microsoft / microsoft/DirectXShaderCompiler

`InterlockedCompareStoreFloatBitwise` intrinsic function unimplemented

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Description

error: InterlockedCompareStoreFloatBitwise intrinsic function unimplemented.
Only happens in SPIR-V compilation.

The diagnostic appears for the free-function form. The method form on
RWByteAddressBuffer gives a different text:

error: intrinsic 'InterlockedCompareStoreFloatBitwise' method unimplemented

DXIL compiles without an error at  cs_6_5  and  cs_6_6 . Only  -spirv  fails.
Measured with dxc 1.10(5369-d6e0ca4a).

This matches the shape of DXC #7782, which covers the exchange variant.
godbolt link: https://godbolt.org/z/7jTdnTT3j

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Research direction

Start with the Godbolt reproduction and compare -spirv compilation against DXIL for shader models cs_6_5 and cs_6_6. Trace handling of the InterlockedCompareStoreFloatBitwise free-function and RWByteAddressBuffer method forms, using the existing exchange variant issue DXC #7782 as context. Done means the intrinsic no longer reports unimplemented during SPIR-V compilation and the relevant forms behave consistently.

Written by the indexing model from the issue text.

Assessment

Tech stack
cpp
Domain
compilers
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Active
Clarity
Mostly clear
Newbie friendliness
55/100

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