contrib/llvm-project/llvm/lib/Support/Threading.cpp

   1 //===-- llvm/Support/Threading.cpp- Control multithreading mode --*- C++ -*-==//
   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 defines helper functions for running LLVM in a multi-threaded
  10 // environment.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/Support/Threading.h"
  15 #include "llvm/ADT/Optional.h"
  16 #include "llvm/Config/config.h"
  17 #include "llvm/Support/Host.h"
  18
  19 #include <cassert>
  20 #include <errno.h>
  21 #include <stdlib.h>
  22 #include <string.h>
  23
  24 using namespace llvm;
  25
  26 //===----------------------------------------------------------------------===//
  27 //=== WARNING: Implementation here must contain only TRULY operating system
  28 //===          independent code.
  29 //===----------------------------------------------------------------------===//
  30
  31 bool llvm::llvm_is_multithreaded() {
  32 #if LLVM_ENABLE_THREADS != 0
  33   return true;
  34 #else
  35   return false;
  36 #endif
  37 }
  38
  39 #if LLVM_ENABLE_THREADS == 0 ||                                                \
  40     (!defined(_WIN32) && !defined(HAVE_PTHREAD_H))
  41 // Support for non-Win32, non-pthread implementation.
  42 void llvm::llvm_execute_on_thread(void (*Fn)(void *), void *UserData,
  43                                   llvm::Optional<unsigned> StackSizeInBytes) {
  44   (void)StackSizeInBytes;
  45   Fn(UserData);
  46 }
  47
  48 unsigned llvm::heavyweight_hardware_concurrency() { return 1; }
  49
  50 unsigned llvm::hardware_concurrency() { return 1; }
  51
  52 uint64_t llvm::get_threadid() { return 0; }
  53
  54 uint32_t llvm::get_max_thread_name_length() { return 0; }
  55
  56 void llvm::set_thread_name(const Twine &Name) {}
  57
  58 void llvm::get_thread_name(SmallVectorImpl<char> &Name) { Name.clear(); }
  59
  60 #if LLVM_ENABLE_THREADS == 0
  61 void llvm::llvm_execute_on_thread_async(
  62     llvm::unique_function<void()> Func,
  63     llvm::Optional<unsigned> StackSizeInBytes) {
  64   (void)Func;
  65   (void)StackSizeInBytes;
  66   report_fatal_error("Spawning a detached thread doesn't make sense with no "
  67                      "threading support");
  68 }
  69 #else
  70 // Support for non-Win32, non-pthread implementation.
  71 void llvm::llvm_execute_on_thread_async(
  72     llvm::unique_function<void()> Func,
  73     llvm::Optional<unsigned> StackSizeInBytes) {
  74   (void)StackSizeInBytes;
  75   std::thread(std::move(Func)).detach();
  76 }
  77 #endif
  78
  79 #else
  80
  81 #include <thread>
  82 unsigned llvm::heavyweight_hardware_concurrency() {
  83   // Since we can't get here unless LLVM_ENABLE_THREADS == 1, it is safe to use
  84   // `std::thread` directly instead of `llvm::thread` (and indeed, doing so
  85   // allows us to not define `thread` in the llvm namespace, which conflicts
  86   // with some platforms such as FreeBSD whose headers also define a struct
  87   // called `thread` in the global namespace which can cause ambiguity due to
  88   // ADL.
  89   int NumPhysical = sys::getHostNumPhysicalCores();
  90   if (NumPhysical == -1)
  91     return std::thread::hardware_concurrency();
  92   return NumPhysical;
  93 }
  94
  95 unsigned llvm::hardware_concurrency() {
  96 #if defined(HAVE_SCHED_GETAFFINITY) && defined(HAVE_CPU_COUNT)
  97   cpu_set_t Set;
  98   if (sched_getaffinity(0, sizeof(Set), &Set))
  99     return CPU_COUNT(&Set);
 100 #endif
 101   // Guard against std::thread::hardware_concurrency() returning 0.
 102   if (unsigned Val = std::thread::hardware_concurrency())
 103     return Val;
 104   return 1;
 105 }
 106
 107 namespace {
 108 struct SyncThreadInfo {
 109   void (*UserFn)(void *);
 110   void *UserData;
 111 };
 112
 113 using AsyncThreadInfo = llvm::unique_function<void()>;
 114
 115 enum class JoiningPolicy { Join, Detach };
 116 } // namespace
 117
 118 // Include the platform-specific parts of this class.
 119 #ifdef LLVM_ON_UNIX
 120 #include "Unix/Threading.inc"
 121 #endif
 122 #ifdef _WIN32
 123 #include "Windows/Threading.inc"
 124 #endif
 125
 126 void llvm::llvm_execute_on_thread(void (*Fn)(void *), void *UserData,
 127                                   llvm::Optional<unsigned> StackSizeInBytes) {
 128
 129   SyncThreadInfo Info = {Fn, UserData};
 130   llvm_execute_on_thread_impl(threadFuncSync, &Info, StackSizeInBytes,
 131                               JoiningPolicy::Join);
 132 }
 133
 134 void llvm::llvm_execute_on_thread_async(
 135     llvm::unique_function<void()> Func,
 136     llvm::Optional<unsigned> StackSizeInBytes) {
 137   llvm_execute_on_thread_impl(&threadFuncAsync,
 138                               new AsyncThreadInfo(std::move(Func)),
 139                               StackSizeInBytes, JoiningPolicy::Detach);
 140 }
 141
 142 #endif