X-Git-Url: http://git.sourceforge.jp/view?a=blobdiff_plain;f=gcc%2Fcfgcleanup.c;h=51182e3f400db64d7933cb480cf985e73f4a2f8b;hb=4e623ed28f4db7f2c056f2f9bf6f69a93b728022;hp=d4a929d50a7dec8db7ba1b7efa6d3ec150c8656c;hpb=1b52f60076a44addfb2e6f9425a62d611b80474c;p=pf3gnuchains%2Fgcc-fork.git diff --git a/gcc/cfgcleanup.c b/gcc/cfgcleanup.c index d4a929d50a7..51182e3f400 100644 --- a/gcc/cfgcleanup.c +++ b/gcc/cfgcleanup.c @@ -1,6 +1,6 @@ /* Control flow optimization code for GNU compiler. Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998, - 1999, 2000, 2001 Free Software Foundation, Inc. + 1999, 2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc. This file is part of GCC. @@ -23,16 +23,18 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA cleanup_cfg. Following optimizations are performed: - Unreachable blocks removal - - Edge forwarding (edge to the forwarder block is forwarded to it's - succesor. Simplification of the branch instruction is performed by + - 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 - elliminated). + 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 "basic-block.h" @@ -42,55 +44,61 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA #include "flags.h" #include "recog.h" #include "toplev.h" - -#include "obstack.h" +#include "cselib.h" +#include "params.h" +#include "tm_p.h" +#include "target.h" +#include "regs.h" +#include "cfglayout.h" +#include "expr.h" /* cleanup_cfg maintains following flags for each basic block. */ -enum bb_flags { - /* Set if life info needs to be recomputed for given BB. */ - BB_UPDATE_LIFE = 1, + +enum bb_flags +{ /* Set if BB is the forwarder block to avoid too many forwarder_block_p calls. */ - BB_FORWARDER_BLOCK = 2 - }; - -#define BB_FLAGS(bb) (enum bb_flags)(bb)->aux -#define BB_SET_FLAG(bb,flag) \ - (bb)->aux = (void *) (long) ((enum bb_flags)(bb)->aux | (flag)) -#define BB_CLEAR_FLAG(bb,flag) \ - (bb)->aux = (void *) (long) ((enum bb_flags)(bb)->aux & ~(flag)) - -#define FORWARDER_BLOCK_P(bb) (BB_FLAGS(bb) & BB_FORWARDER_BLOCK) - -static bool try_crossjump_to_edge PARAMS ((int, edge, edge)); -static bool try_crossjump_bb PARAMS ((int, basic_block)); -static bool outgoing_edges_match PARAMS ((basic_block, basic_block)); -static int flow_find_cross_jump PARAMS ((int, basic_block, basic_block, - rtx *, rtx *)); - -static bool delete_unreachable_blocks PARAMS ((void)); -static bool tail_recursion_label_p PARAMS ((rtx)); -static void merge_blocks_move_predecessor_nojumps PARAMS ((basic_block, - basic_block)); -static void merge_blocks_move_successor_nojumps PARAMS ((basic_block, - basic_block)); -static bool merge_blocks PARAMS ((edge,basic_block,basic_block, - int)); -static bool try_optimize_cfg PARAMS ((int)); -static bool try_simplify_condjump PARAMS ((basic_block)); -static bool try_forward_edges PARAMS ((int, basic_block)); -static void notice_new_block PARAMS ((basic_block)); -static void update_forwarder_flag PARAMS ((basic_block)); + BB_FORWARDER_BLOCK = 1, + BB_NONTHREADABLE_BLOCK = 2 +}; + +#define BB_FLAGS(BB) (enum bb_flags) (BB)->aux +#define BB_SET_FLAG(BB, FLAG) \ + (BB)->aux = (void *) (long) ((enum bb_flags) (BB)->aux | (FLAG)) +#define BB_CLEAR_FLAG(BB, FLAG) \ + (BB)->aux = (void *) (long) ((enum bb_flags) (BB)->aux & ~(FLAG)) + +#define FORWARDER_BLOCK_P(BB) (BB_FLAGS (BB) & 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 insns_match_p (int, rtx, rtx); + +static bool tail_recursion_label_p (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 (bb) - basic_block bb; +notice_new_block (basic_block bb) { if (!bb) return; - BB_SET_FLAG (bb, BB_UPDATE_LIFE); + if (forwarder_block_p (bb)) BB_SET_FLAG (bb, BB_FORWARDER_BLOCK); } @@ -98,8 +106,7 @@ notice_new_block (bb) /* Recompute forwarder flag after block has been modified. */ static void -update_forwarder_flag (bb) - basic_block bb; +update_forwarder_flag (basic_block bb) { if (forwarder_block_p (bb)) BB_SET_FLAG (bb, BB_FORWARDER_BLOCK); @@ -111,12 +118,13 @@ update_forwarder_flag (bb) Return true if something changed. */ static bool -try_simplify_condjump (cbranch_block) - basic_block cbranch_block; +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; + rtx insn, next; + rtx end; /* Verify that there are exactly two successors. */ if (!cbranch_block->succ @@ -126,7 +134,7 @@ try_simplify_condjump (cbranch_block) /* Verify that we've got a normal conditional branch at the end of the block. */ - cbranch_insn = cbranch_block->end; + cbranch_insn = BB_END (cbranch_block); if (!any_condjump_p (cbranch_insn)) return false; @@ -138,11 +146,20 @@ try_simplify_condjump (cbranch_block) unconditional jump. */ jump_block = cbranch_fallthru_edge->dest; if (jump_block->pred->pred_next - || jump_block->index == n_basic_blocks - 1 + || jump_block->next_bb == EXIT_BLOCK_PTR || !FORWARDER_BLOCK_P (jump_block)) return false; jump_dest_block = jump_block->succ->dest; + /* 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. */ + + if (flag_reorder_blocks_and_partition + && (jump_block->partition != jump_dest_block->partition + || cbranch_jump_edge->crossing_edge)) + return false; + /* The conditional branch must target the block after the unconditional branch. */ cbranch_dest_block = cbranch_jump_edge->dest; @@ -154,9 +171,9 @@ try_simplify_condjump (cbranch_block) if (!invert_jump (cbranch_insn, block_label (jump_dest_block), 0)) return false; - if (rtl_dump_file) - fprintf (rtl_dump_file, "Simplifying condjump %i around jump %i\n", - INSN_UID (cbranch_insn), INSN_UID (jump_block->end)); + 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 @@ -167,53 +184,345 @@ try_simplify_condjump (cbranch_block) jump_dest_block); cbranch_jump_edge->flags |= EDGE_FALLTHRU; cbranch_fallthru_edge->flags &= ~EDGE_FALLTHRU; - + update_br_prob_note (cbranch_block); + + end = BB_END (jump_block); + /* Deleting a block may produce unreachable code warning even when we are + not deleting anything live. Suppress it by moving all the line number + notes out of the block. */ + for (insn = BB_HEAD (jump_block); insn != NEXT_INSN (BB_END (jump_block)); + insn = next) + { + next = NEXT_INSN (insn); + if (GET_CODE (insn) == NOTE && NOTE_LINE_NUMBER (insn) > 0) + { + if (insn == BB_END (jump_block)) + { + BB_END (jump_block) = PREV_INSN (insn); + if (insn == end) + break; + } + reorder_insns_nobb (insn, insn, end); + end = insn; + } + } /* Delete the block with the unconditional jump, and clean up the mess. */ - flow_delete_block (jump_block); - tidy_fallthru_edge (cbranch_jump_edge, cbranch_block, cbranch_dest_block); + delete_basic_block (jump_block); + tidy_fallthru_edge (cbranch_jump_edge); 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; + int i; + regset nonequal; + bool failed = false; + + if (BB_FLAGS (b) & 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 (!e->src->succ->succ_next || e->src->succ->succ_next->succ_next) + return NULL; + if (!b->succ || !b->succ->succ_next || b->succ->succ_next->succ_next) + { + BB_SET_FLAG (b, 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))) + { + BB_SET_FLAG (b, 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))) + { + BB_SET_FLAG (b, 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_XMALLOC(); + 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 < 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) + { + BB_SET_FLAG (b, 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->global_live_at_end); + + EXECUTE_IF_SET_IN_REG_SET (nonequal, 0, i, goto failed_exit;); + + BITMAP_XFREE (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_XFREE (nonequal); + cselib_finish (); + return NULL; +} + /* Attempt to forward edges leaving basic block B. - Return true if sucessful. */ + Return true if successful. */ static bool -try_forward_edges (mode, b) - basic_block b; - int mode; +try_forward_edges (int mode, basic_block b) { bool changed = false; - edge e, next; + edge e, next, *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. */ + + if (flag_reorder_blocks_and_partition + && find_reg_note (BB_END (b), REG_CROSSING_JUMP, NULL_RTX)) + return false; - for (e = b->succ; e ; e = next) + for (e = b->succ; e; e = next) { basic_block target, first; int counter; + bool threaded = false; + int nthreaded_edges = 0; + bool may_thread = first_pass | (b->flags & BB_DIRTY); next = e->succ_next; /* Skip complex edges because we don't know how to update them. - Still handle fallthru edges, as we can suceed to forward fallthru + 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 unconditonal branch. */ + and turn conditional branch to an unconditional branch. */ if (e->flags & EDGE_COMPLEX) continue; target = first = e->dest; counter = 0; - /* Look for the real destination of the jump. - Avoid inifinite loop in the infinite empty loop by counting - up to n_basic_blocks. */ - while (FORWARDER_BLOCK_P (target) - && target->succ->dest != EXIT_BLOCK_PTR - && counter < n_basic_blocks) + while (counter < n_basic_blocks) { - /* Bypass trivial infinite loops. */ - if (target == target->succ->dest) - 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) + && target->succ->dest != EXIT_BLOCK_PTR) + { + /* Bypass trivial infinite loops. */ + if (target == target->succ->dest) + counter = n_basic_blocks; + new_target = target->succ->dest; + } + + /* 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 = xmalloc (sizeof (*threaded_edges) + * 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; + + if (nthreaded_edges >= n_basic_blocks) + abort (); + threaded_edges[nthreaded_edges++] = t; + + new_target = t->dest; + new_target_threaded = true; + } + } + + if (!new_target) + break; /* Avoid killing of loop pre-headers, as it is the place loop optimizer wants to hoist code to. @@ -221,15 +530,15 @@ try_forward_edges (mode, b) For fallthru forwarders, the LOOP_BEG note must appear between the header of block and CODE_LABEL of the loop, for non forwarders it must appear before the JUMP_INSN. */ - if (mode & CLEANUP_PRE_LOOP) + if ((mode & CLEANUP_PRE_LOOP) && optimize) { rtx insn = (target->succ->flags & EDGE_FALLTHRU - ? target->head : prev_nonnote_insn (target->end)); + ? BB_HEAD (target) : prev_nonnote_insn (BB_END (target))); if (GET_CODE (insn) != NOTE) insn = NEXT_INSN (insn); - for (;insn && GET_CODE (insn) != CODE_LABEL && !INSN_P (insn); + for (; insn && GET_CODE (insn) != CODE_LABEL && !INSN_P (insn); insn = NEXT_INSN (insn)) if (GET_CODE (insn) == NOTE && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG) @@ -237,14 +546,26 @@ try_forward_edges (mode, b) if (GET_CODE (insn) == NOTE) break; + + /* Do not clean up branches to just past the end of a loop + at this time; it can mess up the loop optimizer's + recognition of some patterns. */ + + insn = PREV_INSN (BB_HEAD (target)); + if (insn && GET_CODE (insn) == NOTE + && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END) + break; } - target = target->succ->dest, counter++; + + counter++; + target = new_target; + threaded |= new_target_threaded; } if (counter >= n_basic_blocks) { - if (rtl_dump_file) - fprintf (rtl_dump_file, "Infinite loop in BB %i.\n", + if (dump_file) + fprintf (dump_file, "Infinite loop in BB %i.