1 files changed, 23 insertions, 0 deletions
diff --git a/compiler-rt/lib/builtins/ffssi2.c b/compiler-rt/lib/builtins/ffssi2.c
new file mode 100644
index 000000000000..cba1f72fdc61
--- /dev/null
+++ b/compiler-rt/lib/builtins/ffssi2.c
@@ -0,0 +1,23 @@
+//===-- ffssi2.c - Implement __ffssi2 -------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements __ffssi2 for the compiler_rt library.
+//
+//===----------------------------------------------------------------------===//
+
+#include "int_lib.h"
+
+// Returns: the index of the least significant 1-bit in a, or
+// the value zero if a is zero. The least significant bit is index one.
+
+COMPILER_RT_ABI si_int __ffssi2(si_int a) {
+  if (a == 0) {
+    return 0;
+  }
+  return __builtin_ctz(a) + 1;
+}