1 files changed, 28 insertions, 0 deletions
diff --git a/lib/ctzdi2.c b/lib/ctzdi2.c
new file mode 100644
index 000000000..8ea3ab319
--- /dev/null
+++ b/lib/ctzdi2.c
@@ -0,0 +1,28 @@
+//===-- ctzdi2.c - Implement __ctzdi2 -------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements __ctzdi2 for the compiler_rt library.
+//
+//===----------------------------------------------------------------------===//
+
+#include "int_lib.h"
+
+// Returns: the number of trailing 0-bits
+
+// Precondition: a != 0
+
+si_int
+__ctzdi2(di_int a)
+{
+    dwords x;
+    x.all = a;
+    const si_int f = -(x.low == 0);
+    return __builtin_ctz((x.high & f) | (x.low & ~f)) +
+              (f & ((si_int)(sizeof(si_int) * CHAR_BIT)));
+}