tree.c (build_constructor): Propagate TREE_SIDE_EFFECTS.

* tree.c (build_constructor): Propagate TREE_SIDE_EFFECTS.
testsuite/
	* gcc.dg/stmt-expr-4.c: New.

From-SVN: r187923

gcc/ChangeLog

@@ -1,3 +1,7 @@
+2012-05-27  Nathan Sidwell  <nathan@acm.org>
+
+	* tree.c (build_constructor): Propagate TREE_SIDE_EFFECTS.
+
 2012-05-26  Jason Merrill  <jason@redhat.com>
 
 	PR c++/53220

gcc/testsuite/ChangeLog

@@ -1,3 +1,7 @@
+2012-05-27  Nathan Sidwell  <nathan@acm.org>
+
+	* gcc.dg/stmt-expr-4.c: New.
+
 2012-05-26  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	PR c++/53491

gcc/testsuite/gcc.dg/stmt-expr-4.c

@@ -0,0 +1,22 @@
+
+/* { dg-options "-O2 -std=gnu99" } */
+/* Internal compiler error in iterative_hash_expr */
+
+struct tree_string
+{
+  char str[1];
+};
+
+union tree_node
+{
+  struct tree_string string;
+};
+
+char *Foo (union tree_node * num_string)
+{
+  char *str = ((union {const char * _q; char * _nq;})
+	       ((const char *)(({ __typeof (num_string) const __t
+				     = num_string;  __t; })
+			       ->string.str)))._nq;
+  return str;
+}

gcc/tree.c

@@ -1416,17 +1416,24 @@ build_constructor (tree type, VEC(constructor_elt,gc) *vals)
   unsigned int i;
   constructor_elt *elt;
   bool constant_p = true;
+  bool side_effects_p = false;
 
   TREE_TYPE (c) = type;
   CONSTRUCTOR_ELTS (c) = vals;
 
   FOR_EACH_VEC_ELT (constructor_elt, vals, i, elt)
-    if (!TREE_CONSTANT (elt->value))
+    {
-      {
+      /* Mostly ctors will have elts that don't have side-effects, so
+	 the usual case is to scan all the elements.  Hence a single
+	 loop for both const and side effects, rather than one loop
+	 each (with early outs).  */
+      if (!TREE_CONSTANT (elt->value))
 	constant_p = false;
-	break;
+      if (TREE_SIDE_EFFECTS (elt->value))
-      }
+	side_effects_p = true;
+    }
 
+  TREE_SIDE_EFFECTS (c) = side_effects_p;
   TREE_CONSTANT (c) = constant_p;
 
   return c;