diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 86a2b832cf1e..85ec2e607479 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2011-04-20  Easwaran Raman  <eraman@google.com>
+
+	* cfgexpand.c (add_alias_set_conflicts): Add conflicts with a variable
+	containing union type only with -fstrict-aliasing.
+
 2011-04-20  Jim Meyering  <meyering@redhat.com>
 
 	Remove useless if-before-free tests.
diff --git a/gcc/cfgexpand.c b/gcc/cfgexpand.c
index a3abc8497df2..e88bec149458 100644
--- a/gcc/cfgexpand.c
+++ b/gcc/cfgexpand.c
@@ -373,8 +373,9 @@ add_alias_set_conflicts (void)
 		 to elements will conflict.  In case of unions we have
 		 to be careful as type based aliasing rules may say
 		 access to the same memory does not conflict.  So play
-		 safe and add a conflict in this case.  */
-	      || contains_union)
+		 safe and add a conflict in this case when
+                 -fstrict-aliasing is used.  */
+              || (contains_union && flag_strict_aliasing))
 	    add_stack_var_conflict (i, j);
 	}
     }
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 3528f3e43c25..dfa5c8c00ced 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2011-04-20  Easwaran Raman  <eraman@google.com>
+
+	* gcc.dg/stack-layout-1.c: New test.
+
 2011-04-20  Daniel Jacobowitz  <dan@codesourcery.com>
 
 	* gcc.dg/vect/vect-shift-3.c, gcc.dg/vect/vect-shift-4.c: New.
diff --git a/gcc/testsuite/gcc.dg/stack-layout-1.c b/gcc/testsuite/gcc.dg/stack-layout-1.c
new file mode 100644
index 000000000000..389a4eb051eb
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/stack-layout-1.c
@@ -0,0 +1,25 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fno-strict-aliasing -fdump-rtl-expand" } */
+union U {
+  int a;
+  float b;
+};
+struct A {
+  union U u1;
+  char a[100];
+};
+void bar (struct A *);
+void foo ()
+  {
+    {
+      struct A a;
+      bar (&a);
+    }
+    {
+      struct A a;
+      bar (&a);
+    }
+  }
+
+/* { dg-final { scan-rtl-dump-times "Partition" 1 "expand" } } */
+/* { dg-final { cleanup-rtl-dump "expand" } } */