1 files changed, 29 insertions, 0 deletions
diff --git a/lib/builtins/clzdi2.c b/lib/builtins/clzdi2.c
new file mode 100644
index 000000000..b9e64da49
--- /dev/null
+++ b/lib/builtins/clzdi2.c
@@ -0,0 +1,29 @@
+/* ===-- clzdi2.c - Implement __clzdi2 -------------------------------------===
+ *
+ *               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 __clzdi2 for the compiler_rt library.
+ *
+ * ===----------------------------------------------------------------------===
+ */
+
+#include "int_lib.h"
+
+/* Returns: the number of leading 0-bits */
+
+/* Precondition: a != 0 */
+
+COMPILER_RT_ABI si_int
+__clzdi2(di_int a)
+{
+    dwords x;
+    x.all = a;
+    const si_int f = -(x.s.high == 0);
+    return __builtin_clz((x.s.high & ~f) | (x.s.low & f)) +
+           (f & ((si_int)(sizeof(si_int) * CHAR_BIT)));
+}