re PR c/8439 (empty struct causes crash)

	PR c/8439
	* recog.c (validate_replace_rtx_1) [PLUS]: Simplify only
	if there is something new to be simplified.

From-SVN: r59005

gcc/ChangeLog

+2002-11-09  Eric Botcazou  <ebotcazou@libertysurf.fr>
+
+	PR c/8439
+	* recog.c (validate_replace_rtx_1) [PLUS]: Simplify only
+	if there is something new to be simplified.
+
 2002-11-10  H.J. Lu <hjl@gnu.org>
 
 	* calls.c (PUSH_ARGS_REVERSED): Define only if not defined.

gcc/recog.c

@@ -522,10 +522,10 @@ validate_replace_rtx_1 (loc, from, to, object)
     {
     case PLUS:
       /* If we have a PLUS whose second operand is now a CONST_INT, use
-         plus_constant to try to simplify it.
+         simplify_gen_binary to try to simplify it.
          ??? We may want later to remove this, once simplification is
          separated from this function.  */
-      if (GET_CODE (XEXP (x, 1)) == CONST_INT)
+      if (GET_CODE (XEXP (x, 1)) == CONST_INT && XEXP (x, 1) == to)
 	validate_change (object, loc,
 			 simplify_gen_binary
 			 (PLUS, GET_MODE (x), XEXP (x, 0), XEXP (x, 1)), 1);

gcc/testsuite/ChangeLog

+2002-11-09  Eric Botcazou  <ebotcazou@libertysurf.fr>
+
+	PR c/8439
+	* gcc.dg/testsuite/20021110.c: New test.
+	
 2002-11-10  Mark Mitchell  <mark@codesourcery.com>
 
 	* g++.dg/abi/vthunk3.C: Run only on x86.

gcc/testsuite/gcc.dg/20021110.c

+/* PR c/8439 */
+/* Verify that GCC properly handles null increments. */
+
+struct empty {
+};
+
+void foo(struct empty *p)
+{
+   p++;
+}