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1//===-- popcountti2.c - Implement __popcountti22//----------------------------===//3//4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.5// See https://llvm.org/LICENSE.txt for license information.6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception7//8//===----------------------------------------------------------------------===//9//10// This file implements __popcountti2 for the compiler_rt library.11//12//===----------------------------------------------------------------------===//13 14#include "int_lib.h"15 16#ifdef CRT_HAS_128BIT17 18// Returns: count of 1 bits19 20COMPILER_RT_ABI int __popcountti2(ti_int a) {21 tu_int x3 = (tu_int)a;22 x3 = x3 - ((x3 >> 1) &23 (((tu_int)0x5555555555555555uLL << 64) | 0x5555555555555555uLL));24 // Every 2 bits holds the sum of every pair of bits (64)25 x3 = ((x3 >> 2) &26 (((tu_int)0x3333333333333333uLL << 64) | 0x3333333333333333uLL)) +27 (x3 & (((tu_int)0x3333333333333333uLL << 64) | 0x3333333333333333uLL));28 // Every 4 bits holds the sum of every 4-set of bits (3 significant bits) (32)29 x3 = (x3 + (x3 >> 4)) &30 (((tu_int)0x0F0F0F0F0F0F0F0FuLL << 64) | 0x0F0F0F0F0F0F0F0FuLL);31 // Every 8 bits holds the sum of every 8-set of bits (4 significant bits) (16)32 du_int x2 = (du_int)(x3 + (x3 >> 64));33 // Every 8 bits holds the sum of every 8-set of bits (5 significant bits) (8)34 su_int x = (su_int)(x2 + (x2 >> 32));35 // Every 8 bits holds the sum of every 8-set of bits (6 significant bits) (4)36 x = x + (x >> 16);37 // Every 8 bits holds the sum of every 8-set of bits (7 significant bits) (2)38 //39 // Upper 16 bits are garbage40 return (x + (x >> 8)) & 0xFF; // (8 significant bits)41}42 43#endif // CRT_HAS_128BIT44