[PATCH] D51544: [OpenCL] Split opencl-c.h header

[Andrew Savonichev via Phabricator via cfe-commits]

asavonic added a comment.

In https://reviews.llvm.org/D51544#1229105, @Anastasia wrote:

> > With this setup, we can compile opencl-c-common.h, opencl-c-fp16.h and
> >  opencl-c-fp64.h into PCHs with one set of extensions/OpenCL version,
> >  and use them for any other set of extensions/OpenCL version. Clang
> >  will detect this and throw out an error, which can be safely disabled
> >  by -fno-validate-pch option.
>
> However, keeping this as a permanent solution is unsafe. Because this way can result in unexpected errors to be silent out and allow erroneous configurations to be accepted successfully without any notification.


Agree. LIT test in `test/Headers/opencl-c-header-split.cl` is supposed
to verify that common/fp16/fp64 headers do not use preprocessor macros
and it should catch most of the issues, but this is definitely not the
most robust solution.

> So I am wondering if there is any plan to put a proper solution in place at some point?

This solution can be improved if we implement `convert` and `shuffle`
as clang builtins with custom typechecking: these two builtins (with
all their overloadings) take ~90% of `opencl-c-common.h` and ~50% of
fp16/fp64 headers.

However, this can be a non-trivial change: it is difficult to do a
proper mangling for clang builtins and rounding modes must be handled
as well.

I'll take a few days to prototype this. If it turns out to be good in
terms of performance/footprint, we can drop this patch.


Repository:
  rC Clang

https://reviews.llvm.org/D51544