/* 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 Free Software Foundation, Inc.
This file is part of GCC.
- Unreachable blocks removal
- Edge forwarding (edge to the forwarder block is forwarded to it's
- succesor. Simplification of the branch instruction is performed by
+ 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"
#include "flags.h"
#include "recog.h"
#include "toplev.h"
+#include "cselib.h"
+#include "tm_p.h"
+#include "target.h"
-#include "obstack.h"
+/* cleanup_cfg maintains following flags for each basic block. */
+
+enum bb_flags
+{
+ /* Set if BB is the forwarder block to avoid too many
+ forwarder_block_p calls. */
+ 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)
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 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 bool try_optimize_cfg PARAMS ((int));
static bool try_simplify_condjump PARAMS ((basic_block));
static bool try_forward_edges PARAMS ((int, basic_block));
+static edge thread_jump PARAMS ((int, edge, basic_block));
+static bool mark_effect PARAMS ((rtx, bitmap));
+static void notice_new_block PARAMS ((basic_block));
+static void update_forwarder_flag PARAMS ((basic_block));
+static int mentions_nonequal_regs PARAMS ((rtx *, void *));
+\f
+/* Set flags for newly created block. */
+
+static void
+notice_new_block (bb)
+ basic_block bb;
+{
+ if (!bb)
+ return;
+
+ 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;
+{
+ if (forwarder_block_p (bb))
+ BB_SET_FLAG (bb, BB_FORWARDER_BLOCK);
+ else
+ BB_CLEAR_FLAG (bb, BB_FORWARDER_BLOCK);
+}
\f
/* Simplify a conditional jump around an unconditional jump.
Return true if something changed. */
unconditional jump. */
jump_block = cbranch_fallthru_edge->dest;
if (jump_block->pred->pred_next
- || jump_block->index == n_basic_blocks - 1
- || !forwarder_block_p (jump_block))
+ || jump_block->next_bb == EXIT_BLOCK_PTR
+ || !FORWARDER_BLOCK_P (jump_block))
return false;
jump_dest_block = jump_block->succ->dest;
if (!can_fallthru (jump_block, cbranch_dest_block))
return false;
- /* Invert the conditional branch. Prevent jump.c from deleting
- "unreachable" instructions. */
- LABEL_NUSES (JUMP_LABEL (cbranch_insn))++;
- if (!invert_jump (cbranch_insn, block_label (jump_dest_block), 1))
- {
- LABEL_NUSES (JUMP_LABEL (cbranch_insn))--;
- return false;
- }
+ /* Invert the conditional branch. */
+ 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",
jump_dest_block);
cbranch_jump_edge->flags |= EDGE_FALLTHRU;
cbranch_fallthru_edge->flags &= ~EDGE_FALLTHRU;
+ update_br_prob_note (cbranch_block);
/* Delete the block with the unconditional jump, and clean up the mess. */
flow_delete_block (jump_block);
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 (exp, nonequal)
+ 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 an register set in regset DATA.
+ Called via for_each_rtx. */
+static int
+mentions_nonequal_regs (x, data)
+ 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 (mode, e, b)
+ 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 (e->src->end))
+ return NULL;
+
+ if (!any_condjump_p (b->end) || !onlyjump_p (b->end))
+ {
+ BB_SET_FLAG (b, BB_NONTHREADABLE_BLOCK);
+ return NULL;
+ }
+
+ set1 = pc_set (e->src->end);
+ set2 = pc_set (b->end);
+ 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, e->src->end);
+ else
+ code1 = GET_CODE (cond1);
+
+ code2 = GET_CODE (cond2);
+ reversed_code2 = reversed_comparison_code (cond2, b->end);
+
+ 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 (b->head); insn != NEXT_INSN (b->end);
+ insn = NEXT_INSN (insn))
+ if (INSN_P (insn) && side_effects_p (PATTERN (insn)))
+ {
+ BB_SET_FLAG (b, BB_NONTHREADABLE_BLOCK);
+ return NULL;
+ }
+
+ cselib_init ();
+
+ /* First process all values computed in the source basic block. */
+ for (insn = NEXT_INSN (e->src->head); insn != NEXT_INSN (e->src->end);
+ 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 (b->head); insn != NEXT_INSN (b->end) && !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 sucessful. */
+ Return true if successful. */
static bool
try_forward_edges (mode, b)
int mode;
{
bool changed = false;
- edge e, next;
+ edge e, next, *threaded_edges = NULL;
- 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;
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;
+
+ 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)
+ {
+ 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.
