/* Control flow optimization code for GNU compiler.
Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
- 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007
+ 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008
Free Software Foundation, Inc.
This file is part of GCC.
and cold sections.
Basic block partitioning may result in some jumps that appear to
- be optimizable (or blocks that appear to be mergeable), but which really m
- ust be left untouched (they are required to make it safely across
+ be optimizable (or blocks that appear to be mergeable), but which really
+ must be left untouched (they are required to make it safely across
partition boundaries). See the comments at the top of
bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
for (ei = ei_start (b->succs); (e = ei_safe_edge (ei)); )
{
basic_block target, first;
- int counter;
+ int counter, goto_locus;
bool threaded = false;
int nthreaded_edges = 0;
bool may_thread = first_pass | df_get_bb_dirty (b);
target = first = e->dest;
counter = NUM_FIXED_BLOCKS;
+ goto_locus = e->goto_locus;
/* If we are partitioning hot/cold basic_blocks, we don't want to mess
up jumps that cross between hot/cold sections.
new_target = single_succ (target);
if (target == new_target)
counter = n_basic_blocks;
+ else if (!optimize)
+ {
+ /* When not optimizing, ensure that edges or forwarder
+ blocks with different locus are not optimized out. */
+ int locus = single_succ_edge (target)->goto_locus;
+
+ if (locus && goto_locus && !locator_eq (locus, goto_locus))
+ counter = n_basic_blocks;
+ else if (locus)
+ goto_locus = locus;
+
+ if (INSN_P (BB_END (target)))
+ {
+ locus = INSN_LOCATOR (BB_END (target));
+
+ if (locus && goto_locus
+ && !locator_eq (locus, goto_locus))
+ counter = n_basic_blocks;
+ else if (locus)
+ goto_locus = locus;
+ }
+ }
}
/* Allow to thread only over one edge at time to simplify updating
int edge_frequency;
int n = 0;
+ e->goto_locus = goto_locus;
+
/* Don't force if target is exit block. */
if (threaded && target != EXIT_BLOCK_PTR)
{
if (GET_CODE (i1) != GET_CODE (i2))
return false;
+ /* __builtin_unreachable() may lead to empty blocks (ending with
+ NOTE_INSN_BASIC_BLOCK). They may be crossjumped. */
+ if (NOTE_INSN_BASIC_BLOCK_P (i1) && NOTE_INSN_BASIC_BLOCK_P (i2))
+ return true;
+
p1 = PATTERN (i1);
p2 = PATTERN (i2);
? rtx_renumbered_equal_p (p1, p2) : rtx_equal_p (p1, p2))
return true;
- /* Do not do EQUIV substitution after reload. First, we're undoing the
- work of reload_cse. Second, we may be undoing the work of the post-
- reload splitting pass. */
- /* ??? Possibly add a new phase switch variable that can be used by
- targets to disallow the troublesome insns after splitting. */
- if (!reload_completed)
- {
- /* The following code helps take care of G++ cleanups. */
- rtx equiv1 = find_reg_equal_equiv_note (i1);
- rtx equiv2 = find_reg_equal_equiv_note (i2);
-
- if (equiv1 && equiv2
- /* If the equivalences are not to a constant, they may
- reference pseudos that no longer exist, so we can't
- use them. */
- && (! reload_completed
- || (CONSTANT_P (XEXP (equiv1, 0))
- && rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0)))))
- {
- rtx s1 = single_set (i1);
