expr.c (store_constructor): Only set RTX_UNCHANGING_P for read-only field if cleared is 0.

	* expr.c (store_constructor): Only set RTX_UNCHANGING_P for
	read-only field if cleared is 0.

	* gcc.dg/20031202-1.c: New test.

From-SVN: r74251

gcc/ChangeLog

+2003-12-03  Jakub Jelinek  <jakub@redhat.com>
+
+	* expr.c (store_constructor): Only set RTX_UNCHANGING_P for
+	read-only field if cleared is 0.
+
 2003-12-03  Nathanael Nerode  <neroden@gcc.gnu.org>
 
 	* config.gcc: Mark obsolete targets for GCC 3.4.

gcc/expr.c

@@ -4643,7 +4643,10 @@ store_constructor (tree exp, rtx target, int cleared, HOST_WIDE_INT size)
 				       highest_pow2_factor (offset));
 	    }
 
-	  if (TREE_READONLY (field))
+	  /* If the constructor has been cleared, setting RTX_UNCHANGING_P
+	     on the MEM might lead to scheduling the clearing after the
+	     store.  */
+	  if (TREE_READONLY (field) && !cleared)
 	    {
 	      if (GET_CODE (to_rtx) == MEM)
 		to_rtx = copy_rtx (to_rtx);

gcc/testsuite/ChangeLog

+2003-12-03  Jakub Jelinek  <jakub@redhat.com>
+
+	* gcc.dg/20031202-1.c: New test.
+
 2003-12-03  Mark Mitchell  <mark@codesourcery.com>
 
 	PR c++/10771

gcc/testsuite/gcc.dg/20031202-1.c

+/* { dg-do run } */
+/* { dg-options "-O2" } */
+/* { dg-options "-O2 -mtune=i686" { target i?86-*-* } } */
+
+extern void abort (void);
+extern void exit (int);
+
+struct A { char p[6]; } __attribute__((packed));
+struct B {
+    struct A a;
+    void * const b;
+    struct A const * const c;
+    struct A const *d;
+};
+
+char v;
+
+int __attribute__((noinline))
+foo (struct B *b)
+{
+  int i;
+  for (i = 0; i < 6; ++i)
+    if (b->a.p[i])
+      abort ();
+  if (b->b != &v || b->c || b->d)
+    abort ();
+  return 12;
+}
+
+int __attribute__((noinline))
+bar (void *x)
+{
+  __asm __volatile ("" : "=r" (x) : "0" (x));
+  struct B y = { .b = x, .c = (void *) 0 };
+  return foo (&y) + 1;
+}
+
+int
+main (void)
+{
+  if (bar (&v) != 13)
+    abort ();
+  exit (0);
+}