1 /* ===-- ctzdi2.c - Implement __ctzdi2 -------------------------------------===
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 __ctzdi2 for the compiler_rt library.
11  *
12  * ===----------------------------------------------------------------------===
13  */
14 
15 #include "int_lib.h"
16 
17 /* Returns: the number of trailing 0-bits  */
18 
19 /* Precondition: a != 0 */
20 
21 COMPILER_RT_ABI si_int
__ctzdi2(di_int a)22 __ctzdi2(di_int a)
23 {
24     dwords x;
25     x.all = a;
26     const si_int f = -(x.s.low == 0);
27     return __builtin_ctz((x.s.high & f) | (x.s.low & ~f)) +
28               (f & ((si_int)(sizeof(si_int) * CHAR_BIT)));
29 }
30