\n", target->index); } else if (target == first) @@ -254,48 +575,105 @@ try_forward_edges (mode, b) /* 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; - if (redirect_edge_and_branch (e, target)) + /* Don't force if target is exit block. */ + if (threaded && target != EXIT_BLOCK_PTR) { - /* We successfully forwarded the edge. Now update profile - data: for each edge we traversed in the chain, remove - the original edge's execution count. */ - int edge_frequency = ((edge_probability * b->frequency - + REG_BR_PROB_BASE / 2) - / REG_BR_PROB_BASE); - - if (!FORWARDER_BLOCK_P (b) && forwarder_block_p (b)) - BB_SET_FLAG (b, BB_FORWARDER_BLOCK); - BB_SET_FLAG (b, BB_UPDATE_LIFE); - - do - { - first->count -= edge_count; - first->succ->count -= edge_count; - first->frequency -= edge_frequency; - first = first->succ->dest; - } - while (first != target); - - changed = true; + notice_new_block (redirect_edge_and_branch_force (e, target)); + if (dump_file) + fprintf (dump_file, "Conditionals threaded.\n"); } - else + else if (!redirect_edge_and_branch (e, target)) { - if (rtl_dump_file) - fprintf (rtl_dump_file, "Forwarding edge %i->%i to %i failed.\n", + if (dump_file) + fprintf (dump_file, + "Forwarding edge %i->%i to %i failed.\n", b->index, e->dest->index, target->index); + 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)) + BB_SET_FLAG (b, BB_FORWARDER_BLOCK); + + do + { + edge t; + + first->count -= edge_count; + if (first->count < 0) + first->count = 0; + first->frequency -= edge_frequency; + if (first->frequency < 0) + first->frequency = 0; + if (first->succ->succ_next) + { + edge e; + int prob; + if (n >= nthreaded_edges) + abort (); + t = threaded_edges [n++]; + if (t->src != first) + abort (); + if (first->frequency) + prob = edge_frequency * REG_BR_PROB_BASE / first->frequency; + else + prob = 0; + if (prob > t->probability) + prob = t->probability; + t->probability -= prob; + prob = REG_BR_PROB_BASE - prob; + if (prob <= 0) + { + first->succ->probability = REG_BR_PROB_BASE; + first->succ->succ_next->probability = 0; + } + else + for (e = first->succ; e; e = e->succ_next) + e->probability = ((e->probability * REG_BR_PROB_BASE) + / (double) prob); + update_br_prob_note (first); + } + else + { + /* 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 = first->succ; + } + + t->count -= edge_count; + if (t->count < 0) + t->count = 0; + first = t->dest; + } + while (first != target); + + changed = true; } } + if (threaded_edges) + free (threaded_edges); return changed; } /* Return true if LABEL is used for tail recursion. */ static bool -tail_recursion_label_p (label) - rtx label; +tail_recursion_label_p (rtx label) { rtx x; @@ -311,13 +689,20 @@ tail_recursion_label_p (label) any jumps (aside from the jump from A to B). */ static void -merge_blocks_move_predecessor_nojumps (a, b) - basic_block a, b; +merge_blocks_move_predecessor_nojumps (basic_block a, basic_block b) { rtx barrier; - int index; - barrier = next_nonnote_insn (a->end); + /* 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. */ + + if (flag_reorder_blocks_and_partition + && (a->partition != b->partition + || find_reg_note (BB_END (a), REG_CROSSING_JUMP, NULL_RTX))) + return; + + barrier = next_nonnote_insn (BB_END (a)); if (GET_CODE (barrier) != BARRIER) abort (); delete_insn (barrier); @@ -329,30 +714,25 @@ merge_blocks_move_predecessor_nojumps (a, b) 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. */ - squeeze_notes (&a->head, &a->end); + if (squeeze_notes (&BB_HEAD (a), &BB_END (a))) + abort (); /* Scramble the insn chain. */ - if (a->end != PREV_INSN (b->head)) - reorder_insns_nobb (a->head, a->end, PREV_INSN (b->head)); - BB_SET_FLAG (a, BB_UPDATE_LIFE); + 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 (rtl_dump_file) - { - fprintf (rtl_dump_file, "Moved block %d before %d and merged.\n", - a->index, b->index); - } + 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. */ - /* 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; + unlink_block (a); + link_block (a, b->prev_bb); /* Now blocks A and B are contiguous. Merge them. */ - merge_blocks_nomove (a, b); + merge_blocks (a, b); } /* Blocks A and B are to be merged into a single block. B has no outgoing @@ -360,29 +740,32 @@ merge_blocks_move_predecessor_nojumps (a, b) any jumps (aside from the jump from A to B). */ static void -merge_blocks_move_successor_nojumps (a, b) - basic_block a, b; +merge_blocks_move_successor_nojumps (basic_block a, basic_block b) { rtx barrier, real_b_end; + rtx label, table; + + /* 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. */ + + if (flag_reorder_blocks_and_partition + && (find_reg_note (BB_END (a), REG_CROSSING_JUMP, NULL_RTX) + || a->partition != b->partition)) + return; - real_b_end = b->end; - barrier = NEXT_INSN (b->end); + real_b_end = BB_END (b); - /* Recognize a jump table following block B. */ - if (barrier - && 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)) + /* 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)) { - /* Temporarily add the table jump insn to b, so that it will also - be moved to the correct location. */ - b->end = NEXT_INSN (barrier); - barrier = NEXT_INSN (b->end); + BB_END (b) = table; } /* There had better have been a barrier there. Delete it. */ + barrier = NEXT_INSN (BB_END (b)); if (barrier && GET_CODE (barrier) == BARRIER) delete_insn (barrier); @@ -393,63 +776,74 @@ merge_blocks_move_successor_nojumps (a, b) 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. */ - squeeze_notes (&b->head, &b->end); + if (squeeze_notes (&BB_HEAD (b), &BB_END (b))) + abort (); /* Scramble the insn chain. */ - reorder_insns_nobb (b->head, b->end, a->end); + reorder_insns_nobb (BB_HEAD (b), BB_END (b), BB_END (a)); /* Restore the real end of b. */ - b->end = real_b_end; + BB_END (b) = real_b_end; - /* Now blocks A and B are contiguous. Merge them. */ - merge_blocks_nomove (a, b); - BB_SET_FLAG (a, BB_UPDATE_LIFE); + if (dump_file) + fprintf (dump_file, "Moved block %d after %d and merged.