -static void merge_blocks_move_successor_nojumps (basic_block, basic_block); -static bool try_optimize_cfg (int); -static bool try_simplify_condjump (basic_block); -static bool try_forward_edges (int, basic_block); -static edge thread_jump (int, edge, basic_block); -static bool mark_effect (rtx, bitmap); -static void notice_new_block (basic_block); -static void update_forwarder_flag (basic_block); -static int mentions_nonequal_regs (rtx *, void *); -static void merge_memattrs (rtx, rtx); - -/* Set flags for newly created block. */ - -static void -notice_new_block (basic_block bb) -{ - if (!bb) - return; - - if (forwarder_block_p (bb)) - bb->flags |= BB_FORWARDER_BLOCK; -} - -/* Recompute forwarder flag after block has been modified. */ - -static void -update_forwarder_flag (basic_block bb) -{ - if (forwarder_block_p (bb)) - bb->flags |= BB_FORWARDER_BLOCK; - else - bb->flags &= ~BB_FORWARDER_BLOCK; -} - -/* Simplify a conditional jump around an unconditional jump. - Return true if something changed. */ - -static bool -try_simplify_condjump (basic_block cbranch_block) -{ - basic_block jump_block, jump_dest_block, cbranch_dest_block; - edge cbranch_jump_edge, cbranch_fallthru_edge; - rtx cbranch_insn; - - /* Verify that there are exactly two successors. */ - if (EDGE_COUNT (cbranch_block->succs) != 2) - return false; - - /* Verify that we've got a normal conditional branch at the end - of the block. */ - cbranch_insn = BB_END (cbranch_block); - if (!any_condjump_p (cbranch_insn)) - return false; - - cbranch_fallthru_edge = FALLTHRU_EDGE (cbranch_block); - cbranch_jump_edge = BRANCH_EDGE (cbranch_block); - - /* The next block must not have multiple predecessors, must not - be the last block in the function, and must contain just the - unconditional jump. */ - jump_block = cbranch_fallthru_edge->dest; - if (!single_pred_p (jump_block) - || jump_block->next_bb == EXIT_BLOCK_PTR - || !FORWARDER_BLOCK_P (jump_block)) - return false; - jump_dest_block = single_succ (jump_block); - - /* If we are partitioning hot/cold basic blocks, we don't want to - mess up unconditional or indirect jumps that cross between hot - and cold sections. - - Basic block partitioning may result in some jumps that appear to - be optimizable (or blocks that appear to be mergeable), but which really - must be left untouched (they are required to make it safely across - partition boundaries). See the comments at the top of - bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */ - - if (BB_PARTITION (jump_block) != BB_PARTITION (jump_dest_block) - || (cbranch_jump_edge->flags & EDGE_CROSSING)) - return false; - - /* The conditional branch must target the block after the - unconditional branch. */ - cbranch_dest_block = cbranch_jump_edge->dest; - - if (cbranch_dest_block == EXIT_BLOCK_PTR - || !can_fallthru (jump_block, cbranch_dest_block)) - return false; - - /* Invert the conditional branch. */ - if (!invert_jump (cbranch_insn, block_label (jump_dest_block), 0)) - return false; - - if (dump_file) - fprintf (dump_file, "Simplifying condjump %i around jump %i\n", - INSN_UID (cbranch_insn), INSN_UID (BB_END (jump_block))); - - /* Success. Update the CFG to match. Note that after this point - the edge variable names appear backwards; the redirection is done - this way to preserve edge profile data. */ - cbranch_jump_edge = redirect_edge_succ_nodup (cbranch_jump_edge, - cbranch_dest_block); - cbranch_fallthru_edge = redirect_edge_succ_nodup (cbranch_fallthru_edge, - jump_dest_block); - cbranch_jump_edge->flags |= EDGE_FALLTHRU; - cbranch_fallthru_edge->flags &= ~EDGE_FALLTHRU; - update_br_prob_note (cbranch_block); - - /* Delete the block with the unconditional jump, and clean up the mess. */ - delete_basic_block (jump_block); - tidy_fallthru_edge (cbranch_jump_edge); - update_forwarder_flag (cbranch_block); - - return true; -} - -/* Attempt to prove that operation is NOOP using CSElib or mark the effect - on register. Used by jump threading. */ - -static bool -mark_effect (rtx exp, regset nonequal) -{ - int regno; - rtx dest; - switch (GET_CODE (exp)) - { - /* In case we do clobber the register, mark it as equal, as we know the - value is dead so it don't have to match. */ - case CLOBBER: - if (REG_P (XEXP (exp, 0))) - { - dest = XEXP (exp, 0); - regno = REGNO (dest); - CLEAR_REGNO_REG_SET (nonequal, regno); - if (regno < FIRST_PSEUDO_REGISTER) - { - int n = hard_regno_nregs[regno][GET_MODE (dest)]; - while (--n > 0) - CLEAR_REGNO_REG_SET (nonequal, regno + n); - } - } - return false; - - case SET: - if (rtx_equal_for_cselib_p (SET_DEST (exp), SET_SRC (exp))) - return false; - dest = SET_DEST (exp); - if (dest == pc_rtx) - return false; - if (!REG_P (dest)) - return true; - regno = REGNO (dest); - SET_REGNO_REG_SET (nonequal, regno); - if (regno < FIRST_PSEUDO_REGISTER) - { - int n = hard_regno_nregs[regno][GET_MODE (dest)]; - while (--n > 0) - SET_REGNO_REG_SET (nonequal, regno + n); - } - return false; - - default: - return false; - } -} - -/* Return nonzero if X is a register set in regset DATA. - Called via for_each_rtx. */ -static int -mentions_nonequal_regs (rtx *x, void *data) -{ - regset nonequal = (regset) data; - if (REG_P (*x)) - { - int regno; - - regno = REGNO (*x); - if (REGNO_REG_SET_P (nonequal, regno)) - return 1; - if (regno < FIRST_PSEUDO_REGISTER) - { - int n = hard_regno_nregs[regno][GET_MODE (*x)]; - while (--n > 0) - if (REGNO_REG_SET_P (nonequal, regno + n)) - return 1; - } - } - return 0; -} -/* Attempt to prove that the basic block B will have no side effects and - always continues in the same edge if reached via E. Return the edge - if exist, NULL otherwise. */ - -static edge -thread_jump (int mode, edge e, basic_block b) -{ - rtx set1, set2, cond1, cond2, insn; - enum rtx_code code1, code2, reversed_code2; - bool reverse1 = false; - unsigned i; - regset nonequal; - bool failed = false; - reg_set_iterator rsi; - - if (b->flags & BB_NONTHREADABLE_BLOCK) - return NULL; - - /* At the moment, we do handle only conditional jumps, but later we may - want to extend this code to tablejumps and others. */ - if (EDGE_COUNT (e->src->succs) != 2) - return NULL; - if (EDGE_COUNT (b->succs) != 2) - { - b->flags |= BB_NONTHREADABLE_BLOCK; - return NULL; - } - - /* Second branch must end with onlyjump, as we will eliminate the jump. */ - if (!any_condjump_p (BB_END (e->src))) - return NULL; - - if (!any_condjump_p (BB_END (b)) || !onlyjump_p (BB_END (b))) - { - b->flags |= BB_NONTHREADABLE_BLOCK; - return NULL; - } - - set1 = pc_set (BB_END (e->src)); - set2 = pc_set (BB_END (b)); - if (((e->flags & EDGE_FALLTHRU) != 0) - != (XEXP (SET_SRC (set1), 1) == pc_rtx)) - reverse1 = true; - - cond1 = XEXP (SET_SRC (set1), 0); - cond2 = XEXP (SET_SRC (set2), 0); - if (reverse1) - code1 = reversed_comparison_code (cond1, BB_END (e->src)); - else - code1 = GET_CODE (cond1); - - code2 = GET_CODE (cond2); - reversed_code2 = reversed_comparison_code (cond2, BB_END (b)); - - if (!comparison_dominates_p (code1, code2) - && !comparison_dominates_p (code1, reversed_code2)) - return NULL; - - /* Ensure that the comparison operators are equivalent. - ??? This is far too pessimistic. We should allow swapped operands, - different CCmodes, or for example comparisons for interval, that - dominate even when operands are not equivalent. */ - if (!rtx_equal_p (XEXP (cond1, 0), XEXP (cond2, 0)) - || !rtx_equal_p (XEXP (cond1, 1), XEXP (cond2, 1))) - return NULL; - - /* Short circuit cases where block B contains some side effects, as we can't - safely bypass it. */ - for (insn = NEXT_INSN (BB_HEAD (b)); insn != NEXT_INSN (BB_END (b)); - insn = NEXT_INSN (insn)) - if (INSN_P (insn) && side_effects_p (PATTERN (insn))) - { - b->flags |= BB_NONTHREADABLE_BLOCK; - return