1 /* ===-- ctzdi2.c - Implement __ctzdi2 -------------------------------------===
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 __ctzdi2 for the compiler_rt library.
12 * ===----------------------------------------------------------------------===
17 /* Returns: the number of trailing 0-bits */
19 /* Precondition: a != 0 */
21 COMPILER_RT_ABI si_int
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)));