[PATCH] D146031: [AMDGPU] Add MMOs for GFX11 Streamout Instructions

Tue Mar 14 18:19:04 PDT 2023

t-tye added inline comments.

================
Comment at: llvm/docs/AMDGPUUsage.rst:788
+**Streamout Registers**
+  Dedicated registers used by the GS NGG Streamout Instructions.
+
----------------
My understanding is that address spaces are about memory, not registers. So why is an address space being used for this purpose? Is it that the values are being passed in memory?

================
Comment at: llvm/lib/Target/AMDGPU/AMDGPU.h:388

+    STREAMOUT_REGISTER = 8, ///< Address space for GS NGG Streamout registers.
+
----------------
foad wrote:
> Maybe add a comment here saying "the following address spaces are internal-only and can be freely renumbered"? E.g. @Pierre-vh plans to add a new user-visible address space 8, but I think it should be fine to do that by renumbering STREAMOUT_REGISTER to 9 to make room.
> 
> I am assuming we will end up with more internal-only address spaces similar to this one.
Or could the internal address spaces start at a higher number so they do not have to be renumbered? AMDGPUUsage could then reserve a set of values to "internal use".

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D146031/new/

https://reviews.llvm.org/D146031