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pongba via llvm-dev

2019-Apr-04 01:24 UTC

[llvm-dev] single-threaded code-gen and how to make it support multi-thread

Hi llvm-dev,

Our code base has a ancient copy of llvm (ver 3.5.1), and it uses the LLVM
code gen for some domain-specific language.

The previous dev left a global lock around the usage of LLVM code gen
stating that because LLVM code gen can only be accessed single-threaded it
needs to be protected with this global lock.

But now this lock has caused some perf issues as we pretty much lose
concurrency when having to compile a large number of source files.

I've tried to remove the global lock and what I have observed in crashing
stack is something like below:

(I did make sure LLVM_ENABLE_THREADS is defined to be 1, apparently it
didn't seem to help)

The document around this seems vague, I have not found a clear instruction
as to how to solve this, hence this post. Can anyone help with some
pointers?

Any guidance is appreciated:)

  ntdll.dll!RtlReportCriticalFailure(long StatusCode, void * FailureInfo,
unsigned long BreakIfDbgPresent) Line 201 C
  ntdll.dll!RtlpHeapHandleError(long ErrorLevel) Line 344 C
  ntdll.dll!RtlpHpHeapHandleError(_HEAP_FAILURE_TYPE FailureType, unsigned
__int64 HeapAddress, unsigned __int64 Address) Line 670 C
  ntdll.dll!RtlpLogHeapFailure(_HEAP_FAILURE_TYPE FailureType, void *
HeapAddress, void * Address, void * Param1, void * Param2, void * Param3)
Line 158 C
  ntdll.dll!RtlFreeHeap(void * HeapHandle, unsigned long Flags, void *
BaseAddress) Line 352 C
  ucrtbase.dll!_free_base(void * block) Line 105 C++
  XXXTest.exe!llvm::StringMapImpl::RehashTable(unsigned int BucketNo) Line
238 C++
  XXXTest.exe!llvm::StringMap<llvm::ConstantDataSequential *
__ptr64,llvm::MallocAllocator>::insert(std::pair<llvm::StringRef,llvm::ConstantDataSequential
*> KV) Line 344 C++
  [Inline Frame] XXXTest.exe!llvm::StringMap<llvm::Value
*,llvm::MallocAllocator>::GetOrCreateValue(llvm::StringRef) Line 371 C++
  [Inline Frame] XXXTest.exe!llvm::StringMap<llvm::Value
*,llvm::MallocAllocator>::GetOrCreateValue(llvm::StringRef) Line 375 C++
  XXXTest.exe!llvm::ValueSymbolTable::createValueName(llvm::StringRef Name,
llvm::Value * V) Line 98 C++
  XXXTest.exe!llvm::Value::setName(const llvm::Twine & NewName) Line 236 C++
 
XXXTest.exe!llvm::IRBuilder<1,llvm::ConstantFolder,llvm::IRBuilderDefaultInserter<1>>::Insert<llvm::GetElementPtrInst>(llvm::GetElementPtrInst * I, constllvm::Twine & Name) Line 497 C++
 
XXXTest.exe!llvm::IRBuilder<1,llvm::ConstantFolder,llvm::IRBuilderDefaultInserter<1>>::CreateConstInBoundsGEP1_32(llvm::Value * Ptr, unsigned int Idx0, const
llvm::Twine & Name) Line 1014 C++> XXXTest.exe!XXX::LlvmCodeGenerator::Visit(const XXX::FeatureRefExpression& p_expr) Line 953 C++
  XXXTest.exe!XXX::FeatureRefExpression::Accept(XXX::Visitor & p_visitor)
Line 46 C++
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Doerfert, Johannes via llvm-dev

2019-Apr-04 01:33 UTC

head link

[llvm-dev] single-threaded code-gen and how to make it support multi-thread

Do you use one llvm context or one per thread that interacts with llvm? I'm
not an expert but the former might not be supported.

Cheers,
  Johannes

Get Outlook for Android<https://aka.ms/ghei36>

________________________________
From: llvm-dev <llvm-dev-bounces at lists.llvm.org> on behalf of pongba
via llvm-dev <llvm-dev at lists.llvm.org>
Sent: Wednesday, April 3, 2019 7:24:25 PM
To: llvm-dev at lists.llvm.org
Subject: [llvm-dev] single-threaded code-gen and how to make it support
multi-thread

Hi llvm-dev,

Our code base has a ancient copy of llvm (ver 3.5.1), and it uses the LLVM code
gen for some domain-specific language.

