diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index ca501249a3a51216501df3682a3ac053c6261a00..74ad7d2dec6a5eae9a8f96d8613faca3d820d5ce 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2012-09-06  Andrew Pinski  <apinski@cavium.com>
+
+	PR tree-opt/54494
+	* tree-inline.c (remap_gimple_op_r): Copy TREE_SIDE_EFFECTS also.
+
 2012-09-06  Jakub Jelinek  <jakub@redhat.com>
 
 	PR rtl-optimization/54455
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 8589e9ec4634e0a69553aa42ae9238c90c2004f5..56b6e0db9b2ac812aa1b1c1379f7aa90aeab91ab 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2012-09-06  Andrew Pinski  <apinski@cavium.com>
+
+	PR tree-opt/54494
+	* gcc.dg/tree-ssa/strlen-1.c: New testcase.
+
 2012-09-06  Jakub Jelinek  <jakub@redhat.com>
 
 	PR rtl-optimization/54455
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/strlen-1.c b/gcc/testsuite/gcc.dg/tree-ssa/strlen-1.c
new file mode 100644
index 0000000000000000000000000000000000000000..f6ff3e1570fe9d60689ff33a16e9c2775a71beb7
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/strlen-1.c
@@ -0,0 +1,17 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+extern const unsigned long base;
+static inline void wreg(unsigned char val, unsigned long addr) __attribute__((always_inline));
+static inline void wreg(unsigned char val, unsigned long addr)
+{
+   *((volatile unsigned char *) (__SIZE_TYPE__) (base + addr)) = val;
+}
+void wreg_twice(void)
+{
+   wreg(0, 42);
+   wreg(0, 42);
+}
+
+/* We should not remove the second null character store to (base+42) address. */
+/* { dg-final { scan-tree-dump-times " ={v} 0;" 2 "optimized" } }  */
+/* { dg-final { cleanup-tree-dump "optimized" } }  */
diff --git a/gcc/tree-inline.c b/gcc/tree-inline.c
index 20d33173a6ddde3b05c9273a16bb2fc216b3fa6e..05f271fc8fadf65de7dea3ad6447df406b5edf09 100644
--- a/gcc/tree-inline.c
+++ b/gcc/tree-inline.c
@@ -848,6 +848,7 @@ remap_gimple_op_r (tree *tp, int *walk_subtrees, void *data)
 			     ptr, TREE_OPERAND (*tp, 1));
 	  TREE_THIS_NOTRAP (*tp) = TREE_THIS_NOTRAP (old);
 	  TREE_THIS_VOLATILE (*tp) = TREE_THIS_VOLATILE (old);
+	  TREE_SIDE_EFFECTS (*tp) = TREE_SIDE_EFFECTS (old);
 	  TREE_NO_WARNING (*tp) = TREE_NO_WARNING (old);
 	  *walk_subtrees = 0;
 	  return NULL;