- rtx s2 = single_set (i2);
- if (s1 != 0 && s2 != 0
- && rtx_renumbered_equal_p (SET_DEST (s1), SET_DEST (s2)))
- {
- validate_change (i1, &SET_SRC (s1), XEXP (equiv1, 0), 1);
- validate_change (i2, &SET_SRC (s2), XEXP (equiv2, 0), 1);
- if (! rtx_renumbered_equal_p (p1, p2))
- cancel_changes (0);
- else if (apply_change_group ())
- return true;
- }
- }
- }
-
return false;
}
\f
while (true)
{
/* Ignore notes. */
- while (!INSN_P (i1) && i1 != BB_HEAD (bb1))
+ while (!NONDEBUG_INSN_P (i1) && i1 != BB_HEAD (bb1))
i1 = PREV_INSN (i1);
- while (!INSN_P (i2) && i2 != BB_HEAD (bb2))
+ while (!NONDEBUG_INSN_P (i2) && i2 != BB_HEAD (bb2))
i2 = PREV_INSN (i2);
if (i1 == BB_HEAD (bb1) || i2 == BB_HEAD (bb2))
Two, it keeps line number notes as matched as may be. */
if (ninsns)
{
- while (last1 != BB_HEAD (bb1) && !INSN_P (PREV_INSN (last1)))
+ while (last1 != BB_HEAD (bb1) && !NONDEBUG_INSN_P (PREV_INSN (last1)))
last1 = PREV_INSN (last1);
if (last1 != BB_HEAD (bb1) && LABEL_P (PREV_INSN (last1)))
last1 = PREV_INSN (last1);
- while (last2 != BB_HEAD (bb2) && !INSN_P (PREV_INSN (last2)))
+ while (last2 != BB_HEAD (bb2) && !NONDEBUG_INSN_P (PREV_INSN (last2)))
last2 = PREV_INSN (last2);
if (last2 != BB_HEAD (bb2) && LABEL_P (PREV_INSN (last2)))
we require the existing branches to have probabilities that are
roughly similar. */
if (match
- && !optimize_size
- && maybe_hot_bb_p (bb1)
- && maybe_hot_bb_p (bb2))
+ && optimize_bb_for_speed_p (bb1)
+ && optimize_bb_for_speed_p (bb2))
{
int prob2;
/* Skip possible basic block header. */
if (LABEL_P (newpos2))
newpos2 = NEXT_INSN (newpos2);
+ while (DEBUG_INSN_P (newpos2))
+ newpos2 = NEXT_INSN (newpos2);
if (NOTE_P (newpos2))
newpos2 = NEXT_INSN (newpos2);
+ while (DEBUG_INSN_P (newpos2))
+ newpos2 = NEXT_INSN (newpos2);
}
if (dump_file)
if (LABEL_P (newpos1))
newpos1 = NEXT_INSN (newpos1);
- if (NOTE_P (newpos1))
+ while (DEBUG_INSN_P (newpos1))
+ newpos1 = NEXT_INSN (newpos1);
+
+ if (NOTE_INSN_BASIC_BLOCK_P (newpos1))
+ newpos1 = NEXT_INSN (newpos1);
+
+ while (DEBUG_INSN_P (newpos1))
newpos1 = NEXT_INSN (newpos1);
redirect_from = split_block (src1, PREV_INSN (newpos1))->src;
/* Don't crossjump if this block ends in a computed jump,
unless we are optimizing for size. */
- if (!optimize_size
+ if (optimize_bb_for_size_p (bb)
&& bb != EXIT_BLOCK_PTR
&& computed_jump_p (BB_END (bb)))
return false;
return changed;
}
+/* Return true if BB contains just bb note, or bb note followed
+ by only DEBUG_INSNs. */
+
+static bool
+trivially_empty_bb_p (basic_block bb)
+{
+ rtx insn = BB_END (bb);
+
+ while (1)
+ {
+ if (insn == BB_HEAD (bb))
+ return true;
+ if (!DEBUG_INSN_P (insn))
+ return false;
+ insn = PREV_INSN (insn);
+ }
+}
+
/* Do simple CFG optimizations - basic block merging, simplifying of jump
instructions etc. Return nonzero if changes were made. */
edge s;
bool changed_here = false;
- /* Delete trivially dead basic blocks. */
- if (EDGE_COUNT (b->preds) == 0)
+ /* Delete trivially dead basic blocks. This is either
+ blocks with no predecessors, or empty blocks with no
+ successors. However if the empty block with no
+ successors is the successor of the ENTRY_BLOCK, it is
+ kept. This ensures that the ENTRY_BLOCK will have a
