re PR tree-optimization/50472 (Volatile qualification in data is not enough to…

re PR tree-optimization/50472 (Volatile qualification in data is not enough to avoid optimization over pointer to data)

2011-09-26  Richard Guenther  <rguenther@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.

From-SVN: r179196

gcc/ChangeLog

+2011-09-26  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/50472
+	* gimple-fold.c (fold_const_aggregate_ref_1): Do not fold
+	volatile references.
+
 2011-09-26  Bingfeng Mei <bmei@broadcom.com>
+
 	* doc/tm.texi: Correct documentation for TARGET_ADDR_SPACE_SUBSET_P.
 	* target.def: (addr_space_subset_p): Likewise.
 

gcc/gimple-fold.c

@@ -2919,6 +2919,9 @@ fold_const_aggregate_ref_1 (tree t, tree (*valueize) (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);
 

gcc/testsuite/ChangeLog

+2011-09-26  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/50472
+	* gcc.dg/torture/pr50472.c: New testcase.
+
 2011-09-26  Eric Botcazou  <ebotcazou@adacore.com>
 
 	* gnat.dg/opt22.adb: New test.

gcc/testsuite/gcc.dg/torture/pr50472.c

+/* { 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" } } */