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//===-- 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/ADT/Optional.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,
llvm::Optional<unsigned> StackSizeInBytes) {
(void)StackSizeInBytes;
Fn(UserData);
}
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(); }
llvm::BitVector llvm::get_thread_affinity_mask() { return {}; }
unsigned llvm::ThreadPoolStrategy::compute_thread_count() const {
// When threads are disabled, ensure clients will loop at least once.
return 1;
}
#if LLVM_ENABLE_THREADS == 0
void llvm::llvm_execute_on_thread_async(
llvm::unique_function<void()> Func,
llvm::Optional<unsigned> StackSizeInBytes) {
(void)Func;
(void)StackSizeInBytes;
report_fatal_error("Spawning a detached thread doesn't make sense with no "
"threading support");
}
#else
// Support for non-Win32, non-pthread implementation.
void llvm::llvm_execute_on_thread_async(
llvm::unique_function<void()> Func,
llvm::Optional<unsigned> StackSizeInBytes) {
(void)StackSizeInBytes;
std::thread(std::move(Func)).detach();
}
#endif
#else
int computeHostNumHardwareThreads();
unsigned llvm::ThreadPoolStrategy::compute_thread_count() const {
int MaxThreadCount = UseHyperThreads ? computeHostNumHardwareThreads()
: sys::getHostNumPhysicalCores();
if (MaxThreadCount <= 0)
MaxThreadCount = 1;
// No need to create more threads than there are hardware threads, it would
// uselessly induce more context-switching and cache eviction.
if (!ThreadsRequested || ThreadsRequested > (unsigned)MaxThreadCount)
return MaxThreadCount;
return ThreadsRequested;
}
namespace {
struct SyncThreadInfo {
void (*UserFn)(void *);
void *UserData;
};
using AsyncThreadInfo = llvm::unique_function<void()>;
enum class JoiningPolicy { Join, Detach };
} // namespace
// Include the platform-specific parts of this class.
#ifdef LLVM_ON_UNIX
#include "Unix/Threading.inc"
#endif
#ifdef _WIN32
#include "Windows/Threading.inc"
#endif
void llvm::llvm_execute_on_thread(void (*Fn)(void *), void *UserData,
llvm::Optional<unsigned> StackSizeInBytes) {
SyncThreadInfo Info = {Fn, UserData};
llvm_execute_on_thread_impl(threadFuncSync, &Info, StackSizeInBytes,
JoiningPolicy::Join);
}
void llvm::llvm_execute_on_thread_async(
llvm::unique_function<void()> Func,
llvm::Optional<unsigned> StackSizeInBytes) {
llvm_execute_on_thread_impl(&threadFuncAsync,
new AsyncThreadInfo(std::move(Func)),
StackSizeInBytes, JoiningPolicy::Detach);
}
#endif
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