if (mode & CLEANUP_PRE_LOOP)
{
rtx insn = (target->succ->flags & EDGE_FALLTHRU
- ? target->head : prev_nonnote_insn (target->end));
+ ? target->head : prev_nonnote_insn (target->end));
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 (target->head);
+ 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)
/* 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);
-
- 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 (rtl_dump_file)
+ fprintf (rtl_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",
+ fprintf (rtl_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;
}
\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. */
+
+static bool
+label_is_jump_target_p (label, jump_insn)
+ rtx label, jump_insn;
+{
+ rtx tmp = JUMP_LABEL (jump_insn);
+
+ if (label == tmp)
+ return true;
+
+ 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);
+
+ for (i = 0; i < veclen; ++i)
+ if (XEXP (RTVEC_ELT (vec, i), 0) == label)
+ return true;
+ }
+
+ return false;
+}
+
/* Return true if LABEL is used for tail recursion. */
static bool
basic_block a, b;
{
rtx barrier;
- int index;
barrier = next_nonnote_insn (a->end);
if (GET_CODE (barrier) != BARRIER)
abort ();
- flow_delete_insn (barrier);
+ delete_insn (barrier);
/* Move block and loop notes out of the chain so that we do not
disturb their order.
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 (&a->head, &a->end))
+ abort ();
/* Scramble the insn chain. */
if (a->end != PREV_INSN (b->head))
reorder_insns_nobb (a->head, a->end, PREV_INSN (b->head));
+ a->flags |= BB_DIRTY;
if (rtl_dump_file)
- {
- fprintf (rtl_dump_file, "Moved block %d before %d and merged.\n",
- a->index, b->index);
- }
+ fprintf (rtl_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_move_successor_nojumps (a, b)
basic_block a, b;
{
- rtx barrier;
+ rtx barrier, real_b_end;
+ real_b_end = b->end;
barrier = NEXT_INSN (b->end);
/* Recognize a jump table following block B. */
&& (GET_CODE (PATTERN (NEXT_INSN (barrier))) == ADDR_VEC
|| GET_CODE (PATTERN (NEXT_INSN (barrier))) == ADDR_DIFF_VEC))
{
+ /* 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);
}
/* There had better have been a barrier there. Delete it. */
if (barrier && GET_CODE (barrier) == BARRIER)
- flow_delete_insn (barrier);
+ delete_insn (barrier);
/* Move block and loop notes out of the chain so that we do not
disturb their order.
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 (&b->head, &b->end))
+ abort ();
/* Scramble the insn chain. */
reorder_insns_nobb (b->head, b->end, a->end);
- /* Now blocks A and B are contiguous. Merge them. */
- merge_blocks_nomove (a, b);
+ /* Restore the real end of b. */
+ b->end = real_b_end;
if (rtl_dump_file)
- {
- fprintf (rtl_dump_file, "Moved block %d after %d and merged.\n",
- b->index, a->index);
- }
+ 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_nomove (a, b);
}
/* Attempt to merge basic blocks that are potentially non-adjacent.
