[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#1227313, @Anastasia wrote:

> Currently the main header still contains everything, so the size of the PCH won't change.


The idea is that we don't pre-compile the whole opencl-c.h, we split
it into several headers (3 of them are target independent) and
pre-compile them instead.

With this approach, we can reuse target-independent PCHs (common,
fp16, fp64) and only duplicate target-specific PCHs if needed
(opencl-c-platform.h).

The idea is basically:

1. Compile target-independent headers into modules:
  - opencl-c-common.h -> opencl-c-common.pcm
  - opencl-c-fp16.h -> opencl-c-fp16.pcm
  - opencl-c-fp64.h -> opencl-c-fp64.pcm

2. Implicitly include opencl-c.h (plain header), which has the following content:



  #include "opencl-c-common.h"
  #if cl_khr_fp16
  #include "opencl-c-fp16.h"
  #endif
  #if cl_khr_fp64
  #include "opencl-c-fp16.h"
  #endif
  #include "opencl-c-platform.h"

When compiler reaches an #include statement in opencl-c.h, it loads a
corresponding PCH. Headers that were not pre-compiled are included as
usual.


Repository:
  rC Clang

https://reviews.llvm.org/D51544