The previous dev left a global lock around the usage of LLVM code gen stating
that because LLVM code gen can only be accessed single-threaded it needs to be
protected with this global lock.

But now this lock has caused some perf issues as we pretty much lose concurrency
when having to compile a large number of source files.

I've tried to remove the global lock and what I have observed in crashing
stack is something like below:

(I did make sure LLVM_ENABLE_THREADS is defined to be 1, apparently it
didn't seem to help)

The document around this seems vague, I have not found a clear instruction as to
how to solve this, hence this post. Can anyone help with some pointers?

Any guidance is appreciated:)

  ntdll.dll!RtlReportCriticalFailure(long StatusCode, void * FailureInfo,
unsigned long BreakIfDbgPresent) Line 201 C
  ntdll.dll!RtlpHeapHandleError(long ErrorLevel) Line 344 C
  ntdll.dll!RtlpHpHeapHandleError(_HEAP_FAILURE_TYPE FailureType, unsigned
__int64 HeapAddress, unsigned __int64 Address) Line 670 C
  ntdll.dll!RtlpLogHeapFailure(_HEAP_FAILURE_TYPE FailureType, void *
HeapAddress, void * Address, void * Param1, void * Param2, void * Param3) Line
158 C
  ntdll.dll!RtlFreeHeap(void * HeapHandle, unsigned long Flags, void *
BaseAddress) Line 352 C
  ucrtbase.dll!_free_base(void * block) Line 105 C++
  XXXTest.exe!llvm::StringMapImpl::RehashTable(unsigned int BucketNo) Line 238
C++
  XXXTest.exe!llvm::StringMap<llvm::ConstantDataSequential *
__ptr64,llvm::MallocAllocator>::insert(std::pair<llvm::StringRef,llvm::ConstantDataSequential
*> KV) Line 344 C++
  [Inline Frame] XXXTest.exe!llvm::StringMap<llvm::Value
*,llvm::MallocAllocator>::GetOrCreateValue(llvm::StringRef) Line 371 C++
  [Inline Frame] XXXTest.exe!llvm::StringMap<llvm::Value
*,llvm::MallocAllocator>::GetOrCreateValue(llvm::StringRef) Line 375 C++
  XXXTest.exe!llvm::ValueSymbolTable::createValueName(llvm::StringRef Name,
llvm::Value * V) Line 98 C++
  XXXTest.exe!llvm::Value::setName(const llvm::Twine & NewName) Line 236 C++
 
XXXTest.exe!llvm::IRBuilder<1,llvm::ConstantFolder,llvm::IRBuilderDefaultInserter<1>
>::Insert<llvm::GetElementPtrInst>(llvm::GetElementPtrInst * I, const
llvm::Twine & Name) Line 497 C++
 
XXXTest.exe!llvm::IRBuilder<1,llvm::ConstantFolder,llvm::IRBuilderDefaultInserter<1>
>::CreateConstInBoundsGEP1_32(llvm::Value * Ptr, unsigned int Idx0, const
llvm::Twine & Name) Line 1014 C++> XXXTest.exe!XXX::LlvmCodeGenerator::Visit(const XXX::FeatureRefExpression
& p_expr) Line 953 C++  XXXTest.exe!XXX::FeatureRefExpression::Accept(XXX::Visitor & p_visitor)
Line 46 C++
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pongba via llvm-dev

2019-Apr-04 02:12 UTC

head link

[llvm-dev] single-threaded code-gen and how to make it support multi-thread

Thank you Johannes, I looked it up and it seems that we're creating one
LLVMContext per compilation "unit", not sure if that matters. i.e.
there's
no single globally shared LLVMContext object.

Is LLVMContext *the* concurrency isolation (or unit) here?

