[PATCH] Fix PR50472

[Richard Guenther]

Bootstrapped and tested on x86_64-unknown-linux-gnu, applied.

Richard.

2011-09-26  Richard Guenther  <rguent...@suse.de>

        PR tree-optimization/50472
        * gimple-fold.c (fold_const_aggregate_ref_1): Do not fold
        volatile references.

        * gcc.dg/torture/pr50472.c: New testcase.

Index: gcc/gimple-fold.c
===================================================================
--- gcc/gimple-fold.c   (revision 179185)
+++ gcc/gimple-fold.c   (working copy)
@@ -2919,6 +2919,9 @@ fold_const_aggregate_ref_1 (tree t, tree
   HOST_WIDE_INT offset, size, max_size;
   tree tem;
 
+  if (TREE_THIS_VOLATILE (t))
+    return NULL_TREE;
+
   if (TREE_CODE_CLASS (TREE_CODE (t)) == tcc_declaration)
     return get_symbol_constant_value (t);
 
Index: gcc/testsuite/gcc.dg/torture/pr50472.c
===================================================================
--- gcc/testsuite/gcc.dg/torture/pr50472.c      (revision 0)
+++ gcc/testsuite/gcc.dg/torture/pr50472.c      (revision 0)
@@ -0,0 +1,12 @@
+/* { dg-do compile } */
+/* { dg-options "-fdump-tree-optimized" } */
+
+static const unsigned int foo = 1;
+unsigned int test( void )
+{
+  const volatile unsigned int *bar = &foo;
+  return ( *bar );
+}
+
+/* { dg-final { scan-tree-dump-not "return 1" "optimized" } } */
+/* { dg-final { cleanup-tree-dump "optimized" } } */