NULL; - } - - cselib_init (false); - - /* First process all values computed in the source basic block. */ - for (insn = NEXT_INSN (BB_HEAD (e->src)); - insn != NEXT_INSN (BB_END (e->src)); - insn = NEXT_INSN (insn)) - if (INSN_P (insn)) - cselib_process_insn (insn); - - nonequal = BITMAP_ALLOC (NULL); - CLEAR_REG_SET (nonequal); - - /* Now assume that we've continued by the edge E to B and continue - processing as if it were same basic block. - Our goal is to prove that whole block is an NOOP. */ - - for (insn = NEXT_INSN (BB_HEAD (b)); - insn != NEXT_INSN (BB_END (b)) && !failed; - insn = NEXT_INSN (insn)) - { - if (INSN_P (insn)) - { - rtx pat = PATTERN (insn); - - if (GET_CODE (pat) == PARALLEL) - { - for (i = 0; i < (unsigned)XVECLEN (pat, 0); i++) - failed |= mark_effect (XVECEXP (pat, 0, i), nonequal); - } - else - failed |= mark_effect (pat, nonequal); - } - - cselib_process_insn (insn); - } - - /* Later we should clear nonequal of dead registers. So far we don't - have life information in cfg_cleanup. */ - if (failed) - { - b->flags |= BB_NONTHREADABLE_BLOCK; - goto failed_exit; - } - - /* cond2 must not mention any register that is not equal to the - former block. */ - if (for_each_rtx (&cond2, mentions_nonequal_regs, nonequal)) - goto failed_exit; - - /* In case liveness information is available, we need to prove equivalence - only of the live values. */ - if (mode & CLEANUP_UPDATE_LIFE) - AND_REG_SET (nonequal, b->il.rtl->global_live_at_end); - - EXECUTE_IF_SET_IN_REG_SET (nonequal, 0, i, rsi) - goto failed_exit; - - BITMAP_FREE (nonequal); - cselib_finish (); - if ((comparison_dominates_p (code1, code2) != 0) - != (XEXP (SET_SRC (set2), 1) == pc_rtx)) - return BRANCH_EDGE (b); - else - return FALLTHRU_EDGE (b); - -failed_exit: - BITMAP_FREE (nonequal); - cselib_finish (); - return NULL; -} - -/* Attempt to forward edges leaving basic block B. - Return true if successful. */ - -static bool -try_forward_edges (int mode, basic_block b) -{ - bool changed = false; - edge_iterator ei; - edge e, *threaded_edges = NULL; - - /* If we are partitioning hot/cold basic blocks, we don't want to - mess up unconditional or indirect jumps that cross between hot - and cold sections. - - Basic block partitioning may result in some jumps that appear to - be optimizable (or blocks that appear to be mergeable), but which really m - ust be left untouched (they are required to make it safely across - partition boundaries). See the comments at the top of - bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */ - - if (find_reg_note (BB_END (b), REG_CROSSING_JUMP, NULL_RTX)) - return false; - - for (ei = ei_start (b->succs); (e = ei_safe_edge (ei)); ) - { - basic_block target, first; - int counter; - bool threaded = false; - int nthreaded_edges = 0; - bool may_thread = first_pass | (b->flags & BB_DIRTY); - - /* Skip complex edges because we don't know how to update them. - - Still handle fallthru edges, as we can succeed to forward fallthru - edge to the same place as the branch edge of conditional branch - and turn conditional branch to an unconditional branch. */ - if (e->flags & EDGE_COMPLEX) - { - ei_next (&ei); - continue; - } - - target = first = e->dest; - counter = NUM_FIXED_BLOCKS; - - /* If we are partitioning hot/cold basic_blocks, we don't want to mess - up jumps that cross between hot/cold sections. - - Basic block partitioning may result in some jumps that appear - to be optimizable (or blocks that appear to be mergeable), but which - really must be left untouched (they are required to make it safely - across partition boundaries). See the comments at the top of - bb-reorder.c:partition_hot_cold_basic_blocks for complete - details. */ - - if (first != EXIT_BLOCK_PTR - && find_reg_note (BB_END (first), REG_CROSSING_JUMP, NULL_RTX)) - return false; - - while (counter < n_basic_blocks) - { - basic_block new_target = NULL; - bool new_target_threaded = false; - may_thread |= target->flags & BB_DIRTY; - - if (FORWARDER_BLOCK_P (target) - && !(single_succ_edge (target)->flags & EDGE_CROSSING) - && single_succ (target) != EXIT_BLOCK_PTR) - { - /* Bypass trivial infinite loops. */ - new_target = single_succ (target); - if (target == new_target) - counter = n_basic_blocks; - } - - /* Allow to thread only over one edge at time to simplify updating - of probabilities. */ - else if ((mode & CLEANUP_THREADING) && may_thread) - { - edge t = thread_jump (mode, e, target); - if (t) - { - if (!threaded_edges) - threaded_edges = XNEWVEC (edge, n_basic_blocks); - else - { - int i; - - /* Detect an infinite loop across blocks not - including the start block. */ - for (i = 0; i < nthreaded_edges; ++i) - if (threaded_edges[i] == t) - break; - if (i < nthreaded_edges) - { - counter = n_basic_blocks; - break; - } - } - - /* Detect an infinite loop across the start block. */ - if (t->dest == b) - break; - - gcc_assert (nthreaded_edges < n_basic_blocks - NUM_FIXED_BLOCKS); - threaded_edges[nthreaded_edges++] = t; - - new_target = t->dest; - new_target_threaded = true; - } - } - - if (!new_target) - break; - - counter++; - target = new_target; - threaded |= new_target_threaded; - } - - if (counter >= n_basic_blocks) - { - if (dump_file) - fprintf (dump_file, "Infinite loop in BB %i.\n", - target->index); - } - else if (target == first) - ; /* We didn't do anything. */ - else - { - /* Save the values now, as the edge may get removed. */ - gcov_type edge_count = e->count; - int edge_probability = e->probability; - int edge_frequency; - int n = 0; - - /* Don't force if target is exit block. */ - if (threaded && target != EXIT_BLOCK_PTR) - { - notice_new_block (redirect_edge_and_branch_force (e, target)); - if (dump_file) - fprintf (dump_file, "Conditionals threaded.\n"); - } - else if (!redirect_edge_and_branch (e, target)) - { - if (dump_file) - fprintf (dump_file, - "Forwarding edge %i->%i to %i failed.\n", - b->index, e->dest->index, target->index); - ei_next (&ei); - continue; - } - - /* We successfully forwarded the edge. Now update profile - data: for each edge we traversed in the chain, remove - the original edge's execution count. */ - edge_frequency = ((edge_probability * b->frequency - + REG_BR_PROB_BASE / 2) - / REG_BR_PROB_BASE); - - if (!FORWARDER_BLOCK_P (b) && forwarder_block_p (b)) - b->flags |= BB_FORWARDER_BLOCK; - - do - { - edge t; - - if (!single_succ_p (first)) - { - gcc_assert (n < nthreaded_edges); - t = threaded_edges [n++]; - gcc_assert (t->src == first); - update_bb_profile_for_threading (first, edge_frequency, - edge_count, t); - update_br_prob_note (first); - } - else - { - first->count -= edge_count; - if (first->count < 0) - first->count = 0; - first->frequency -= edge_frequency; - if (first->frequency < 0) - first->frequency = 0; - /* It is possible that as the result of - threading we've removed edge as it is - threaded to the fallthru edge. Avoid - getting out of sync. */ - if (n < nthreaded_edges - && first == threaded_edges [n]->src) - n++; - t = single_succ_edge (first); - } - - t->count -= edge_count; - if (t->count < 0) - t->count = 0; - first = t->dest; - } - while (first != target); - - changed = true; - continue; - } - ei_next (&ei); - } - - if (threaded_edges) - free (threaded_edges); - return changed; -} - - -/* 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 void -merge_blocks_move_predecessor_nojumps (basic_block a, basic_block b) -{ - rtx barrier; - bool only_notes; - - /* If we are partitioning hot/cold basic blocks, we don't want to - mess up unconditional or indirect jumps that cross between hot - and cold sections. - - Basic block partitioning may result in some jumps that appear to - be optimizable (or blocks that appear to be mergeable), but which really - must be left untouched (they are required to make it safely across - partition boundaries). See the comments at the top of - bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */ - - if (BB_PARTITION (a) != BB_PARTITION (b)) - return; - - barrier = next_nonnote_insn (BB_END (a)); - gcc_assert (BARRIER_P (barrier)); - 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. */ - only_notes = squeeze_notes (&BB_HEAD (a), &BB_END (a)); - gcc_assert (!only_notes); - - /* Scramble the insn chain. */ - if (BB_END (a) != PREV_INSN (BB_HEAD (b))) - reorder_insns_nobb (BB_HEAD (a), BB_END (a), PREV_INSN (BB_HEAD (b))); - a->flags |= BB_DIRTY; - - if (dump_file) - fprintf (dump_file, "Moved block %d before %d and merged.