On Wed, Apr 3, 2019 at 6:34 PM Doerfert, Johannes <jdoerfert at anl.gov>
wrote:
> Do you use one llvm context or one per thread that interacts with llvm?
> I'm not an expert but the former might not be supported.
>
> Cheers,
>   Johannes
>
> Get Outlook for Android <https://aka.ms/ghei36>
>
> ------------------------------
> *From:* llvm-dev <llvm-dev-bounces at lists.llvm.org> on behalf of
pongba
> via llvm-dev <llvm-dev at lists.llvm.org>
> *Sent:* Wednesday, April 3, 2019 7:24:25 PM
> *To:* llvm-dev at lists.llvm.org
> *Subject:* [llvm-dev] single-threaded code-gen and how to make it support
> multi-thread
>
> Hi llvm-dev,
>
> Our code base has a ancient copy of llvm (ver 3.5.1), and it uses the LLVM
> code gen for some domain-specific language.
>
> The previous dev left a global lock around the usage of LLVM code gen
> stating that because LLVM code gen can only be accessed single-threaded it
> needs to be protected with this global lock.
>
> But now this lock has caused some perf issues as we pretty much lose
> concurrency when having to compile a large number of source files.
>
> I've tried to remove the global lock and what I have observed in
crashing
> stack is something like below:
>
> (I did make sure LLVM_ENABLE_THREADS is defined to be 1, apparently it
> didn't seem to help)
>
> The document around this seems vague, I have not found a clear instruction
> as to how to solve this, hence this post. Can anyone help with some
> pointers?
>
> Any guidance is appreciated:)
>
>   ntdll.dll!RtlReportCriticalFailure(long StatusCode, void * FailureInfo,
> unsigned long BreakIfDbgPresent) Line 201 C
>   ntdll.dll!RtlpHeapHandleError(long ErrorLevel) Line 344 C
>   ntdll.dll!RtlpHpHeapHandleError(_HEAP_FAILURE_TYPE FailureType,
> unsigned __int64 HeapAddress, unsigned __int64 Address) Line 670 C
>   ntdll.dll!RtlpLogHeapFailure(_HEAP_FAILURE_TYPE FailureType, void *
> HeapAddress, void * Address, void * Param1, void * Param2, void * Param3)
> Line 158 C
>   ntdll.dll!RtlFreeHeap(void * HeapHandle, unsigned long Flags, void *
> BaseAddress) Line 352 C
>   ucrtbase.dll!_free_base(void * block) Line 105 C++
>   XXXTest.exe!llvm::StringMapImpl::RehashTable(unsigned int BucketNo)
> Line 238 C++
>   XXXTest.exe!llvm::StringMap<llvm::ConstantDataSequential *
>
__ptr64,llvm::MallocAllocator>::insert(std::pair<llvm::StringRef,llvm::ConstantDataSequential
> *> KV) Line 344 C++
>   [Inline Frame] XXXTest.exe!llvm::StringMap<llvm::Value
> *,llvm::MallocAllocator>::GetOrCreateValue(llvm::StringRef) Line 371 C++
>   [Inline Frame] XXXTest.exe!llvm::StringMap<llvm::Value
> *,llvm::MallocAllocator>::GetOrCreateValue(llvm::StringRef) Line 375 C++
>   XXXTest.exe!llvm::ValueSymbolTable::createValueName(llvm::StringRef
> Name, llvm::Value * V) Line 98 C++
>   XXXTest.exe!llvm::Value::setName(const llvm::Twine & NewName) Line
236
> C++
>  
XXXTest.exe!llvm::IRBuilder<1,llvm::ConstantFolder,llvm::IRBuilderDefaultInserter<1>
> >::Insert<llvm::GetElementPtrInst>(llvm::GetElementPtrInst * I,
const
> llvm::Twine & Name) Line 497 C++
>  
XXXTest.exe!llvm::IRBuilder<1,llvm::ConstantFolder,llvm::IRBuilderDefaultInserter<1>
> >::CreateConstInBoundsGEP1_32(llvm::Value * Ptr, unsigned int Idx0,
const
> llvm::Twine & Name) Line 1014 C++
> > XXXTest.exe!XXX::LlvmCodeGenerator::Visit(const
> XXX::FeatureRefExpression & p_expr) Line 953 C++
>   XXXTest.exe!XXX::FeatureRefExpression::Accept(XXX::Visitor &
p_visitor)
> Line 46 C++
>

-- 
刘未鹏(pongba)
http://mindhacks.cn
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