--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/gcc.dg/tree-ssa/loop-interchange-9.c	Thu Oct 25 07:37:49 2018 +0900
@@ -0,0 +1,63 @@
+/* { dg-do run } */
+/* { dg-options "-O2 -floop-interchange -fdump-tree-linterchange-details" } */
+/* { dg-skip-if "too big data segment" { avr-*-* visium-*-* } } */
+
+#define M 256
+int a[M][M], b[M][M], c[M], d[M];
+void __attribute__((noinline))
+simple_reduc_1 (int n)
+{
+  for (int j = 0; j < n; j++)
+    {
+      int sum = c[j];
+      for (int i = 0; i < n; i++)
+	sum = sum + a[i][j]*b[i][j];
+
+      c[j] = sum;
+    }
+}
+
+void __attribute__((noinline))
+simple_reduc_2 (int n)
+{
+  for (int j = 0; j < n; j++)
+    {
+      int sum = d[j];
+      for (int i = 0; i < n; i++)
+	sum = sum + a[i][j]*b[i][j];
+
+      asm volatile ("" ::: "memory");
+      d[j] = sum;
+    }
+}
+
+extern void abort ();
+
+static void __attribute__((noinline))
+init (int i)
+{
+  c[i] = 0;
+  d[i] = 0;
+  for (int j = 0; j < M; j++)
+    {
+      a[i][j] = i;
+      b[i][j] = j;
+    }
+}
+
+int main (void)
+{
+  for (int i = 0; i < M; ++i)
+    init (i);
+
+  simple_reduc_1 (M);
+  simple_reduc_2 (M);
+
+  for (int i = 0; i < M; ++i)
+    if (c[i] != d[i])
+      abort ();
+
+  return 0;
+}
+
+/* { dg-final { scan-tree-dump-times "Loop_pair<outer:., inner:.> is interchanged" 1 "linterchange" } } */