2006-08-17  Jakub Jelinek  <jakub@redhat.com>

	PR middle-end/28755
	* expr.c (expand_expr_real_1) <case ARRAY_REF>: Make sure
	the const array field optimization doesn't create an extra constant
	MEM.

	* gcc.dg/pr28755.c: New test.

--- gcc/expr.c.jj	2006-08-09 17:54:03.000000000 +0200
+++ gcc/expr.c	2006-08-17 13:00:33.000000000 +0200
@@ -7105,13 +7105,25 @@ expand_expr_real_1 (tree exp, rtx target
 					      field, value)
 		      if (tree_int_cst_equal (field, index))
 			{
-			  if (!TREE_SIDE_EFFECTS (value))
+			  if (TREE_SIDE_EFFECTS (value))
+			    break;
+
+			  if (TREE_CODE (value) != CONSTRUCTOR)
 			    return expand_expr (fold (value), target, tmode,
 						modifier);
+
+			  /* For CONSTRUCTOR this optimization is not always
+			     a win - if expand_expr creates a temporary
+			     constant, we just waste unnecessarily rodata
+			     space.  */
+			  temp = expand_expr (value, target, tmode, modifier);
+			  if (temp == target
+			      || (temp && GET_CODE (temp) != MEM))
+			    return temp;
 			  break;
 			}
 		  }
-		else if(TREE_CODE (init) == STRING_CST)
+		else if (TREE_CODE (init) == STRING_CST)
 		  {
 		    tree index1 = index;
 		    tree low_bound = array_ref_low_bound (exp);
--- gcc/testsuite/gcc.dg/pr28755.c.jj	2006-08-17 12:59:57.000000000 +0200
+++ gcc/testsuite/gcc.dg/pr28755.c	2006-08-17 12:59:57.000000000 +0200
@@ -0,0 +1,22 @@
+/* PR middle-end/28755 */
+/* { dg-do compile } */
+/* { dg-options "-Os" } */
+/* { dg-final { scan-assembler-times "2112543726\|7deadbee" 2 } } */
+
+struct S
+{
+  void *s1;
+  unsigned s2, s3, s4, s5, s6, s7, s8, s9, s10, s11, s12, s13, s14;
+};
+
+const struct S array[] = {
+  { (void *) 0, 60, 640, 2112543726, 39682, 48, 16, 33, 10, 96, 2, 0, 0, 4 },
+  { (void *) 0, 60, 2112543726, 192, 18251, 16, 33, 10, 96, 2, 0, 0, 4, 212 }
+};
+
+void
+foo (struct S *x)
+{
+  x[0] = array[0];
+  x[5] = array[1];
+}