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 * ===----------------------------------------------------------------------===
17 /* Returns: the number of leading 0-bits */
19 #if !defined(__clang__) && (defined(__sparc64__) || defined(__mips64) || defined(__riscv__))
20 /* gcc resolves __builtin_clz -> __clzdi2 leading to infinite recursion */
21 #define __builtin_clz(a) __clzsi2(a)
22 extern si_int __clzsi2(si_int);
25 /* Precondition: a != 0 */
27 COMPILER_RT_ABI si_int
32 const si_int f = -(x.s.high == 0);
33 return __builtin_clz((x.s.high & ~f) | (x.s.low & f)) +
34 (f & ((si_int)(sizeof(si_int) * CHAR_BIT)));