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 defines helper functions for running LLVM in a multi-threaded
11 // environment.
12 //
13 //===----------------------------------------------------------------------===//
14
15 #include "llvm/Support/Threading.h"
16 #include "llvm/Config/config.h"
17 #include "llvm/Support/Atomic.h"
18 #include "llvm/Support/Host.h"
19 #include "llvm/Support/Mutex.h"
20 #include "llvm/Support/thread.h"
21 #include <cassert>
22
23 using namespace llvm;
24
llvm_is_multithreaded()25 bool llvm::llvm_is_multithreaded() {
26 #if LLVM_ENABLE_THREADS != 0
27 return true;
28 #else
29 return false;
30 #endif
31 }
32
33 #if LLVM_ENABLE_THREADS != 0 && defined(HAVE_PTHREAD_H)
34 #include <pthread.h>
35
36 struct ThreadInfo {
37 void (*UserFn)(void *);
38 void *UserData;
39 };
ExecuteOnThread_Dispatch(void * Arg)40 static void *ExecuteOnThread_Dispatch(void *Arg) {
41 ThreadInfo *TI = reinterpret_cast<ThreadInfo*>(Arg);
42 TI->UserFn(TI->UserData);
43 return nullptr;
44 }
45
llvm_execute_on_thread(void (* Fn)(void *),void * UserData,unsigned RequestedStackSize)46 void llvm::llvm_execute_on_thread(void (*Fn)(void*), void *UserData,
47 unsigned RequestedStackSize) {
48 ThreadInfo Info = { Fn, UserData };
49 pthread_attr_t Attr;
50 pthread_t Thread;
51
52 // Construct the attributes object.
53 if (::pthread_attr_init(&Attr) != 0)
54 return;
55
56 // Set the requested stack size, if given.
57 if (RequestedStackSize != 0) {
58 if (::pthread_attr_setstacksize(&Attr, RequestedStackSize) != 0)
59 goto error;
60 }
61
62 // Construct and execute the thread.
63 if (::pthread_create(&Thread, &Attr, ExecuteOnThread_Dispatch, &Info) != 0)
64 goto error;
65
66 // Wait for the thread and clean up.
67 ::pthread_join(Thread, nullptr);
68
69 error:
70 ::pthread_attr_destroy(&Attr);
71 }
72 #elif LLVM_ENABLE_THREADS!=0 && defined(LLVM_ON_WIN32)
73 #include "Windows/WindowsSupport.h"
74 #include <process.h>
75
76 // Windows will at times define MemoryFence.
77 #ifdef MemoryFence
78 #undef MemoryFence
79 #endif
80
81 struct ThreadInfo {
82 void (*func)(void*);
83 void *param;
84 };
85
ThreadCallback(void * param)86 static unsigned __stdcall ThreadCallback(void *param) {
87 struct ThreadInfo *info = reinterpret_cast<struct ThreadInfo *>(param);
88 info->func(info->param);
89
90 return 0;
91 }
92
llvm_execute_on_thread(void (* Fn)(void *),void * UserData,unsigned RequestedStackSize)93 void llvm::llvm_execute_on_thread(void (*Fn)(void*), void *UserData,
94 unsigned RequestedStackSize) {
95 struct ThreadInfo param = { Fn, UserData };
96
97 HANDLE hThread = (HANDLE)::_beginthreadex(NULL,
98 RequestedStackSize, ThreadCallback,
99 ¶m, 0, NULL);
100
101 if (hThread) {
102 // We actually don't care whether the wait succeeds or fails, in
103 // the same way we don't care whether the pthread_join call succeeds
104 // or fails. There's not much we could do if this were to fail. But
105 // on success, this call will wait until the thread finishes executing
106 // before returning.
107 (void)::WaitForSingleObject(hThread, INFINITE);
108 ::CloseHandle(hThread);
109 }
110 }
111 #else
112 // Support for non-Win32, non-pthread implementation.
llvm_execute_on_thread(void (* Fn)(void *),void * UserData,unsigned RequestedStackSize)113 void llvm::llvm_execute_on_thread(void (*Fn)(void*), void *UserData,
114 unsigned RequestedStackSize) {
115 (void) RequestedStackSize;
116 Fn(UserData);
117 }
118
119 #endif
120
heavyweight_hardware_concurrency()121 unsigned llvm::heavyweight_hardware_concurrency() {
122 #if !LLVM_ENABLE_THREADS
123 return 1;
124 #endif
125 int NumPhysical = sys::getHostNumPhysicalCores();
126 if (NumPhysical == -1)
127 return thread::hardware_concurrency();
128 return NumPhysical;
129 }
130