[backport from gcc-4.8/trunk r185465 <mikpe@it.uu.se>]

gcc/

2012-03-16  Richard Guenther  <rguenther@suse.de>
	Kai Tietz  <ktietz@redhat.com>

	PR middle-end/48814
	* gimplify.c (gimplify_self_mod_expr): Evaluate postfix
	side-effects completely in the pre-queue and use a temporary
	for the result.

gcc/testsuite/

2012-03-16  Richard Guenther  <rguenther@suse.de>
	Kai Tietz  <ktietz@redhat.com>

	PR middle-end/48814
	* gcc.c-torture/execute/pr48814-1.c: New test.
	* gcc.c-torture/execute/pr48814-2.c: New test.
	* gcc.dg/tree-ssa/assign-1.c: New test.
	* gcc.dg/tree-ssa/assign-2.c: New test.
	* gcc.dg/tree-ssa/assign-3.c: New test.

--- gcc-4.7.1/gcc/gimplify.c.~1~	2012-05-10 17:00:11.000000000 +0200
+++ gcc-4.7.1/gcc/gimplify.c	2012-09-01 22:23:51.000000000 +0200
@@ -2272,17 +2272,18 @@ gimplify_self_mod_expr (tree *expr_p, gi
       arith_code = POINTER_PLUS_EXPR;
     }
 
-  t1 = build2 (arith_code, TREE_TYPE (*expr_p), lhs, rhs);
-
   if (postfix)
     {
-      gimplify_assign (lvalue, t1, orig_post_p);
+      tree t2 = get_initialized_tmp_var (lhs, pre_p, NULL);
+      t1 = build2 (arith_code, TREE_TYPE (*expr_p), t2, rhs);
+      gimplify_assign (lvalue, t1, pre_p);
       gimplify_seq_add_seq (orig_post_p, post);
-      *expr_p = lhs;
+      *expr_p = t2;
       return GS_ALL_DONE;
     }
   else
     {
+      t1 = build2 (arith_code, TREE_TYPE (*expr_p), lhs, rhs);
       *expr_p = build2 (MODIFY_EXPR, TREE_TYPE (lvalue), lvalue, t1);
       return GS_OK;
     }
--- gcc-4.7.1/gcc/testsuite/gcc.c-torture/execute/pr48814-1.c.~1~	1970-01-01 01:00:00.000000000 +0100
+++ gcc-4.7.1/gcc/testsuite/gcc.c-torture/execute/pr48814-1.c	2012-09-01 22:23:51.000000000 +0200
@@ -0,0 +1,18 @@
+extern void abort (void);
+
+int arr[] = {1,2,3,4};
+int count = 0;
+
+int __attribute__((noinline))
+incr (void)
+{
+  return ++count;
+}
+
+int main()
+{
+  arr[count++] = incr ();
+  if (count != 2 || arr[count] != 3)
+    abort ();
+  return 0;
+}
--- gcc-4.7.1/gcc/testsuite/gcc.c-torture/execute/pr48814-2.c.~1~	1970-01-01 01:00:00.000000000 +0100
+++ gcc-4.7.1/gcc/testsuite/gcc.c-torture/execute/pr48814-2.c	2012-09-01 22:23:51.000000000 +0200
@@ -0,0 +1,18 @@
+extern void abort (void);
+
+int arr[] = {1,2,3,4};
+int count = 0;
+
+int
+incr (void)
+{
+  return ++count;
+}
+
+int main()
+{
+  arr[count++] = incr ();
+  if (count != 2 || arr[count] != 3)
+    abort ();
+  return 0;
+}
--- gcc-4.7.1/gcc/testsuite/gcc.dg/tree-ssa/assign-1.c.~1~	1970-01-01 01:00:00.000000000 +0100
+++ gcc-4.7.1/gcc/testsuite/gcc.dg/tree-ssa/assign-1.c	2012-09-01 22:23:51.000000000 +0200
@@ -0,0 +1,12 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+volatile int count;
+void bar(int);
+void foo()
+{
+ bar(count++);
+}
+
+/* { dg-final { scan-tree-dump-times "count =" 1 "optimized"} } */
+/* { dg-final { cleanup-tree-dump "optimized" } } */
--- gcc-4.7.1/gcc/testsuite/gcc.dg/tree-ssa/assign-2.c.~1~	1970-01-01 01:00:00.000000000 +0100
+++ gcc-4.7.1/gcc/testsuite/gcc.dg/tree-ssa/assign-2.c	2012-09-01 22:23:51.000000000 +0200
@@ -0,0 +1,13 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+volatile int count;
+int arr[4];
+void foo()
+{
+ arr[count++] = 0;
+}
+
+/* { dg-final { scan-tree-dump-times "count =" 1 "optimized"} } */
+/* { dg-final { cleanup-tree-dump "optimized" } } */
+
--- gcc-4.7.1/gcc/testsuite/gcc.dg/tree-ssa/assign-3.c.~1~	1970-01-01 01:00:00.000000000 +0100
+++ gcc-4.7.1/gcc/testsuite/gcc.dg/tree-ssa/assign-3.c	2012-09-01 22:23:51.000000000 +0200
@@ -0,0 +1,24 @@
+/* { dg-do run } */
+/* { dg-options "-O2 -fdump-tree-gimple" } */
+
+extern void abort (void);
+struct S { int i; };
+struct S arr[32];
+volatile int count = 0;
+
+struct S __attribute__((noinline))
+incr ()
+{
+  ++count;
+}
+
+int main()
+{
+  arr[count++] = incr ();
+  if (count != 2)
+    abort ();
+  return 0;
+}
+
+/* { dg-final { scan-tree-dump-times " = count;" 3 "gimple" } } */
+/* { dg-final { cleanup-tree-dump "gimple" } } */