<div dir="ltr"><div dir="ltr"><div dir="ltr">Yes, the LLVM Context is the unit of isolation.<div><br></div><div>In the LLVM tree, the best example is likely ThinLTO using a ThreadPool to codegen modules in parallel, see: </div><div><br></div><div><a href="https://github.com/llvm/llvm-project/blob/master/llvm/lib/LTO/LTOBackend.cpp#L347">https://github.com/llvm/llvm-project/blob/master/llvm/lib/LTO/LTOBackend.cpp#L347</a><br></div><div>and/or:</div><div><a href="https://github.com/llvm/llvm-project/blob/master/llvm/lib/LTO/ThinLTOCodeGenerator.cpp#L833">https://github.com/llvm/llvm-project/blob/master/llvm/lib/LTO/ThinLTOCodeGenerator.cpp#L833</a><br></div><div><br></div><div>Hope this'll help!</div><div><br></div><div>-- </div><div>Mehdi</div><div><br></div><div><br></div></div></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, Apr 3, 2019 at 7:19 PM Doerfert, Johannes via llvm-dev <<a href="mailto:llvm-dev@lists.llvm.org">llvm-dev@lists.llvm.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;border-left-color:rgb(204,204,204);padding-left:1ex">I thought isolation is guaranteed per LLVMContext, but I might be wrong. Maybe somebody else can help.<br>
<br>
________________________________________<br>
From: pongba <<a href="mailto:pongba@gmail.com" target="_blank">pongba@gmail.com</a>><br>
Sent: Wednesday, April 3, 2019 21:12<br>
To: Doerfert, Johannes<br>
Cc: <a href="mailto:llvm-dev@lists.llvm.org" target="_blank">llvm-dev@lists.llvm.org</a><br>
Subject: Re: [llvm-dev] single-threaded code-gen and how to make it support multi-thread<br>
<br>
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.<br>
<br>
Is LLVMContext *the* concurrency isolation (or unit) here?<br>
<br>
On Wed, Apr 3, 2019 at 6:34 PM Doerfert, Johannes <<a href="mailto:jdoerfert@anl.gov" target="_blank">jdoerfert@anl.gov</a><mailto:<a href="mailto:jdoerfert@anl.gov" target="_blank">jdoerfert@anl.gov</a>>> wrote:<br>
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.<br>
<br>
Cheers,<br>
Johannes<br>
<br>
Get Outlook for Android<<a href="https://aka.ms/ghei36" rel="noreferrer" target="_blank">https://aka.ms/ghei36</a>><br>
<br>
________________________________<br>
From: llvm-dev <<a href="mailto:llvm-dev-bounces@lists.llvm.org" target="_blank">llvm-dev-bounces@lists.llvm.org</a><mailto:<a href="mailto:llvm-dev-bounces@lists.llvm.org" target="_blank">llvm-dev-bounces@lists.llvm.org</a>>> on behalf of pongba via llvm-dev <<a href="mailto:llvm-dev@lists.llvm.org" target="_blank">llvm-dev@lists.llvm.org</a><mailto:<a href="mailto:llvm-dev@lists.llvm.org" target="_blank">llvm-dev@lists.llvm.org</a>>><br>
Sent: Wednesday, April 3, 2019 7:24:25 PM<br>
To: <a href="mailto:llvm-dev@lists.llvm.org" target="_blank">llvm-dev@lists.llvm.org</a><mailto:<a href="mailto:llvm-dev@lists.llvm.org" target="_blank">llvm-dev@lists.llvm.org</a>><br>
Subject: [llvm-dev] single-threaded code-gen and how to make it support multi-thread<br>
<br>
Hi llvm-dev,<br>
<br>
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.<br>
<br>
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.<br>
<br>
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.<br>
<br>
I've tried to remove the global lock and what I have observed in crashing stack is something like below:<br>
<br>
(I did make sure LLVM_ENABLE_THREADS is defined to be 1, apparently it didn't seem to help)<br>
<br>
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?<br>
<br>
Any guidance is appreciated:)<br>
<br>
ntdll.dll!RtlReportCriticalFailure(long StatusCode, void * FailureInfo, unsigned long BreakIfDbgPresent) Line 201 C<br>
ntdll.dll!RtlpHeapHandleError(long ErrorLevel) Line 344 C<br>
ntdll.dll!RtlpHpHeapHandleError(_HEAP_FAILURE_TYPE FailureType, unsigned __int64 HeapAddress, unsigned __int64 Address) Line 670 C<br>
ntdll.dll!RtlpLogHeapFailure(_HEAP_FAILURE_TYPE FailureType, void * HeapAddress, void * Address, void * Param1, void * Param2, void * Param3) Line 158 C<br>
ntdll.dll!RtlFreeHeap(void * HeapHandle, unsigned long Flags, void * BaseAddress) Line 352 C<br>
ucrtbase.dll!_free_base(void * block) Line 105 C++<br>
XXXTest.exe!llvm::StringMapImpl::RehashTable(unsigned int BucketNo) Line 238 C++<br>
XXXTest.exe!llvm::StringMap<llvm::ConstantDataSequential * __ptr64,llvm::MallocAllocator>::insert(std::pair<llvm::StringRef,llvm::ConstantDataSequential *> KV) Line 344 C++<br>
[Inline Frame] XXXTest.exe!llvm::StringMap<llvm::Value *,llvm::MallocAllocator>::GetOrCreateValue(llvm::StringRef) Line 371 C++<br>
[Inline Frame] XXXTest.exe!llvm::StringMap<llvm::Value *,llvm::MallocAllocator>::GetOrCreateValue(llvm::StringRef) Line 375 C++<br>
XXXTest.exe!llvm::ValueSymbolTable::createValueName(llvm::StringRef Name, llvm::Value * V) Line 98 C++<br>
XXXTest.exe!llvm::Value::setName(const llvm::Twine & NewName) Line 236 C++<br>
XXXTest.exe!llvm::IRBuilder<1,llvm::ConstantFolder,llvm::IRBuilderDefaultInserter<1> >::Insert<llvm::GetElementPtrInst>(llvm::GetElementPtrInst * I, const llvm::Twine & Name) Line 497 C++<br>
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++<br>
> XXXTest.exe!XXX::LlvmCodeGenerator::Visit(const XXX::FeatureRefExpression & p_expr) Line 953 C++<br>
XXXTest.exe!XXX::FeatureRefExpression::Accept(XXX::Visitor & p_visitor) Line 46 C++<br>
<br>
<br>
--<br>
刘未鹏(pongba)<br>
<a href="http://mindhacks.cn" rel="noreferrer" target="_blank">http://mindhacks.cn</a><br>
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</blockquote></div>