Fix tree-optimization/78886.

	PR tree-optimization/78886
	* gcc.dg/tree-ssa/pr78886.c: New test.
	PR tree-optimization/78886
	* tree-ssa-strlen.c (handle_builtin_malloc): Return when LHS
	is equal to NULL.

From-SVN: r243886

gcc/ChangeLog

+2016-12-22  Martin Liska  <mliska@suse.cz>
+
+	PR tree-optimization/78886
+	* tree-ssa-strlen.c (handle_builtin_malloc): Return when LHS
+	is equal to NULL.
+
 2016-12-22  Jakub Jelinek  <jakub@redhat.com>
 
 	PR bootstrap/78817

gcc/testsuite/ChangeLog

+2016-12-22  Martin Liska  <mliska@suse.cz>
+
+	PR tree-optimization/78886
+	* gcc.dg/tree-ssa/pr78886.c: New test.
+
 2016-12-22  Georg-Johann Lay  <avr@gjlay.de>
 
 	PR testsuite/52641

gcc/testsuite/gcc.dg/tree-ssa/pr78886.c

+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+void *malloc(unsigned long x);
+
+void foo(void)
+{
+ volatile int i;
+ malloc(1);
+ i;
+}

gcc/tree-ssa-strlen.c

@@ -1869,6 +1869,9 @@ handle_builtin_malloc (enum built_in_function bcode, gimple_stmt_iterator *gsi)
 {
   gimple *stmt = gsi_stmt (*gsi);
   tree lhs = gimple_call_lhs (stmt);
+  if (lhs == NULL_TREE)
+    return;
+
   gcc_assert (get_stridx (lhs) == 0);
   int idx = new_stridx (lhs);
   tree length = NULL_TREE;