DRAFT: OpenMP Target Build Scripts for El Cap #1937

rchen20 · 2025-11-04T19:09:13Z

Summary

This PR is a feature
It does the following:
- Adds OpenMP Target build scripts for the El Cap platform at the request of me

rchen20 · 2025-11-04T19:13:33Z

The following linking error occurs:

[ 21%] Linking CXX executable ../../../test-forall-atomic-basic-OpenMPTarget.exe
cd /p/vast1/chen59/allraja/rajaomptarget/raja_git_omptargetelcap/build_lc_toss4-amdclang-omptarget-6.4.2-gfx942/test/functional/forall/atomic-basic && /usr/tce/backend/installations/linux-rhel8-x86_64/gcc-8.3.1/cmake-3.24.2-ywx52e32uh6gkxzuyubpwkulzgdvxyh6/bin/cmake -E cmake_link_script CMakeFiles/test-forall-atomic-basic-OpenMPTarget.exe.dir/link.txt --verbose=1
/opt/rocm-6.4.2/llvm/bin/amdclang++  -Wall -Wextra      --gcc-toolchain=/opt/rh/gcc-toolset-13/root/usr -O2 -fopenmp -fopenmp-targets=amdgcn-amd-amdhsa -Xopenmp-target=amdgcn-amd-amdhsa -march=gfx942 "CMakeFiles/test-forall-atomic-basic-OpenMPTarget.exe.dir/test-forall-atomic-basic-OpenMPTarget.cpp.o" -o ../../../test-forall-atomic-basic-OpenMPTarget.exe  ../../../../lib/libgtest_main.a ../../../../lib/libgtest.a -lpthread ../../../../lib/libRAJA.a -lpthread ../../../../lib/libcamp.a -ldl 
/opt/rocm-6.4.2/lib/llvm/bin/clang-offload-packager: warning: Multiple inputs match to a single file, '/var/tmp/chen59/libRAJA-openmp-amdgcn-amd-amdhsa-unpackaged-f17783.bc'
lld: error: undefined symbol: memcpy
>>> referenced by /var/tmp/chen59/libcamp-openmp-amdgcn-amd-amdhsa-2f0fcc.o:(__omp_offloading_4e_55a8c43a__ZN4RAJA6policy3omp11forall_implILm8ERNS_17TypedRangeSegmentIllEEZ25ForallAtomicBasicTestImplINS1_28omp_target_parallel_for_execILm8EEENS_11auto_atomicEN4camp9resources2v13OmpElS4_dEvT2_EUllE_NS_4expt15ForallParamPackIJEEEEENSt9enable_ifIXsr6all_ofINSG_11type_traits18is_ForallParamPackISE_EENSK_24is_ForallParamPack_emptyISE_EEEE5valueENSC_10EventProxyISD_EEE4typeESD_RKNS7_IXT_EEEOT0_OT1_SE__l137)
>>> referenced by /var/tmp/chen59/libcamp-openmp-amdgcn-amd-amdhsa-2f0fcc.o:(__omp_offloading_4e_55a8c43a__ZN4RAJA6policy3omp11forall_implILm8ERNS_17TypedRangeSegmentIllEEZ25ForallAtomicBasicTestImplINS1_28omp_target_parallel_for_execILm8EEENS_11auto_atomicEN4camp9resources2v13OmpElS4_dEvT2_EUllE_NS_4expt15ForallParamPackIJEEEEENSt9enable_ifIXsr6all_ofINSG_11type_traits18is_ForallParamPackISE_EENSK_24is_ForallParamPack_emptyISE_EEEE5valueENSC_10EventProxyISD_EEE4typeESD_RKNS7_IXT_EEEOT0_OT1_SE__l137)
>>> referenced by /var/tmp/chen59/libcamp-openmp-amdgcn-amd-amdhsa-2f0fcc.o:(__omp_offloading_4e_55a8c43a__ZN4RAJA6policy3omp11forall_implILm8ERNS_17TypedRangeSegmentIllEEZ25ForallAtomicBasicTestImplINS1_28omp_target_parallel_for_execILm8EEENS_11auto_atomicEN4camp9resources2v13OmpElS4_dEvT2_EUllE_NS_4expt15ForallParamPackIJEEEEENSt9enable_ifIXsr6all_ofINSG_11type_traits18is_ForallParamPackISE_EENSK_24is_ForallParamPack_emptyISE_EEEE5valueENSC_10EventProxyISD_EEE4typeESD_RKNS7_IXT_EEEOT0_OT1_SE__l137)
>>> referenced 969 more times
clang++: error: linker command failed with exit code 1 (use -v to see invocation)

After consultation, John G. found in his own tests that this error occurs when a memcpy occurs within an OpenMP Target region, which shouldn't be allowed within such a region. @trws or @MrBurmark would you have any insight to how this might happen?

