re PR tree-optimization/69776 (Wrong optimization with aliasing)

2016-02-16  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/69776
	* tree-ssa-alias.c (indirect_ref_may_alias_decl_p): Get alias
	sets from caller.
	(indirect_refs_may_alias_p): Likewise.
	(refs_may_alias_p_1): Pass alias sets as from ao_ref.
	* tree-ssa-sccvn.c (vn_reference_lookup): Also adjust vr alias-set
	according to tbaa_p.
	* tree-ssa-dom.c (lookup_avail_expr): Add tbaa_p flag.
	(optimize_stmt): For redundant store discovery do not allow tbaa.

	* gcc.dg/torture/pr69776-2.c: New testcase.

From-SVN: r233453

gcc/ChangeLog

+2016-02-16  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/69776
+	* tree-ssa-alias.c (indirect_ref_may_alias_decl_p): Get alias
+	sets from caller.
+	(indirect_refs_may_alias_p): Likewise.
+	(refs_may_alias_p_1): Pass alias sets as from ao_ref.
+	* tree-ssa-sccvn.c (vn_reference_lookup): Also adjust vr alias-set
+	according to tbaa_p.
+	* tree-ssa-dom.c (lookup_avail_expr): Add tbaa_p flag.
+	(optimize_stmt): For redundant store discovery do not allow tbaa.
+
 2016-02-16  Bernd Schmidt  <bschmidt@redhat.com>
 
 	PR tree-optimization/69714

gcc/testsuite/ChangeLog

+2016-02-16  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/69776
+	* gcc.dg/torture/pr69776-2.c: New testcase.
+
 2016-02-16  Bernd Schmidt  <bschmidt@redhat.com>
 
 	PR tree-optimization/69714

gcc/testsuite/gcc.dg/torture/pr69776-2.c

+/* { dg-do run } */
+/* { dg-additional-options "-fstrict-aliasing" } */
+
+extern void *malloc (__SIZE_TYPE__);
+extern void abort (void);
+
+__attribute__((noinline,noclone))
+void f(int *qi, double *qd)
+{
+  int i = *qi;
+  *qd = 0;
+  *qi = i;
+}
+
+int main()
+{
+  int *p = malloc(sizeof(double));
+
+  *p = 1;
+  f(p, (double *)p);
+  if (*p != 1)
+    abort();
+  return 0;
+}
+

gcc/tree-ssa-alias.c

@@ -1067,12 +1067,8 @@ indirect_ref_may_alias_decl_p (tree ref1 ATTRIBUTE_UNUSED, tree base1,
   ptrtype1 = TREE_TYPE (TREE_OPERAND (base1, 1));
 
   /* If the alias set for a pointer access is zero all bets are off.  */
-  if (base1_alias_set == -1)
-    base1_alias_set = get_deref_alias_set (ptrtype1);
   if (base1_alias_set == 0)
     return true;
-  if (base2_alias_set == -1)
-    base2_alias_set = get_alias_set (base2);
 
   /* When we are trying to disambiguate an access with a pointer dereference
      as base versus one with a decl as base we can use both the size
@@ -1239,13 +1235,8 @@ indirect_refs_may_alias_p (tree ref1 ATTRIBUTE_UNUSED, tree base1,
   ptrtype2 = TREE_TYPE (TREE_OPERAND (base2, 1));
 
   /* If the alias set for a pointer access is zero all bets are off.  */
-  if (base1_alias_set == -1)
-    base1_alias_set = get_deref_alias_set (ptrtype1);
-  if (base1_alias_set == 0)
-    return true;
-  if (base2_alias_set == -1)
-    base2_alias_set = get_deref_alias_set (ptrtype2);
-  if (base2_alias_set == 0)
+  if (base1_alias_set == 0
+      || base2_alias_set == 0)
     return true;
 
