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[flang][OpenMP] Compiler crash with nowait on target construct #124578

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abidh opened this issue Jan 27, 2025 · 2 comments · Fixed by #124720
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[flang][OpenMP] Compiler crash with nowait on target construct #124578

abidh opened this issue Jan 27, 2025 · 2 comments · Fixed by #124720
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@ergawy
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crash Prefer [crash-on-valid] or [crash-on-invalid] llvm:openmpirbuilder Issues related to problems in the llvm-project/lib/Frontend/OpenMP/OMPIRBuilder.cpp

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@abidh
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abidh commented Jan 27, 2025

Consider the following program.

program nowait_reproducer
   implicit none

   real x

   !$omp target map(tofrom: x) nowait
      x = 5
   !$omp end target

end program nowait_reproducer

Compiling it with the following cause the compiler to crash

flang -fopenmp test.f90

Note that adding --offload-arch makes the crash go away. The call stack of the crash site looks like as follows:

llvm::CallInst::init
llvm::IRBuilderBase::CreateCall
llvm::OpenMPIRBuilder::emitTargetTask
llvm::OpenMPIRBuilder::finalize
mlir::LLVM::ModuleTranslation::~ModuleTranslation
@llvmbot llvmbot added the flang Flang issues not falling into any other category label Jan 27, 2025
@abidh
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abidh commented Jan 27, 2025

Hi @ergawy
I thought I will bring it to your notice as you seem to have worked in this area.

@ergawy
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ergawy commented Jan 27, 2025

Thanks Abid. I will take a look at this.

@ergawy ergawy self-assigned this Jan 27, 2025
@EugeneZelenko EugeneZelenko added crash Prefer [crash-on-valid] or [crash-on-invalid] flang:openmp and removed flang Flang issues not falling into any other category labels Jan 27, 2025
ergawy added a commit to ergawy/llvm-project that referenced this issue Jan 28, 2025
@ergawy
[OpenMP][IRBuilder] Handle target ... nowait when codegen targets host
30656df 
Fixes llvm#124578

Handles the `nowait` clause for `omp.target` ops when the actual target
is the host (i.e. there is no target device). Rather than only checking
for the `HasNoWait` boolean, we also check for the presence/absence of a
`DeviceID` value. We only emit the target task if both are present.
@ergawy ergawy mentioned this issue Jan 28, 2025
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@ergawy ergawy closed this as completed in 83433d9 Jan 28, 2025
github-actions bot pushed a commit to arm/arm-toolchain that referenced this issue Jan 28, 2025
@ergawy @github-actions
Automerge: [OpenMP][IRBuilder] Handle target ... nowait when codege…
5305fa7 
…n targets host (#124720)

Fixes llvm/llvm-project#124578

Handles the `nowait` clause for `omp.target` ops when the actual target
is the host (i.e. there is no target device). Rather than only checking
for the `HasNoWait` boolean, we also check for the presence/absence of a
`DeviceID` value. We only emit the target task if both are present.
@EugeneZelenko EugeneZelenko added llvm:openmpirbuilder Issues related to problems in the llvm-project/lib/Frontend/OpenMP/OMPIRBuilder.cpp and removed flang:openmp labels Jan 28, 2025
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crash Prefer [crash-on-valid] or [crash-on-invalid] llvm:openmpirbuilder Issues related to problems in the llvm-project/lib/Frontend/OpenMP/OMPIRBuilder.cpp
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[OpenMP][IRBuilder] Handle target ... nowait when codegen targets host ergawy/llvm-project
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@ergawy @abidh @EugeneZelenko @llvmbot