fixes#133199
PR #132252 Created a second file that shared `<TargetName>.cpp` in
`clang/lib/CodeGen/CMakeLists.txt`
For example There were two `AMDGPU.cpp`'s one in `TargetBuiltins` and
the other in `Targets`. Even though these were in different directories
`libtool` warns that it might not distinguish them because they share
the same base name.
There are two potential fixes. The easy fix is to rename one of them and
keep one cmake file. That solution though doesn't future proof this
problem in the event of a third `<TargetName>.cpp` and it seems teams
want to just use the target name
https://github.com/llvm/llvm-project/pull/132252#issuecomment-2758178483.
The alternative fix is to seperate the cmake files into their own sub
directories. I chose to create static libraries. It might of been
possible to build an OBJECT, but I only saw examples of this in
compiler-rt and test directories so assumed there was a reason it wasn't
used.
Summary:
When we were first porting to COV5, this lead to some ABI issues due to
a change in how we looked up the work group size. Bitcode libraries
relied on the builtins to emit code, but this was changed between
versions. This prevented the bitcode libraries, like OpenMP or libc,
from being used for both COV4 and COV5. The solution was to have this
'none' functionality which effectively emitted code that branched off of
a global to resolve to either version.
This isn't a great solution because it forced every TU to have this
variable in it. The patch in
https://github.com/llvm/llvm-project/pull/131033 removed support for
COV4 from OpenMP, which was the only consumer of this functionality.
Other users like HIP and OpenCL did not use this because they linked the
ROCm Device Library directly which has its own handling (The name was
borrowed from it after all).
So, now that we don't need to worry about backward compatibility with
COV4, we can remove this special handling. Users can still emit COV4
code, this simply removes the special handling used to make the OpenMP
device runtime bitcode version agnostic.
clang/lib/CodeGen/CGBuiltin.cpp is over 1MB long (>23k LoC), and can
take minutes to recompile (depending on compiler and host system) when
modified, and 5 seconds for clangd to update for every edit. Splitting
this file was discussed in this thread:
https://discourse.llvm.org/t/splitting-clang-s-cgbuiltin-cpp-over-23k-lines-long-takes-1min-to-compile/
and the idea has received a number of +1 votes, hence this change.
