Issue #0
Welcome to the pilot issue of LLVM GPU News, a bi-weekly newsletter on all the GPU things under the LLVM umbrella. This issue covers the period from November 27 to December 4 2020.
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.
LLVM
Discussions
- Jay Foad ran into issues with preserved and required transitive analyses in the Legacy Pass Manager in AMDGPU. Jay proposes to add a new pass preservation rule, but some existing passes currently violate it.
- Arthur Eubanks is working towards enabling the New Pass Manager.
Arthur looked into AMDGPU support for the NPN and points out that
passes that depended on
TargetMachine::adjustPassManagerneed to be tweaked to work with NPN. - João Paulo L. de Carvalho asked about modeling address space casts in the Scalar Evolution analysis. This prevents simple SYCL loops from being vectorized. There are no responses as of writing.
- Nichols A. Romero proposed to add Fortran tests to the LLVM Test Suite. The tests will focus on language features, high-performance proxy programs, and OpenMP multi-threading and GPU offloading.
Commits
- (In-review) Ongoing work and discussion on Adding convergence control operand bundle and intrinsics to LLVM IR.
- Clang Offload Bundler gained AMDGPU code object V4 ABI documentation.
- Various fixes to AMDGPU assembler diagnostics: [1], [2].
- (In-review) Don’t sink ptrtoint/inttoptr sequences into non-noop address space casts. This resolves an illegal memory access with atomic shared memory JuliaGPU bug.
- CUDA/HIP hostness function overloading fixes.
A new
-fgpu-exclude-wrong-side-overloadsClang flag controls the related behavior.
MLIR
Discussions
Commits
External Compilers
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