Hi!
We want to terminate a chain if a chain with different base (or insn
outside of any chain) has a store that the current stmt might use, or
overwrite. The functions it used didn't cover the store after store
case which in the middle-end aliasing model needs to avoid tbaa, because
the latter store might be after a placement new or might otherwise change
the dynamic object type of the object.
The following patch does that. Bootstrapped/regtested on x86_64-linux and
i686-linux, additionally profiledbootstrapped with the configure options
Markus mentioned in the PR. Ok for trunk?
2017-11-09 Jakub Jelinek <ja...@redhat.com>
PR bootstrap/82916
* gimple-ssa-store-merging.c
(pass_store_merging::terminate_all_aliasing_chains): For
gimple_store_p stmts also call refs_output_dependent_p.
* gcc.dg/store_merging_2.c: Only expect 2 successful mergings instead
of 3.
* gcc.dg/pr82916.c: New test.
--- gcc/gimple-ssa-store-merging.c.jj 2017-11-09 15:51:08.000000000 +0100
+++ gcc/gimple-ssa-store-merging.c 2017-11-09 18:01:20.789236951 +0100
@@ -945,6 +945,7 @@ pass_store_merging::terminate_all_aliasi
if (!gimple_vuse (stmt))
return false;
+ tree store_lhs = gimple_store_p (stmt) ? gimple_get_lhs (stmt) : NULL_TREE;
for (imm_store_chain_info *next = m_stores_head, *cur = next; cur; cur =
next)
{
next = cur->next;
@@ -958,8 +959,10 @@ pass_store_merging::terminate_all_aliasi
unsigned int i;
FOR_EACH_VEC_ELT (cur->m_store_info, i, info)
{
- if (ref_maybe_used_by_stmt_p (stmt, gimple_assign_lhs (info->stmt))
- || stmt_may_clobber_ref_p (stmt, gimple_assign_lhs (info->stmt)))
+ tree lhs = gimple_assign_lhs (info->stmt);
+ if (ref_maybe_used_by_stmt_p (stmt, lhs)
+ || stmt_may_clobber_ref_p (stmt, lhs)
+ || (store_lhs && refs_output_dependent_p (store_lhs, lhs)))
{
if (dump_file && (dump_flags & TDF_DETAILS))
{
--- gcc/testsuite/gcc.dg/store_merging_2.c.jj 2017-11-08 16:46:19.000000000
+0100
+++ gcc/testsuite/gcc.dg/store_merging_2.c 2017-11-09 18:16:33.482344795
+0100
@@ -77,4 +77,4 @@ main (void)
return 0;
}
-/* { dg-final { scan-tree-dump-times "Merging successful" 3 "store-merging" }
} */
+/* { dg-final { scan-tree-dump-times "Merging successful" 2 "store-merging" }
} */
--- gcc/testsuite/gcc.dg/pr82916.c.jj 2017-11-09 18:12:40.707128841 +0100
+++ gcc/testsuite/gcc.dg/pr82916.c 2017-11-09 18:12:19.000000000 +0100
@@ -0,0 +1,47 @@
+/* PR bootstrap/82916 */
+/* { dg-do run } */
+/* { dg-options "-O2 -fno-tree-dse" } */
+
+struct A { struct A *next; };
+struct C
+{
+ int *of;
+ struct C *parent, *prev, *next;
+ int depth;
+ int min;
+ struct C *min_occ;
+};
+
+__attribute__((noipa)) struct C *
+foo (int *node)
+{
+ struct A *p = __builtin_malloc (sizeof (struct C));
+ if (!p)
+ return 0;
+ p->next = 0;
+ /* Originally placement new. */
+ struct C *nw = (struct C *)(void *)p;
+ nw->of = node;
+ nw->parent = 0;
+ nw->prev = 0;
+ nw->next = 0;
+ nw->depth = 0;
+ nw->min_occ = nw;
+ nw->min = 0;
+ return nw;
+}
+
+int
+main ()
+{
+ int o;
+ struct C *p = foo (&o);
+ if (p)
+ {
+ if (p->of != &o || p->parent || p->prev || p->next || p->depth
+ || p->min || p->min_occ != p)
+ __builtin_abort ();
+ }
+ __builtin_free (p);
+ return 0;
+}
Jakub
