--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/gcc.target/i386/pr94956.c	Mon May 25 07:50:57 2020 +0900
@@ -0,0 +1,28 @@
+/* PR tree-optimization/94956 */
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+/* { dg-final { scan-assembler-not "\tcmovne\t" } } */
+/* { dg-final { scan-assembler-not "\tsete\t" } } */
+
+int
+foo (unsigned x)
+{
+  if (x == 0) __builtin_unreachable ();
+  return __builtin_ffs (x) - 1;
+}
+
+int
+bar (unsigned long x)
+{
+  if (x == 0) __builtin_unreachable ();
+  return __builtin_ffsl (x) - 1;
+}
+
+#ifdef __x86_64__
+int
+baz (unsigned long long x)
+{
+  if (x == 0) __builtin_unreachable ();
+  return __builtin_ffsll (x) - 1;
+}
+#endif