1 files changed, 33 insertions, 0 deletions
diff --git a/compiler-rt/lib/builtins/clzti2.c b/compiler-rt/lib/builtins/clzti2.c
new file mode 100644
index 00000000000..355c20e4239
--- /dev/null
+++ b/compiler-rt/lib/builtins/clzti2.c
@@ -0,0 +1,33 @@
+/* ===-- clzti2.c - Implement __clzti2 -------------------------------------===
+ *
+ *      	       The LLVM Compiler Infrastructure
+ *
+ * This file is dual licensed under the MIT and the University of Illinois Open
+ * Source Licenses. See LICENSE.TXT for details.
+ *
+ * ===----------------------------------------------------------------------===
+ *
+ * This file implements __clzti2 for the compiler_rt library.
+ *
+ * ===----------------------------------------------------------------------===
+ */
+
+#include "int_lib.h"
+
+#if __x86_64
+
+/* Returns: the number of leading 0-bits */
+
+/* Precondition: a != 0 */
+
+si_int
+__clzti2(ti_int a)
+{
+    twords x;
+    x.all = a;
+    const di_int f = -(x.s.high == 0);
+    return __builtin_clzll((x.s.high & ~f) | (x.s.low & f)) +
+           ((si_int)f & ((si_int)(sizeof(di_int) * CHAR_BIT)));
+}
+
+#endif /* __x86_64 */