re PR middle-end/40204 (segfault with bitfields in structs)

	PR middle-end/40204
	* fold-const.c (fold_binary) <case BIT_AND_EXPR>: Avoid infinite
	recursion if build_int_cst_type returns the same INTEGER_CST as
	arg1.

	* gcc.c-torture/compile/pr40204.c: New test.

From-SVN: r147749

gcc/ChangeLog

+2009-05-20  Jakub Jelinek  <jakub@redhat.com>
+
+	PR middle-end/40204
+	* fold-const.c (fold_binary) <case BIT_AND_EXPR>: Avoid infinite
+	recursion if build_int_cst_type returns the same INTEGER_CST as
+	arg1.
+
 2009-05-20  Eric Botcazou  <ebotcazou@adacore.com>
 
 	* fold-const.c (build_fold_addr_expr_with_type): Take the address of

gcc/fold-const.c

@@ -11382,6 +11382,8 @@ fold_binary (enum tree_code code, tree type, tree op0, tree op1)
 	      if (prec < HOST_BITS_PER_WIDE_INT
 		  || newmask == ~(unsigned HOST_WIDE_INT) 0)
 		{
+		  tree newmaskt;
+
 		  if (shift_type != TREE_TYPE (arg0))
 		    {
 		      tem = fold_build2 (TREE_CODE (arg0), shift_type,
@@ -11392,9 +11394,9 @@ fold_binary (enum tree_code code, tree type, tree op0, tree op1)
 		    }
 		  else
 		    tem = op0;
-		  return fold_build2 (BIT_AND_EXPR, type, tem,
-				      build_int_cst_type (TREE_TYPE (op1),
-							  newmask));
+		  newmaskt = build_int_cst_type (TREE_TYPE (op1), newmask);
+		  if (!tree_int_cst_equal (newmaskt, arg1))
+		    return fold_build2 (BIT_AND_EXPR, type, tem, newmaskt);
 		}
 	    }
 	}

gcc/testsuite/ChangeLog

+2009-05-20  Jakub Jelinek  <jakub@redhat.com>
+
+	PR middle-end/40204
+	* gcc.c-torture/compile/pr40204.c: New test.
+
 2009-05-20  Richard Guenther  <rguenther@suse.de>
 
 	* gcc.c-torture/compile/20090518-1.c: New testcase.

gcc/testsuite/gcc.c-torture/compile/pr40204.c

+/* PR middle-end/40204 */
+
+struct S
+{
+  unsigned int a : 4;
+  unsigned int b : 28;
+} s;
+char c;
+
+void
+f (void)
+{
+  s.a = (c >> 4) & ~(1 << 4);
+}