/* If B has a fallthru edge to C, no need to move anything. */
if (e->flags & EDGE_FALLTHRU)
{
+ int b_index = b->index, c_index = c->index;
merge_blocks_nomove (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);
- }
+ fprintf (rtl_dump_file, "Merged %d and %d without moving.\n",
+ b_index, c_index);
return true;
}
+
/* Otherwise we will need to move code around. Do that only if expensive
transformations are allowed. */
else if (mode & CLEANUP_EXPENSIVE)
eliminated by edge redirection instead. One exception might have
been if B is a forwarder block and C has no fallthru edge, but
that should be cleaned up by bb-reorder instead. */
- if (forwarder_block_p (b) || forwarder_block_p (c))
+ if (FORWARDER_BLOCK_P (b) || FORWARDER_BLOCK_P (c))
return false;
/* We must make sure to not munge nesting of lexical blocks,
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;
if (b_has_incoming_fallthru)
{
+ basic_block bb;
+
if (b_fallthru_edge->src == ENTRY_BLOCK_PTR)
return false;
- force_nonfallthru (b_fallthru_edge);
+ bb = force_nonfallthru (b_fallthru_edge);
+ if (bb)
+ notice_new_block (bb);
}
+
merge_blocks_move_predecessor_nojumps (b, c);
return true;
}
+
return false;
}
\f
+
+/* Return true if I1 and I2 are equivalent and thus can be crossjumped. */
+
+static bool
+insns_match_p (mode, i1, i2)
+ int mode ATTRIBUTE_UNUSED;
+ rtx i1, i2;
+{
+ rtx p1, p2;
+
+ /* Verify that I1 and I2 are equivalent. */
+ if (GET_CODE (i1) != GET_CODE (i2))
+ return false;
+
+ p1 = PATTERN (i1);
+ p2 = PATTERN (i2);
+
+ if (GET_CODE (p1) != GET_CODE (p2))
+ return false;
+
+ /* If this is a CALL_INSN, compare register usage information.
+ If we don't check this on stack register machines, the two
+ CALL_INSNs might be merged leaving reg-stack.c with mismatching
+ numbers of stack registers in the same basic block.
+ If we don't check this on machines with delay slots, a delay slot may
+ be filled that clobbers a parameter expected by the subroutine.
+
+ ??? We take the simple route for now and assume that if they're
+ equal, they were constructed identically. */
+
+ if (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 ((mode & CLEANUP_POST_REGSTACK) && stack_regs_mentioned (i1))
+ {
+ /* If register stack conversion has already been done, then
+ death notes must also be compared before it is certain that
+ the two instruction streams match. */
+
+ rtx note;
+ HARD_REG_SET i1_regset, i2_regset;
+
+ CLEAR_HARD_REG_SET (i1_regset);
+ CLEAR_HARD_REG_SET (i2_regset);
+
+ for (note = REG_NOTES (i1); note; note = XEXP (note, 1))
+ if (REG_NOTE_KIND (note) == REG_DEAD && STACK_REG_P (XEXP (note, 0)))
+ SET_HARD_REG_BIT (i1_regset, REGNO (XEXP (note, 0)));
+
+ for (note = REG_NOTES (i2); note; note = XEXP (note, 1))
+ if (REG_NOTE_KIND (note) == REG_DEAD && STACK_REG_P (XEXP (note, 0)))
+ SET_HARD_REG_BIT (i2_regset, REGNO (XEXP (note, 0)));
+
+ GO_IF_HARD_REG_EQUAL (i1_regset, i2_regset, done);
+
+ return false;
+
+ done:
+ ;
+ }
+#endif
+
+ if (reload_completed
+ ? ! rtx_renumbered_equal_p (p1, p2) : ! rtx_equal_p (p1, p2))
+ {
+ /* The following code helps take care of G++ cleanups. */
+ rtx equiv1 = find_reg_equal_equiv_note (i1);
+ rtx equiv2 = find_reg_equal_equiv_note (i2);
+
+ if (equiv1 && equiv2
+ /* If the equivalences are not to a constant, they may
+ reference pseudos that no longer exist, so we can't
+ use them. */
+ && (! reload_completed
+ || (CONSTANT_P (XEXP (equiv1, 0))
+ && rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0)))))
+ {
+ rtx s1 = single_set (i1);
+ rtx s2 = single_set (i2);
+ if (s1 != 0 && s2 != 0
+ && rtx_renumbered_equal_p (SET_DEST (s1), SET_DEST (s2)))
+ {
+ validate_change (i1, &SET_SRC (s1), XEXP (equiv1, 0), 1);
+ validate_change (i2, &SET_SRC (s2), XEXP (equiv2, 0), 1);
+ if (! rtx_renumbered_equal_p (p1, p2))
+ cancel_changes (0);
+ else if (apply_change_group ())
+ return true;
+ }
+ }
+
+ return false;
+ }
+
+ return true;
+}
+\f
/* 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.
