compiler-rt/lib/builtins/clzti2.c

   1 //===-- clzti2.c - Implement __clzti2 -------------------------------------===//
   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 __clzti2 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 leading 0-bits
  18
  19 // Precondition: a != 0
  20
  21 COMPILER_RT_ABI int __clzti2(ti_int a) {
  22   twords x;
  23   x.all = a;
  24   const di_int f = -(x.s.high == 0);
  25   return __builtin_clzll((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