[all-commits] [llvm/llvm-project] 3c9988: [OpenMP] Allow exceptions in target regions when o...

Anton Rydahl via All-commits all-commits at lists.llvm.org
Wed Aug 30 09:38:57 PDT 2023

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 3c9988f85d2508bdbc64c81fed7c4b9b8db54262
  Author: Anton Rydahl <rydahl2610 at gmail.com>
  Date:   2023-08-30 (Wed, 30 Aug 2023)

  Changed paths:
    M clang/include/clang/Basic/DiagnosticCommonKinds.td
    M clang/include/clang/Basic/DiagnosticGroups.td
    M clang/lib/CodeGen/CGException.cpp
    M clang/lib/Sema/SemaExprCXX.cpp
    M clang/lib/Sema/SemaStmt.cpp
    A clang/test/OpenMP/amdgpu_exceptions.cpp
    A clang/test/OpenMP/amdgpu_throw.cpp
    A clang/test/OpenMP/amdgpu_throw_trap.cpp
    A clang/test/OpenMP/amdgpu_try_catch.cpp
    A clang/test/OpenMP/nvptx_exceptions.cpp
    M clang/test/OpenMP/nvptx_target_exceptions_messages.cpp
    A clang/test/OpenMP/nvptx_throw.cpp
    A clang/test/OpenMP/nvptx_throw_trap.cpp
    A clang/test/OpenMP/nvptx_try_catch.cpp
    A clang/test/OpenMP/x86_target_exceptions.cpp
    A clang/test/OpenMP/x86_target_throw.cpp
    A clang/test/OpenMP/x86_target_try_catch.cpp

  Log Message:
  [OpenMP] Allow exceptions in target regions when offloading to GPUs

The motivation for this patch is that many code bases use exception handling. As GPUs are not expected to support exception handling in the near future, we can experiment with compiling the code for GPU targets anyway. This will
allow us to run the code, as long as no exception is thrown.

The overall idea is very simple:
- If a throw expression is compiled to AMDGCN or NVPTX, it is replaced with a trap during code generation.
- If a try/catch statement is compiled to AMDGCN or NVPTX, we generate code for the try statement as if it were a basic block.

With this patch, the compilation of the following example
int gaussian_sum(int a,int b){
	if ((a + b) % 2 == 0) {throw -1;};
	return (a+b) * ((a+b)/2);

int main(void) {
	int gauss = 0;
	#pragma omp target map(from:gauss)
		try {
			gauss = gaussian_sum(1,100);
		catch (int e){
			gauss = e;
	std::cout << "GaussianSum(1,100)="<<gauss<<std::endl;
        #pragma omp target map(from:gauss)
                try {
                     	gauss = gaussian_sum(1,101);
                catch (int e){
                        gauss = e;
	std::cout << "GaussianSum(1,101)="<<gauss<<std::endl;
	return (gauss > 1) ? 0 : 1;
with offloading to `gfx906` results in
AMDGPU fatal error 1: Received error in queue 0x155555506000: HSA_STATUS_ERROR_EXCEPTION: An HSAIL operation resulted in a hardware exception.
zsh: abort (core dumped)

Reviewed By: jdoerfert

Differential Revision: https://reviews.llvm.org/D153924

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