CODEWITHSUNDEEP
c++buildcudaclangcub
Serge Rogatch
Serge Rogatch

Reputation: 15100

Compilation of CUB library with clang as the CUDA compiler

I set clang++-12 as the CUDA compiler in CMake as follows:

cmake .. -DCMAKE_BUILD_TYPE=Debug \
  -DCMAKE_CUDA_ARCHITECTURES="75" \
  -DCMAKE_CUDA_COMPILER=clang++-12 \
  -DCMAKE_CXX_COMPILER=clang++-12 -DCMAKE_C_COMPILER=clang-12

I try to compile a large codebase with it, but essentially it fails for a .cu file that includes CUB and uses some textures with the following error:

clang: warning: Unknown CUDA version. cuda.h: CUDA_VERSION=11040. Assuming the latest supported version 10.1 [-Wunknown-cuda-version]
clang: warning: argument unused during compilation: '-G -Werror' [-Wunused-command-line-argument]
In file included from /scratch/src/libgpu/src/skelapp/skel_dummy.cu:2:
In file included from /scratch/src/libgpu/include/gg.cuh:5:
In file included from /scratch/src/libgpu/include/AppendOnlyList.cuh:6:
In file included from /usr/local/cuda-11.4/include/cub/cub.cuh:61:
In file included from /usr/local/cuda-11.4/include/cub/device/device_spmv.cuh:41:
In file included from /usr/local/cuda-11.4/include/cub/device/dispatch/dispatch_spmv_orig.cuh:42:
In file included from /usr/local/cuda-11.4/include/cub/device/dispatch/../../agent/agent_spmv_orig.cuh:47:
/usr/local/cuda-11.4/include/cub/device/dispatch/../../agent/../iterator/tex_ref_input_iterator.cuh:133:39: error: reference to __host__ variable 'ref' in __device__ function
                words[i] = tex1Dfetch(ref, (tex_offset * TEXTURE_MULTIPLE) + i);
                                      ^
In file included from <built-in>:1:
In file included from /usr/lib/llvm-12/lib/clang/12.0.1/include/__clang_cuda_runtime_wrapper.h:333:
/usr/local/cuda-11.4/include/texture_indirect_functions.h:111:4: error: use of undeclared identifier '__nv_tex_surf_handler'
   __nv_tex_surf_handler("__itex1Dfetch", ptr, obj, x);
   ^
/usr/local/cuda-11.4/include/texture_indirect_functions.h:120:3: note: in instantiation of function template specialization 'tex1Dfetch<int>' requested here
  tex1Dfetch(&ret, texObject, x);
  ^
/scratch/src/libgpu/include/worklist.cuh:393:12: note: in instantiation of function template specialization 'tex1Dfetch<int>' requested here
    item = tex1Dfetch<int>(tx, id);
           ^
2 errors generated when compiling for sm_75.
make[2]: *** [libgpu/CMakeFiles/some_gpu.dir/build.make:146: libgpu/CMakeFiles/some_gpu.dir/src/skelapp/skel_dummy.cu.o] Error 1

How to work around this? Shall I submit bugs to NVIDIA or LLVM?

The environment is Ubuntu 20.04 with LLVM/Clang 12 and CUDA Toolkit 11.4.1 . CUB is bundled with CUDA Toolkit.

Upvotes: -2

Views: 874

Answers (1)

ArtemB
ArtemB

Reputation: 3632

How to work around this? Shall I submit bugs to NVIDIA or LLVM?

There's no workaround. Right now Clang does not support texture/surface lookups, regardless of the CUDA version used. There's already a bug open: https://bugs.llvm.org/show_bug.cgi?id=26400

Texture support can be implemented, but there's been no specific need to justify the effort so far.

Upvotes: 3

Related Questions