+ successor which is a precondition for many RTL
+ passes. Empty blocks may result from expanding
+ __builtin_unreachable (). */
+ if (EDGE_COUNT (b->preds) == 0
+ || (EDGE_COUNT (b->succs) == 0
+ && trivially_empty_bb_p (b)
+ && single_succ_edge (ENTRY_BLOCK_PTR)->dest != b))
{
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;
delete_basic_block (b);
changed = true;
b = c;
+ continue;
}
if (single_succ_p (b)
delete_unreachable_blocks (void)
{
bool changed = false;
- basic_block b, next_bb;
+ basic_block b, prev_bb;
find_unreachable_blocks ();
- /* Delete all unreachable basic blocks. */
-
- for (b = ENTRY_BLOCK_PTR->next_bb; b != EXIT_BLOCK_PTR; b = next_bb)
+ /* When we're in GIMPLE mode and there may be debug insns, we should
+ delete blocks in reverse dominator order, so as to get a chance
+ to substitute all released DEFs into debug stmts. If we don't
+ have dominators information, walking blocks backward gets us a
+ better chance of retaining most debug information than
+ otherwise. */
+ if (MAY_HAVE_DEBUG_STMTS && current_ir_type () == IR_GIMPLE
+ && dom_info_available_p (CDI_DOMINATORS))
{
- next_bb = b->next_bb;
+ for (b = EXIT_BLOCK_PTR->prev_bb; b != ENTRY_BLOCK_PTR; b = prev_bb)
+ {
+ prev_bb = b->prev_bb;
+
+ if (!(b->flags & BB_REACHABLE))
+ {
+ /* Speed up the removal of blocks that don't dominate
+ others. Walking backwards, this should be the common
+ case. */
+ if (!first_dom_son (CDI_DOMINATORS, b))
+ delete_basic_block (b);
+ else
+ {
+ VEC (basic_block, heap) *h
+ = get_all_dominated_blocks (CDI_DOMINATORS, b);
+
+ while (VEC_length (basic_block, h))
+ {
+ b = VEC_pop (basic_block, h);
+
+ prev_bb = b->prev_bb;
+
+ gcc_assert (!(b->flags & BB_REACHABLE));
- if (!(b->flags & BB_REACHABLE))
+ delete_basic_block (b);
+ }
+
+ VEC_free (basic_block, heap, h);
+ }
+
+ changed = true;
+ }
+ }
+ }
+ else
+ {
+ for (b = EXIT_BLOCK_PTR->prev_bb; b != ENTRY_BLOCK_PTR; b = prev_bb)
{
- delete_basic_block (b);
- changed = true;
+ prev_bb = b->prev_bb;
+
+ if (!(b->flags & BB_REACHABLE))
+ {
+ delete_basic_block (b);
+ changed = true;
+ }
}
}
next = NEXT_INSN (insn);
if (LABEL_P (insn)
&& LABEL_NUSES (insn) == LABEL_PRESERVE_P (insn)
- && JUMP_P (next)
- && (GET_CODE (PATTERN (next)) == ADDR_VEC
- || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
+ && JUMP_TABLE_DATA_P (next))
{
rtx label = insn, jump = next;
static unsigned int
rest_of_handle_jump (void)
{
- delete_unreachable_blocks ();
-
- if (cfun->tail_call_emit)
+ if (crtl->tail_call_emit)
fixup_tail_calls ();
return 0;
}
-struct tree_opt_pass pass_jump =
+struct rtl_opt_pass pass_jump =
{
+ {
+ RTL_PASS,
"sibling", /* name */
NULL, /* gate */
rest_of_handle_jump, /* execute */
0, /* properties_destroyed */
TODO_ggc_collect, /* todo_flags_start */
TODO_verify_flow, /* todo_flags_finish */
- 'i' /* letter */
+ }
};
}
-struct tree_opt_pass pass_jump2 =
+struct rtl_opt_pass pass_jump2 =
{
+ {
+ RTL_PASS,
"jump", /* name */
NULL, /* gate */
rest_of_handle_jump2, /* execute */
0, /* properties_destroyed */
TODO_ggc_collect, /* todo_flags_start */
TODO_dump_func | TODO_verify_rtl_sharing,/* todo_flags_finish */
- 'j' /* letter */
+ }
};
OSDN Git Service
