blob: 9d7e99f97fb5637c7f837abc834c0f238c174031 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
|
//===-- ManagedStatic.cpp - Static Global wrapper -------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the ManagedStatic class and llvm_shutdown().
//
//===----------------------------------------------------------------------===//
#include "llvm/Support/ManagedStatic.h"
#include "llvm/Config/config.h"
#include "llvm/Support/Atomic.h"
#include <cassert>
#include <mutex>
using namespace llvm;
static const ManagedStaticBase *StaticList = nullptr;
// ManagedStatics can get created during execution of static constructors. As a
// result, we cannot use a global static std::mutex object for the lock since it
// may not have been constructed. Instead, we do a call-once initialization of
// a pointer to a mutex.
static std::once_flag MutexInitializationFlag;
static std::recursive_mutex* ManagedStaticMutex = nullptr;
// Not all supported platforms (in particular VS2012) have thread-safe function
// static initialization, so roll our own.
static std::recursive_mutex& GetManagedStaticMutex() {
std::call_once(MutexInitializationFlag,
[]() { ManagedStaticMutex = new std::recursive_mutex(); } );
return *ManagedStaticMutex;
}
void ManagedStaticBase::RegisterManagedStatic(void *(*Creator)(),
void (*Deleter)(void*)) const {
assert(Creator);
if (llvm_is_multithreaded()) {
std::lock_guard<std::recursive_mutex> Lock(GetManagedStaticMutex());
if (!Ptr) {
void* tmp = Creator();
TsanHappensBefore(this);
sys::MemoryFence();
// This write is racy against the first read in the ManagedStatic
// accessors. The race is benign because it does a second read after a
// memory fence, at which point it isn't possible to get a partial value.
TsanIgnoreWritesBegin();
Ptr = tmp;
TsanIgnoreWritesEnd();
DeleterFn = Deleter;
// Add to list of managed statics.
Next = StaticList;
StaticList = this;
}
} else {
assert(!Ptr && !DeleterFn && !Next &&
"Partially initialized ManagedStatic!?");
Ptr = Creator();
DeleterFn = Deleter;
// Add to list of managed statics.
Next = StaticList;
StaticList = this;
}
}
void ManagedStaticBase::destroy() const {
assert(DeleterFn && "ManagedStatic not initialized correctly!");
assert(StaticList == this &&
"Not destroyed in reverse order of construction?");
// Unlink from list.
StaticList = Next;
Next = nullptr;
// Destroy memory.
DeleterFn(Ptr);
// Cleanup.
Ptr = nullptr;
DeleterFn = nullptr;
}
/// llvm_shutdown - Deallocate and destroy all ManagedStatic variables.
void llvm::llvm_shutdown() {
std::lock_guard<std::recursive_mutex> Lock(GetManagedStaticMutex());
while (StaticList)
StaticList->destroy();
if (llvm_is_multithreaded()) llvm_stop_multithreaded();
}
|
