1//===-- ffsdi2.c - Implement __ffsdi2 -------------------------------------===// 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 __ffsdi2 for the compiler_rt library. 10// 11//===----------------------------------------------------------------------===// 12 13#include "int_lib.h" 14 15// Returns: the index of the least significant 1-bit in a, or 16// the value zero if a is zero. The least significant bit is index one. 17 18COMPILER_RT_ABI si_int __ffsdi2(di_int a) { 19 dwords x; 20 x.all = a; 21 if (x.s.low == 0) { 22 if (x.s.high == 0) 23 return 0; 24 return __builtin_ctz(x.s.high) + (1 + sizeof(si_int) * CHAR_BIT); 25 } 26 return __builtin_ctz(x.s.low) + 1; 27} 28