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//===-- 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 "llvm/Support/Mutex.h"
#include "llvm/Support/MutexGuard.h"
#include <cassert>
using namespace llvm;
static const ManagedStaticBase *StaticList = nullptr;
static sys::Mutex& getManagedStaticMutex() {
// We need to use a function local static here, since this can get called
// during a static constructor and we need to guarantee that it's initialized
// correctly.
static sys::Mutex ManagedStaticMutex;
return ManagedStaticMutex;
}
void ManagedStaticBase::RegisterManagedStatic(void *(*Creator)(),
void (*Deleter)(void*)) const {
assert(Creator);
if (llvm_is_multithreaded()) {
MutexGuard 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() {
MutexGuard Lock(getManagedStaticMutex());
while (StaticList)
StaticList->destroy();
}
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