/* Control flow optimization code for GNU compiler.
Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
- 1999, 2000, 2001, 2002, 2003 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 "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. */
#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 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. */
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",
+ 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
}
}
/* Delete the block with the unconditional jump, and clean up the mess. */
- 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;
}
CLEAR_REGNO_REG_SET (nonequal, regno);
if (regno < FIRST_PSEUDO_REGISTER)
{
- int n = HARD_REGNO_NREGS (regno, GET_MODE (dest));
+ int n = hard_regno_nregs[regno][GET_MODE (dest)];
while (--n > 0)
CLEAR_REGNO_REG_SET (nonequal, regno + n);
}
SET_REGNO_REG_SET (nonequal, regno);
if (regno < FIRST_PSEUDO_REGISTER)
{
- int n = HARD_REGNO_NREGS (regno, GET_MODE (dest));
+ int n = hard_regno_nregs[regno][GET_MODE (dest)];
while (--n > 0)
SET_REGNO_REG_SET (nonequal, regno + n);
}
return 1;
if (regno < FIRST_PSEUDO_REGISTER)
{
- int n = HARD_REGNO_NREGS (regno, GET_MODE (*x));
+ int n = hard_regno_nregs[regno][GET_MODE (*x)];
while (--n > 0)
if (REGNO_REG_SET_P (nonequal, regno + n))
return 1;
return NULL;
}
- cselib_init ();
+ 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));
bool changed = false;
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)
{
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;
{
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)
/* Allow to thread only over one edge at time to simplify updating
of probabilities. */
- else if (mode & CLEANUP_THREADING)
+ else if ((mode & CLEANUP_THREADING) && may_thread)
{
edge t = thread_jump (mode, e, target);
if (t)
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)
if (threaded && target != EXIT_BLOCK_PTR)
{
notice_new_block (redirect_edge_and_branch_force (e, target));
- if (rtl_dump_file)
- fprintf (rtl_dump_file, "Conditionals threaded.\n");
+ if (dump_file)
+ fprintf (dump_file, "Conditionals threaded.\n");
}
else if (!redirect_edge_and_branch (e, target))
{
- if (rtl_dump_file)
- fprintf (rtl_dump_file,
+ if (dump_file)
+ fprintf (dump_file,
"Forwarding edge %i->%i to %i failed.\n",
b->index, e->dest->index, target->index);
continue;
{
rtx barrier;
+ /* 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 ();
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",
+ 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. */
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 = BB_END (b);
/* If there is a jump table following block B temporarily add the jump table
/* Restore the real end of b. */
BB_END (b) = real_b_end;
- if (rtl_dump_file)
- fprintf (rtl_dump_file, "Moved block %d after %d and merged.\n",
+ if (dump_file)
+ fprintf (dump_file, "Moved block %d after %d and merged.\n",
b->index, a->index);
/* Now blocks A and B are contiguous. Merge them. */
&& 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)
{
merge_blocks (b, c);
update_forwarder_flag (b);
- if (rtl_dump_file)
- fprintf (rtl_dump_file, "Merged %d and %d without moving.\n",
+ if (dump_file)
+ fprintf (dump_file, "Merged %d and %d without moving.\n",
b_index, c_index);
return b->prev_bb == ENTRY_BLOCK_PTR ? b : b->prev_bb;
}
\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
if (!insns_match_p (mode, i1, i2))
break;
+ merge_memattrs (i1, i2);
+
/* Don't begin a cross-jump with a NOTE insn. */
if (INSN_P (i1))
{
outcomes. */
if (abs (b1->probability - prob2) > REG_BR_PROB_BASE / 2)
{
- if (rtl_dump_file)
- fprintf (rtl_dump_file,
+ 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);
}
}
- 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;
/* The labels should never be the same rtx. If they really are same
the jump tables are same too. So disable crossjumping of blocks BB1
and BB2 because when deleting the common insns in the end of BB1
- by delete_block () the jump table would be deleted too. */
+ 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. */
for_each_rtx (&BB_END (bb1), replace_label, &rr);
match = insns_match_p (mode, BB_END (bb1), BB_END (bb2));
- if (rtl_dump_file && match)
- fprintf (rtl_dump_file,
+ if (dump_file && match)
+ fprintf (dump_file,
"Tablejumps in bb %i and %i match.\n",
bb1->index, bb2->index);
rtx newpos1, newpos2;
edge s;
+ 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
away. We do this to look past the unconditional jump following a
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);
to_remove = redirect_from->succ->dest;
redirect_edge_and_branch_force (redirect_from->succ, redirect_to);
- delete_block (to_remove);
+ delete_basic_block (to_remove);
update_forwarder_flag (redirect_from);
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. */
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;
FOR_EACH_BB (bb)
update_forwarder_flag (bb);
- if (mode & CLEANUP_UPDATE_LIFE)
+ if (mode & (CLEANUP_UPDATE_LIFE | CLEANUP_CROSSJUMP | CLEANUP_THREADING))
clear_bb_flags ();
- if (! (* targetm.cannot_modify_jumps_p) ())
+ if (! targetm.cannot_modify_jumps_p ())
{
+ first_pass = true;
/* Attempt to merge blocks as made possible by edge removal. If
a block has only one successor, and the successor has only
one predecessor, they may be combined. */
changed = false;
iterations++;
- if (rtl_dump_file)
- fprintf (rtl_dump_file,
+ if (dump_file)
+ fprintf (dump_file,
"\n\ntry_optimize_cfg iteration %i\n\n",
iterations);
while (b->pred == NULL)
{
c = b->prev_bb;
- if (rtl_dump_file)
- fprintf (rtl_dump_file, "Deleting block %i.\n",
+ if (dump_file)
+ fprintf (dump_file, "Deleting block %i.\n",
b->index);
- delete_block (b);
+ delete_basic_block (b);
if (!(mode & CLEANUP_CFGLAYOUT))
changed = true;
b = c;
reorder_insns_nobb (label, label, bb_note);
BB_HEAD (b) = bb_note;
}
- if (rtl_dump_file)
- fprintf (rtl_dump_file, "Deleted label in block %i.\n",
+ if (dump_file)
+ fprintf (dump_file, "Deleted label in block %i.\n",
b->index);
}
&& (b->succ->flags & EDGE_FALLTHRU)
&& n_basic_blocks > 1)
{
- if (rtl_dump_file)
- fprintf (rtl_dump_file,
+ 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_block (b);
+ delete_basic_block (b);
changed = true;
b = c;
}
/* 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. */
+ with a simple unconditional jump. */
if (b->succ
&& ! b->succ->succ_next
&& b->succ->dest != EXIT_BLOCK_PTR
&& onlyjump_p (BB_END (b))
- && redirect_edge_and_branch (b->succ, b->succ->dest))
+ && !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;
#endif
changed_overall |= changed;
+ first_pass = false;
}
while (changed);
}
if (!(b->flags & BB_REACHABLE))
{
- delete_block (b);
+ delete_basic_block (b);
changed = true;
}
}
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. */
PROP_DEATH_NOTES
| PROP_SCAN_DEAD_CODE
| PROP_KILL_DEAD_CODE
- | PROP_LOG_LINKS))
+ | ((mode & CLEANUP_LOG_LINKS)
+ ? PROP_LOG_LINKS : 0)))
break;
}
else if (!(mode & (CLEANUP_NO_INSN_DEL | CLEANUP_PRE_SIBCALL))
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