ctzti2.c revision b3a6901e66f55b35aa9e01bcb24134e6a65ea004 
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#if __x86_64
15
16#include "int_lib.h"
17
18// Returns: the number of trailing 0-bits
19
20// Precondition: a != 0
21
22si_int
23__ctzti2(ti_int a)
24{
25    twords x;
26    x.all = a;
27    const di_int f = -(x.low == 0);
28    return __builtin_ctzll((x.high & f) | (x.low & ~f)) +
29              ((si_int)f & ((si_int)(sizeof(di_int) * CHAR_BIT)));
30}
31
32#endif
33