[PATCH] D41651: AMDGPU: Add 32-bit constant address space

[Nicolai Hähnle via Phabricator via llvm-commits]

nhaehnle added a comment.

This needs documentation in AMDGPUUsage.rst.

Relying on metadata for correctness is indeed not okay. We should either say that CONSTANT_ADDRESS_32BIT just assumes uniformness, and move the address to an SGPR (via v_readfirstlane) if required, *or* support this also with VMEM instructions.

As far as I understand, the point of this change is to use 32-bit pointers for descriptor tables. It doesn't seem too far-fetched that we'll eventually have to supported extensions with divergent resource descriptors, so I vaguely prefer the second solution.

The other question is, why do we need a new address space at all? Can't we synthesize an appropriate pointer via inttoptr casts? I believe this is what SCPC is doing.


https://reviews.llvm.org/D41651