diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index cefbca950f92b63700956ba8c9f0447b90e94a47..20680cbbaa7f1078e54737ba27acf98e2015c223 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2016-09-27  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/77478
+	* gcc.dg/torture/pr77478.c: New testcase.
+
 2016-09-27  Martin Liska  <mliska@suse.cz>
 
 	PR gcov-profile/7970
diff --git a/gcc/testsuite/gcc.dg/torture/pr77478.c b/gcc/testsuite/gcc.dg/torture/pr77478.c
new file mode 100644
index 0000000000000000000000000000000000000000..b5965bf574fd1e2eabcca73ddc44bae06d7f5cf2
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr77478.c
@@ -0,0 +1,22 @@
+/* { dg-do run } */
+/* { dg-additional-options "-ffast-math" } */
+
+static const float A[10] = {1};
+
+float
+foo(float *f, int n)
+{
+  int i, j;
+  float a = 0, b = 0;
+  for (i = n/2; i < n; i++)
+    a += f[i]*.1f;
+  for (i = n/2, j = 0; i < n; i++, j++)
+    b += f[i]*A[j]+a*A[j];
+  return b;
+}
+
+int main()
+{
+  float a[21] = {0};
+  return foo(a+1, 20) + foo(a, 20);
+}