From: Jakub Jelinek <jakub@redhat.com>
Date: Thu, 7 Apr 2011 18:22:50 +0000 (+0200)
Subject: re PR tree-optimization/47391 (read from const volatile incorrectly eliminated)
X-Git-Tag: releases/gcc-4.5.3~95
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5fea577bd07eaa4cd4ee6d7bf4f7e80e9f2bf842;p=thirdparty%2Fgcc.git

re PR tree-optimization/47391 (read from const volatile incorrectly eliminated)

	PR tree-optimization/47391
	* tree-ssa-ccp.c (get_symbol_constant_value): Don't optimize
	if sym is volatile.

	Backport from mainline
	2011-01-21  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/47391
	* gcc.dg/pr47391.c: New test.

From-SVN: r172112
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index d04de4db30a2..0d6cf493cd8d 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,9 @@
 2011-04-07  Jakub Jelinek  <jakub@redhat.com>
 
+	PR tree-optimization/47391
+	* tree-ssa-ccp.c (get_symbol_constant_value): Don't optimize
+	if sym is volatile.
+
 	Backported from mainline
 	2010-07-01  Richard Guenther  <rguenther@suse.de>
 
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 7e4d4f5cd3fc..b8f8cb752852 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,11 @@
+2011-04-07  Jakub Jelinek  <jakub@redhat.com>
+
+	Backport from mainline
+	2011-01-21  Jakub Jelinek  <jakub@redhat.com>
+ 
+	PR tree-optimization/47391
+	* gcc.dg/pr47391.c: New test.
+
 2011-04-07  Andrey Belevantsev  <abel@ispras.ru>
 
 	Backport from mainline
diff --git a/gcc/testsuite/gcc.dg/pr47391.c b/gcc/testsuite/gcc.dg/pr47391.c
new file mode 100644
index 000000000000..5ec98f10850c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr47391.c
@@ -0,0 +1,22 @@
+/* PR tree-optimization/47391 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+const volatile int v = 1;
+int i = 0;
+
+void
+foo (void)
+{
+  i = v;
+}
+
+int
+main (void)
+{
+  foo ();
+  return 0;
+}
+
+/* { dg-final { scan-tree-dump-not "i = 1;" "optimized" } } */
+/* { dg-final { cleanup-tree-dump "optimized" } } */
diff --git a/gcc/tree-ssa-ccp.c b/gcc/tree-ssa-ccp.c
index b570548d55aa..9f2c59b4f49d 100644
--- a/gcc/tree-ssa-ccp.c
+++ b/gcc/tree-ssa-ccp.c
@@ -277,7 +277,7 @@ tree
 get_symbol_constant_value (tree sym)
 {
   if (TREE_STATIC (sym)
-      && (TREE_READONLY (sym)
+      && ((TREE_READONLY (sym) && !TREE_THIS_VOLATILE (sym))
 	  || TREE_CODE (sym) == CONST_DECL))
     {
       tree val = DECL_INITIAL (sym);