/* 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.
cleanup_cfg. Following optimizations are performed:
- Unreachable blocks removal
- - Edge forwarding (edge to the forwarder block is forwarded to it's
+ - 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).
#include "config.h"
#include "system.h"
+#include "coretypes.h"
+#include "tm.h"
#include "rtl.h"
#include "hard-reg-set.h"
#include "basic-block.h"
#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 ((int,
- basic_block, basic_block));
-static int flow_find_cross_jump PARAMS ((int, basic_block, basic_block,
- rtx *, rtx *));
-static bool insns_match_p PARAMS ((int, rtx, rtx));
-
-static bool delete_unreachable_blocks PARAMS ((void));
-static bool label_is_jump_target_p PARAMS ((rtx, rtx));
-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);
\f
/* 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);
}
/* 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);
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
/* 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;
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;
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
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;
}
\f
+/* 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;
+}
+\f
/* Attempt to forward edges leaving basic block B.
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;
target = first = e->dest;
counter = 0;
- /* Look for the real destination of the jump.
- Avoid infinite 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.
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)
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)
/* 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;
}
- }
- }
- return changed;
-}
-\f
-/* Return true if LABEL is a target of JUMP_INSN. This applies only
- to non-complex jumps. That is, direct unconditional, conditional,
- and tablejumps, but not computed jumps or returns. It also does
- not apply to the fallthru case of a conditional jump. */
+ /* 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);
-static bool
-label_is_jump_target_p (label, jump_insn)
- rtx label, jump_insn;
-{
- rtx tmp = JUMP_LABEL (jump_insn);
+ if (!FORWARDER_BLOCK_P (b) && forwarder_block_p (b))
+ BB_SET_FLAG (b, BB_FORWARDER_BLOCK);
- if (label == tmp)
- return true;
+ 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;
+ }
- if (tmp != NULL_RTX
- && (tmp = NEXT_INSN (tmp)) != NULL_RTX
- && GET_CODE (tmp) == JUMP_INSN
- && (tmp = PATTERN (tmp),
- GET_CODE (tmp) == ADDR_VEC
- || GET_CODE (tmp) == ADDR_DIFF_VEC))
- {
- rtvec vec = XVEC (tmp, GET_CODE (tmp) == ADDR_DIFF_VEC);
- int i, veclen = GET_NUM_ELEM (vec);
+ t->count -= edge_count;
+ if (t->count < 0)
+ t->count = 0;
+ first = t->dest;
+ }
+ while (first != target);
- for (i = 0; i < veclen; ++i)
- if (XEXP (RTVEC_ELT (vec, i), 0) == label)
- return true;
+ changed = true;
+ }
}
- return false;
+ if (threaded_edges)
+ free (threaded_edges);
+ return changed;
}
-
+\f
/* 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;
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);
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. */
- if (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
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);
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. */
- if (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)
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
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
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
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;
}
\f
+/* 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
+ {
+ 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));
+
+ 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
-insns_match_p (mode, i1, i2)
- int mode;
- rtx i1, i2;
+insns_match_p (int mode ATTRIBUTE_UNUSED, rtx i1, rtx i2)
{
rtx p1, p2;
equal, they were constructed identically. */
if (GET_CODE (i1) == CALL_INSN
- && !rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1),
- CALL_INSN_FUNCTION_USAGE (i2)))
+ && (!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
#endif
if (reload_completed
- ? ! rtx_renumbered_equal_p (p1, p2) : ! rtx_equal_p (p1, p2))
+ ? 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);
return true;
}
}
- return false;
}
- return true;
+
+ return false;
}
\f
/* Look through the insns at the end of BB1 and BB2 and find the longest
store the head of the blocks in *F1 and *F2. */
static int
-flow_find_cross_jump (mode, bb1, bb2, f1, f2)
- int mode ATTRIBUTE_UNUSED;
- basic_block bb1, bb2;
- rtx *f1, *f2;
+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 = bb1->end;
+ i1 = BB_END (bb1);
last1 = afterlast1 = last2 = afterlast2 = NULL_RTX;
if (onlyjump_p (i1)
|| (returnjump_p (i1) && !side_effects_p (PATTERN (i1))))
{
last1 = i1;
- /* Count everything except for unconditional jump as insn. */
- if (!simplejump_p (i1) && !returnjump_p (i1))
- ninsns++;
i1 = PREV_INSN (i1);
}
- i2 = bb2->end;
+
+ 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 (!active_insn_p (i1) && i1 != bb1->head)
+ while (!INSN_P (i1) && i1 != BB_HEAD (bb1))
i1 = PREV_INSN (i1);
- while (!active_insn_p (i2) && i2 != bb2->head)
+
+ while (!INSN_P (i2) && i2 != BB_HEAD (bb2))
i2 = PREV_INSN (i2);
- if (i1 == bb1->head || i2 == bb2->head)
+ if (i1 == BB_HEAD (bb1) || i2 == BB_HEAD (bb2))
break;
if (!insns_match_p (mode, i1, i2))
break;
- /* Don't begin a cross-jump with a USE or CLOBBER insn. */
- if (active_insn_p (i1))
+ 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. */
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 preceding notes and labels in the cross-jump. One,
Two, it keeps line number notes as matched as may be. */
if (ninsns)
{
- while (last1 != bb1->head && !active_insn_p (PREV_INSN (last1)))
+ 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 && !active_insn_p (PREV_INSN (last2)))
+
+ 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;
We may assume that there exists one edge with a common destination. */
static bool
-outgoing_edges_match (mode, bb1, bb2)
- int mode;
- basic_block bb1;
- basic_block bb2;
+outgoing_edges_match (int mode, basic_block bb1, basic_block bb2)
{
int nehedges1 = 0, nehedges2 = 0;
edge fallthru1 = 0, fallthru2 = 0;
edge e1, e2;
- /* 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);
+ /* 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;
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);
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;
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;
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;
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 (note1 && note2)
+ 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)
{
- 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;
}
- /* Generic case - we are seeing an computed jump, table jump or trapping
+ /* 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_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 = 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.
