Summary:
Currently, we build a single `libomptarget.devicertl.a` which is a
fatbinary. It is a host object file that contains the embedded archive
files for both the NVIDIA and AMDGPU targets. This was done primarily as
a convenience due to naming conflicts. Now that the clang driver for the
GPU targets can appropriate link via the per-target runtime-dir, we can
just make two separate static libraries and remove the indirection.
This patch creates two new static libraries that get installed into
```
/lib/amdgcn-amd-amdhsa/libomp.a
/lib/nvptx64-nvidia-cuda/libomp.a
```
for AMDGPU and NVPTX respectively. The link job created by the linker
wrapper now simply needs to do `-lomp` and it will search those
directories and link those static libraries. This requires far less
special handling.
This patch is a precursor to changing the build system entirely to be a
runtimes based one. Soon this target will be a standard `add_library`
and done through the GPU runtime targets.
NOTE that this actually does remove an additional optimization step.
Previously we merged all of the files into a single bitcode object and
forcibly internalized some definitions. This, instead, just treats them
like a normal static library. This may possibly affect performance for
some files, but I think it's better overall to use static library
semantics because it allows us to have an 'include-what-you-use'
relationship with the library.
Performance testing will be required. If we really need the merged blob
then we can simply pack that into a new static library.
db0f754c5a