Design Meeting Minutes: 2025/02/04

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Administrivia

• No topics

Issues

• No marked issues
• Action Item: @llvm-beanz to review issues for HLSL 202x

PRs

Carried Forward

• [0007] Big update to flesh out const instance methods
  • Action Item: @llvm-beanz update based on @tex3d’s feedback
  • Action Item: @pow2clk to review the PR and comment
• [0002] Specify the grammar formulations for attributes
  • Action Item: @pow2clk to review.
• [SM6.8] Add proposal for DXIL 1.8
  • This isn’t really in a great shape, but it is useful documentation to not lose.
  • Action Item: @llvm-beanz to merge
• [dxil] Proposal to add new debug printf dxil op
  • @pow2clk and @tex3d will review this in more detail.
• Rework hlsl-vector-type into two specs
  • Action Item: @llvm-beanz to review.

Current Business

• Add proposal for scalar layout for constant buffers
  • Action Item: @llvm-beanz to review updates from AMD
• [202y] Propose adding C++11-style constructors
  • Action Item: @farzonl & @V-FEXrt to review.
• [202x] Propose adding vk::SampledTexture* types
  • Action Item: @llvm-beanz to review.
• Add resource chapter documenting buffers and bindings
  • Action Item: @llvm-beanz to review.
• Specification language to describe flat conversions and aggregate splats
  • The PR needs revision based on feedback, but one outstanding question is what do we name the cast?
  • @llvm-beanz: Flat doesn’t describe what the conversion does
  • We had a lengthy discussion about @llvm-beanz’s dislike of the “flat” term.
  • Alternatives suggested: elementwise conversion, reshape conversion
  • Action Item: @spall to update

Other Discussion

• Effects Syntax support in HLSL 202x
  • We have an issue to turn effects syntax usage into errors in HLSL 202x - [202x] Remove HLSL Effects Syntax Support
  • This will potentially cause some source breakage for codebases that are shared between DX 10/11 and DX 12.
  • There is at least one known case where DXC assumes valid C++11 syntax is an effects annotation (C++-style initialization of vectors (int2 x{0,1}) does not work, but compiles).
  • Today, DXC ignores the effects annotation, which seems to users to be ignoring a valid intializer.
  • This syntax is C++11 initialization syntax that is not intended to be supported in DXC (which is C++98-based), but will be supported in Clang.
  • Proposed Solution:
    • In DXC: Make all effects syntax parsing errors in HLSL 202x mode.
    • In Clang: Make any effects-like syntax that is valid in modern C++ warn that it is a 202y extension.