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/**
* Copyright (C) 2018-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#pragma once
/**
* MONGO_YIELD_CORE_FOR_SMT
* - An architecture specific processor hint to allow the processor to yield. It is designed to
* improve the performance of spin-wait loops.
*
* See src/third_party/wiredtiger/src/include/gcc.h
*/
#ifndef _MSC_VER
#if defined(x86_64) || defined(__x86_64__)
#include <xmmintrin.h>
/* Pause instruction to prevent excess processor bus usage */
#define MONGO_YIELD_CORE_FOR_SMT() _mm_pause()
#elif defined(i386) || defined(__i386__)
#include <xmmintrin.h>
#define MONGO_YIELD_CORE_FOR_SMT() _mm_pause()
#elif defined(__PPC64__) || defined(PPC64)
/* ori 0,0,0 is the PPC64 noop instruction */
#define MONGO_YIELD_CORE_FOR_SMT() __asm__ volatile("ori 0,0,0" ::: "memory")
#elif defined(__aarch64__) || defined(__arm__)
/* See https://jira.mongodb.org/browse/WT-6872 for details on using `isb` instead of `yield`. */
#define MONGO_YIELD_CORE_FOR_SMT() __asm__ volatile("isb" ::: "memory")
#elif defined(__s390x__)
#define MONGO_YIELD_CORE_FOR_SMT() __asm__ volatile("lr 0,0" ::: "memory")
#elif defined(__sparc__)
#define MONGO_YIELD_CORE_FOR_SMT() __asm__ volatile("rd %%ccr, %%g0" ::: "memory")
#elif defined(__EMSCRIPTEN__)
// TODO: What should this be?
#define MONGO_YIELD_CORE_FOR_SMT()
#else
#error "No processor pause implementation for this architecture."
#endif
#else
// On Windows, use the winnt.h YieldProcessor macro
#define MONGO_YIELD_CORE_FOR_SMT() YieldProcessor()
#endif
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