Summary:
This PR simply changes the behavior of the `wchar_size` flag. Currently,
we emit this in all cases for all targets. This causes problems during
LLVM-IR linking, specifically because this would vary between Linux and
Windows in unintuitive ways. Now we have an llvm::Triple helper to
determine the size from the known values. The module flag will only be
emitted if these do not match (indicating a non-standard environment).
In addition to fixing AMDGCN bitcode linking, this also means we don't
need to bloat *every* IR module compiled by clang with this flag. The
changed tests reflects this, one less unnecessary piece of metadata.
This just added unnecessary work to the IR, since they are only used for
load and store, which just causes some IR noise. Tests updated by UTC
script to remove the extra lines.
This PR adds checks for when emitting weak aliases in: `void
CodeGenModule::EmitGlobal(GlobalDecl GD)`, before for device compilation
for OpenMP, HIP and Cuda, clang would look for the aliasee even if it
was never marked for device compilation.
For OpenMP the following case now works:
> Failed before when compiling with device, ie: `clang -fopenmp
-fopenmp-targets=amdgcn-amd-amdhsa`
> ```
> int __Two(void) { return 2; }
> int Two(void) __attribute__ ((weak, alias("__Two")));
> ```
For HIP / Cuda:
>
> ```
> int __HostFunc(void) { return 42; }
> int HostFunc(void) __attribute__ ((weak, alias("__HostFunc")));
> ```
For HIP:
>Failed before on HIP, Cuda fails due to: `NVPTX aliasee must not be
'.weak'` error
> ```
> __device__ int __One(void) { return 2; }
> __device__ int One(void) __attribute__ ((weak, alias("__One")));
> ```
Included are Codegen LIT tests for the above cases, and also cases for
weak alias cases that currently work in clang.
Fixes https://github.com/llvm/llvm-project/issues/117369
