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Diffstat (limited to 'contrib/llvm/lib/Support/ManagedStatic.cpp')
-rw-r--r-- | contrib/llvm/lib/Support/ManagedStatic.cpp | 90 |
1 files changed, 90 insertions, 0 deletions
diff --git a/contrib/llvm/lib/Support/ManagedStatic.cpp b/contrib/llvm/lib/Support/ManagedStatic.cpp new file mode 100644 index 0000000..b8fb284 --- /dev/null +++ b/contrib/llvm/lib/Support/ManagedStatic.cpp @@ -0,0 +1,90 @@ +//===-- 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(); +} |