--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/gcc.dg/torture/pr24257.c	Fri Oct 27 22:46:09 2017 +0900
@@ -0,0 +1,26 @@
+/* { dg-do compile } */
+/* { dg-options "-fgcse -fgcse-sm" } */
+
+typedef struct A {
+    int buf, left;
+} A;
+
+static void flush(A *s, int n)
+{
+    s->buf <<= n;
+
+    while (s->left < 32) {
+        s->buf <<= 8;
+        s->left += 8;
+    }
+
+    s->buf=0;
+}
+
+void oof(A *s, int n)
+{
+    s->buf = n;
+    s->left = n;
+
+    flush(s, n);
+}