MrBurmark · 2025-11-04T19:33:48Z

It looks like this occurs within an atomic test. This might come from use of memcpy in the implementation of atomics for types that are not natively supported.

rhornung67 · 2025-11-04T19:56:08Z

scripts/lc-builds/toss4_amdclang_omptarget.sh

+  -DHIP_ROOT_DIR="/opt/rocm-${COMP_VER}/hip" \
+  -DHIP_PATH=/opt/rocm-${COMP_VER}/llvm/bin \
+  -DENABLE_CLANGFORMAT=On \
+  -DCLANGFORMAT_EXECUTABLE=/opt/rocm-5.2.3/llvm/bin/clang-format \


This should point at regular clang for clang-format

rhornung67 · 2025-11-04T19:57:16Z

host-configs/lc-builds/toss4/hip_3_X.cmake

-set(CMAKE_CXX_FLAGS_RELEASE "-O2" CACHE STRING "")
-set(CMAKE_CXX_FLAGS_RELWITHDEBINFO "-O2 -g" CACHE STRING "")
-set(CMAKE_CXX_FLAGS_DEBUG "-O0 -g" CACHE STRING "")
+set(CMAKE_CXX_FLAGS_RELEASE "--gcc-toolchain=/opt/rh/gcc-toolset-13/root/usr -O2" CACHE STRING "")


We should be using the hip_4 host-config file

rhornung67 · 2025-11-04T19:59:56Z

@rchen20 does the regular clang compiler work?

Looking through the code, I don't see anything obviously wrong. Could the memcpy be related to the camp EventProxy?

rchen20 · 2025-11-04T20:16:23Z

@rchen20 does the regular clang compiler work?

The regular clang compiler is not available on our El Cap platforms, so I should remove that particular script.

Looking through the code, I don't see anything obviously wrong. Could the memcpy be related to the camp EventProxy?

I don't see any memcpy's in Camp::EventProxy, but there are implementations of memcpy in Camp::resource. After removing those implementations, the same memcpy linking error occurs. I may need to do as Jason suggests and dig in to our atomic implementations and see if the memcpy is coming from there.

rhornung67 · 2025-11-04T20:27:16Z

@rchen20 I skimmed the RAJA atomics and did not see any memcpy calls. A thought....what happens if you remove the CAS atomic check here https://github.com/LLNL/RAJA/blob/develop/test/functional/forall/atomic-basic/tests/test-forall-atomic-basic.hpp#L105?

rchen20 · 2025-11-04T21:09:48Z

@rchen20 I skimmed the RAJA atomics and did not see any memcpy calls. A thought....what happens if you remove the CAS atomic check here https://github.com/LLNL/RAJA/blob/develop/test/functional/forall/atomic-basic/tests/test-forall-atomic-basic.hpp#L105?

That's a good idea, but it still gave the same error after removing the CAS operation.

rhornung67 · 2025-11-04T22:11:28Z

Maybe try eliminating entries in the list of data types we test to see if that can help pin down the issue?

…o task/chen59/omptargetelcap

rchen20 · 2025-11-12T00:11:25Z

include/RAJA/util/TypeConvert.hpp

+void * custom_memcpy( void * dest, const void * src, size_t len )
+{
+  char * customdest = (char *) dest;
+  const char * customsrc = (const char *) src;
+
+  for ( size_t ii = 0; ii < len; ++ii )
+  {
+    customdest[ii] = customsrc[ii];
+  }
+
+  return dest;
+}


We shouldn't need to do this. Asking AMD about this.

Did you hear anything back? It shouldn't be required, makes me wonder if there's a header or builtin missing that's causing problems.

They reproduced it a couple weeks ago and are looking in to solving it. The Cray compiler has these symbols in libu.a, where they apparently keep a hodgepodge collection of these implementations. I don't know where AMD's implementations lie, but they probably just need to add these memory functions in somewhere.

Thanks @rchen20. If you don't get satisfaction on this, let me know. I'm going to try and mention it on our checkin with AMD engineering this afternoon to keep it on their radar.

rchen20 added 2 commits November 4, 2025 11:06

OpenMP Target build scripts for El Cap.

cd946d8

Temporary setting of gcc-toolchain.

9940386

rchen20 self-assigned this Nov 4, 2025

rhornung67 reviewed Nov 4, 2025

View reviewed changes

Merge branch 'develop' into task/chen59/omptargetelcap

dac8a89

rchen20 added 2 commits November 11, 2025 16:08

Temporarily re-implement memcpy.

cc9fae8

Merge branch 'task/chen59/omptargetelcap' of github.com:LLNL/RAJA int…

1988b43

…o task/chen59/omptargetelcap

rchen20 commented Nov 12, 2025

View reviewed changes

rchen20 mentioned this pull request Nov 14, 2025

OpenMP Target build script and config for CCE compiler. #1944

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DRAFT: OpenMP Target Build Scripts for El Cap #1937

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DRAFT: OpenMP Target Build Scripts for El Cap #1937

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rchen20 commented Nov 4, 2025

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