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tree-ssa-alias.c (maybe_skip_until): Cache also at the point of the first store we visit in a basic-block.

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2011-10-12  Richard Guenther  <rguenther@suse.de>

	* tree-ssa-alias.c (maybe_skip_until): Cache also at the point
	of the first store we visit in a basic-block.
	(get_continuation_for_phi): Search for a candidate VUSE that
	might dominates all others.  Do pairwise disambiguation against
	that candidate.

From-SVN: r179858
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Richard Guenther 2011-10-12 15:28:48 +00:00 committed by Richard Biener
parent ebbcd0c6ea
commit d660a3db5c
2 changed files with 41 additions and 6 deletions
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8
gcc/ChangeLog
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@ -1,3 +1,11 @@
2011-10-12 Richard Guenther <rguenther@suse.de>
* tree-ssa-alias.c (maybe_skip_until): Cache also at the point
of the first store we visit in a basic-block.
(get_continuation_for_phi): Search for a candidate VUSE that
might dominates all others. Do pairwise disambiguation against
that candidate.
2011-10-12 Paul Koning <pkoning@gcc.gnu.org>
PR tree-optimization/50189

39
gcc/tree-ssa-alias.c
View File

@ -1846,6 +1846,8 @@ static bool
maybe_skip_until (gimple phi, tree target, ao_ref *ref,
tree vuse, bitmap *visited)
{
basic_block bb = gimple_bb (phi);
if (!*visited)
*visited = BITMAP_ALLOC (NULL);
@ -1870,6 +1872,14 @@ maybe_skip_until (gimple phi, tree target, ao_ref *ref,
else if (gimple_nop_p (def_stmt)
|| stmt_may_clobber_ref_p_1 (def_stmt, ref))
return false;
/* If we reach a new basic-block see if we already skipped it
in a previous walk that ended successfully. */
if (gimple_bb (def_stmt) != bb)
{
if (!bitmap_set_bit (*visited, SSA_NAME_VERSION (vuse)))
return true;
bb = gimple_bb (def_stmt);
}
vuse = gimple_vuse (def_stmt);
}
return true;
@ -1948,18 +1958,35 @@ get_continuation_for_phi (gimple phi, ao_ref *ref, bitmap *visited)
until we hit the phi argument definition that dominates the other one. */
else if (nargs >= 2)
{
tree arg0 = PHI_ARG_DEF (phi, 0);
tree arg1;
unsigned i = 1;
do
tree arg0, arg1;
unsigned i;
/* Find a candidate for the virtual operand which definition
dominates those of all others. */
arg0 = PHI_ARG_DEF (phi, 0);
if (!SSA_NAME_IS_DEFAULT_DEF (arg0))
for (i = 1; i < nargs; ++i)
{
arg1 = PHI_ARG_DEF (phi, i);
if (SSA_NAME_IS_DEFAULT_DEF (arg1))
{
arg0 = arg1;
break;
}
if (dominated_by_p (CDI_DOMINATORS,
gimple_bb (SSA_NAME_DEF_STMT (arg0)),
gimple_bb (SSA_NAME_DEF_STMT (arg1))))
arg0 = arg1;
}
/* Then pairwise reduce against the found candidate. */
for (i = 0; i < nargs; ++i)
{
arg1 = PHI_ARG_DEF (phi, i);
arg0 = get_continuation_for_phi_1 (phi, arg0, arg1, ref, visited);
if (!arg0)
return NULL_TREE;
}
while (++i < nargs);
return arg0;
}