ctzti2.c revision 77ed6142daed1e068fbda64405d0de9845e40e1a 
1/* ===-- ctzti2.c - Implement __ctzti2 -------------------------------------===
2 *
3 *                     The LLVM Compiler Infrastructure
4 *
5 * This file is distributed under the University of Illinois Open Source
6 * License. See LICENSE.TXT for details.
7 *
8 * ===----------------------------------------------------------------------===
9 *
10 * This file implements __ctzti2 for the compiler_rt library.
11 *
12 * ===----------------------------------------------------------------------===
13 */
14
15#if __x86_64
16
17#include "int_lib.h"
18
19/* Returns: the number of trailing 0-bits */
20
21/* Precondition: a != 0 */
22
23si_int
24__ctzti2(ti_int a)
25{
26    twords x;
27    x.all = a;
28    const di_int f = -(x.s.low == 0);
29    return __builtin_ctzll((x.s.high & f) | (x.s.low & ~f)) +
30              ((si_int)f & ((si_int)(sizeof(di_int) * CHAR_BIT)));
31}
32
33#endif
34