\n", + b->index, a->index); - if (rtl_dump_file) - { - fprintf (rtl_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 true iff the attempt succeeded. */ - -static bool -merge_blocks (e, b, c, mode) - edge e; - basic_block b, c; - int mode; + 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 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 ((mode & CLEANUP_PRE_SIBCALL) - && GET_CODE (c->head) == CODE_LABEL - && tail_recursion_label_p (c->head)) - return false; + && GET_CODE (BB_HEAD (c)) == CODE_LABEL + && tail_recursion_label_p (BB_HEAD (c))) + return 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. */ + + if (flag_reorder_blocks_and_partition + && (find_reg_note (BB_END (b), REG_CROSSING_JUMP, NULL_RTX) + || find_reg_note (BB_END (c), REG_CROSSING_JUMP, NULL_RTX) + || b->partition != c->partition)) + return NULL; + + /* If B has a fallthru edge to C, no need to move anything. */ if (e->flags & EDGE_FALLTHRU) { - /* We need to update liveness in case C already has broken liveness - or B ends by conditional jump to next instructions that will be - removed. */ - if ((BB_FLAGS (c) & BB_UPDATE_LIFE) - || GET_CODE (b->end) == JUMP_INSN) - BB_SET_FLAG (b, BB_UPDATE_LIFE); - merge_blocks_nomove (b, c); + int b_index = b->index, c_index = c->index; + merge_blocks (b, c); update_forwarder_flag (b); - if (rtl_dump_file) - { - fprintf (rtl_dump_file, "Merged %d and %d without moving.\n", - b->index, c->index); - } + if (dump_file) + fprintf (dump_file, "Merged %d and %d without moving.\n", + b_index, c_index); - return true; + 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) @@ -463,7 +857,7 @@ merge_blocks (e, b, c, mode) 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 false; + 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 @@ -472,13 +866,18 @@ merge_blocks (e, b, c, mode) 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); 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 @@ -486,7 +885,7 @@ merge_blocks (e, b, c, mode) if (! c_has_outgoing_fallthru) { merge_blocks_move_successor_nojumps (b, c); - return true; + return next == ENTRY_BLOCK_PTR ? next->next_bb : next; } /* If B does not have an incoming fallthru, then it can be moved @@ -497,154 +896,268 @@ merge_blocks (e, b, c, mode) if (b_has_incoming_fallthru) { basic_block bb; + if (b_fallthru_edge->src == ENTRY_BLOCK_PTR) - return false; + return NULL; bb = force_nonfallthru (b_fallthru_edge); if (bb) notice_new_block (bb); - else - BB_SET_FLAG (b_fallthru_edge->src, BB_UPDATE_LIFE); } + merge_blocks_move_predecessor_nojumps (b, c); - return true; + return next == ENTRY_BLOCK_PTR ? next->next_bb : next; } - return false; + + return NULL; } -/* 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. */ +/* Removes the memory attributes of MEM expression + if they are not equal. */ -static int -flow_find_cross_jump (mode, bb1, bb2, f1, f2) - int mode ATTRIBUTE_UNUSED; - basic_block bb1, bb2; - rtx *f1, *f2; +void +merge_memattrs (rtx x, rtx y) { - rtx i1, i2, p1, p2, last1, last2, afterlast1, afterlast2; - int ninsns = 0; + int i; + int j; + enum rtx_code code; + const char *fmt; - /* Skip simple jumps at the end of the blocks. Complex jumps still - need to be compared for equivalence, which we'll do below. */ + if (x == y) + return; + if (x == 0 || y == 0) + return; - i1 = bb1->end; - if (onlyjump_p (i1) - || (returnjump_p (i1) && !side_effects_p (PATTERN (i1)))) - i1 = PREV_INSN (i1); - i2 = bb2->end; - if (onlyjump_p (i2) - || (returnjump_p (i2) && !side_effects_p (PATTERN (i2)))) - i2 = PREV_INSN (i2); + code = GET_CODE (x); - last1 = afterlast1 = last2 = afterlast2 = NULL_RTX; - while (true) + if (code != GET_CODE (y)) + return; + + if (GET_MODE (x) != GET_MODE (y)) + return; + + if (code == MEM && MEM_ATTRS (x) != MEM_ATTRS (y)) { - /* Ignore notes. */ - while ((GET_CODE (i1) == NOTE && i1 != bb1->head)) - i1 = PREV_INSN (i1); - while ((GET_CODE (i2) == NOTE && i2 != bb2->head)) - i2 = PREV_INSN (i2); + if (! MEM_ATTRS (x)) + MEM_ATTRS (y) = 0; + else if (! MEM_ATTRS (y)) + MEM_ATTRS (x) = 0; + else + { + 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); + } + + set_mem_size (x, MAX (MEM_SIZE (x), MEM_SIZE (y))); + set_mem_size (y, MEM_SIZE (x)); - if (i1 == bb1->head || i2 == bb2->head) - break; + 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; - /* Verify that I1 and I2 are equivalent. */ + 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; +} - if (GET_CODE (i1) != GET_CODE (i2)) - break; - p1 = PATTERN (i1); - p2 = PATTERN (i2); +/* Return true if I1 and I2 are equivalent and thus can be crossjumped. */ - /* 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. +static bool +insns_match_p (int mode ATTRIBUTE_UNUSED, rtx i1, rtx i2) +{ + rtx p1, p2; - ??? We take the simple route for now and assume that if they're - equal, they were constructed identically. */ + /* Verify that I1 and I2 are equivalent. */ + if (GET_CODE (i1) != GET_CODE (i2)) + return false; - if (GET_CODE (i1) == CALL_INSN - && ! rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1), - CALL_INSN_FUNCTION_USAGE (i2))) - break; + 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 (GET_CODE (i1) == CALL_INSN + && (!