llvm/lib/Support/Threading.cpp
Chandler Carruth 6b547686c5 Update the file headers across all of the LLVM projects in the monorepo
to reflect the new license.

We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.

Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@351636 91177308-0d34-0410-b5e6-96231b3b80d8
2019-01-19 08:50:56 +00:00

96 lines
2.9 KiB
C++

//===-- llvm/Support/Threading.cpp- Control multithreading mode --*- C++ -*-==//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file defines helper functions for running LLVM in a multi-threaded
// environment.
//
//===----------------------------------------------------------------------===//
#include "llvm/Support/Threading.h"
#include "llvm/Config/config.h"
#include "llvm/Support/Host.h"
#include <cassert>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
using namespace llvm;
//===----------------------------------------------------------------------===//
//=== WARNING: Implementation here must contain only TRULY operating system
//=== independent code.
//===----------------------------------------------------------------------===//
bool llvm::llvm_is_multithreaded() {
#if LLVM_ENABLE_THREADS != 0
return true;
#else
return false;
#endif
}
#if LLVM_ENABLE_THREADS == 0 || \
(!defined(_WIN32) && !defined(HAVE_PTHREAD_H))
// Support for non-Win32, non-pthread implementation.
void llvm::llvm_execute_on_thread(void (*Fn)(void *), void *UserData,
unsigned RequestedStackSize) {
(void)RequestedStackSize;
Fn(UserData);
}
unsigned llvm::heavyweight_hardware_concurrency() { return 1; }
unsigned llvm::hardware_concurrency() { return 1; }
uint64_t llvm::get_threadid() { return 0; }
uint32_t llvm::get_max_thread_name_length() { return 0; }
void llvm::set_thread_name(const Twine &Name) {}
void llvm::get_thread_name(SmallVectorImpl<char> &Name) { Name.clear(); }
#else
#include <thread>
unsigned llvm::heavyweight_hardware_concurrency() {
// Since we can't get here unless LLVM_ENABLE_THREADS == 1, it is safe to use
// `std::thread` directly instead of `llvm::thread` (and indeed, doing so
// allows us to not define `thread` in the llvm namespace, which conflicts
// with some platforms such as FreeBSD whose headers also define a struct
// called `thread` in the global namespace which can cause ambiguity due to
// ADL.
int NumPhysical = sys::getHostNumPhysicalCores();
if (NumPhysical == -1)
return std::thread::hardware_concurrency();
return NumPhysical;
}
unsigned llvm::hardware_concurrency() {
#if defined(HAVE_SCHED_GETAFFINITY) && defined(HAVE_CPU_COUNT)
cpu_set_t Set;
if (sched_getaffinity(0, sizeof(Set), &Set))
return CPU_COUNT(&Set);
#endif
// Guard against std::thread::hardware_concurrency() returning 0.
if (unsigned Val = std::thread::hardware_concurrency())
return Val;
return 1;
}
// Include the platform-specific parts of this class.
#ifdef LLVM_ON_UNIX
#include "Unix/Threading.inc"
#endif
#ifdef _WIN32
#include "Windows/Threading.inc"
#endif
#endif