[llvm] r220932 - Removing the static initializer in ManagedStatic.cpp by using llvm_call_once to initialize the ManagedStatic mutex.
Jiangning Liu
liujiangning1 at gmail.com
Tue Nov 4 00:12:13 PST 2014
BTW, my OS is debian and "uname -a" shows,
Linux 3.15.0-rc8+ #9 SMP PREEMPT aarch64 GNU/Linux
Thanks,
-Jiangning
2014-11-04 16:09 GMT+08:00 Jiangning Liu <liujiangning1 at gmail.com>:
> Hi Chris,
>
> This commit triggered a llvm/clang build failure on aarch64 host machine.
> The error message is like,
>
> /bin/sh: line 1: 16677 Segmentation fault ../../../../bin/clang-tblgen
> -gen-arm-neon -I
> /work/slave/performance-daily/build/tools/clang/lib/Headers -I
> /work/slave/performance-daily/build/lib/Target -I
> /work/slave/performance-daily/build/include
> /work/slave/performance-daily/build/tools/clang/include/clang/Basic/
> arm_neon.td -o
> /work/slave/performance-daily/build/build/tools/clang/lib/Headers/arm_neon.h.tmp
>
> It seems pthread doesn't work well on aarch64 target, so the following
> code doesn't work.
>
> +void llvm::call_once(once_flag& flag, void (*fptr)(void)) {
> + std::call_once(flag, fptr);
> +}
>
> Can we use the same solution as windows rather than call std::call_once
> directly?
>
> Thanks,
> -Jiangning
>
>
> 2014-10-31 6:07 GMT+08:00 Chris Bieneman <beanz at apple.com>:
>
>> Author: cbieneman
>> Date: Thu Oct 30 17:07:09 2014
>> New Revision: 220932
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=220932&view=rev
>> Log:
>> Removing the static initializer in ManagedStatic.cpp by using
>> llvm_call_once to initialize the ManagedStatic mutex.
>>
>> Summary:
>> This patch adds an llvm_call_once which is a wrapper around
>> std::call_once on platforms where it is available and devoid of bugs. The
>> patch also migrates the ManagedStatic mutex to be allocated using
>> llvm_call_once.
>>
>> These changes are philosophically equivalent to the changes added in
>> r219638, which were reverted due to a hang on Win32 which was the result of
>> a bug in the Windows implementation of std::call_once.
>>
>> Reviewers: aaron.ballman, chapuni, chandlerc, rnk
>>
>> Reviewed By: rnk
>>
>> Subscribers: majnemer, llvm-commits
>>
>> Differential Revision: http://reviews.llvm.org/D5922
>>
>> Added:
>> llvm/trunk/lib/Support/Unix/Threading.inc
>> llvm/trunk/lib/Support/Windows/Threading.inc
>> Modified:
>> llvm/trunk/include/llvm/Support/Threading.h
>> llvm/trunk/lib/Support/CMakeLists.txt
>> llvm/trunk/lib/Support/ManagedStatic.cpp
>> llvm/trunk/lib/Support/Threading.cpp
>>
>> Modified: llvm/trunk/include/llvm/Support/Threading.h
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Support/Threading.h?rev=220932&r1=220931&r2=220932&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/include/llvm/Support/Threading.h (original)
>> +++ llvm/trunk/include/llvm/Support/Threading.h Thu Oct 30 17:07:09 2014
>> @@ -15,6 +15,14 @@
>> #ifndef LLVM_SUPPORT_THREADING_H
>> #define LLVM_SUPPORT_THREADING_H
>>
>> +#include "llvm/Config/llvm-config.h" // for LLVM_ON_UNIX
>> +
>> +#if defined(LLVM_ON_UNIX)
>> +#include <mutex>
>> +#else
>> +#include "llvm/Support/Atomic.h"
>> +#endif
>> +
>> namespace llvm {
>> /// Returns true if LLVM is compiled with support for multi-threading,
>> and
>> /// false otherwise.
>> @@ -33,6 +41,35 @@ namespace llvm {
>> /// the thread stack.
>> void llvm_execute_on_thread(void (*UserFn)(void*), void *UserData,
>> unsigned RequestedStackSize = 0);
>> +
>> +#if defined(LLVM_ON_UNIX)
>> +typedef std::once_flag once_flag;
>> +#define LLVM_DEFINE_ONCE_FLAG(flag) static once_flag flag
>> +#else
>> +enum InitStatus {
>> + Done = -1,
>> + Uninitialized = 0,
>> + Wait = 1
>> +};
>> +typedef volatile sys::cas_flag once_flag;
>> +
>> +#define LLVM_DEFINE_ONCE_FLAG(flag) static once_flag flag = Uninitialized
>> +#endif
>> +
>> +/// \brief Execute the function specified as a parameter once.
