The following fixes PR54498 - we may not treat already visited
parts of the CFG as non-aliasing after re-writing the expression
we lookup. Just abort the walk in this case.
Bootstrapped and tested on x86_64-unknown-linux-gnu on the 4.7
branch, trunk testing in progress.
Richard.
2012-09-06 Richard Guenther <rguent...@suse.de>
PR tree-optimization/54498
* tree-ssa-alias.h (get_continuation_for_phi): Add flag to
abort when reaching an already visited region.
* tree-ssa-alias.c (maybe_skip_until): Likewise. And do it.
(get_continuation_for_phi_1): Likewise.
(walk_non_aliased_vuses): When we translated the reference,
abort when we re-visit a region.
* tree-ssa-pre.c (translate_vuse_through_block): Adjust.
Index: gcc/tree-ssa-alias.h
===================================================================
--- gcc/tree-ssa-alias.h (revision 191016)
+++ gcc/tree-ssa-alias.h (working copy)
@@ -108,7 +108,7 @@ extern bool stmt_may_clobber_ref_p (gimp
extern bool stmt_may_clobber_ref_p_1 (gimple, ao_ref *);
extern bool call_may_clobber_ref_p (gimple, tree);
extern bool stmt_kills_ref_p (gimple, tree);
-extern tree get_continuation_for_phi (gimple, ao_ref *, bitmap *);
+extern tree get_continuation_for_phi (gimple, ao_ref *, bitmap *, bool);
extern void *walk_non_aliased_vuses (ao_ref *, tree,
void *(*)(ao_ref *, tree, void *),
void *(*)(ao_ref *, tree, void *), void *);
Index: gcc/tree-ssa-alias.c
===================================================================
--- gcc/tree-ssa-alias.c (revision 191016)
+++ gcc/tree-ssa-alias.c (working copy)
@@ -1886,7 +1886,7 @@ stmt_kills_ref_p (gimple stmt, tree ref)
static bool
maybe_skip_until (gimple phi, tree target, ao_ref *ref,
- tree vuse, bitmap *visited)
+ tree vuse, bitmap *visited, bool abort_on_visited)
{
basic_block bb = gimple_bb (phi);
@@ -1904,8 +1904,9 @@ maybe_skip_until (gimple phi, tree targe
{
/* An already visited PHI node ends the walk successfully. */
if (bitmap_bit_p (*visited, SSA_NAME_VERSION (PHI_RESULT (def_stmt))))
- return true;
- vuse = get_continuation_for_phi (def_stmt, ref, visited);
+ return !abort_on_visited;
+ vuse = get_continuation_for_phi (def_stmt, ref,
+ visited, abort_on_visited);
if (!vuse)
return false;
continue;
@@ -1919,7 +1920,7 @@ maybe_skip_until (gimple phi, tree targe
if (gimple_bb (def_stmt) != bb)
{
if (!bitmap_set_bit (*visited, SSA_NAME_VERSION (vuse)))
- return true;
+ return !abort_on_visited;
bb = gimple_bb (def_stmt);
}
vuse = gimple_vuse (def_stmt);
@@ -1933,7 +1934,8 @@ maybe_skip_until (gimple phi, tree targe
static tree
get_continuation_for_phi_1 (gimple phi, tree arg0, tree arg1,
- ao_ref *ref, bitmap *visited)
+ ao_ref *ref, bitmap *visited,
+ bool abort_on_visited)
{
gimple def0 = SSA_NAME_DEF_STMT (arg0);
gimple def1 = SSA_NAME_DEF_STMT (arg1);
@@ -1946,14 +1948,14 @@ get_continuation_for_phi_1 (gimple phi,
&& dominated_by_p (CDI_DOMINATORS,
gimple_bb (def1), gimple_bb (def0))))
{
- if (maybe_skip_until (phi, arg0, ref, arg1, visited))
+ if (maybe_skip_until (phi, arg0, ref, arg1, visited, abort_on_visited))
return arg0;
}
else if (gimple_nop_p (def1)
|| dominated_by_p (CDI_DOMINATORS,
gimple_bb (def0), gimple_bb (def1)))
{
- if (maybe_skip_until (phi, arg1, ref, arg0, visited))
+ if (maybe_skip_until (phi, arg1, ref, arg0, visited, abort_on_visited))
return arg1;
}
/* Special case of a diamond:
@@ -1988,7 +1990,8 @@ get_continuation_for_phi_1 (gimple phi,
be found. */
tree
-get_continuation_for_phi (gimple phi, ao_ref *ref, bitmap *visited)
+get_continuation_for_phi (gimple phi, ao_ref *ref, bitmap *visited,
+ bool abort_on_visited)
{
unsigned nargs = gimple_phi_num_args (phi);
@@ -2025,7 +2028,8 @@ get_continuation_for_phi (gimple phi, ao
for (i = 0; i < nargs; ++i)
{
arg1 = PHI_ARG_DEF (phi, i);
- arg0 = get_continuation_for_phi_1 (phi, arg0, arg1, ref, visited);
+ arg0 = get_continuation_for_phi_1 (phi, arg0, arg1, ref, visited,
+ abort_on_visited);
if (!arg0)
return NULL_TREE;
}
@@ -2061,6 +2065,7 @@ walk_non_aliased_vuses (ao_ref *ref, tre
{
bitmap visited = NULL;
void *res;
+ bool translated = false;
timevar_push (TV_ALIAS_STMT_WALK);
@@ -2077,7 +2082,7 @@ walk_non_aliased_vuses (ao_ref *ref, tre
if (gimple_nop_p (def_stmt))
break;
else if (gimple_code (def_stmt) == GIMPLE_PHI)
- vuse = get_continuation_for_phi (def_stmt, ref, &visited);
+ vuse = get_continuation_for_phi (def_stmt, ref, &visited, translated);
else
{
if (stmt_may_clobber_ref_p_1 (def_stmt, ref))
@@ -2095,6 +2100,7 @@ walk_non_aliased_vuses (ao_ref *ref, tre
else if (res != NULL)
break;
/* Translation succeeded, continue walking. */
+ translated = true;
}
vuse = gimple_vuse (def_stmt);
}
Index: gcc/tree-ssa-pre.c
===================================================================
--- gcc/tree-ssa-pre.c (revision 191016)
+++ gcc/tree-ssa-pre.c (working copy)
@@ -1283,7 +1283,7 @@ translate_vuse_through_block (VEC (vn_re
bitmap visited = NULL;
/* Try to find a vuse that dominates this phi node by skipping
non-clobbering statements. */
- vuse = get_continuation_for_phi (phi, &ref, &visited);
+ vuse = get_continuation_for_phi (phi, &ref, &visited, false);
if (visited)
BITMAP_FREE (visited);
}