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 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. */ + 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; + rtx note; + HARD_REG_SET i1_regset, i2_regset; - CLEAR_HARD_REG_SET (i1_regset); - CLEAR_HARD_REG_SET (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 (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))); + 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); + GO_IF_HARD_REG_EQUAL (i1_regset, i2_regset, done); - break; + return false; - done: - ; - } + done: + ; + } #endif - if (GET_CODE (p1) != GET_CODE (p2)) - break; + if (reload_completed + ? rtx_renumbered_equal_p (p1, p2) : rtx_equal_p (p1, p2)) + return true; - if (! rtx_renumbered_equal_p (p1, p2)) + /* 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))))) { - /* 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. */ - && 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))) { - 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 ()) - goto win; - } + 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; } - break; } + } + + 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 (!insns_match_p (mode, i1, i2)) + break; - win: - /* Don't begin a cross-jump with a USE or CLOBBER insn. */ - if (GET_CODE (p1) != USE && GET_CODE (p1) != CLOBBER) + 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. */ @@ -661,37 +1174,38 @@ flow_find_cross_jump (mode, bb1, bb2, f1, f2) remove_note (i1, equiv1); remove_note (i2, equiv2); } - + afterlast1 = last1, afterlast2 = last2; last1 = i1, last2 = i2; - ninsns++; + ninsns++; } + i1 = PREV_INSN (i1); i2 = PREV_INSN (i2); } #ifdef HAVE_cc0 - if (ninsns) - { - /* Don't allow the insn after a compare to be shared by - cross-jumping unless the compare is also shared. */ - if (reg_mentioned_p (cc0_rtx, last1) && ! sets_cc0_p (last1)) - last1 = afterlast1, last2 = afterlast2, ninsns--; - } + /* 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 preceeding notes and labels in the cross-jump. One, + /* 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 != bb1->head && GET_CODE (PREV_INSN (last1)) == NOTE) + while (last1 != BB_HEAD (bb1) && !INSN_P (PREV_INSN (last1))) last1 = PREV_INSN (last1); - if (last1 != bb1->head && GET_CODE (PREV_INSN (last1)) == CODE_LABEL) + + if (last1 != BB_HEAD (bb1) && GET_CODE (PREV_INSN (last1)) == CODE_LABEL) last1 = PREV_INSN (last1); - while (last2 != bb2->head && GET_CODE (PREV_INSN (last2)) == NOTE) + + while (last2 != BB_HEAD (bb2) && !INSN_P (PREV_INSN (last2))) last2 = PREV_INSN (last2); - if (last2 != bb2->head && GET_CODE (PREV_INSN (last2)) == CODE_LABEL) + + if (last2 != BB_HEAD (bb2) && GET_CODE (PREV_INSN (last2)) == CODE_LABEL) last2 = PREV_INSN (last2); *f1 = last1; @@ -708,22 +1222,28 @@ flow_find_cross_jump (mode, bb1, bb2, f1, f2) We may assume that there exists one edge with a common destination. */ static bool -outgoing_edges_match (bb1, bb2) - basic_block bb1; - basic_block bb2; +outgoing_edges_match (int mode, basic_block bb1, basic_block bb2) { - /* If BB1 has only one successor, we must be looking at an unconditional - jump. Which, by the assumption above, means that we only need to check - that BB2 has one successor. */ - if (bb1->succ && !bb1->succ->succ_next) - return (bb2->succ && !bb2->succ->succ_next); + int nehedges1 = 0, nehedges2 = 0; + edge fallthru1 = 0, fallthru2 = 0; + edge e1, e2; + + /* If BB1 has only one successor, we may be looking at either an + unconditional jump, or a fake edge to exit. */ + if (bb1->succ && !bb1->succ->succ_next + && (bb1->succ->flags & (EDGE_COMPLEX | EDGE_FAKE)) == 0 + && (GET_CODE (BB_END (bb1)) != JUMP_INSN || simplejump_p (BB_END (bb1)))) + return (bb2->succ && !bb2->succ->succ_next + && (bb2->succ->flags & (EDGE_COMPLEX | EDGE_FAKE)) == 0 + && (GET_CODE (BB_END (bb2)) != JUMP_INSN || simplejump_p (BB_END (bb2)))); /* Match conditional jumps - this may get tricky when fallthru and branch edges are crossed. */ if (bb1->succ && bb1->succ->succ_next && !bb1->succ->succ_next->succ_next - && any_condjump_p (bb1->end)) + && any_condjump_p (BB_END (bb1)) + && onlyjump_p (BB_END (bb1))) { edge b1, f1, b2, f2; bool reverse, match; @@ -731,9 +1251,10 @@ outgoing_edges_match (bb1, bb2) enum rtx_code code1, code2; if (!bb2->succ - || !bb2->succ->succ_next - || bb1->succ->succ_next->succ_next - || !any_condjump_p (bb2->end)) + || !bb2->succ->succ_next + || bb2->succ->succ_next->succ_next + || !any_condjump_p (BB_END (bb2)) + || !onlyjump_p (BB_END (bb2))) return false; b1 = BRANCH_EDGE (bb1); @@ -745,6 +1266,7 @@ outgoing_edges_match (bb1, bb2) should be optimized out already. */ if (FORWARDER_BLOCK_P (f1->dest)) f1 = f1->dest->succ; + if (FORWARDER_BLOCK_P (f2->dest)) f2 = f2->dest->succ; @@ -764,8 +1286,8 @@ outgoing_edges_match (bb1, bb2) else return false; - set1 = pc_set (bb1->end); - set2 = pc_set (bb2->end); + 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; @@ -774,9 +1296,10 @@ outgoing_edges_match (bb1, bb2) cond2 = XEXP (SET_SRC (set2), 0); code1 = GET_CODE (cond1); if (reverse) - code2 = reversed_comparison_code (cond2, bb2->end); + code2 = reversed_comparison_code (cond2, BB_END (bb2)); else code2 = GET_CODE (cond2); + if (code2 == UNKNOWN) return false; @@ -794,43 +1317,175 @@ outgoing_edges_match (bb1, bb2) we will only have one branch prediction bit to work with. Thus we require the existing branches to have probabilities that are roughly similar. */ - /* ??? We should use bb->frequency to allow merging in infrequently - executed blocks, but at the moment it is not available when - cleanup_cfg is run. */ - if (match && !optimize_size) + if (match + && !optimize_size + && maybe_hot_bb_p (bb1) + && maybe_hot_bb_p (bb2)) { - rtx note1, note2; - int prob1, prob2; - note1 = find_reg_note (bb1->end, REG_BR_PROB, 0); - note2 = find_reg_note (bb2->end, REG_BR_PROB, 0); + 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; - if (note1 && note2) + /* 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) { - prob1 = INTVAL (XEXP (note1, 0)); - prob2 = INTVAL (XEXP (note2, 0)); - if (reverse) - prob2 = REG_BR_PROB_BASE - prob2; - - /* Fail if the difference in probabilities is - greater than 5%. */ - if (abs (prob1 - prob2) > REG_BR_PROB_BASE / 20) - return false; + if (dump_file) + fprintf (dump_file, + "Outcomes of branch in bb %i and %i differs to much (%i %i)\n", + bb1->index, bb2->index, b1->probability, prob2); + + return false; } - else if (note1 || note2) - return false; } - if (rtl_dump_file && match) - fprintf (rtl_dump_file, "Conditionals in bb %i and %i match.