--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/gcc.dg/vect/vect-reduc-dot-1.c	Thu Oct 25 07:37:49 2018 +0900
@@ -0,0 +1,49 @@
+/* { dg-require-effective-target vect_int } */
+
+#include "tree-vect.h"
+
+#define N 50
+
+#ifndef SIGNEDNESS_1
+#define SIGNEDNESS_1 unsigned
+#define SIGNEDNESS_2 unsigned
+#define SIGNEDNESS_3 unsigned
+#endif
+
+SIGNEDNESS_1 int __attribute__ ((noipa))
+f (SIGNEDNESS_1 int res, SIGNEDNESS_3 char *restrict a,
+   SIGNEDNESS_3 char *restrict b)
+{
+  for (__INTPTR_TYPE__ i = 0; i < N; ++i)
+    {
+      int av = a[i];
+      int bv = b[i];
+      SIGNEDNESS_2 short mult = av * bv;
+      res += mult;
+    }
+  return res;
+}
+
+#define BASE ((SIGNEDNESS_3 int) -1 < 0 ? -126 : 4)
+#define OFFSET 20
+
+int
+main (void)
+{
+  check_vect ();
+
+  SIGNEDNESS_3 char a[N], b[N];
+  int expected = 0x12345;
+  for (int i = 0; i < N; ++i)
+    {
+      a[i] = BASE + i * 5;
+      b[i] = BASE + OFFSET + i * 4;
+      asm volatile ("" ::: "memory");
+      expected += (SIGNEDNESS_2 short) (a[i] * b[i]);
+    }
+  if (f (0x12345, a, b) != expected)
+    __builtin_abort ();
+}
+
+/* { dg-final { scan-tree-dump "vect_recog_dot_prod_pattern: detected" "vect" } } */
+/* { dg-final { scan-tree-dump-times "vectorized 1 loop" 1 "vect" { target vect_sdot_qi } } } */