1//===-- ManagedStatic.cpp - Static Global wrapper -------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file implements the ManagedStatic class and llvm_shutdown().
10//
11//===----------------------------------------------------------------------===//
12
13#include "llvm/Support/ManagedStatic.h"
14#include "llvm/Config/config.h"
15#include "llvm/Support/Threading.h"
16#include <cassert>
17#include <mutex>
18using namespace llvm;
19
20static const ManagedStaticBase *StaticList = nullptr;
21static std::recursive_mutex *ManagedStaticMutex = nullptr;
22static llvm::once_flag mutex_init_flag;
23
24static void initializeMutex() {
25  ManagedStaticMutex = new std::recursive_mutex();
26}
27
28static std::recursive_mutex *getManagedStaticMutex() {
29  llvm::call_once(mutex_init_flag, initializeMutex);
30  return ManagedStaticMutex;
31}
32
33void ManagedStaticBase::RegisterManagedStatic(void *(*Creator)(),
34                                              void (*Deleter)(void*)) const {
35  assert(Creator);
36  if (llvm_is_multithreaded()) {
37    std::lock_guard<std::recursive_mutex> Lock(*getManagedStaticMutex());
38
39    if (!Ptr.load(std::memory_order_relaxed)) {
40      void *Tmp = Creator();
41
42      Ptr.store(Tmp, std::memory_order_release);
43      DeleterFn = Deleter;
44
45      // Add to list of managed statics.
46      Next = StaticList;
47      StaticList = this;
48    }
49  } else {
50    assert(!Ptr && !DeleterFn && !Next &&
51           "Partially initialized ManagedStatic!?");
52    Ptr = Creator();
53    DeleterFn = Deleter;
54
55    // Add to list of managed statics.
56    Next = StaticList;
57    StaticList = this;
58  }
59}
60
61void ManagedStaticBase::destroy() const {
62  assert(DeleterFn && "ManagedStatic not initialized correctly!");
63  assert(StaticList == this &&
64         "Not destroyed in reverse order of construction?");
65  // Unlink from list.
66  StaticList = Next;
67  Next = nullptr;
68
69  // Destroy memory.
70  DeleterFn(Ptr);
71
72  // Cleanup.
73  Ptr = nullptr;
74  DeleterFn = nullptr;
75}
76
77/// llvm_shutdown - Deallocate and destroy all ManagedStatic variables.
78void llvm::llvm_shutdown() {
79  std::lock_guard<std::recursive_mutex> Lock(*getManagedStaticMutex());
80
81  while (StaticList)
82    StaticList->destroy();
83}
84