\n", + if (dump_file && match) + fprintf (dump_file, "Conditionals in bb %i and %i match.\n", bb1->index, bb2->index); return match; } - /* ??? We can handle computed jumps too. This may be important for - inlined functions containing switch statements. Also jumps w/o - fallthru edges can be handled by simply matching whole insn. */ - return false; + /* Generic case - we are seeing a computed jump, table jump or trapping + instruction. */ + +#ifndef CASE_DROPS_THROUGH + /* 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_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 = 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; + } + } +#endif + + /* First ensure that the instructions match. There may be many outgoing + edges so this test is generally cheaper. */ + if (!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. */ + for (e1 = bb1->succ, e2 = bb2->succ; e1 && e2; + e1 = e1->succ_next, e2 = e2->succ_next) + { + 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 (e1 || e2 + || 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) + ? fallthru1->dest->succ->dest: fallthru1->dest); + basic_block d2 = (forwarder_block_p (fallthru2->dest) + ? fallthru2->dest->succ->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; + } + + /* We don't need to match the rest of edges as above checks should be enough + to ensure that they are equivalent. */ + return true; } /* E1 and E2 are edges with the same destination block. Search their @@ -838,18 +1493,19 @@ outgoing_edges_match (bb1, bb2) (maybe the middle of) E1->SRC to (maybe the middle of) E2->SRC. */ static bool -try_crossjump_to_edge (mode, e1, e2) - int mode; - edge e1, e2; +try_crossjump_to_edge (int mode, edge e1, edge e2) { int nmatch; basic_block src1 = e1->src, src2 = e2->src; - basic_block redirect_to; + basic_block redirect_to, redirect_from, to_remove; rtx newpos1, newpos2; edge s; - rtx last; - rtx label; - rtx note; + + /* If we have partitioned hot/cold basic blocks, it is a bad idea + to try this optimization. */ + + 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 @@ -858,17 +1514,12 @@ try_crossjump_to_edge (mode, e1, e2) if (src1->pred && !src1->pred->pred_next && FORWARDER_BLOCK_P (src1)) - { - e1 = src1->pred; - src1 = e1->src; - } + e1 = src1->pred, src1 = e1->src; + if (src2->pred && !src2->pred->pred_next && FORWARDER_BLOCK_P (src2)) - { - e2 = src2->pred; - src2 = e2->src; - } + e2 = src2->pred, src2 = e2->src; /* Nothing to do if we reach ENTRY, or a common source block. */ if (src1 == ENTRY_BLOCK_PTR || src2 == ENTRY_BLOCK_PTR) @@ -880,6 +1531,7 @@ try_crossjump_to_edge (mode, e1, e2) if (FORWARDER_BLOCK_P (e1->dest) && FORWARDER_BLOCK_P (e1->dest->succ->dest)) return false; + if (FORWARDER_BLOCK_P (e2->dest) && FORWARDER_BLOCK_P (e2->dest->succ->dest)) return false; @@ -889,14 +1541,8 @@ try_crossjump_to_edge (mode, e1, e2) if (!src1->pred || !src2->pred) return false; - /* Likewise with complex edges. - ??? We should be able to handle most complex edges later with some - care. */ - if (e1->flags & EDGE_COMPLEX) - return false; - /* Look for the common insn sequence, part the first ... */ - if (!outgoing_edges_match (src1, src2)) + if (!outgoing_edges_match (mode, src1, src2)) return false; /* ... and part the second. */ @@ -904,24 +1550,59 @@ try_crossjump_to_edge (mode, e1, e2) if (!nmatch) return false; +#ifndef CASE_DROPS_THROUGH + /* 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); + } + } + } +#endif + /* Avoid splitting if possible. */ - if (newpos2 == src2->head) + if (newpos2 == BB_HEAD (src2)) redirect_to = src2; else { - if (rtl_dump_file) - fprintf (rtl_dump_file, "Splitting bb %i before %i insns\n", + 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 (rtl_dump_file) - fprintf (rtl_dump_file, + 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 trought the block. */ + redirect_to->flags |= BB_DIRTY; /* Recompute the frequencies and counts of outgoing edges. */ for (s = redirect_to->succ; s; s = s->succ_next) @@ -931,6 +1612,7 @@ try_crossjump_to_edge (mode, e1, e2) if (FORWARDER_BLOCK_P (d)) d = d->succ->dest; + for (s2 = src1->succ; ; s2 = s2->succ_next) { basic_block d2 = s2->dest; @@ -939,6 +1621,7 @@ try_crossjump_to_edge (mode, e1, e2) if (d == d2) break; } + s->count += s2->count; /* Take care to update possible forwarder blocks. We verified @@ -950,55 +1633,47 @@ try_crossjump_to_edge (mode, e1, e2) s->dest->count += s2->count; s->dest->frequency += EDGE_FREQUENCY (s); } + if (FORWARDER_BLOCK_P (s2->dest)) { s2->dest->succ->count -= s2->count; + if (s2->dest->succ->count < 0) + s2->dest->succ->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)); + s->probability + = ((s->probability * redirect_to->frequency + + s2->probability * src1->frequency) + / (redirect_to->frequency + src1->frequency)); } - note = find_reg_note (redirect_to->end, REG_BR_PROB, 0); - if (note) - XEXP (note, 0) = GEN_INT (BRANCH_EDGE (redirect_to)->probability); + update_br_prob_note (redirect_to); /* Edit SRC1 to go to REDIRECT_TO at