Issue #14
Welcome to LLVM GPU News, a bi-weekly newsletter on all the GPU things under the LLVM umbrella. This issue covers the period from June 4 to June 17 2021.
We welcome your feedback and suggestions. Let us know if we missed anything interesting, or want us to bring attention to your (sub)project, revisions under review, or proposals. Please see the bottom of the page for details on how to submit suggestions and contribute.
Industry News and Conferences
- The Game Developers Conference (GDC) is a month away (July 19-23 2021). The “Programming” topic sessions include the “Advanced Graphics Summit”.
LLVM and Clang
Discussions
- Sameer Sahasrabuddhe posted an update on the “Abstracting over SSA form IRs” RFC. The newest experimental results show performance comparison of two proposed ‘CycleInfo’ analysis implementations: dynamic polymorphism via virtual calls is 5% slower on average than static polymorphism via templates.
- Sameer Sahasrabuddhe submitted an RFC: “Update token semantics with default convergent attribute”. The RFC is designed to look like an incremental change over Nicolai’s original spec for convergence control intrinsics.
Commits
- The Attributor pass performs heap-2-stack for the GPU correctly now.
- A new AMDGPU target gfx1013 has been added, reverted, and relanded.
- HIP gained a new flag
--gpu-bundle-outputto control bundling/unbundling output of HIP device compilation.
MLIR
Discussions
Commits
- The SPIR-V dialect now uses SingleBlock + NoTerminator. This allows the removal of the
spv.mlir.endmoduleop. - Conversion of MMA type to NVVM got simplified.
OpenMP (Target Offloading)
Discussions
- To ensure the “atomicity of updates” we are working on fine grained locking in the mapping table.
Commits
- Dependency on libelf has been removed in favor of the LLVM ELF utilities.
- A fine-grained globalization scheme for local variables with middle-end optimizations will be merged.
External Compilers
LLPC
- Initial patches updating the existing LLPC passes with the New Pass Manager support have been merged.