\n", - a->index, b->index); - - /* Swap the records for the two blocks around. */ - - unlink_block (a); - link_block (a, b->prev_bb); - - /* Now blocks A and B are contiguous. Merge them. */ - merge_blocks (a, b); -} - -/* 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 void -merge_blocks_move_successor_nojumps (basic_block a, basic_block b) -{ - rtx barrier, real_b_end; - rtx label, table; - bool only_notes; - - /* If we are partitioning hot/cold basic blocks, we don't want to - mess up unconditional or indirect jumps that cross between hot - and cold sections. - - Basic block partitioning may result in some jumps that appear to - be optimizable (or blocks that appear to be mergeable), but which really - must be left untouched (they are required to make it safely across - partition boundaries). See the comments at the top of - bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */ - - if (BB_PARTITION (a) != BB_PARTITION (b)) - return; - - real_b_end = BB_END (b); - - /* If there is a jump table following block B temporarily add the jump table - to block B so that it will also be moved to the correct location. */ - if (tablejump_p (BB_END (b), &label, &table) - && prev_active_insn (label) == BB_END (b)) - { - BB_END (b) = table; - } - - /* There had better have been a barrier there. Delete it. */ - barrier = NEXT_INSN (BB_END (b)); - if (barrier && BARRIER_P (barrier)) - 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. */ - only_notes = squeeze_notes (&BB_HEAD (b), &BB_END (b)); - gcc_assert (!only_notes); - - - /* Scramble the insn chain. */ - reorder_insns_nobb (BB_HEAD (b), BB_END (b), BB_END (a)); - - /* Restore the real end of b. */ - BB_END (b) = real_b_end; - - if (dump_file) - fprintf (dump_file, "Moved block %d after %d and merged.\n", - b->index, a->index); - - /* Now blocks A and B are contiguous. Merge them. */ - merge_blocks (a, b); -} - -/* Attempt to merge basic blocks that are potentially non-adjacent. - Return NULL iff the attempt failed, otherwise return basic block - where cleanup_cfg should continue. Because the merging commonly - moves basic block away or introduces another optimization - possibility, return basic block just before B so cleanup_cfg don't - need to iterate. - - It may be good idea to return basic block before C in the case - C has been moved after B and originally appeared earlier in the - insn sequence, but we have no information available about the - relative ordering of these two. Hopefully it is not too common. */ - -static basic_block -merge_blocks_move (edge e, basic_block b, basic_block c, int mode) -{ - basic_block next; - - /* If we are partitioning hot/cold basic blocks, we don't want to - mess up unconditional or indirect jumps that cross between hot - and cold sections. - - Basic block partitioning may result in some jumps that appear to - be optimizable (or blocks that appear to be mergeable), but which really - must be left untouched (they are required to make it safely across - partition boundaries). See the comments at the top of - bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */ - - if (BB_PARTITION (b) != BB_PARTITION (c)) - return NULL; - - - - /* If B has a fallthru edge to C, no need to move anything. */ - if (e->flags & EDGE_FALLTHRU) - { - int b_index = b->index, c_index = c->index; - merge_blocks (b, c); - update_forwarder_flag (b); - - if (dump_file) - fprintf (dump_file, "Merged %d and %d without moving.\n", - b_index, c_index); - - return b->prev_bb == ENTRY_BLOCK_PTR ? b : b->prev_bb; - } - - /* Otherwise we will need to move code around. Do that only if expensive - transformations are allowed. */ - else if (mode & CLEANUP_EXPENSIVE) - { - edge tmp_edge, b_fallthru_edge; - bool c_has_outgoing_fallthru; - bool b_has_incoming_fallthru; - edge_iterator ei; - - /* Avoid overactive code motion, as the forwarder blocks should be - eliminated by edge redirection instead. One exception might have - been if B is a forwarder block and C has no fallthru edge, but - that should be cleaned up by bb-reorder instead. */ - if (FORWARDER_BLOCK_P (b) || FORWARDER_BLOCK_P (c)) - return NULL; - - /* We must make sure to not munge nesting of lexical blocks, - and loop notes. This is done by squeezing out all the notes - and leaving them there to lie. Not ideal, but functional. */ - - FOR_EACH_EDGE (tmp_edge, ei, c->succs) - if (tmp_edge->flags & EDGE_FALLTHRU) - break; - - c_has_outgoing_fallthru = (tmp_edge != NULL); - - FOR_EACH_EDGE (tmp_edge, ei, b->preds) - if (tmp_edge->flags & EDGE_FALLTHRU) - break; - - b_has_incoming_fallthru = (tmp_edge != NULL); - b_fallthru_edge = tmp_edge; - next = b->prev_bb; - if (next == c) - next = next->prev_bb; - - /* Otherwise, we're going to try to move C after B. 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) - { - merge_blocks_move_successor_nojumps (b, c); - return next == ENTRY_BLOCK_PTR ? next->next_bb : next; - } - - /* If B does not have an incoming fallthru, then it can be moved - immediately before C without introducing or modifying jumps. - C cannot be the first block, so we do not have to worry about - accessing a non-existent block. */ - - if (b_has_incoming_fallthru) - { - basic_block bb; - - if (b_fallthru_edge->src == ENTRY_BLOCK_PTR) - return NULL; - bb = force_nonfallthru (b_fallthru_edge); - if (bb) - notice_new_block (bb); - } - - merge_blocks_move_predecessor_nojumps (b, c); - return next == ENTRY_BLOCK_PTR ? next->next_bb : next; - } - - return NULL; -} - - -/* Removes the memory attributes of MEM expression - if they are not equal. */ - -void -merge_memattrs (rtx x, rtx y) -{ - int i; - int j; - enum rtx_code code; - const char *fmt; - - if (x == y) - return; - if (x == 0 || y == 0) - return; - - code = GET_CODE (x); - - if (code != GET_CODE (y)) - return; - - if (GET_MODE (x) != GET_MODE (y)) - return; - - if (code == MEM && MEM_ATTRS (x) != MEM_ATTRS (y)) - { - if (! MEM_ATTRS (x)) - MEM_ATTRS (y) = 0; - else if (! MEM_ATTRS (y)) - MEM_ATTRS (x) = 0; - else - { - rtx mem_size; - - if (MEM_ALIAS_SET (x) != MEM_ALIAS_SET (y)) - { - set_mem_alias_set (x, 0); - set_mem_alias_set (y, 0); - } - - if (! mem_expr_equal_p (MEM_EXPR (x), MEM_EXPR (y))) - { - set_mem_expr (x, 0); - set_mem_expr (y, 0); - set_mem_offset (x, 0); - set_mem_offset (y, 0); - } - else if (MEM_OFFSET (x) != MEM_OFFSET (y)) - { - set_mem_offset (x, 0); - set_mem_offset (y, 0); - } - - if (!MEM_SIZE (x)) - mem_size = NULL_RTX; - else if (!MEM_SIZE (y)) - mem_size = NULL_RTX; - else - mem_size = GEN_INT (MAX (INTVAL (MEM_SIZE (x)), - INTVAL (MEM_SIZE (y)))); - set_mem_size (x, mem_size); - set_mem_size (y, mem_size); - - set_mem_align (x, MIN (MEM_ALIGN (x), MEM_ALIGN (y))); - set_mem_align (y, MEM_ALIGN (x)); - } - } - - fmt = GET_RTX_FORMAT (code); - for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) - { - switch (fmt[i]) - { - case 'E': - /* Two vectors must have the same length. */ - if (XVECLEN (x, i) != XVECLEN (y, i)) - return; - - for (j = 0; j < XVECLEN (x, i); j++) - merge_memattrs (XVECEXP (x, i, j), XVECEXP (y, i, j)); - - break; - - case 'e': - merge_memattrs (XEXP (x, i), XEXP (y, i)); - } - } - return; -} - - -/* Return true if I1 and I2 are equivalent and thus can be crossjumped. */ - -static bool -old_insns_match_p (int mode ATTRIBUTE_UNUSED, rtx i1, rtx i2) -{ - rtx p1, p2; - - /* Verify that I1 and I2 are equivalent. */ - if (GET_CODE (i1) != GET_CODE (i2)) - return false; - - p1 = PATTERN (i1); - p2 = PATTERN (i2); - - if (GET_CODE (p1) != GET_CODE (p2)) - return false; - - /* If this is a CALL_INSN, compare register usage information. - If we don't check this on stack register machines, the two - CALL_INSNs might be merged leaving reg-stack.c with mismatching - numbers of stack registers in the same basic block. - If we don't check this on machines with delay slots, a delay slot may - be filled that clobbers a parameter expected by the subroutine. - - ??? We take the simple route for now and assume that if they're - equal, they were constructed identically. */ - - if (CALL_P (i1) - && (!rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1), - CALL_INSN_FUNCTION_USAGE (i2)) - || SIBLING_CALL_P (i1) != SIBLING_CALL_P (i2))) - return false; - -#ifdef STACK_REGS - /* If cross_jump_death_matters is not 0, the insn's mode - indicates whether or not the insn contains any stack-like - regs. */ - - if ((mode & CLEANUP_POST_REGSTACK) && stack_regs_mentioned (i1)) - { - /* If register stack conversion has already been done, then - death notes must also be compared before it is certain that - the two instruction streams match. */ - - rtx note; - HARD_REG_SET i1_regset, i2_regset; - - CLEAR_HARD_REG_SET (i1_regset); - CLEAR_HARD_REG_SET (i2_regset); - - for (note = REG_NOTES (i1); note; note = XEXP (note, 1)) - if (REG_NOTE_KIND (note) == REG_DEAD && STACK_REG_P (XEXP (note, 0))) - SET_HARD_REG_BIT (i1_regset, REGNO (XEXP (note, 0))); - - for (note = REG_NOTES (i2); note; note = XEXP (note, 1)) - if (REG_NOTE_KIND (note) == REG_DEAD && STACK_REG_P (XEXP (note, 0))) - SET_HARD_REG_BIT (i2_regset, REGNO (XEXP (note, 0))); - - GO_IF_HARD_REG_EQUAL (i1_regset, i2_regset, done); - - return false; - - done: - ; - } -#endif - - if (reload_completed - ? rtx_renumbered_equal_p (p1, p2) : rtx_equal_p (p1, p2)) - return true; - - /* Do not do EQUIV substitution after reload. First, we're undoing the - work of reload_cse. Second, we may be undoing the work of the post- - reload splitting pass. */ - /* ??? Possibly add a new phase switch variable that can be used by - targets to disallow the troublesome insns after splitting. */ - if (!reload_completed) - { - /* The following code helps take care of G++ cleanups. */ - rtx equiv1 = find_reg_equal_equiv_note (i1); - rtx equiv2 = find_reg_equal_equiv_note (i2); - - if (equiv1 && equiv2 - /* If the equivalences are not to a constant, they may - reference pseudos that no longer exist, so we can't - use them. */ - && (! reload_completed - || (CONSTANT_P (XEXP (equiv1, 0)) - && rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0))))) - { - rtx s1 = single_set (i1); - rtx s2 = single_set (i2); - if (s1 != 0 && s2 != 0 - && rtx_renumbered_equal_p (SET_DEST (s1), SET_DEST (s2))) - { - validate_change (i1, &SET_SRC (s1), XEXP (equiv1, 0), 1); - validate_change (i2, &SET_SRC (s2), XEXP (equiv2, 0), 1); - if (! rtx_renumbered_equal_p (p1, p2)) - cancel_changes (0); - else if (apply_change_group ()) - return true; - } - } - } - - return false; -} - -/* Look through the insns at the end of BB1 and BB2 and find the longest - sequence that are equivalent. Store the first insns for that sequence - in *F1 and *F2 and return the sequence length. - - To simplify callers of this function, if the blocks match exactly, - store the head of the blocks in *F1 and *F2. */ - -static int -flow_find_cross_jump (int mode ATTRIBUTE_UNUSED, basic_block bb1, - basic_block bb2, rtx *f1, rtx *f2) -{ - rtx i1, i2, last1, last2, afterlast1, afterlast2; - int ninsns = 0; - - /* Skip simple jumps at the end of the blocks. Complex jumps still - need to be compared for equivalence, which we'll do below. */ - - i1 = BB_END (bb1); - last1 = afterlast1 = last2 = afterlast2 = NULL_RTX; - if (onlyjump_p (i1) - || (returnjump_p (i1) && !side_effects_p (PATTERN (i1)))) - { - last1 = i1; - i1 = PREV_INSN (i1); - } - - i2 = BB_END (bb2); - if (onlyjump_p (i2) - || (returnjump_p (i2) && !side_effects_p (PATTERN (i2)))) - { - last2 = i2; - /* Count everything except for unconditional jump as insn. */ - if (!simplejump_p (i2) && !returnjump_p (i2) && last1) - ninsns++; - i2 = PREV_INSN (i2); - } - - while (true) - { - /* Ignore notes. */ - while (!INSN_P (i1) && i1 != BB_HEAD (bb1)) - i1 = PREV_INSN (i1); - - while (!INSN_P (i2) && i2 != BB_HEAD (bb2)) - i2 = PREV_INSN (i2); - - if (i1 == BB_HEAD (bb1) || i2 == BB_HEAD (bb2)) - break; - - if (!old_insns_match_p (mode, i1, i2)) - break; - - merge_memattrs (i1, i2); - - /* Don't begin a cross-jump with a NOTE insn. */ - if (INSN_P (i1)) - { - /* If the merged insns have different REG_EQUAL notes, then - remove them. */ - rtx equiv1 = find_reg_equal_equiv_note (i1); - rtx equiv2 = find_reg_equal_equiv_note (i2); - - if (equiv1 && !equiv2) - remove_note (i1, equiv1); - else if (!equiv1 && equiv2) - remove_note (i2, equiv2); - else if (equiv1 && equiv2 - && !rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0))) - { - remove_note (i1, equiv1); - remove_note (i2, equiv2); - } - - afterlast1 = last1, afterlast2 = last2; - last1 = i1, last2 = i2; - ninsns++; - } - - i1 = PREV_INSN (i1); - i2 = PREV_INSN (i2); - } - -#ifdef HAVE_cc0 - /* Don't allow the insn after a compare to be shared by - cross-jumping unless the compare is also shared. */ - if (ninsns && reg_mentioned_p (cc0_rtx, last1) && ! sets_cc0_p (last1)) - last1 = afterlast1, last2 = afterlast2, ninsns--; -#endif - - /* Include preceding notes and labels in the cross-jump. One, - this may bring us to the head of the blocks as requested above. - Two, it keeps line number notes as matched as may be. */ - if (ninsns) - { - while (last1 != BB_HEAD (bb1) && !INSN_P (PREV_INSN (last1))) - last1 = PREV_INSN (last1); - - if (last1 != BB_HEAD (bb1) && LABEL_P (PREV_INSN (last1))) - last1 = PREV_INSN (last1); - - while (last2 != BB_HEAD (bb2) && !INSN_P (PREV_INSN (last2))) - last2 = PREV_INSN (last2); - - if (last2 != BB_HEAD (bb2) && LABEL_P (PREV_INSN (last2))) - last2 = PREV_INSN (last2); - - *f1 = last1; - *f2 = last2; - } - - return ninsns; -} - -/* Return true iff the condbranches at the end of BB1 and BB2 match. */ -bool -condjump_equiv_p (struct equiv_info *info, bool call_init) -{ - basic_block bb1 = info->x_block; - basic_block bb2 = info->y_block; - edge b1 = BRANCH_EDGE (bb1); - edge b2 = BRANCH_EDGE (bb2); - edge f1 = FALLTHRU_EDGE (bb1); - edge f2 = FALLTHRU_EDGE (bb2); - bool reverse, match; - rtx set1, set2, cond1, cond2; - rtx src1, src2; - enum rtx_code code1, code2; - - /* Get around possible forwarders on fallthru edges. Other cases - should be optimized out already. */ - if (FORWARDER_BLOCK_P (f1->dest)) - f1 = single_succ_edge (f1->dest); - - if (FORWARDER_BLOCK_P (f2->dest)) - f2 = single_succ_edge (f2->dest); - - /* To simplify use of this function, return false if there are - unneeded forwarder blocks. These will get eliminated later - during cleanup_cfg. */ - if (FORWARDER_BLOCK_P (f1->dest) - || FORWARDER_BLOCK_P (f2->dest) - || FORWARDER_BLOCK_P (b1->dest) - || FORWARDER_BLOCK_P (b2->dest)) - return false; - - if (f1->dest == f2->dest && b1->dest == b2->dest) - reverse = false; - else if (f1->dest == b2->dest && b1->dest == f2->dest) - reverse = true; - else - return false; - - set1 = pc_set (BB_END (bb1)); - set2 = pc_set (BB_END (bb2)); - if ((XEXP (SET_SRC (set1), 1) == pc_rtx) - != (XEXP (SET_SRC (set2), 1) == pc_rtx)) - reverse = !reverse; - - src1 = SET_SRC (set1); - src2 = SET_SRC (set2); - cond1 = XEXP (src1, 0); - cond2 = XEXP (src2, 0); - code1 = GET_CODE (cond1); - if (reverse) - code2 = reversed_comparison_code (cond2, BB_END (bb2)); - else - code2 = GET_CODE (cond2); - - if (code2 == UNKNOWN) - return false; - - if (call_init && !struct_equiv_init (STRUCT_EQUIV_START | info->mode, info)) - gcc_unreachable (); - /* Make the sources of the pc sets unreadable so that when we call - insns_match_p it won't process them. - The death_notes_match_p from insns_match_p won't see the local registers - used for the pc set, but that could only cause missed optimizations when - there are actually condjumps that use stack registers. */ - SET_SRC (set1) = pc_rtx; - SET_SRC (set2) = pc_rtx; - /* Verify codes and operands match. */ - if (code1 == code2) - { - match = (insns_match_p (BB_END (bb1), BB_END (bb2), info) - && rtx_equiv_p (&XEXP (cond1, 0), XEXP (cond2, 0), 1, info) - && rtx_equiv_p (&XEXP (cond1, 1), XEXP (cond2, 1), 1, info)); - - } - else if (code1 == swap_condition (code2)) - { - match = (insns_match_p (BB_END (bb1), BB_END (bb2), info) - && rtx_equiv_p (&XEXP (cond1, 1), XEXP (cond2, 0), 1, info) - && rtx_equiv_p (&XEXP (cond1, 0), XEXP (cond2, 1), 1, info)); - - } - else - match = false; - SET_SRC (set1) = src1; - SET_SRC (set2) = src2; - match &= verify_changes (0); - - /* If we return true, we will join the blocks. Which means that - we will only have one branch prediction bit to work with. Thus - we require the existing branches to have probabilities that are - roughly similar. */ - if (match - && !optimize_size - && maybe_hot_bb_p (bb1) - && maybe_hot_bb_p (bb2)) - { - int prob2; - - if (b1->dest == b2->dest) - prob2 = b2->probability; - else - /* Do not use f2 probability as f2 may be forwarded. */ - prob2 = REG_BR_PROB_BASE - b2->probability; - - /* Fail if the difference in probabilities is greater than 50%. - This rules out two well-predicted branches with opposite - outcomes. */ - if (abs (b1->probability - prob2) > REG_BR_PROB_BASE / 2) - { - if (dump_file) - fprintf (dump_file, - "Outcomes of branch in bb %i and %i differ too much (%i %i)\n", - bb1->index, bb2->index, b1->probability, prob2); - - match = false; - } - } - - if (dump_file && match) - fprintf (dump_file, "Conditionals in bb %i and %i match.\n", - bb1->index, bb2->index); - - if (!match) - cancel_changes (0); - return match; -} - -/* Return true iff outgoing edges of BB1 and BB2 match, together with - the branch instruction. This means that if we commonize the control - flow before end of the basic block, the semantic remains unchanged. - - We may assume that there exists one edge with a common destination. */ - -static bool -outgoing_edges_match (int mode, basic_block bb1, basic_block bb2) -{ - int nehedges1 = 0, nehedges2 = 0; - edge fallthru1 = 0, fallthru2 = 0; - edge e1, e2; - edge_iterator ei; - - /* If BB1 has only one successor, we may be looking at either an - unconditional jump, or a fake edge to exit. */ - if (single_succ_p (bb1) - && (single_succ_edge (bb1)->flags & (EDGE_COMPLEX | EDGE_FAKE)) == 0 - && (!JUMP_P (BB_END (bb1)) || simplejump_p (BB_END (bb1)))) - return (single_succ_p (bb2) - && (single_succ_edge (bb2)->flags - & (EDGE_COMPLEX | EDGE_FAKE)) == 0 - && (!JUMP_P (BB_END (bb2)) || simplejump_p (BB_END (bb2)))); - - /* Match conditional jumps - this may get tricky when fallthru and branch - edges are crossed. */ - if (EDGE_COUNT (bb1->succs) == 2 - && any_condjump_p (BB_END (bb1)) - && onlyjump_p (BB_END (bb1))) - { - edge b1, f1, b2, f2; - bool reverse, match; - rtx set1, set2, cond1, cond2; - enum rtx_code code1, code2; - - if (EDGE_COUNT (bb2->succs) != 2 - || !any_condjump_p (BB_END (bb2)) - || !onlyjump_p (BB_END (bb2))) - return false; - - b1 = BRANCH_EDGE (bb1); - b2 = BRANCH_EDGE (bb2); - f1 = FALLTHRU_EDGE (bb1); - f2 = FALLTHRU_EDGE (bb2); - - /* Get around possible forwarders on fallthru edges. Other cases - should be optimized out already. */ - if (FORWARDER_BLOCK_P (f1->dest)) - f1 = single_succ_edge (f1->dest); - - if (FORWARDER_BLOCK_P (f2->dest)) - f2 = single_succ_edge (f2->dest); - - /* To simplify use of this function, return false if there are - unneeded forwarder blocks. These will get eliminated later - during cleanup_cfg. */ - if (FORWARDER_BLOCK_P (f1->dest) - || FORWARDER_BLOCK_P (f2->dest) - || FORWARDER_BLOCK_P (b1->dest) - || FORWARDER_BLOCK_P (b2->dest)) - return false; - - if (f1->dest == f2->dest && b1->dest == b2->dest) - reverse = false; - else if (f1->dest == b2->dest && b1->dest == f2->dest) - reverse = true; - else - return false; - - set1 = pc_set (BB_END (bb1)); - set2 = pc_set (BB_END (bb2)); - if ((XEXP (SET_SRC (set1), 1) == pc_rtx) - != (XEXP (SET_SRC (set2), 1) == pc_rtx)) - reverse = !reverse; - - cond1 = XEXP (SET_SRC (set1), 0); - cond2 = XEXP (SET_SRC (set2), 0); - code1 = GET_CODE (cond1); - if (reverse) - code2 = reversed_comparison_code (cond2, BB_END (bb2)); - else - code2 = GET_CODE (cond2); - - if (code2 == UNKNOWN) - return false; - - /* Verify codes and operands match. */ - match = ((code1 == code2 - && rtx_renumbered_equal_p (XEXP (cond1, 0), XEXP (cond2, 0)) - && rtx_renumbered_equal_p (XEXP (cond1, 1), XEXP (cond2, 1))) - || (code1 == swap_condition (code2) - && rtx_renumbered_equal_p (XEXP (cond1, 1), - XEXP (cond2, 0)) - && rtx_renumbered_equal_p (XEXP (cond1, 0), - XEXP (cond2, 1)))); - - /* If we return true, we will join the blocks. Which means that - we will only have one branch prediction bit to work with. Thus - we require the existing branches to have probabilities that are - roughly similar. */ - if (match - && !optimize_size - && maybe_hot_bb_p (bb1) - && maybe_hot_bb_p (bb2)) - { - int prob2; - - if (b1->dest == b2->dest) - prob2 = b2->probability; - else - /* Do not use f2 probability as f2 may be forwarded. */ - prob2 = REG_BR_PROB_BASE - b2->probability; - - /* Fail if the difference in probabilities is greater than 50%. - This rules out two well-predicted branches with opposite - outcomes. */ - if (abs (b1->probability - prob2) > REG_BR_PROB_BASE / 2) - { - if (dump_file) - fprintf (dump_file, - "Outcomes of branch in bb %i and %i differ too much (%i %i)\n", - bb1->index, bb2->index, b1->probability, prob2); - - return false; - } - } - - if (dump_file && match) - fprintf (dump_file, "Conditionals in bb %i and %i match.\n", - bb1->index, bb2->index); - - return match; - } - - /* Generic case - we are seeing a computed jump, table jump or trapping - instruction. */ - - /* Check whether there are tablejumps in the end of BB1 and BB2. - Return true if they are identical. */ - { - rtx label1, label2; - rtx table1, table2; - - if (tablejump_p (BB_END (bb1), &label1, &table1) - && tablejump_p (BB_END (bb2), &label2, &table2) - && GET_CODE (PATTERN (table1)) == GET_CODE (PATTERN (table2))) - { - /* The labels should never be the same rtx. If they really are same - the jump tables are same too. So disable crossjumping of blocks BB1 - and BB2 because when deleting the common insns in the end of BB1 - by delete_basic_block () the jump table would be deleted too. */ - /* If LABEL2 is referenced in BB1->END do not do anything - because we would loose information when replacing - LABEL1 by LABEL2 and then LABEL2 by LABEL1 in BB1->END. */ - if (label1 != label2 && !rtx_referenced_p (label2, BB_END (bb1))) - { - /* Set IDENTICAL to true when the tables are identical. */ - bool identical = false; - rtx p1, p2; - - p1 = PATTERN (table1); - p2 = PATTERN (table2); - if (GET_CODE (p1) == ADDR_VEC && rtx_equal_p (p1, p2)) - { - identical = true; - } - else if (GET_CODE (p1) == ADDR_DIFF_VEC - && (XVECLEN (p1, 1) == XVECLEN (p2, 1)) - && rtx_equal_p (XEXP (p1, 2), XEXP (p2, 2)) - && rtx_equal_p (XEXP (p1, 3), XEXP (p2, 3))) - { - int i; - - identical = true; - for (i = XVECLEN (p1, 1) - 1; i >= 0 && identical; i--) - if (!rtx_equal_p (XVECEXP (p1, 1, i), XVECEXP (p2, 1, i))) - identical = false; - } - - if (identical) - { - replace_label_data rr; - bool match; - - /* Temporarily replace references to LABEL1 with LABEL2 - in BB1->END so that we could compare the instructions. */ - rr.r1 = label1; - rr.r2 = label2; - rr.update_label_nuses = false; - for_each_rtx (&BB_END (bb1), replace_label, &rr); - - match = old_insns_match_p (mode, BB_END (bb1), BB_END (bb2)); - if (dump_file && match) - fprintf (dump_file, - "Tablejumps in bb %i and %i match.