[SofaCUDA] Compilation error fix (CudaStandardTetrahedralFEMForceField.cu)

[Ant0nin]

Compilation error fix. When CMake variables PLUGIN_SOFACUDA and SOFACUDA_DOUBLE are enabled, CudaStandardTetrahedralFEMForceField.cu try to be compiled through NVCC (Nvidia compiler). It was leading to a compile error because of 2 missing function prototypes in the .cu file. This commit fixes the issue. Compilation was tested on my side on Fedora 29 with CUDA Toolkit v10.1

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This PR:

• builds with SUCCESS for all platforms on the CI.
• does not generate new warnings.
• does not generate new unit test failures.
• does not generate new scene test failures.
• does not break API compatibility.
• is more than 1 week old (or has fast-merge label).

Reviewers will merge only if all these checks are true.

[guparan]

Congrats for your first PR @Ant0nin 👏
I guess we never enable SOFACUDA_DOUBLE on our CI 😞

[guparan]

From SOFA-dev meeting: we had a hard time understanding why it did not compile with CUDA_DOUBLE in the first place. Could you explain why?

[epernod]

hello @Ant0nin , are you speaking about the option:
SOFACUDA_DOUBLE
or
SOFA_GPU_CUDA_DOUBLE_PRECISE

my version with SOFACUDA_DOUBLE activated compile on windows 10 with recent cudaToolkit.
Maybe can you put here the error log.

[Ant0nin]

@guparan @epernod , I just tested the compilation again (without my patch) and I realized that SOFACUDA_DOUBLE has nothing to do with this issue, I was wrong about that. On my setup, the compilation does not works regardless of the SOFACUDA_DOUBLE option. I'm a bit surprized it works on your side.

Here are information on my setup:
OS => Fedora 29
NVCC version => V10.1.105
CMake variable SOFACUDA_ARCH=sm_60
CMake variable CUDA_VERSION=10.1

And here are the output errors from ninja:

[1/96] Building NVCC (Device) object applications/plugins/SofaCUDA/CMakeFiles/SofaCUDA.dir/sofa/gpu/cuda/SofaCUDA_generated_CudaStandardTetrahedralFEMForceField.cu.o
FAILED: applications/plugins/SofaCUDA/CMakeFiles/SofaCUDA.dir/sofa/gpu/cuda/SofaCUDA_generated_CudaStandardTetrahedralFEMForceField.cu.o 
cd /home/abernard/Workspace/sofa/build_master/applications/plugins/SofaCUDA/CMakeFiles/SofaCUDA.dir/sofa/gpu/cuda && /usr/bin/cmake -E make_directory /home/abernard/Workspace/sofa/build_master/applications/plugins/SofaCUDA/CMakeFiles/SofaCUDA.dir/sofa/gpu/cuda/. && /usr/bin/cmake -D verbose:BOOL=OFF -D build_configuration:STRING=Release -D generated_file:STRING=/home/abernard/Workspace/sofa/build_master/applications/plugins/SofaCUDA/CMakeFiles/SofaCUDA.dir/sofa/gpu/cuda/./SofaCUDA_generated_CudaStandardTetrahedralFEMForceField.cu.o -D generated_cubin_file:STRING=/home/abernard/Workspace/sofa/build_master/applications/plugins/SofaCUDA/CMakeFiles/SofaCUDA.dir/sofa/gpu/cuda/./SofaCUDA_generated_CudaStandardTetrahedralFEMForceField.cu.o.cubin.txt -P /home/abernard/Workspace/sofa/build_master/applications/plugins/SofaCUDA/CMakeFiles/SofaCUDA.dir/sofa/gpu/cuda/SofaCUDA_generated_CudaStandardTetrahedralFEMForceField.cu.o.Release.cmake
/home/abernard/Workspace/sofa/src_master/applications/plugins/SofaCUDA/sofa/gpu/cuda/CudaStandardTetrahedralFEMForceField.cu(1251): warning: variable "threads2" was declared but never referenced

/home/abernard/Workspace/sofa/src_master/applications/plugins/SofaCUDA/sofa/gpu/cuda/CudaStandardTetrahedralFEMForceField.cu(360): error: identifier "StandardTetrahedralFEMForceFieldCuda_BoyceAndArruda_deriveSPKTensor" is undefined
          detected during instantiation of "void StandardTetrahedralFEMForceFieldCuda_addForce_kernel(int, real *, real *, const real *, __nv_bool, const real *, float, float) [with real=float]" 
(1248): here

/home/abernard/Workspace/sofa/src_master/applications/plugins/SofaCUDA/sofa/gpu/cuda/CudaStandardTetrahedralFEMForceField.cu(587): error: identifier "StandardTetrahedralFEMForceFieldCuda_BoyceAndArruda_ElasticityTensor" is undefined
          detected during instantiation of "void StandardTetrahedralFEMForceFieldCuda_addDForce_kernel(int, real *, real *, real, real, real *) [with real=float]" 
(1266): here

2 errors detected in the compilation of "/tmp/tmpxft_0000044c_00000000-6_CudaStandardTetrahedralFEMForceField.cpp1.ii".
CMake Error at SofaCUDA_generated_CudaStandardTetrahedralFEMForceField.cu.o.Release.cmake:275 (message):
  Error generating file
  /home/abernard/Workspace/sofa/build_master/applications/plugins/SofaCUDA/CMakeFiles/SofaCUDA.dir/sofa/gpu/cuda/./SofaCUDA_generated_CudaStandardTetrahedralFEMForceField.cu.o

[epernod]

I'm using sofaCUDA on windows. Will try to install it on my ubuntu 18.04