1/* ===-- clzdi2.c - Implement __clzdi2 -------------------------------------===
2 *
3 *               The LLVM Compiler Infrastructure
4 *
5 * This file is dual licensed under the MIT and the University of Illinois Open
6 * Source Licenses. See LICENSE.TXT for details.
7 *
8 * ===----------------------------------------------------------------------===
9 *
10 * This file implements __clzdi2 for the compiler_rt library.
11 *
12 * ===----------------------------------------------------------------------===
13 */
14
15#include "int_lib.h"
16
17/* Returns: the number of leading 0-bits */
18
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)
22extern si_int __clzsi2(si_int);
23#endif
24
25/* Precondition: a != 0 */
26
27COMPILER_RT_ABI si_int
28__clzdi2(di_int a)
29{
30    dwords x;
31    x.all = a;
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)));
35}
36