\n", - bb1->index, bb2->index); - - /* Set the original label in BB1->END because when deleting - a block whose end is a tablejump, the tablejump referenced - from the instruction is deleted too. */ - rr.r1 = label2; - rr.r2 = label1; - for_each_rtx (&BB_END (bb1), replace_label, &rr); - - return match; - } - } - return false; - } - } - - /* First ensure that the instructions match. There may be many outgoing - edges so this test is generally cheaper. */ - if (!old_insns_match_p (mode, BB_END (bb1), BB_END (bb2))) - return false; - - /* Search the outgoing edges, ensure that the counts do match, find possible - fallthru and exception handling edges since these needs more - validation. */ - if (EDGE_COUNT (bb1->succs) != EDGE_COUNT (bb2->succs)) - return false; - - FOR_EACH_EDGE (e1, ei, bb1->succs) - { - e2 = EDGE_SUCC (bb2, ei.index); - - if (e1->flags & EDGE_EH) - nehedges1++; - - if (e2->flags & EDGE_EH) - nehedges2++; - - if (e1->flags & EDGE_FALLTHRU) - fallthru1 = e1; - if (e2->flags & EDGE_FALLTHRU) - fallthru2 = e2; - } - - /* If number of edges of various types does not match, fail. */ - if (nehedges1 != nehedges2 - || (fallthru1 != 0) != (fallthru2 != 0)) - return false; - - /* fallthru edges must be forwarded to the same destination. */ - if (fallthru1) - { - basic_block d1 = (forwarder_block_p (fallthru1->dest) - ? single_succ (fallthru1->dest): fallthru1->dest); - basic_block d2 = (forwarder_block_p (fallthru2->dest) - ? single_succ (fallthru2->dest): fallthru2->dest); - - if (d1 != d2) - return false; - } - - /* Ensure the same EH region. */ - { - rtx n1 = find_reg_note (BB_END (bb1), REG_EH_REGION, 0); - rtx n2 = find_reg_note (BB_END (bb2), REG_EH_REGION, 0); - - if (!n1 && n2) - return false; - - if (n1 && (!n2 || XEXP (n1, 0) != XEXP (n2, 0))) - return false; - } - - /* The same checks as in try_crossjump_to_edge. It is required for RTL - version of sequence abstraction. */ - FOR_EACH_EDGE (e1, ei, bb2->succs) - { - edge e2; - edge_iterator ei; - basic_block d1 = e1->dest; - - if (FORWARDER_BLOCK_P (d1)) - d1 = EDGE_SUCC (d1, 0)->dest; - - FOR_EACH_EDGE (e2, ei, bb1->succs) - { - basic_block d2 = e2->dest; - if (FORWARDER_BLOCK_P (d2)) - d2 = EDGE_SUCC (d2, 0)->dest; - if (d1 == d2) - break; - } - - if (!e2) - return false; - } - - return true; -} - -/* Returns true if BB basic block has a preserve label. */ - -static bool -block_has_preserve_label (basic_block bb) -{ - return (bb - && block_label (bb) - && LABEL_PRESERVE_P (block_label (bb))); -} - -/* E1 and E2 are edges with the same destination block. Search their - predecessors for common code. If found, redirect control flow from - (maybe the middle of) E1->SRC to (maybe the middle of) E2->SRC. */ - -static bool -try_crossjump_to_edge (int mode, edge e1, edge e2) -{ - int nmatch; - basic_block src1 = e1->src, src2 = e2->src; - basic_block redirect_to, redirect_from, to_remove; - rtx newpos1, newpos2; - edge s; - edge_iterator ei; - - newpos1 = newpos2 = NULL_RTX; - - /* If we have partitioned hot/cold basic blocks, it is a bad idea - to try this optimization. - - Basic block partitioning may result in some jumps that appear to - be optimizable (or blocks that appear to be mergeable), but which really - must be left untouched (they are required to make it safely across - partition boundaries). See the comments at the top of - bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */ - - if (flag_reorder_blocks_and_partition && no_new_pseudos) - return false; - - /* Search backward through forwarder blocks. We don't need to worry - about multiple entry or chained forwarders, as they will be optimized - away. We do this to look past the unconditional jump following a - conditional jump that is required due to the current CFG shape. */ - if (single_pred_p (src1) - && FORWARDER_BLOCK_P (src1)) - e1 = single_pred_edge (src1), src1 = e1->src; - - if (single_pred_p (src2) - && FORWARDER_BLOCK_P (src2)) - e2 = single_pred_edge (src2), src2 = e2->src; - - /* Nothing to do if we reach ENTRY, or a common source block. */ - if (src1 == ENTRY_BLOCK_PTR || src2 == ENTRY_BLOCK_PTR) - return false; - if (src1 == src2) - return false; - - /* Seeing more than 1 forwarder blocks would confuse us later... */ - if (FORWARDER_BLOCK_P (e1->dest) - && FORWARDER_BLOCK_P (single_succ (e1->dest))) - return false; - - if (FORWARDER_BLOCK_P (e2->dest) - && FORWARDER_BLOCK_P (single_succ (e2->dest))) - return false; - - /* Likewise with dead code (possibly newly created by the other optimizations - of cfg_cleanup). */ - if (EDGE_COUNT (src1->preds) == 0 || EDGE_COUNT (src2->preds) == 0) - return false; - - /* Look for the common insn sequence, part the first ... */ - if (!outgoing_edges_match (mode, src1, src2)) - return false; - - /* ... and part the second. */ - nmatch = flow_find_cross_jump (mode, src1, src2, &newpos1, &newpos2); - - /* Don't proceed with the crossjump unless we found a sufficient number - of matching instructions or the 'from' block was totally matched - (such that its predecessors will hopefully be redirected and the - block removed). */ - if ((nmatch < PARAM_VALUE (PARAM_MIN_CROSSJUMP_INSNS)) - && (newpos1 != BB_HEAD (src1))) - return false; - - /* Avoid deleting preserve label when redirecting ABNORMAL edges. */ - if (block_has_preserve_label (e1->dest) - && (e1->flags & EDGE_ABNORMAL)) - return false; - - /* Here we know that the insns in the end of SRC1 which are common with SRC2 - will be deleted. - If we have tablejumps in the end of SRC1 and SRC2 - they have been already compared for equivalence in outgoing_edges_match () - so replace the references to TABLE1 by references to TABLE2. */ - { - rtx label1, label2; - rtx table1, table2; - - if (tablejump_p (BB_END (src1), &label1, &table1) - && tablejump_p (BB_END (src2), &label2, &table2) - && label1 != label2) - { - replace_label_data rr; - rtx insn; - - /* Replace references to LABEL1 with LABEL2. */ - rr.r1 = label1; - rr.r2 = label2; - rr.update_label_nuses = true; - for (insn = get_insns (); insn; insn = NEXT_INSN (insn)) - { - /* Do not replace the label in SRC1->END because when deleting - a block whose end is a tablejump, the tablejump referenced - from the instruction is deleted too. */ - if (insn != BB_END (src1)) - for_each_rtx (&insn, replace_label, &rr); - } - } - } - - /* Avoid splitting if possible. We must always split when SRC2 has - EH predecessor edges, or we may end up with basic blocks with both - normal and EH predecessor edges. */ - if (newpos2 == BB_HEAD (src2) - && !