NEWPOS1. */ /* Skip possible basic block header. */ if (GET_CODE (newpos1) == CODE_LABEL) newpos1 = NEXT_INSN (newpos1); + if (GET_CODE (newpos1) == NOTE) newpos1 = NEXT_INSN (newpos1); - last = src1->end; - - /* Emit the jump insn. */ - label = block_label (redirect_to); - emit_jump_insn_after (gen_jump (label), src1->end); - JUMP_LABEL (src1->end) = label; - LABEL_NUSES (label)++; - /* Delete the now unreachable instructions. */ - delete_insn_chain (newpos1, last); + redirect_from = split_block (src1, PREV_INSN (newpos1))->src; + to_remove = redirect_from->succ->dest; - /* Make sure there is a barrier after the new jump. */ - last = next_nonnote_insn (src1->end); - if (!last || GET_CODE (last) != BARRIER) - emit_barrier_after (src1->end); + redirect_edge_and_branch_force (redirect_from->succ, redirect_to); + delete_basic_block (to_remove); - /* Update CFG. */ - while (src1->succ) - remove_edge (src1->succ); - make_single_succ_edge (src1, redirect_to, 0); - - BB_SET_FLAG (src1, BB_UPDATE_LIFE); - update_forwarder_flag (src1); + update_forwarder_flag (redirect_from); return true; } @@ -1008,34 +1683,43 @@ try_crossjump_to_edge (mode, e1, e2) any changes made. */ static bool -try_crossjump_bb (mode, bb) - int mode; - basic_block bb; +try_crossjump_bb (int mode, basic_block bb) { edge e, e2, nexte2, nexte, fallthru; bool changed; + int n = 0, max; /* Nothing to do if there is not at least two incoming edges. */ if (!bb->pred || !bb->pred->pred_next) 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. */ + + if (flag_reorder_blocks_and_partition + && (bb->pred->src->partition != bb->pred->pred_next->src->partition + || bb->pred->crossing_edge)) + 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. */ - for (fallthru = bb->pred; fallthru; fallthru = fallthru->pred_next) - if (fallthru->flags & EDGE_FALLTHRU) - break; + fallthru = NULL; + max = PARAM_VALUE (PARAM_MAX_CROSSJUMP_EDGES); + for (e = bb->pred; e ; e = e->pred_next, n++) + { + if (e->flags & EDGE_FALLTHRU) + fallthru = e; + if (n > max) + return false; + } changed = false; for (e = bb->pred; e; e = nexte) { nexte = e->pred_next; - /* Elide complex edges now, as neither try_crossjump_to_edge - nor outgoing_edges_match can handle them. */ - if (e->flags & EDGE_COMPLEX) - continue; - /* As noted above, first try with the fallthru predecessor. */ if (fallthru) { @@ -1043,6 +1727,12 @@ try_crossjump_bb (mode, bb) 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)) { @@ -1078,11 +1768,6 @@ try_crossjump_bb (mode, bb) if (e2 == fallthru) continue; - /* Again, neither try_crossjump_to_edge nor outgoing_edges_match - can handle complex edges. */ - if (e2->flags & EDGE_COMPLEX) - 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 @@ -1090,6 +1775,13 @@ try_crossjump_bb (mode, bb) 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; @@ -1106,201 +1798,235 @@ try_crossjump_bb (mode, bb) instructions etc. Return nonzero if changes were made. */ static bool -try_optimize_cfg (mode) - int mode; +try_optimize_cfg (int mode) { - int i; bool changed_overall = false; bool changed; int iterations = 0; - sbitmap blocks; + basic_block bb, b, next; if (mode & CLEANUP_CROSSJUMP) add_noreturn_fake_exit_edges (); - for (i = 0; i < n_basic_blocks; i++) - update_forwarder_flag (BASIC_BLOCK (i)); + FOR_EACH_BB (bb) + update_forwarder_flag (bb); - /* 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. */ + if (mode & (CLEANUP_UPDATE_LIFE | CLEANUP_CROSSJUMP | CLEANUP_THREADING)) + clear_bb_flags (); - do + if (! targetm.cannot_modify_jumps_p ()) { - changed = false; - iterations++; - - if (rtl_dump_file) - fprintf (rtl_dump_file, "\n\ntry_optimize_cfg iteration %i\n\n", - iterations); - - for (i = 0; i < n_basic_blocks;) + 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 { - basic_block c, b = BASIC_BLOCK (i); - edge s; - bool changed_here = false; + changed = false; + iterations++; - /* Delete trivially dead basic blocks. */ - while (b->pred == NULL) - { - c = BASIC_BLOCK (b->index - 1); - if (rtl_dump_file) - fprintf (rtl_dump_file, "Deleting block %i.\n", b->index); - flow_delete_block (b); - changed = true; - b = c; - } + if (dump_file) + fprintf (dump_file, + "\n\ntry_optimize_cfg iteration %i\n\n", + iterations); - /* Remove code labels no longer used. Don't do this before - CALL_PLACEHOLDER is removed, as some branches may be hidden - within. */ - if (b->pred->pred_next == NULL - && (b->pred->flags & EDGE_FALLTHRU) - && !(b->pred->flags & EDGE_COMPLEX) - && GET_CODE (b->head) == CODE_LABEL - && (!(mode & CLEANUP_PRE_SIBCALL) - || !tail_recursion_label_p (b->head)) - /* If previous block ends with condjump jumping to next BB, - we can't delete the label. */ - && (b->pred->src == ENTRY_BLOCK_PTR - || !reg_mentioned_p (b->head, b->pred->src->end))) + for (b = ENTRY_BLOCK_PTR->next_bb; b != EXIT_BLOCK_PTR;) { - rtx label = b->head; - b->head = NEXT_INSN (b->head); - delete_insn_chain (label, label); - if (rtl_dump_file) - fprintf (rtl_dump_file, "Deleted label in block %i.\n", - b->index); - } + basic_block c; + edge s; + bool changed_here = false; - /* If we fall through an empty block, we can remove it. */ - if (b->pred->pred_next == NULL - && (b->pred->flags & EDGE_FALLTHRU) - && GET_CODE (b->head) != CODE_LABEL - && FORWARDER_BLOCK_P (b) - /* Note that forwarder_block_p true ensures that there - is a successor for this block. */ - && (b->succ->flags & EDGE_FALLTHRU) - && n_basic_blocks > 1) - { - if (rtl_dump_file) - fprintf (rtl_dump_file, "Deleting fallthru block %i.