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Threading.cpp
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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 
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().
35  return true;
36 #else
37  return false;
38 #endif
39 }
40 
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().
48 
49  multithreaded_mode = false;
50  delete global_lock;
51 #endif
52 }
53 
55  return multithreaded_mode;
56 }
57 
60 }
61 
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 };
73 static void *ExecuteOnThread_Dispatch(void *Arg) {
74  ThreadInfo *TI = reinterpret_cast<ThreadInfo*>(Arg);
75  TI->UserFn(TI->UserData);
76  return 0;
77 }
78 
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 
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 
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  &param, 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.
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
void llvm_acquire_global_lock()
Definition: Threading.cpp:58
static bool multithreaded_mode
Definition: Threading.cpp:22
void * UserData
Definition: Threading.cpp:71
void llvm_release_global_lock()
Definition: Threading.cpp:62
static void * ExecuteOnThread_Dispatch(void *Arg)
Definition: Threading.cpp:73
bool llvm_start_multithreaded()
Definition: Threading.cpp:26
lazy value info
SmartMutex< false > Mutex
Mutex - A standard, always enforced mutex.
Definition: Mutex.h:135
static sys::Mutex * global_lock
Definition: Threading.cpp:24
bool llvm_is_multithreaded()
Definition: Threading.cpp:54
void MemoryFence()
Definition: Atomic.cpp:28
void llvm_execute_on_thread(void(*UserFn)(void *), void *UserData, unsigned RequestedStackSize=0)
Definition: Threading.cpp:79
void llvm_stop_multithreaded()
Definition: Threading.cpp:41
void(* UserFn)(void *)
Definition: Threading.cpp:70