[PATCH] D50845: [CUDA/OpenMP] Define only some host macros during device compilation

[Gheorghe-Teodor Bercea via Phabricator via cfe-commits]

gtbercea added a comment.

In https://reviews.llvm.org/D50845#1202973, @ABataev wrote:

> >> If I understand it correctly, the root cause of this exercise is that we want to compile for GPU using plain C. CUDA avoids this issue by separating device and host code via target attributes and clang has few special cases to ignore inline assembly errors in the host code if we're compiling for device. For OpenMP there's no such separation, not in the system headers, at least.
> > 
> > Yes, that's one of the nice properties of CUDA (for the compiler). There used to be the same restriction for OpenMP where all functions used in `target` regions needed to be put in `declare target`. However that was relaxed in favor of implicitly marking all **called** functions in that TU to be `declare target`.
> >  So ideally I think Clang should determine which functions are really `declare target` (either explicit or implicit) and only run semantical analysis on them. If a function is then found to be "broken" it's perfectly desirable to error back to the user.
>
> It is not possible for OpenMP because we support implicit declare target functions. Clang cannot identify whether the function is going to be used on the device or not during sema analysis.


Sounds like that is a recipe for just disabling sema analysis for all implicit declare target functions.


Repository:
  rC Clang

https://reviews.llvm.org/D50845