1//===-- ManagedStatic.cpp - Static Global wrapper -------------------------===//
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 the ManagedStatic class and llvm_shutdown().
11//
12//===----------------------------------------------------------------------===//
13
14#include "llvm/Support/ManagedStatic.h"
15#include "llvm/Config/config.h"
16#include "llvm/Support/Mutex.h"
17#include "llvm/Support/MutexGuard.h"
18#include "llvm/Support/Threading.h"
19#include <cassert>
20using namespace llvm;
21
22static const ManagedStaticBase *StaticList = nullptr;
23static sys::Mutex *ManagedStaticMutex = nullptr;
24LLVM_DEFINE_ONCE_FLAG(mutex_init_flag);
25
26static void initializeMutex() {
27  ManagedStaticMutex = new sys::Mutex();
28}
29
30static sys::Mutex* getManagedStaticMutex() {
31  // We need to use a function local static here, since this can get called
32  // during a static constructor and we need to guarantee that it's initialized
33  // correctly.
34  llvm::call_once(mutex_init_flag, initializeMutex);
35  return ManagedStaticMutex;
36}
37
38void ManagedStaticBase::RegisterManagedStatic(void *(*Creator)(),
39                                              void (*Deleter)(void*)) const {
40  assert(Creator);
41  if (llvm_is_multithreaded()) {
42    MutexGuard Lock(*getManagedStaticMutex());
43
44    if (!Ptr.load(std::memory_order_relaxed)) {
45      void *Tmp = Creator();
46
47      Ptr.store(Tmp, std::memory_order_release);
48      DeleterFn = Deleter;
49
50      // Add to list of managed statics.
51      Next = StaticList;
52      StaticList = this;
53    }
54  } else {
55    assert(!Ptr && !DeleterFn && !Next &&
56           "Partially initialized ManagedStatic!?");
57    Ptr = Creator();
58    DeleterFn = Deleter;
59
60    // Add to list of managed statics.
61    Next = StaticList;
62    StaticList = this;
63  }
64}
65
66void ManagedStaticBase::destroy() const {
67  assert(DeleterFn && "ManagedStatic not initialized correctly!");
68  assert(StaticList == this &&
69         "Not destroyed in reverse order of construction?");
70  // Unlink from list.
71  StaticList = Next;
72  Next = nullptr;
73
74  // Destroy memory.
75  DeleterFn(Ptr);
76
77  // Cleanup.
78  Ptr = nullptr;
79  DeleterFn = nullptr;
80}
81
82/// llvm_shutdown - Deallocate and destroy all ManagedStatic variables.
83void llvm::llvm_shutdown() {
84  MutexGuard Lock(*getManagedStaticMutex());
85
86  while (StaticList)
87    StaticList->destroy();
88}
89