basic_block bb1, bb2;
rtx *f1, *f2;
{
- rtx i1, i2, p1, p2, last1, last2, afterlast1, afterlast2;
+ 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;
+ last1 = afterlast1 = last2 = afterlast2 = NULL_RTX;
if (onlyjump_p (i1)
|| (returnjump_p (i1) && !side_effects_p (PATTERN (i1))))
- i1 = PREV_INSN (i1);
+ {
+ last1 = i1;
+ i1 = PREV_INSN (i1);
+ }
+
i2 = bb2->end;
if (onlyjump_p (i2)
|| (returnjump_p (i2) && !side_effects_p (PATTERN (i2))))
- i2 = PREV_INSN (i2);
+ {
+ last2 = i2;
+ /* Count everything except for unconditional jump as insn. */
+ if (!simplejump_p (i2) && !returnjump_p (i2) && last1)
+ ninsns++;
+ i2 = PREV_INSN (i2);
+ }
- last1 = afterlast1 = last2 = afterlast2 = NULL_RTX;
while (true)
{
/* Ignore notes. */
- while ((GET_CODE (i1) == NOTE && i1 != bb1->head))
+ while (!active_insn_p (i1) && i1 != bb1->head)
i1 = PREV_INSN (i1);
- while ((GET_CODE (i2) == NOTE && i2 != bb2->head))
+
+ while (!active_insn_p (i2) && i2 != bb2->head)
i2 = PREV_INSN (i2);
if (i1 == bb1->head || i2 == bb2->head)
break;
- /* Verify that I1 and I2 are equivalent. */
-
- if (GET_CODE (i1) != GET_CODE (i2))
- break;
-
- p1 = PATTERN (i1);
- p2 = PATTERN (i2);
-
- /* 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)))
+ if (!insns_match_p (mode, i1, i2))
break;
-#ifdef STACK_REGS
- /* If cross_jump_death_matters is not 0, the insn's mode
- indicates whether or not the insn contains any stack-like
- regs. */
-
- if ((mode & CLEANUP_POST_REGSTACK) && stack_regs_mentioned (i1))
- {
- /* If register stack conversion has already been done, then
- death notes must also be compared before it is certain that
- the two instruction streams match. */
-
- rtx note;
- HARD_REG_SET i1_regset, i2_regset;
-
- CLEAR_HARD_REG_SET (i1_regset);
- CLEAR_HARD_REG_SET (i2_regset);
-
- for (note = REG_NOTES (i1); note; note = XEXP (note, 1))
- if (REG_NOTE_KIND (note) == REG_DEAD
- && STACK_REG_P (XEXP (note, 0)))
- SET_HARD_REG_BIT (i1_regset, REGNO (XEXP (note, 0)));
-
- for (note = REG_NOTES (i2); note; note = XEXP (note, 1))
- if (REG_NOTE_KIND (note) == REG_DEAD
- && STACK_REG_P (XEXP (note, 0)))
- SET_HARD_REG_BIT (i2_regset, REGNO (XEXP (note, 0)));
-
- GO_IF_HARD_REG_EQUAL (i1_regset, i2_regset, done);
-
- break;
-
- done:
- ;
- }
-#endif
-
- if (GET_CODE (p1) != GET_CODE (p2))
- break;
-
- if (! rtx_renumbered_equal_p (p1, p2))
+ /* Don't begin a cross-jump with a USE or CLOBBER insn. */
+ if (active_insn_p (i1))
{
- /* The following code helps take care of G++ cleanups. */
+ /* If the merged insns have different REG_EQUAL notes, then
+ remove them. */
rtx equiv1 = find_reg_equal_equiv_note (i1);
rtx equiv2 = find_reg_equal_equiv_note (i2);
- if (equiv1 && equiv2
- /* 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)))
+ if (equiv1 && !equiv2)
+ remove_note (i1, equiv1);
+ else if (!equiv1 && equiv2)
+ remove_note (i2, equiv2);
+ else if (equiv1 && equiv2
+ && !rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0)))
{
- 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;
- }
+ remove_note (i1, equiv1);
+ remove_note (i2, equiv2);
}
- break;
- }
- win:
- /* Don't begin a cross-jump with a USE or CLOBBER insn. */
- if (GET_CODE (p1) != USE && GET_CODE (p1) != CLOBBER)
- {
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 != bb1->head && !active_insn_p (PREV_INSN (last1)))
last1 = PREV_INSN (last1);
+
if (last1 != bb1->head && GET_CODE (PREV_INSN (last1)) == CODE_LABEL)
last1 = PREV_INSN (last1);
- while (last2 != bb2->head && GET_CODE (PREV_INSN (last2)) == NOTE)
+
+ while (last2 != bb2->head && !active_insn_p (PREV_INSN (last2)))
last2 = PREV_INSN (last2);
+
if (last2 != bb2->head && GET_CODE (PREV_INSN (last2)) == CODE_LABEL)
last2 = PREV_INSN (last2);
We may assume that there exists one edge with a common destination. */
static bool