- ??? Currently the tablejumps will never match, as they do have
- different tables. */
- if (!insns_match_p (mode, bb1->end, bb2->end))
+ 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
{
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)
- return false;
- if (nehedges1 != nehedges2)
- return false;
- if ((fallthru1 != 0) != (fallthru2 != 0))
+ 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);
+ ? fallthru1->dest->succ->dest: fallthru1->dest);
basic_block d2 = (forwarder_block_p (fallthru2->dest)
- ? fallthru2->dest->succ->dest: fallthru2->dest);
+ ? fallthru2->dest->succ->dest: fallthru2->dest);
+
if (d1 != d2)
return false;
}
- /* In case we do have EH edges, ensure we are in the same region. */
- if (nehedges1)
- {
- rtx n1 = find_reg_note (bb1->end, REG_EH_REGION, 0);
- rtx n2 = find_reg_note (bb2->end, REG_EH_REGION, 0);
- if (XEXP (n1, 0) != XEXP (n2, 0))
- return false;
- }
- /* We don't need to match the rest of edges as above checks should be enought
+
+ /* 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;
}
(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;
+
+ newpos1 = newpos2 = NULL_RTX;
+
+ /* 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
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)
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;
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)
if (FORWARDER_BLOCK_P (d))
d = d->succ->dest;
+
for (s2 = src1->succ; ; s2 = s2->succ_next)
{
basic_block d2 = s2->dest;
if (d == d2)
break;
}
+
s->count += s2->count;
/* Take care to update possible forwarder blocks. We verified
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);
- /* 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_from = split_block (src1, PREV_INSN (newpos1))->src;
+ to_remove = redirect_from->succ->dest;
- /* Update CFG. */
- while (src1->succ)
- remove_edge (src1->succ);
- make_single_succ_edge (src1, redirect_to, 0);
+ redirect_edge_and_branch_force (redirect_from->succ, redirect_to);
+ delete_basic_block (to_remove);
- BB_SET_FLAG (src1, BB_UPDATE_LIFE);
- update_forwarder_flag (src1);
+ update_forwarder_flag (redirect_from);
return true;
}
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)
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))
{
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;
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 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 (b->pred->src->end) != JUMP_INSN
- || ! label_is_jump_target_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))
- {
- BB_SET_FLAG (b, BB_UPDATE_LIFE);
- 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);
+ }
- /* 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;
- }
+ /* 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;
+ }
- /* Simplify branch to branch. */
- if (try_forward_edges (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;
+ }
+ }
- /* Look for shared code between blocks. */
- if ((mode & CLEANUP_CROSSJUMP)
- && try_crossjump_bb (mode, b))
- 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 (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;
+ }
- /* Don't get confused by the index shift caused by deleting
- blocks. */
- if (!changed_here)
- i = b->index + 1;
- else
- changed = 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);
- sbitmap_zero (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;
}
\f
/* 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)
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 (bb->succ
+ && !bb->succ->succ_next
+ && can_merge_blocks_p (bb, bb->succ->dest))
+ {
+ /* Merge the blocks and retry. */
+ merge_blocks (bb, bb->succ->dest);
+ changed = true;
+ continue;
+ }
+
+ bb = bb->next_bb;
+ }
+
+ return changed;
+}
\f
/* 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;
OSDN Git Service
