[llvm] AMDGPU: Ensure both wavesize features are not set (PR #159234)

[Tim Renouf via llvm-commits]

trenouf wrote:

I agree we do use both waveness in the same module in PAL graphics, and we do not want to change that.

> To actually support this you would need to have MCSubtargetInfo specified per function, and not globally. Just turning on both modes globally is not the same thing

Why is that? How come we have been able to use this? Is it maybe limited to compute and the way you write a kernel header or info with wave size? In PAL, we do not do that; instead, the wave size for each graphics shader stage is in the PAL metadata.

How about only adding this assert when not in PAL? And changing the test for both together to specify PAL?

Or making the assert only fire if the two functions with different wave size have the same calling convention?


https://github.com/llvm/llvm-project/pull/159234