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
llvm_is_multithreaded()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.
llvm_execute_on_thread(void (* Fn)(void *),void * UserData,llvm::Optional<unsigned> StackSizeInBytes)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
get_threadid()48 uint64_t llvm::get_threadid() { return 0; }
49
get_max_thread_name_length()50 uint32_t llvm::get_max_thread_name_length() { return 0; }
51
set_thread_name(const Twine & Name)52 void llvm::set_thread_name(const Twine &Name) {}
53
get_thread_name(SmallVectorImpl<char> & Name)54 void llvm::get_thread_name(SmallVectorImpl<char> &Name) { Name.clear(); }
55
get_thread_affinity_mask()56 llvm::BitVector llvm::get_thread_affinity_mask() { return {}; }
57
compute_thread_count() const58 unsigned llvm::ThreadPoolStrategy::compute_thread_count() const {
59 // When threads are disabled, ensure clients will loop at least once.
60 return 1;
61 }
62
63 #if LLVM_ENABLE_THREADS == 0
llvm_execute_on_thread_async(llvm::unique_function<void ()> Func,llvm::Optional<unsigned> StackSizeInBytes)64 void llvm::llvm_execute_on_thread_async(
65 llvm::unique_function<void()> Func,
66 llvm::Optional<unsigned> StackSizeInBytes) {
67 (void)Func;
68 (void)StackSizeInBytes;
69 report_fatal_error("Spawning a detached thread doesn't make sense with no "
70 "threading support");
71 }
72 #else
73 // Support for non-Win32, non-pthread implementation.
llvm_execute_on_thread_async(llvm::unique_function<void ()> Func,llvm::Optional<unsigned> StackSizeInBytes)74 void llvm::llvm_execute_on_thread_async(
75 llvm::unique_function<void()> Func,
76 llvm::Optional<unsigned> StackSizeInBytes) {
77 (void)StackSizeInBytes;
78 std::thread(std::move(Func)).detach();
79 }
80 #endif
81
82 #else
83
84 int computeHostNumHardwareThreads();
85
compute_thread_count() const86 unsigned llvm::ThreadPoolStrategy::compute_thread_count() const {
87 int MaxThreadCount = UseHyperThreads ? computeHostNumHardwareThreads()
88 : sys::getHostNumPhysicalCores();
89 if (MaxThreadCount <= 0)
90 MaxThreadCount = 1;
91 if (ThreadsRequested == 0)
92 return MaxThreadCount;
93 if (!Limit)
94 return ThreadsRequested;
95 return std::min((unsigned)MaxThreadCount, ThreadsRequested);
96 }
97
98 namespace {
99 struct SyncThreadInfo {
100 void (*UserFn)(void *);
101 void *UserData;
102 };
103
104 using AsyncThreadInfo = llvm::unique_function<void()>;
105
106 enum class JoiningPolicy { Join, Detach };
107 } // namespace
108
109 // Include the platform-specific parts of this class.
110 #ifdef LLVM_ON_UNIX
111 #include "Unix/Threading.inc"
112 #endif
113 #ifdef _WIN32
114 #include "Windows/Threading.inc"
115 #endif
116
llvm_execute_on_thread(void (* Fn)(void *),void * UserData,llvm::Optional<unsigned> StackSizeInBytes)117 void llvm::llvm_execute_on_thread(void (*Fn)(void *), void *UserData,
118 llvm::Optional<unsigned> StackSizeInBytes) {
119
120 SyncThreadInfo Info = {Fn, UserData};
121 llvm_execute_on_thread_impl(threadFuncSync, &Info, StackSizeInBytes,
122 JoiningPolicy::Join);
123 }
124
llvm_execute_on_thread_async(llvm::unique_function<void ()> Func,llvm::Optional<unsigned> StackSizeInBytes)125 void llvm::llvm_execute_on_thread_async(
126 llvm::unique_function<void()> Func,
127 llvm::Optional<unsigned> StackSizeInBytes) {
128 llvm_execute_on_thread_impl(&threadFuncAsync,
129 new AsyncThreadInfo(std::move(Func)),
130 StackSizeInBytes, JoiningPolicy::Detach);
131 }
132
133 #endif
134
135 Optional<ThreadPoolStrategy>
get_threadpool_strategy(StringRef Num,ThreadPoolStrategy Default)136 llvm::get_threadpool_strategy(StringRef Num, ThreadPoolStrategy Default) {
137 if (Num == "all")
138 return llvm::hardware_concurrency();
139 if (Num.empty())
140 return Default;
141 unsigned V;
142 if (Num.getAsInteger(10, V))
143 return None; // malformed 'Num' value
144 if (V == 0)
145 return Default;
146
147 // Do not take the Default into account. This effectively disables
148 // heavyweight_hardware_concurrency() if the user asks for any number of
149 // threads on the cmd-line.
150 ThreadPoolStrategy S = llvm::hardware_concurrency();
151 S.ThreadsRequested = V;
152 return S;
153 }
154