Issue #39

Welcome to LLVM GPU News, a bi-weekly newsletter on all the GPU things under the LLVM umbrella. This issue covers the period from July 23 to August 5, 2022.

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 Community Events

LLVM and Clang

Discussions

• Sameer Sahasrabuddhe posted an RFC on ‘Uniformity Analysis for Irreducible Control Flow’. This is a generalization of divergence analysis that included irreducible control flow. The proposed analysis is implemented as a template that can be used by both LLVM IR and Machine IR.

Commits

• DirectX/HLSL/DXIL support:
  • Move support for dxil::TypedPointerType to LLVM core IR. D130592
  • Added a new HLSL builtin, __builtin_hlsl_create_handle, to create pointers out of resource handles. D130016
  • Added initial support for the RWBuffer type. D128569, D130017, D130019
  • Added initial ResourceType documentation. D130794
  • Added support for the -E compilation option that specifies the entry point. D124751
• SPIRVBaseInfo* was reimplemented with TableGen. The previous approach was based on macros. D130518

MLIR

Discussions

• The SPIR-V dialect is planned to be renamed from spv. to spirv., while vendor-specific operations from spirv.<OpName><Vendor> to spirv.<Vendor>.<OpName>. This will be a non-functional change. LLVM#56863

Commits

• A new spv.IAddCarry op was defined. D131281

OpenMP (Target Offloading)

Discussions

• Shilei Tian proposed to update the C++ standard to 17 for libopmtarget. There are no replies at the time of writing.
• Guilherme Valarini posted an RFC on ‘Re-scheduling implicit tasks for non-blocking target nowait execution’.

Commits

External Compilers

LLPC

• Multiple changes advancing the mesh shader support.