--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/gcc.dg/store_merging_10.c	Thu Oct 25 07:37:49 2018 +0900
@@ -0,0 +1,56 @@
+/* { dg-do run } */
+/* { dg-require-effective-target store_merge } */
+/* { dg-options "-O2 -fdump-tree-store-merging" } */
+
+struct S {
+  unsigned int b1:1;
+  unsigned int b2:1;
+  unsigned int b3:1;
+  unsigned int b4:1;
+  unsigned int b5:1;
+  unsigned int b6:27;
+};
+
+struct T {
+  unsigned int b1:1;
+  unsigned int b2:16;
+  unsigned int b3:14;
+  unsigned int b4:1;
+};
+
+__attribute__((noipa)) void
+foo (struct S *x)
+{
+  x->b1 = 1;
+  x->b2 = 0;
+  x->b3 = 1;
+  x->b4 = 1;
+  x->b5 = 0;
+}
+
+__attribute__((noipa)) void
+bar (struct T *x)
+{
+  x->b1 = 1;
+  x->b2 = 0;
+  x->b4 = 0;
+}
+
+struct S s = { 0, 1, 0, 0, 1, 0x3a5f05a };
+struct T t = { 0, 0xf5af, 0x3a5a, 1 };
+
+int
+main ()
+{
+  asm volatile ("" : : : "memory");
+  foo (&s);
+  bar (&t);
+  asm volatile ("" : : : "memory");
+  if (s.b1 != 1 || s.b2 != 0 || s.b3 != 1 || s.b4 != 1 || s.b5 != 0 || s.b6 != 0x3a5f05a)
+    __builtin_abort ();
+  if (t.b1 != 1 || t.b2 != 0 || t.b3 != 0x3a5a || t.b4 != 0)
+    __builtin_abort ();
+  return 0;
+}
+
+/* { dg-final { scan-tree-dump-times "Merging successful" 2 "store-merging" } } */