(EDGE_PRED (src2, 0)->flags & EDGE_EH)) - redirect_to = src2; - else - { - if (newpos2 == BB_HEAD (src2)) - { - /* Skip possible basic block header. */ - if (LABEL_P (newpos2)) - newpos2 = NEXT_INSN (newpos2); - if (NOTE_P (newpos2)) - newpos2 = NEXT_INSN (newpos2); - } - - if (dump_file) - fprintf (dump_file, "Splitting bb %i before %i insns\n", - src2->index, nmatch); - redirect_to = split_block (src2, PREV_INSN (newpos2))->dest; - } - - if (dump_file) - fprintf (dump_file, - "Cross jumping from bb %i to bb %i; %i common insns\n", - src1->index, src2->index, nmatch); - - redirect_to->count += src1->count; - redirect_to->frequency += src1->frequency; - /* We may have some registers visible through the block. */ - redirect_to->flags |= BB_DIRTY; - - /* Recompute the frequencies and counts of outgoing edges. */ - FOR_EACH_EDGE (s, ei, redirect_to->succs) - { - edge s2; - edge_iterator ei; - basic_block d = s->dest; - - if (FORWARDER_BLOCK_P (d)) - d = single_succ (d); - - FOR_EACH_EDGE (s2, ei, src1->succs) - { - basic_block d2 = s2->dest; - if (FORWARDER_BLOCK_P (d2)) - d2 = single_succ (d2); - if (d == d2) - break; - } - - s->count += s2->count; - - /* Take care to update possible forwarder blocks. We verified - that there is no more than one in the chain, so we can't run - into infinite loop. */ - if (FORWARDER_BLOCK_P (s->dest)) - { - single_succ_edge (s->dest)->count += s2->count; - s->dest->count += s2->count; - s->dest->frequency += EDGE_FREQUENCY (s); - } - - if (FORWARDER_BLOCK_P (s2->dest)) - { - single_succ_edge (s2->dest)->count -= s2->count; - if (single_succ_edge (s2->dest)->count < 0) - single_succ_edge (s2->dest)->count = 0; - s2->dest->count -= s2->count; - s2->dest->frequency -= EDGE_FREQUENCY (s); - if (s2->dest->frequency < 0) - s2->dest->frequency = 0; - if (s2->dest->count < 0) - s2->dest->count = 0; - } - - if (!redirect_to->frequency && !src1->frequency) - s->probability = (s->probability + s2->probability) / 2; - else - s->probability - = ((s->probability * redirect_to->frequency + - s2->probability * src1->frequency) - / (redirect_to->frequency + src1->frequency)); - } - - update_br_prob_note (redirect_to); - - /* Edit SRC1 to go to REDIRECT_TO at NEWPOS1. */ - - /* Skip possible basic block header. */ - if (LABEL_P (newpos1)) - newpos1 = NEXT_INSN (newpos1); - - if (NOTE_P (newpos1)) - newpos1 = NEXT_INSN (newpos1); - - redirect_from = split_block (src1, PREV_INSN (newpos1))->src; - to_remove = single_succ (redirect_from); - - redirect_edge_and_branch_force (single_succ_edge (redirect_from), redirect_to); - delete_basic_block (to_remove); - - update_forwarder_flag (redirect_from); - if (redirect_to != src2) - update_forwarder_flag (src2); - - return true; -} - -/* Search the predecessors of BB for common insn sequences. When found, - share code between them by redirecting control flow. Return true if - any changes made. */ - -static bool -try_crossjump_bb (int mode, basic_block bb) -{ - edge e, e2, fallthru; - bool changed; - unsigned max, ix, ix2; - basic_block ev, ev2; - edge_iterator ei; - - /* Nothing to do if there is not at least two incoming edges. */ - if (EDGE_COUNT (bb->preds) < 2) - return false; - - /* Don't crossjump if this block ends in a computed jump, - unless we are optimizing for size. */ - if (!optimize_size - && bb != EXIT_BLOCK_PTR - && computed_jump_p (BB_END (bb))) - return false; - - /* If we are partitioning hot/cold basic blocks, we don't want to - mess up unconditional or indirect jumps that cross between hot - and cold sections. - - Basic block partitioning may result in some jumps that appear to - be optimizable (or blocks that appear to be mergeable), but which really - must be left untouched (they are required to make it safely across - partition boundaries). See the comments at the top of - bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */ - - if (BB_PARTITION (EDGE_PRED (bb, 0)->src) != - BB_PARTITION (EDGE_PRED (bb, 1)->src) - || (EDGE_PRED (bb, 0)->flags & EDGE_CROSSING)) - return false; - - /* It is always cheapest to redirect a block that ends in a branch to - a block that falls through into BB, as that adds no branches to the - program. We'll try that combination first. */ - fallthru = NULL; - max = PARAM_VALUE (PARAM_MAX_CROSSJUMP_EDGES); - - if (EDGE_COUNT (bb->preds) > max) - return false; - - FOR_EACH_EDGE (e, ei, bb->preds) - { - if (e->flags & EDGE_FALLTHRU) - fallthru = e; - } - - changed = false; - for (ix = 0, ev = bb; ix < EDGE_COUNT (ev->preds); ) - { - e = EDGE_PRED (ev, ix); - ix++; - - /* As noted above, first try with the fallthru predecessor. */ - if (fallthru) - { - /* Don't combine the fallthru edge into anything else. - If there is a match, we'll do it the other way around. */ - if (e == fallthru) - continue; - /* If nothing changed since the last attempt, there is nothing - we can do. */ - if (!first_pass - && (!(e->src->flags & BB_DIRTY) - && !(fallthru->src->flags & BB_DIRTY))) - continue; - - if (try_crossjump_to_edge (mode, e, fallthru)) - { - changed = true; - ix = 0; - ev = bb; - continue; - } - } - - /* Non-obvious work limiting check: Recognize that we're going - to call try_crossjump_bb on every basic block. So if we have - two blocks with lots of outgoing edges (a switch) and they - share lots of common destinations, then we would do the - cross-jump check once for each common destination. - - Now, if the blocks actually are cross-jump candidates, then - all of their destinations will be shared. Which means that - we only need check them for cross-jump candidacy once. We - can eliminate redundant checks of crossjump(A,B) by arbitrarily - choosing to do the check from the block for which the edge - in question is the first successor of A. */ - if (EDGE_SUCC (e->src, 0) != e) - continue; - - for (ix2 = 0, ev2 = bb; ix2 < EDGE_COUNT (ev2->preds); ) - { - e2 = EDGE_PRED (ev2, ix2); - ix2++; - - if (e2 == e) - continue; - - /* We've already checked the fallthru edge above. */ - if (e2 == fallthru) - continue; - - /* The "first successor" check above only prevents multiple - checks of crossjump(A,B). In order to prevent redundant - checks of crossjump(B,A), require that A be the block - with the lowest index. */ - if (e->src->index > e2->src->index) - continue; - - /* If nothing changed since the last attempt, there is nothing - we can do. */ - if (!first_pass - && (!(e->src->flags & BB_DIRTY) - && !(e2->src->flags & BB_DIRTY))) - continue; - - if (try_crossjump_to_edge (mode, e, e2)) - { - changed = true; - ev2 = bb; - ix = 0; - break; - } - } - } - - return changed; -} - -/* Do simple CFG optimizations - basic block merging, simplifying of jump - instructions etc. Return nonzero if changes were made. */ - -static bool -try_optimize_cfg (int mode) -{ - bool changed_overall = false; - bool changed; - int iterations = 0; - basic_block bb, b, next; - - if (mode & CLEANUP_CROSSJUMP) - add_noreturn_fake_exit_edges (); - - if (mode & (CLEANUP_UPDATE_LIFE | CLEANUP_CROSSJUMP | CLEANUP_THREADING)) - clear_bb_flags (); - - FOR_EACH_BB (bb) - update_forwarder_flag (bb); - - if (! targetm.cannot_modify_jumps_p ()) - { - first_pass = true; - /* 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. */ - do - { - changed = false; - iterations++; - - if (dump_file) - fprintf (dump_file, - "\n\ntry_optimize_cfg iteration %i\n\n", - iterations); - - for (b = ENTRY_BLOCK_PTR->next_bb; b != EXIT_BLOCK_PTR;) - { - basic_block c; - edge s; - bool changed_here = false; - - /* Delete trivially dead basic blocks. */ - while (EDGE_COUNT (b->preds) == 0) - { - c = b->prev_bb; - if (dump_file) - fprintf (dump_file, "Deleting block %i.\n", - b->index); - - delete_basic_block (b); - if (!(mode & CLEANUP_CFGLAYOUT)) - changed = true; - b = c; - } - - /* Remove code labels no longer used. */ - if (single_pred_p (b) - && (single_pred_edge (b)->flags & EDGE_FALLTHRU) - && !