[llvm] r219638 - Removing the static destructor from ManagedStatic.cpp by controlling the allocation and de-allocation of the mutex.

[Chris Bieneman]

Thank you. I will also see if I can reproduce the hang.

-Chris

> On Oct 14, 2014, at 9:11 AM, NAKAMURA Takumi <geek4civic at gmail.com> wrote:
> 
> Excuse me, I have reverted it in r219687.
> 
> It caused hangup in msc builder, probably deadlock in clang's
> arcmt-test and c-index-test.
> http://bb.pgr.jp/builders/ninja-clang-i686-msc17-R/builds/10976
> 
> I will investigate tomorrow.
> 
> 2014-10-14 7:37 GMT+09:00 Chris Bieneman <beanz at apple.com>:
>> Author: cbieneman
>> Date: Mon Oct 13 17:37:25 2014
>> New Revision: 219638
>> 
>> URL: http://llvm.org/viewvc/llvm-project?rev=219638&view=rev
>> Log:
>> Removing the static destructor from ManagedStatic.cpp by controlling the allocation and de-allocation of the mutex.
>> 
>> This patch adds a new llvm_call_once function which is used by the ManagedStatic implementation to safely initialize a global to avoid static construction and destruction.
>> 
>> Modified:
>>    llvm/trunk/include/llvm/Support/Threading.h
>>    llvm/trunk/lib/Support/ManagedStatic.cpp
>> 
>> Modified: llvm/trunk/include/llvm/Support/Threading.h
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Support/Threading.h?rev=219638&r1=219637&r2=219638&view=diff
>> ==============================================================================
>> --- llvm/trunk/include/llvm/Support/Threading.h (original)
>> +++ llvm/trunk/include/llvm/Support/Threading.h Mon Oct 13 17:37:25 2014
>> @@ -15,6 +15,10 @@
>> #ifndef LLVM_SUPPORT_THREADING_H
>> #define LLVM_SUPPORT_THREADING_H
>> 
>> +#if !defined(__MINGW__)
>> +#include <mutex>
>> +#endif
>> +
>> namespace llvm {
>>   /// Returns true if LLVM is compiled with support for multi-threading, and
>>   /// false otherwise.
>> @@ -33,6 +37,20 @@ namespace llvm {
>>   /// the thread stack.
>>   void llvm_execute_on_thread(void (*UserFn)(void*), void *UserData,
>>                               unsigned RequestedStackSize = 0);
>> +
>> +template <void (*UserFn)(void)> void llvm_call_once() {
>> +
>> +#if !defined(__MINGW__)
>> +  static std::once_flag flag;
>> +  std::call_once(flag, UserFn);
>> +
>> +#else
>> +  struct InitOnceWrapper {
>> +    InitOnceWrapper() { UserFn(); }
>> +  };
>> +  static InitOnceWrapper InitOnceVar;
>> +#endif
>> +}
>> }
>> 
>> #endif
>> 
>> Modified: llvm/trunk/lib/Support/ManagedStatic.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/ManagedStatic.cpp?rev=219638&r1=219637&r2=219638&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/Support/ManagedStatic.cpp (original)
>> +++ llvm/trunk/lib/Support/ManagedStatic.cpp Mon Oct 13 17:37:25 2014
>> @@ -16,16 +16,22 @@
>> #include "llvm/Support/Atomic.h"
>> #include "llvm/Support/Mutex.h"
>> #include "llvm/Support/MutexGuard.h"
>> +#include "llvm/Support/Threading.h"
>> #include <cassert>
>> using namespace llvm;
>> 
>> static const ManagedStaticBase *StaticList = nullptr;
>> +static sys::Mutex *ManagedStaticMutex = nullptr;
>> 
>> -static sys::Mutex& getManagedStaticMutex() {
>> +static void initializeMutex() {
>> +  ManagedStaticMutex = new sys::Mutex();
>> +}
>> +
>> +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;
>> +  llvm_call_once<initializeMutex>();
>>   return ManagedStaticMutex;
>> }
>> 
>> @@ -33,7 +39,7 @@ void ManagedStaticBase::RegisterManagedS
>>                                               void (*Deleter)(void*)) const {
>>   assert(Creator);
>>   if (llvm_is_multithreaded()) {
>> -    MutexGuard Lock(getManagedStaticMutex());
>> +    MutexGuard Lock(*getManagedStaticMutex());
>> 
>>     if (!Ptr) {
>>       void* tmp = Creator();
>> @@ -83,8 +89,13 @@ void ManagedStaticBase::destroy() const
>> 
>> /// llvm_shutdown - Deallocate and destroy all ManagedStatic variables.
>> void llvm::llvm_shutdown() {
>> -  MutexGuard Lock(getManagedStaticMutex());
>> +  {
>> +    MutexGuard Lock(*getManagedStaticMutex());
>> +
>> +    while (StaticList)
>> +      StaticList->destroy();
>> +  }
>> 
>> -  while (StaticList)
>> -    StaticList->destroy();
>> +  delete ManagedStaticMutex;
>> +  ManagedStaticMutex = nullptr;
>> }
>> 
>> 
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