re PR c++/56961 (stack overflow in gimplifier with volatile field)

/cp
2014-06-05  Richard Biener  <rguenther@suse.de>
	    Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/56961
	* cp-gimplify.c (cp_gimplify_expr, [MODIFY_EXPR]): Rework
	handling of empty classes.

/testsuite
2014-06-05  Richard Biener  <rguenther@suse.de>
	    Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/56961
	* g++.dg/parse/pr56961.C: New.

Co-Authored-By: Paolo Carlini <paolo.carlini@oracle.com>

From-SVN: r211286

gcc/cp/ChangeLog

+2014-06-05  Richard Biener  <rguenther@suse.de>
+	    Paolo Carlini  <paolo.carlini@oracle.com>
+
+	PR c++/56961
+	* cp-gimplify.c (cp_gimplify_expr, [MODIFY_EXPR]): Rework
+	handling of empty classes.
+
 2014-06-04  Jason Merrill  <jason@redhat.com>
 
 	* parser.c (cp_parser_diagnose_invalid_type_name): Give helpful note

gcc/cp/cp-gimplify.c

@@ -629,19 +629,12 @@ cp_gimplify_expr (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p)
 
 	       Also drop volatile variables on the RHS to avoid infinite
 	       recursion from gimplify_expr trying to load the value.  */
-	    if (!TREE_SIDE_EFFECTS (op1)
-		|| (DECL_P (op1) && TREE_THIS_VOLATILE (op1)))
+	    if (!TREE_SIDE_EFFECTS (op1))
 	      *expr_p = op0;
-	    else if (TREE_CODE (op1) == MEM_REF
-		     && TREE_THIS_VOLATILE (op1))
-	      {
-		/* Similarly for volatile MEM_REFs on the RHS.  */
-		if (!TREE_SIDE_EFFECTS (TREE_OPERAND (op1, 0)))
-		  *expr_p = op0;
-		else
-		  *expr_p = build2 (COMPOUND_EXPR, TREE_TYPE (*expr_p),
-				    TREE_OPERAND (op1, 0), op0);
-	      }
+	    else if (TREE_THIS_VOLATILE (op1)
+		     && (REFERENCE_CLASS_P (op1) || DECL_P (op1)))
+	      *expr_p = build2 (COMPOUND_EXPR, TREE_TYPE (*expr_p),
+				build_fold_addr_expr (op1), op0);
 	    else
 	      *expr_p = build2 (COMPOUND_EXPR, TREE_TYPE (*expr_p),
 				op0, op1);

gcc/testsuite/ChangeLog

+2014-06-05  Richard Biener  <rguenther@suse.de>
+	    Paolo Carlini  <paolo.carlini@oracle.com>
+
+	PR c++/56961
+	* g++.dg/parse/pr56961.C: New.
+
 2014-06-05  Kai Tietz  <ktietz@redhat.com>
 
 	PR target/46219

gcc/testsuite/g++.dg/parse/pr56961.C

+// PR c++/56961
+
+struct foo { };
+
+typedef struct
+{
+  volatile foo fields;
+} CSPHandleState;
+ 
+CSPHandleState a;
+
+void fn1 ()
+{
+  CSPHandleState b;
+  b.fields = foo();  // { dg-error "discards qualifiers" }
+}