-outgoing_edges_match (bb1, bb2)
+outgoing_edges_match (mode, bb1, bb2)
+ 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 (bb1->end) != JUMP_INSN || simplejump_p (bb1->end)))
+ return (bb2->succ && !bb2->succ->succ_next
+ && (bb2->succ->flags & (EDGE_COMPLEX | EDGE_FAKE)) == 0
+ && (GET_CODE (bb2->end) != JUMP_INSN || simplejump_p (bb2->end)));
/* 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 (bb1->end)
+ && onlyjump_p (bb1->end))
{
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 (bb2->end)
+ || !onlyjump_p (bb2->end))
return false;
b1 = BRANCH_EDGE (bb1);
/* Get around possible forwarders on fallthru edges. Other cases
should be optimized out already. */
- if (forwarder_block_p (f1->dest))
+ if (FORWARDER_BLOCK_P (f1->dest))
f1 = f1->dest->succ;
- if (forwarder_block_p (f2->dest))
+
+ if (FORWARDER_BLOCK_P (f2->dest))
f2 = f2->dest->succ;
/* To simplify use of this function, return false if there are
unneeded forwarder blocks. These will get eliminated later
during cleanup_cfg. */
- if (forwarder_block_p (f1->dest)
- || forwarder_block_p (f2->dest)
- || forwarder_block_p (b1->dest)
- || forwarder_block_p (b2->dest))
+ if (FORWARDER_BLOCK_P (f1->dest)
+ || FORWARDER_BLOCK_P (f2->dest)
+ || FORWARDER_BLOCK_P (b1->dest)
+ || FORWARDER_BLOCK_P (b2->dest))
return false;
if (f1->dest == f2->dest && b1->dest == b2->dest)
code2 = reversed_comparison_code (cond2, bb2->end);
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 (rtl_dump_file)
+ fprintf (rtl_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)
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. */
+
+ /* 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))
+ 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;
+ }
+
+ /* 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
+ to ensure that they are equivalent. */
+ return true;
}
/* E1 and E2 are edges with the same destination block. Search their
{
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;
/* Search backward through forwarder blocks. We don't need to worry
about multiple entry or chained forwarders, as they will be optimized
conditional jump that is required due to the current CFG shape. */
if (src1->pred
&& !src1->pred->pred_next
- && forwarder_block_p (src1))
- {
- e1 = src1->pred;
- src1 = e1->src;
- }
+ && FORWARDER_BLOCK_P (src1))
+ e1 = src1->pred, src1 = e1->src;
+
if (src2->pred
&& !src2->pred->pred_next
- && forwarder_block_p (src2))
- {
- e2 = src2->pred;
- src2 = e2->src;
- }
+ && FORWARDER_BLOCK_P (src2))
+ 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)
return false;
/* Seeing more than 1 forwarder blocks would confuse us later... */
- if (forwarder_block_p (e1->dest)
- && forwarder_block_p (e1->dest->succ->dest))
+ 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))
+
+ if (FORWARDER_BLOCK_P (e2->dest)
+ && FORWARDER_BLOCK_P (e2->dest->succ->dest))
return false;
/* Likewise with dead code (possibly newly created by the other optimizations
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. */
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)
edge s2;
basic_block d = s->dest;
- if (forwarder_block_p (d))
+ if (FORWARDER_BLOCK_P (d))
d = d->succ->dest;
+
for (s2 = src1->succ; ; s2 = s2->succ_next)
{
basic_block d2 = s2->dest;
- if (forwarder_block_p (d2))
+ if (FORWARDER_BLOCK_P (d2))
d2 = d2->succ->dest;
if (d == d2)
break;
}
+
s->count += s2->count;
/* Take care to update possible forwarder blocks. We verified
that there is no more than one in the chain, so we can't run
into infinite loop. */
- if (forwarder_block_p (s->dest))
+ if (FORWARDER_BLOCK_P (s->dest))
{
s->dest->succ->count += s2->count;
s->dest->count += s2->count;
s->dest->frequency += EDGE_FREQUENCY (s);
}
- if (forwarder_block_p (s2->dest))
+
+ 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);