>> +///
>> +/// Typical usage:
>> +/// \code
>> +/// void foo() {...};
>> +/// ...
>> +/// LLVM_DEFINE_ONCE_FLAG(flag);
>> +/// call_once(flag, foo);
>> +/// \endcode
>> +///
>> +/// \param flag Flag used for tracking whether or not this has run.
>> +/// \param UserFn Function to call once.
>> +void call_once(once_flag&, void (*)(void));
>> +
>> }
>>
>> #endif
>>
>> Modified: llvm/trunk/lib/Support/CMakeLists.txt
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/CMakeLists.txt?rev=220932&r1=220931&r2=220932&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/lib/Support/CMakeLists.txt (original)
>> +++ llvm/trunk/lib/Support/CMakeLists.txt Thu Oct 30 17:07:09 2014
>> @@ -102,6 +102,7 @@ add_llvm_library(LLVMSupport
>> Unix/Program.inc
>> Unix/RWMutex.inc
>> Unix/Signals.inc
>> + Unix/Threading.inc
>> Unix/ThreadLocal.inc
>> Unix/TimeValue.inc
>> Unix/Watchdog.inc
>> @@ -114,6 +115,7 @@ add_llvm_library(LLVMSupport
>> Windows/Program.inc
>> Windows/RWMutex.inc
>> Windows/Signals.inc
>> + Windows/Threading.inc
>> Windows/ThreadLocal.inc
>> Windows/TimeValue.inc
>> Windows/Watchdog.inc
>>
>> Modified: llvm/trunk/lib/Support/ManagedStatic.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/ManagedStatic.cpp?rev=220932&r1=220931&r2=220932&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/lib/Support/ManagedStatic.cpp (original)
>> +++ llvm/trunk/lib/Support/ManagedStatic.cpp Thu Oct 30 17:07:09 2014
>> @@ -16,16 +16,23 @@
>> #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;
>> +LLVM_DEFINE_ONCE_FLAG(mutex_init_flag);
>>
>> -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;
>> + call_once(mutex_init_flag, initializeMutex);
>> return ManagedStaticMutex;
>> }
>>
>> @@ -33,7 +40,7 @@ void ManagedStaticBase::RegisterManagedS
>> void (*Deleter)(void*))
>> const {
>> assert(Creator);
>> if (llvm_is_multithreaded()) {
>> - MutexGuard Lock(getManagedStaticMutex());
>> + MutexGuard Lock(*getManagedStaticMutex());
>>
>> if (!Ptr) {
>> void* tmp = Creator();
>> @@ -83,7 +90,7 @@ 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();
>>
>> Modified: llvm/trunk/lib/Support/Threading.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/Threading.cpp?rev=220932&r1=220931&r2=220932&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/lib/Support/Threading.cpp (original)
>> +++ llvm/trunk/lib/Support/Threading.cpp Thu Oct 30 17:07:09 2014
>> @@ -110,3 +110,10 @@ void llvm::llvm_execute_on_thread(void (
>> }
>>
>> #endif
>> +
>> +#if defined(LLVM_ON_UNIX)
>> +#include "Unix/Threading.inc"
>> +#else
>> +#include "Windows/Threading.inc"
>> +#endif
>> +
>>
>> Added: llvm/trunk/lib/Support/Unix/Threading.inc
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/Unix/Threading.inc?rev=220932&view=auto
>>
>> ==============================================================================
>> --- llvm/trunk/lib/Support/Unix/Threading.inc (added)
>> +++ llvm/trunk/lib/Support/Unix/Threading.inc Thu Oct 30 17:07:09 2014
>> @@ -0,0 +1,5 @@
>> +#include <thread>
>> +
>> +void llvm::call_once(once_flag& flag, void (*fptr)(void)) {
>> + std::call_once(flag, fptr);
>> +}
>>
>> Added: llvm/trunk/lib/Support/Windows/Threading.inc
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/Windows/Threading.inc?rev=220932&view=auto
>>
>> ==============================================================================
>> --- llvm/trunk/lib/Support/Windows/Threading.inc (added)
>> +++ llvm/trunk/lib/Support/Windows/Threading.inc Thu Oct 30 17:07:09 2014
>> @@ -0,0 +1,19 @@
>> +#include <winbase.h>
>> +
>> +void llvm::call_once(once_flag &flag, void (*fptr)(void)) {
>> + while (flag != Done) {
>> + if (flag == Wait) {
>> + ::Sleep(1);
>> + continue;
>> + }
>> +
>> + sys::cas_flag old_val = sys::CompareAndSwap(&flag, Wait,
>> Uninitialized);
>> + if (old_val == Uninitialized) {
>> + fptr();
>> + sys::MemoryFence();
>> + flag = Done;
>> + return;
>> + }
>> + }
>> + sys::MemoryFence();
>> +}
>>
>>
>> _______________________________________________
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>>
>
>
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