[PATCH] D16834: AMDGPU: Make max workgroup size settable by subtarget features

[Matt Arsenault via llvm-commits]

arsenm added a comment.

In http://reviews.llvm.org/D16834#342542, @arsenm wrote:

> In http://reviews.llvm.org/D16834#342478, @tstellarAMD wrote:
>
> > Why isn't this a function attribute?
>
>
> This is a property of the runtime. There should be function attributes for related information, such as required workgroup size. There may also be an attribute for maximum to assume but not required, but the subtarget feature would still be needed to validate that it is not above the maximum supported by the runtime, and would also serve as the default if that attribute is missing.


Actually the higher workgroups might technically work with the runtime, they just aren't supported. I think the way it works in AMD OpenCL is the max 256 is rejected by default, but there is an environment variable to increase the limit for internal development.


http://reviews.llvm.org/D16834