re PR tree-optimization/61964 (krb5 database propagation enters infinite loop; reduced test case)

2014-07-31  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/61964
	* tree-ssa-tail-merge.c (gimple_equal_p): Handle non-SSA LHS solely
	by structural equality.

	* gcc.dg/torture/pr61964.c: New testcase.

From-SVN: r213375

gcc/ChangeLog

+2014-07-31  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/61964
+	* tree-ssa-tail-merge.c (gimple_equal_p): Handle non-SSA LHS solely
+	by structural equality.
+
 2014-07-31  Yury Gribov  <y.gribov@samsung.com>
 
 	* doc/cpp.texi (__SANITIZE_ADDRESS__): Updated description.

gcc/testsuite/ChangeLog

+2014-07-31  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/61964
+	* gcc.dg/torture/pr61964.c: New testcase.
+
 2014-07-31  Marc Glisse  <marc.glisse@inria.fr>
 
 	PR c++/60517

gcc/testsuite/gcc.dg/torture/pr61964.c

+/* { dg-do run } */
+
+extern void abort (void);
+
+struct node { struct node *next, *prev; } node;
+struct head { struct node *first; } heads[5];
+int k = 2;
+struct head *head = &heads[2];
+
+static int __attribute__((noinline))
+foo()
+{
+  node.prev = (void *)head;
+  head->first = &node;
+
+  struct node *n = head->first;
+  struct head *h = &heads[k];
+
+  if (n->prev == (void *)h)
+    h->first = n->next;
+  else
+    n->prev->next = n->next;
+
+  n->next = h->first;
+  return n->next == &node;
+}
+
+int main()
+{
+  if (foo ())
+    abort ();
+  return 0;
+}

gcc/tree-ssa-tail-merge.c

@@ -1161,17 +1161,9 @@ gimple_equal_p (same_succ same_succ, gimple s1, gimple s2)
       lhs2 = gimple_get_lhs (s2);
       if (TREE_CODE (lhs1) != SSA_NAME
 	  && TREE_CODE (lhs2) != SSA_NAME)
-	{
-	  /* If the vdef is the same, it's the same statement.  */
-	  if (vn_valueize (gimple_vdef (s1))
-	      == vn_valueize (gimple_vdef (s2)))
-	    return true;
-
-	  /* Test for structural equality.  */
-	  return (operand_equal_p (lhs1, lhs2, 0)
-		  && gimple_operand_equal_value_p (gimple_assign_rhs1 (s1),
-						   gimple_assign_rhs1 (s2)));
-	}
+	return (operand_equal_p (lhs1, lhs2, 0)
+		&& gimple_operand_equal_value_p (gimple_assign_rhs1 (s1),
+						 gimple_assign_rhs1 (s2)));
       else if (TREE_CODE (lhs1) == SSA_NAME
 	       && TREE_CODE (lhs2) == SSA_NAME)
 	return vn_valueize (lhs1) == vn_valueize (lhs2);