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;
21
22static std::recursive_mutex *getManagedStaticMutex() {
23 static std::recursive_mutex m;
24 return &m;
25}
26
27void ManagedStaticBase::RegisterManagedStatic(void *(*Creator)(),
28 void (*Deleter)(void*)) const {
29 assert(Creator);
30 if (llvm_is_multithreaded()) {
31 std::lock_guard<std::recursive_mutex> Lock(*getManagedStaticMutex());
32
33 if (!Ptr.load(m: std::memory_order_relaxed)) {
34 void *Tmp = Creator();
35
36 Ptr.store(p: Tmp, m: std::memory_order_release);
37 DeleterFn = Deleter;
38
39 // Add to list of managed statics.
40 Next = StaticList;
41 StaticList = this;
42 }
43 } else {
44 assert(!Ptr && !DeleterFn && !Next &&
45 "Partially initialized ManagedStatic!?");
46 Ptr = Creator();
47 DeleterFn = Deleter;
48
49 // Add to list of managed statics.
50 Next = StaticList;
51 StaticList = this;
52 }
53}
54
55void ManagedStaticBase::destroy() const {
56 assert(DeleterFn && "ManagedStatic not initialized correctly!");
57 assert(StaticList == this &&
58 "Not destroyed in reverse order of construction?");
59 // Unlink from list.
60 StaticList = Next;
61 Next = nullptr;
62
63 // Destroy memory.
64 DeleterFn(Ptr);
65
66 // Cleanup.
67 Ptr = nullptr;
68 DeleterFn = nullptr;
69}
70
71/// llvm_shutdown - Deallocate and destroy all ManagedStatic variables.
72/// IMPORTANT: it's only safe to call llvm_shutdown() in single thread,
73/// without any other threads executing LLVM APIs.
74/// llvm_shutdown() should be the last use of LLVM APIs.
75void llvm::llvm_shutdown() {
76 while (StaticList)
77 StaticList->destroy();
78}
79