- src1->end = emit_jump_insn_before (gen_jump (label), newpos1);
- JUMP_LABEL (src1->end) = label;
- LABEL_NUSES (label)++;
+ redirect_from = split_block (src1, PREV_INSN (newpos1))->src;
+ to_remove = redirect_from->succ->dest;
- /* Delete the now unreachable instructions. */
- flow_delete_insn_chain (newpos1, last);
+ redirect_edge_and_branch_force (redirect_from->succ, redirect_to);
+ flow_delete_block (to_remove);
- /* 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);
-
- /* Update CFG. */
- while (src1->succ)
- remove_edge (src1->succ);
- make_single_succ_edge (src1, redirect_to, 0);
+ update_forwarder_flag (redirect_from);
return true;
}
{
edge e, e2, nexte2, nexte, fallthru;
bool changed;
+ int n = 0;
- /* Nothing to do if there is not at least two incomming edges. */
+ /* Nothing to do if there is not at least two incoming edges. */
if (!bb->pred || !bb->pred->pred_next)
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;
+ for (fallthru = bb->pred; fallthru; fallthru = fallthru->pred_next, n++)
+ {
+ if (fallthru->flags & EDGE_FALLTHRU)
+ break;
+ if (n > 100)
+ 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)
{
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
try_optimize_cfg (mode)
int mode;
{
- int i;
bool changed_overall = false;
bool changed;
int iterations = 0;
+ basic_block bb, b;
- /* 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_CROSSJUMP)
+ add_noreturn_fake_exit_edges ();
- do
- {
- changed = false;
- iterations++;
+ FOR_EACH_BB (bb)
+ update_forwarder_flag (bb);
- if (rtl_dump_file)
- fprintf (rtl_dump_file, "\n\ntry_optimize_cfg iteration %i\n\n",
- iterations);
+ if (mode & CLEANUP_UPDATE_LIFE)
+ clear_bb_flags ();
- for (i = 0; i < n_basic_blocks;)
+ if (! (* targetm.cannot_modify_jumps_p) ())
+ {
+ /* 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 (rtl_dump_file)
+ fprintf (rtl_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);
- flow_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 (rtl_dump_file)
+ fprintf (rtl_dump_file, "Deleting block %i.\n",
+ b->index);
+
+ flow_delete_block (b);
+ changed = true;
+ b = c;
+ }
+
+ /* 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)))
+ {
+ 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);
+ }
+
+ /* 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 = b->prev_bb == ENTRY_BLOCK_PTR ? b->next_bb : b->prev_bb;
+ redirect_edge_succ_nodup (b->pred, b->succ->dest);
+ flow_delete_block (b);
+ 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
+ && b != c
+ /* If the jump insn has side effects,
+ we can't kill the edge. */
+ && (GET_CODE (b->end) != JUMP_INSN
+ || simplejump_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))
+ {
+ 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;
}
- /* 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))
- 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)
- i = b->index + 1;
- else
+ && 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;
+ }
+ while (changed);
}
- while (changed);
+
+ if (mode & CLEANUP_CROSSJUMP)
+ remove_fake_edges ();
+
+ clear_aux_for_blocks ();
+
return changed_overall;
}
\f
-/* Delete all unreachable basic blocks. */
+/* Delete all unreachable basic blocks. */
-static bool
+bool
delete_unreachable_blocks ()
{
- 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;
+ {
+ flow_delete_block (b);
+ changed = true;
+ }
}
if (changed)
cleanup_cfg (mode)
int mode;
{
- int i;
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
+ | PROP_LOG_LINKS))
+ break;
+ }
+ else if (!(mode & (CLEANUP_NO_INSN_DEL | CLEANUP_PRE_SIBCALL))
+ && !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);
- /* Clear bb->aux on all basic blocks. */
- for (i = 0; i < n_basic_blocks; ++i)
- BASIC_BLOCK (i)->aux = NULL;
return changed;
}
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