1 files changed, 51 insertions, 0 deletions
diff --git a/gcc/testsuite/g++.dg/opt/strength-reduce.C b/gcc/testsuite/g++.dg/opt/strength-reduce.C
new file mode 100644
index 00000000000..7c4619a36fa
--- /dev/null
+++ b/gcc/testsuite/g++.dg/opt/strength-reduce.C
@@ -0,0 +1,51 @@
+// This testcase was miscompiled on s390x, because strength-reduction
+// did not see biv in C::foo as used after loop, but it was used
+// in a REG_EQUAL note.
+// { dg-do run }
+// { dg-options "-O2" }
+
+extern "C" void abort (void);
+
+struct C
+{
+  int foo (char ch, int offset = 0x7fffffff) const;
+  int bar (int offset, char c) const;
+  char *a;
+};
+
+int C::bar (int offset, char c) const
+{
+  char ch = a[offset];
+  if (ch < c)
+    return -1;
+  if (ch > c)
+    return 1;
+  return 0;
+}
+
+int C::foo (char ch, int offset) const
+{
+  int len = __builtin_strlen (a);
+  if (len == 0)
+    return 0x7fffffff;
+  if (offset >= len)
+    offset = len - 1;
+
+  while (bar (offset, ch) != 0)
+    {
+      if (offset == 0)
+        return 0x7fffffff;
+      offset--;
+    }
+
+  return offset;
+}
+
+int main (void)
+{
+  C c;
+  c.a = "/some/dir/file.ext";
+  if (c.foo ('/') != 9)
+    abort ();
+  return 0;
+}