   /* If both references are through the same type, they do not alias
@@ -1417,7 +1408,8 @@ refs_may_alias_p_1 (ao_ref *ref1, ao_ref *ref2, bool tbaa_p)
   if (var1_p && ind2_p)
     return indirect_ref_may_alias_decl_p (ref2->ref, base2,
 					  offset2, max_size2,
-					  ao_ref_alias_set (ref2), -1,
+					  ao_ref_alias_set (ref2),
+					  ao_ref_base_alias_set (ref2),
 					  ref1->ref, base1,
 					  offset1, max_size1,
 					  ao_ref_alias_set (ref1),
@@ -1426,10 +1418,12 @@ refs_may_alias_p_1 (ao_ref *ref1, ao_ref *ref2, bool tbaa_p)
   else if (ind1_p && ind2_p)
     return indirect_refs_may_alias_p (ref1->ref, base1,
 				      offset1, max_size1,
-				      ao_ref_alias_set (ref1), -1,
+				      ao_ref_alias_set (ref1),
+				      ao_ref_base_alias_set (ref1),
 				      ref2->ref, base2,
 				      offset2, max_size2,
-				      ao_ref_alias_set (ref2), -1,
+				      ao_ref_alias_set (ref2),
+				      ao_ref_base_alias_set (ref2),
 				      tbaa_p);
 
   gcc_unreachable ();

gcc/tree-ssa-dom.c

@@ -103,7 +103,8 @@ static struct opt_stats_d opt_stats;
 static edge optimize_stmt (basic_block, gimple_stmt_iterator,
 			   class const_and_copies *,
 			   class avail_exprs_stack *);
-static tree lookup_avail_expr (gimple *, bool, class avail_exprs_stack *);
+static tree lookup_avail_expr (gimple *, bool, class avail_exprs_stack *,
+			       bool = true);
 static void record_cond (cond_equivalence *, class avail_exprs_stack *);
 static void record_equality (tree, tree, class const_and_copies *);
 static void record_equivalences_from_phis (basic_block);
@@ -1893,7 +1894,8 @@ optimize_stmt (basic_block bb, gimple_stmt_iterator si,
 	  else
 	    new_stmt = gimple_build_assign (rhs, lhs);
 	  gimple_set_vuse (new_stmt, gimple_vuse (stmt));
-	  cached_lhs = lookup_avail_expr (new_stmt, false, avail_exprs_stack);
+	  cached_lhs = lookup_avail_expr (new_stmt, false, avail_exprs_stack,
+					  false);
 	  if (cached_lhs
 	      && rhs == cached_lhs)
 	    {
@@ -1997,7 +1999,7 @@ vuse_eq (ao_ref *, tree vuse1, unsigned int cnt, void *data)
 
 static tree
 lookup_avail_expr (gimple *stmt, bool insert,
-		   class avail_exprs_stack *avail_exprs_stack)
+		   class avail_exprs_stack *avail_exprs_stack, bool tbaa_p)
 {
   expr_hash_elt **slot;
   tree lhs;
@@ -2054,7 +2056,8 @@ lookup_avail_expr (gimple *stmt, bool insert,
       if (!(vuse1 && vuse2
 	    && gimple_assign_single_p (stmt)
 	    && TREE_CODE (gimple_assign_lhs (stmt)) == SSA_NAME
-	    && (ao_ref_init (&ref, gimple_assign_rhs1 (stmt)), true)
+	    && (ao_ref_init (&ref, gimple_assign_rhs1 (stmt)),
+		ref.base_alias_set = ref.ref_alias_set = tbaa_p ? -1 : 0, true)
 	    && walk_non_aliased_vuses (&ref, vuse2,
 				       vuse_eq, NULL, NULL, vuse1) != NULL))
 	{

gcc/tree-ssa-sccvn.c

@@ -2249,7 +2249,7 @@ vn_reference_lookup (tree op, tree vuse, vn_lookup_kind kind,
   vr1.operands = operands
     = valueize_shared_reference_ops_from_ref (op, &valuezied_anything);
   vr1.type = TREE_TYPE (op);
-  vr1.set = get_alias_set (op);
+  vr1.set = tbaa_p ? get_alias_set (op) : 0;
   vr1.hashcode = vn_reference_compute_hash (&vr1);
   if ((cst = fully_constant_vn_reference_p (&vr1)))
     return cst;