1 /* ===-- clzdi2.c - Implement __clzdi2 -------------------------------------===
3 * The LLVM Compiler Infrastructure
5 * This file is dual licensed under the MIT and the University of Illinois Open
6 * Source Licenses. See LICENSE.TXT for details.
8 * ===----------------------------------------------------------------------===
10 * This file implements __clzdi2 for the compiler_rt library.
12 * ===----------------------------------------------------------------------===
18 /* Returns: the number of leading 0-bits */
20 /* Precondition: a != 0 */
22 COMPILER_RT_ABI si_int
27 const si_int f = -(x.s.high == 0);
28 return __builtin_clz((x.s.high & ~f) | (x.s.low & f)) +
29 (f & ((si_int)(sizeof(si_int) * CHAR_BIT)));