[llvm] [AMDGPU] Post-RA Peephole for latency-hiding and hazard-avoidance bet… (PR #191319)

[Jeffrey Byrnes via llvm-commits]

jrbyrnes wrote:

> > This seems like a scheduling problem - why doesn't PostRA scheduler do it?
> > My main concern is that this is not always beneficial - for example, if we want to schedule the mfma after the buffer_load to hide the buffer_load latency.
> > I'm also unclear on why we're limiting to just mfma - why not any valu for example?
> 
> The scheduler pre/post RA will consider many elements and trade-offs in a much bigger scope and if our scheduler can handle this case well for now, we can ignore the changes here.
> 

Sure - so I guess my question is why doesn't the post RA scheduler do it? Do you have a complete end-to-end case which demonstrates why the post RA scheduler can't do it?



https://github.com/llvm/llvm-project/pull/191319