compiler-rt/lib/builtins/ctzti2.c

   1 //===-- ctzti2.c - Implement __ctzti2 -------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file implements __ctzti2 for the compiler_rt library.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "int_lib.h"
  14
  15 #ifdef CRT_HAS_128BIT
  16
  17 // Returns: the number of trailing 0-bits
  18
  19 // Precondition: a != 0
  20
  21 COMPILER_RT_ABI int __ctzti2(ti_int a) {
  22   twords x;
  23   x.all = a;
  24   const di_int f = -(x.s.low == 0);
  25   return __builtin_ctzll((x.s.high & f) | (x.s.low & ~f)) +
  26          ((si_int)f & ((si_int)(sizeof(di_int) * CHAR_BIT)));
  27 }
  28
  29 #endif // CRT_HAS_128BIT