1 //===-- llvm/Support/Threading.cpp- Control multithreading mode --*- C++ -*-==//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file implements llvm_start_multithreaded() and friends.
11 //
12 //===----------------------------------------------------------------------===//
13
14 #include "llvm/Support/Threading.h"
15 #include "llvm/Config/config.h"
16 #include "llvm/Support/Atomic.h"
17 #include "llvm/Support/Mutex.h"
18 #include <cassert>
19
20 using namespace llvm;
21
22 static bool multithreaded_mode = false;
23
24 static sys::Mutex* global_lock = 0;
25
llvm_start_multithreaded()26 bool llvm::llvm_start_multithreaded() {
27 #if LLVM_ENABLE_THREADS != 0
28 assert(!multithreaded_mode && "Already multithreaded!");
29 multithreaded_mode = true;
30 global_lock = new sys::Mutex(true);
31
32 // We fence here to ensure that all initialization is complete BEFORE we
33 // return from llvm_start_multithreaded().
34 sys::MemoryFence();
35 return true;
36 #else
37 return false;
38 #endif
39 }
40
llvm_stop_multithreaded()41 void llvm::llvm_stop_multithreaded() {
42 #if LLVM_ENABLE_THREADS != 0
43 assert(multithreaded_mode && "Not currently multithreaded!");
44
45 // We fence here to insure that all threaded operations are complete BEFORE we
46 // return from llvm_stop_multithreaded().
47 sys::MemoryFence();
48
49 multithreaded_mode = false;
50 delete global_lock;
51 #endif
52 }
53
llvm_is_multithreaded()54 bool llvm::llvm_is_multithreaded() {
55 return multithreaded_mode;
56 }
57
llvm_acquire_global_lock()58 void llvm::llvm_acquire_global_lock() {
59 if (multithreaded_mode) global_lock->acquire();
60 }
61
llvm_release_global_lock()62 void llvm::llvm_release_global_lock() {
63 if (multithreaded_mode) global_lock->release();
64 }
65
66 #if LLVM_ENABLE_THREADS != 0 && defined(HAVE_PTHREAD_H)
67 #include <pthread.h>
68
69 struct ThreadInfo {
70 void (*UserFn)(void *);
71 void *UserData;
72 };
ExecuteOnThread_Dispatch(void * Arg)73 static void *ExecuteOnThread_Dispatch(void *Arg) {
74 ThreadInfo *TI = reinterpret_cast<ThreadInfo*>(Arg);
75 TI->UserFn(TI->UserData);
76 return 0;
77 }
78
llvm_execute_on_thread(void (* Fn)(void *),void * UserData,unsigned RequestedStackSize)79 void llvm::llvm_execute_on_thread(void (*Fn)(void*), void *UserData,
80 unsigned RequestedStackSize) {
81 ThreadInfo Info = { Fn, UserData };
82 pthread_attr_t Attr;
83 pthread_t Thread;
84
85 // Construct the attributes object.
86 if (::pthread_attr_init(&Attr) != 0)
87 return;
88
89 // Set the requested stack size, if given.
90 if (RequestedStackSize != 0) {
91 if (::pthread_attr_setstacksize(&Attr, RequestedStackSize) != 0)
92 goto error;
93 }
94
95 // Construct and execute the thread.
96 if (::pthread_create(&Thread, &Attr, ExecuteOnThread_Dispatch, &Info) != 0)
97 goto error;
98
99 // Wait for the thread and clean up.
100 ::pthread_join(Thread, 0);
101
102 error:
103 ::pthread_attr_destroy(&Attr);
104 }
105 #elif LLVM_ENABLE_THREADS!=0 && defined(LLVM_ON_WIN32)
106 #include "Windows/Windows.h"
107 #include <process.h>
108
109 struct ThreadInfo {
110 void (*func)(void*);
111 void *param;
112 };
113
ThreadCallback(void * param)114 static unsigned __stdcall ThreadCallback(void *param) {
115 struct ThreadInfo *info = reinterpret_cast<struct ThreadInfo *>(param);
116 info->func(info->param);
117
118 return 0;
119 }
120
llvm_execute_on_thread(void (* Fn)(void *),void * UserData,unsigned RequestedStackSize)121 void llvm::llvm_execute_on_thread(void (*Fn)(void*), void *UserData,
122 unsigned RequestedStackSize) {
123 struct ThreadInfo param = { Fn, UserData };
124
125 HANDLE hThread = (HANDLE)::_beginthreadex(NULL,
126 RequestedStackSize, ThreadCallback,
127 ¶m, 0, NULL);
128
129 if (hThread) {
130 // We actually don't care whether the wait succeeds or fails, in
131 // the same way we don't care whether the pthread_join call succeeds
132 // or fails. There's not much we could do if this were to fail. But
133 // on success, this call will wait until the thread finishes executing
134 // before returning.
135 (void)::WaitForSingleObject(hThread, INFINITE);
136 ::CloseHandle(hThread);
137 }
138 }
139 #else
140 // Support for non-Win32, non-pthread implementation.
llvm_execute_on_thread(void (* Fn)(void *),void * UserData,unsigned RequestedStackSize)141 void llvm::llvm_execute_on_thread(void (*Fn)(void*), void *UserData,
142 unsigned RequestedStackSize) {
143 (void) RequestedStackSize;
144 Fn(UserData);
145 }
146
147 #endif
148