(single_pred_edge (b)->flags & EDGE_COMPLEX) - && LABEL_P (BB_HEAD (b)) - /* If the previous block ends with a branch to this - block, we can't delete the label. Normally this - is a condjump that is yet to be simplified, but - if CASE_DROPS_THRU, this can be a tablejump with - some element going to the same place as the - default (fallthru). */ - && (single_pred (b) == ENTRY_BLOCK_PTR - || !JUMP_P (BB_END (single_pred (b))) - || ! label_is_jump_target_p (BB_HEAD (b), - BB_END (single_pred (b))))) - { - rtx label = BB_HEAD (b); - - delete_insn_chain (label, label); - /* In the case label is undeletable, move it after the - BASIC_BLOCK note. */ - if (NOTE_LINE_NUMBER (BB_HEAD (b)) == NOTE_INSN_DELETED_LABEL) - { - rtx bb_note = NEXT_INSN (BB_HEAD (b)); - - reorder_insns_nobb (label, label, bb_note); - BB_HEAD (b) = bb_note; - } - if (dump_file) - fprintf (dump_file, "Deleted label in block %i.\n", - b->index); - } - - /* If we fall through an empty block, we can remove it. */ - if (!(mode & CLEANUP_CFGLAYOUT) - && single_pred_p (b) - && (single_pred_edge (b)->flags & EDGE_FALLTHRU) - && !LABEL_P (BB_HEAD (b)) - && FORWARDER_BLOCK_P (b) - /* Note that forwarder_block_p true ensures that - there is a successor for this block. */ - && (single_succ_edge (b)->flags & EDGE_FALLTHRU) - && n_basic_blocks > NUM_FIXED_BLOCKS + 1) - { - if (dump_file) - fprintf (dump_file, - "Deleting fallthru block %i.\n", - b->index); - - c = b->prev_bb == ENTRY_BLOCK_PTR ? b->next_bb : b->prev_bb; - redirect_edge_succ_nodup (single_pred_edge (b), - single_succ (b)); - delete_basic_block (b); - changed = true; - b = c; - } - - if (single_succ_p (b) - && (s = single_succ_edge (b)) - && !(s->flags & EDGE_COMPLEX) - && (c = s->dest) != EXIT_BLOCK_PTR - && single_pred_p (c) - && b != c) - { - /* When not in cfg_layout mode use code aware of reordering - INSN. This code possibly creates new basic blocks so it - does not fit merge_blocks interface and is kept here in - hope that it will become useless once more of compiler - is transformed to use cfg_layout mode. */ - - if ((mode & CLEANUP_CFGLAYOUT) - && can_merge_blocks_p (b, c)) - { - merge_blocks (b, c); - update_forwarder_flag (b); - changed_here = true; - } - else if (!(mode & CLEANUP_CFGLAYOUT) - /* If the jump insn has side effects, - we can't kill the edge. */ - && (!JUMP_P (BB_END (b)) - || (reload_completed - ? simplejump_p (BB_END (b)) - : (onlyjump_p (BB_END (b)) - && !tablejump_p (BB_END (b), - NULL, NULL)))) - && (next = merge_blocks_move (s, b, c, mode))) - { - b = next; - changed_here = true; - } - } - - /* Simplify branch over branch. */ - if ((mode & CLEANUP_EXPENSIVE) - && !(mode & CLEANUP_CFGLAYOUT) - && try_simplify_condjump (b)) - changed_here = true; - - /* If B has a single outgoing edge, but uses a - non-trivial jump instruction without side-effects, we - can either delete the jump entirely, or replace it - with a simple unconditional jump. */ - if (single_succ_p (b) - && single_succ (b) != EXIT_BLOCK_PTR - && onlyjump_p (BB_END (b)) - && !find_reg_note (BB_END (b), REG_CROSSING_JUMP, NULL_RTX) - && try_redirect_by_replacing_jump (single_succ_edge (b), - single_succ (b), - (mode & CLEANUP_CFGLAYOUT) != 0)) - { - update_forwarder_flag (b); - changed_here = true; - } - - /* Simplify branch to branch. */ - if (try_forward_edges (mode, b)) - changed_here = true; - - /* Look for shared code between blocks. */ - if ((mode & CLEANUP_CROSSJUMP) - && try_crossjump_bb (mode, b)) - changed_here = true; - - /* Don't get confused by the index shift caused by - deleting blocks. */ - if (!changed_here) - b = b->next_bb; - else - changed = true; - } - - if ((mode & CLEANUP_CROSSJUMP) - && try_crossjump_bb (mode, EXIT_BLOCK_PTR)) - changed = true; - -#ifdef ENABLE_CHECKING - if (changed) - verify_flow_info (); -#endif - - changed_overall |= changed; - first_pass = false; - } - while (changed); - } - - if (mode & CLEANUP_CROSSJUMP) - remove_fake_exit_edges (); - - FOR_ALL_BB (b) - b->flags &= ~(BB_FORWARDER_BLOCK | BB_NONTHREADABLE_BLOCK); - - return changed_overall; -} - -/* Delete all unreachable basic blocks. */ - -bool -delete_unreachable_blocks (void) -{ - bool changed = false; - basic_block b, next_bb; - - find_unreachable_blocks (); - - /* Delete all unreachable basic blocks. */ - - for (b = ENTRY_BLOCK_PTR->next_bb; b != EXIT_BLOCK_PTR; b = next_bb) - { - next_bb = b->next_bb; - - if (!(b->flags & BB_REACHABLE)) - { - delete_basic_block (b); - changed = true; - } - } - - if (changed) - tidy_fallthru_edges (); - return changed; -} - -/* Merges sequential blocks if possible. */ - -bool -merge_seq_blocks (void) -{ - basic_block bb; - bool changed = false; - - for (bb = ENTRY_BLOCK_PTR->next_bb; bb != EXIT_BLOCK_PTR; ) - { - if (single_succ_p (bb) - && can_merge_blocks_p (bb, single_succ (bb))) - { - /* Merge the blocks and retry. */ - merge_blocks (bb, single_succ (bb)); - changed = true; - continue; - } - - bb = bb->next_bb; - } - - return changed; -} - -/* Tidy the CFG by deleting unreachable code and whatnot. */ - -bool -cleanup_cfg (int mode) -{ - bool changed = false; - - timevar_push (TV_CLEANUP_CFG); - if (delete_unreachable_blocks ()) - { - changed = true; - /* We've possibly created trivially dead code. Cleanup it right - now to introduce more opportunities for try_optimize_cfg. */ - if (!(mode & (CLEANUP_NO_INSN_DEL | CLEANUP_UPDATE_LIFE)) - && !reload_completed) - delete_trivially_dead_insns (get_insns(), max_reg_num ()); - } - - compact_blocks (); - - while (try_optimize_cfg (mode)) - { - delete_unreachable_blocks (), changed = true; - if (mode & CLEANUP_UPDATE_LIFE) - { - /* Cleaning up CFG introduces more opportunities for dead code - removal that in turn may introduce more opportunities for - cleaning up the CFG. */ - if (!update_life_info_in_dirty_blocks (UPDATE_LIFE_GLOBAL_RM_NOTES, - PROP_DEATH_NOTES - | PROP_SCAN_DEAD_CODE - | PROP_KILL_DEAD_CODE - | ((mode & CLEANUP_LOG_LINKS) - ? PROP_LOG_LINKS : 0))) - break; - } - else if (!(mode & CLEANUP_NO_INSN_DEL) - && (mode & CLEANUP_EXPENSIVE) - && !reload_completed) - { - if (!delete_trivially_dead_insns (get_insns(), max_reg_num ())) - break; - } - else - break; - delete_dead_jumptables (); - } - - timevar_pop (TV_CLEANUP_CFG); - - return changed; -} - -static unsigned int -rest_of_handle_jump (void) -{ - delete_unreachable_blocks (); - - if (cfun->tail_call_emit) - fixup_tail_calls (); - return 0; -} - -struct tree_opt_pass pass_jump = -{ - "sibling", /* name */ - NULL, /* gate */ - rest_of_handle_jump, /* execute */ - NULL, /* sub */ - NULL, /* next */ - 0, /* static_pass_number */ - TV_JUMP, /* tv_id */ - 0, /* properties_required */ - 0, /* properties_provided */ - 0, /* properties_destroyed */ - TODO_ggc_collect, /* todo_flags_start */ - TODO_dump_func | - TODO_verify_flow, /* todo_flags_finish */ - 'i' /* letter */ -}; - - -static unsigned int -rest_of_handle_jump2 (void) -{ - /* Turn NOTE_INSN_EXPECTED_VALUE into REG_BR_PROB. Do this - before jump optimization switches branch directions. */ - if (flag_guess_branch_prob) - expected_value_to_br_prob (); - - delete_trivially_dead_insns (get_insns (), max_reg_num ()); - reg_scan (get_insns (), max_reg_num ()); - if (dump_file) - dump_flow_info (dump_file, dump_flags); - cleanup_cfg ((optimize ? CLEANUP_EXPENSIVE : 0) - | (flag_thread_jumps ? CLEANUP_THREADING : 0)); - - purge_line_number_notes (); - - if (optimize) - cleanup_cfg (CLEANUP_EXPENSIVE); - - /* Jump optimization, and the removal of NULL pointer checks, may - have reduced the number of instructions substantially. CSE, and - future passes, allocate arrays whose dimensions involve the - maximum instruction UID, so if we can reduce the maximum UID - we'll save big on memory. */ - renumber_insns (); - return 0; -} - - -struct tree_opt_pass pass_jump2 = -{ - "jump", /* name */ - NULL, /* gate */ - rest_of_handle_jump2, /* execute */ - NULL, /* sub */ - NULL, /* next */ - 0, /* static_pass_number */ - TV_JUMP, /* tv_id */ - 0, /* properties_required */ - 0, /* properties_provided */ - 0, /* properties_destroyed */ - TODO_ggc_collect, /* todo_flags_start */ - TODO_dump_func, /* todo_flags_finish */ - 'j' /* letter */ -}; - - |