\n", - b->index); - c = BASIC_BLOCK (b->index ? b->index - 1 : 1); - redirect_edge_succ_nodup (b->pred, b->succ->dest); - flow_delete_block (b); - changed = true; - b = c; - } + /* Delete trivially dead basic blocks. */ + while (b->pred == NULL) + { + 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; + } - /* Merge blocks. Loop because chains of blocks might be - combineable. */ - while ((s = b->succ) != NULL - && s->succ_next == NULL - && !(s->flags & EDGE_COMPLEX) - && (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, mode)) - changed_here = true; - - /* Simplify branch over branch. */ - if ((mode & CLEANUP_EXPENSIVE) && 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. - Use redirect_edge_and_branch to do the dirty work. */ - if (b->succ - && ! b->succ->succ_next - && b->succ->dest != EXIT_BLOCK_PTR - && onlyjump_p (b->end) - && redirect_edge_and_branch (b->succ, b->succ->dest)) - { - BB_SET_FLAG (b, BB_UPDATE_LIFE); - update_forwarder_flag (b); - changed_here = true; - } + /* Remove code labels no longer used. Don't do this + before CALL_PLACEHOLDER is removed, as some branches + may be hidden within. */ + if (b->pred->pred_next == NULL + && (b->pred->flags & EDGE_FALLTHRU) + && !(b->pred->flags & EDGE_COMPLEX) + && GET_CODE (BB_HEAD (b)) == CODE_LABEL + && (!(mode & CLEANUP_PRE_SIBCALL) + || !tail_recursion_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). */ + && (b->pred->src == ENTRY_BLOCK_PTR + || GET_CODE (BB_END (b->pred->src)) != JUMP_INSN + || ! label_is_jump_target_p (BB_HEAD (b), + BB_END (b->pred->src)))) + { + 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); + } - /* Simplify branch to branch. */ - if (try_forward_edges (mode, b)) - changed_here = true; + /* If we fall through an empty block, we can remove it. */ + if (!(mode & CLEANUP_CFGLAYOUT) + && b->pred->pred_next == NULL + && (b->pred->flags & EDGE_FALLTHRU) + && GET_CODE (BB_HEAD (b)) != CODE_LABEL + && FORWARDER_BLOCK_P (b) + /* Note that forwarder_block_p true ensures that + there is a successor for this block. */ + && (b->succ->flags & EDGE_FALLTHRU) + && n_basic_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 (b->pred, b->succ->dest); + delete_basic_block (b); + changed = true; + b = c; + } - /* Look for shared code between blocks. */ - if ((mode & CLEANUP_CROSSJUMP) - && try_crossjump_bb (mode, b)) - changed_here = true; + if ((s = b->succ) != NULL + && s->succ_next == NULL + && !(s->flags & EDGE_COMPLEX) + && (c = s->dest) != EXIT_BLOCK_PTR + && c->pred->pred_next == NULL + && 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. */ + && (GET_CODE (BB_END (b)) != JUMP_INSN + || (reload_completed + ? simplejump_p (BB_END (b)) + : onlyjump_p (BB_END (b)))) + && (next = merge_blocks_move (s, b, c, mode))) + { + b = next; + changed_here = true; + } + } - /* Don't get confused by the index shift caused by deleting - blocks. */ - if (!changed_here) - i = b->index + 1; - else - changed = 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 (b->succ + && ! b->succ->succ_next + && b->succ->dest != EXIT_BLOCK_PTR + && onlyjump_p (BB_END (b)) + && !find_reg_note (BB_END (b), REG_CROSSING_JUMP, NULL_RTX) + && try_redirect_by_replacing_jump (b->succ, b->succ->dest, + (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; + if ((mode & CLEANUP_CROSSJUMP) + && try_crossjump_bb (mode, EXIT_BLOCK_PTR)) + changed = true; #ifdef ENABLE_CHECKING - if (changed) - verify_flow_info (); + if (changed) + verify_flow_info (); #endif - changed_overall |= changed; + changed_overall |= changed; + first_pass = false; + } + while (changed); } - while (changed); if (mode & CLEANUP_CROSSJUMP) remove_fake_edges (); - if ((mode & CLEANUP_UPDATE_LIFE) & changed_overall) - { - bool found = 0; - blocks = sbitmap_alloc (n_basic_blocks); - for (i = 0; i < n_basic_blocks; i++) - if (BB_FLAGS (BASIC_BLOCK (i)) & BB_UPDATE_LIFE) - { - found = 1; - SET_BIT (blocks, i); - } - if (found) - update_life_info (blocks, UPDATE_LIFE_GLOBAL, - PROP_DEATH_NOTES | PROP_SCAN_DEAD_CODE - | PROP_KILL_DEAD_CODE); - sbitmap_free (blocks); - } - for (i = 0; i < n_basic_blocks; i++) - BASIC_BLOCK (i)->aux = NULL; + clear_aux_for_blocks (); return changed_overall; } /* Delete all unreachable basic blocks. */ -static bool -delete_unreachable_blocks () +bool +delete_unreachable_blocks (void) { - int i; bool changed = false; + basic_block b, next_bb; find_unreachable_blocks (); - /* Delete all unreachable basic blocks. Count down so that we - don't interfere with the block renumbering that happens in - flow_delete_block. */ + /* Delete all unreachable basic blocks. */ - for (i = n_basic_blocks - 1; i >= 0; --i) + for (b = ENTRY_BLOCK_PTR->next_bb; b != EXIT_BLOCK_PTR; b = next_bb) { - basic_block b = BASIC_BLOCK (i); + next_bb = b->next_bb; if (!(b->flags & BB_REACHABLE)) - flow_delete_block (b), changed = true; + { + delete_basic_block (b); + changed = true; + } } if (changed) @@ -1311,19 +2037,54 @@ delete_unreachable_blocks () /* Tidy the CFG by deleting unreachable code and whatnot. */ bool -cleanup_cfg (mode) - int mode; +cleanup_cfg (int mode) { bool changed = false; timevar_push (TV_CLEANUP_CFG); - changed = delete_unreachable_blocks (); - if (try_optimize_cfg (mode)) - delete_unreachable_blocks (), changed = true; + 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 | CLEANUP_PRE_SIBCALL)) + && !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 | CLEANUP_PRE_SIBCALL)) + && (mode & CLEANUP_EXPENSIVE) + && !reload_completed) + { + if (!delete_trivially_dead_insns (get_insns(), max_reg_num ())) + break; + } + else + break; + delete_dead_jumptables (); + } /* Kill the data we won't maintain. */ free_EXPR_LIST_list (&label_value_list); - free_EXPR_LIST_list (&tail_recursion_label_list); timevar_pop (TV_CLEANUP_CFG); return changed;