microsoft / microsoft/DirectXShaderCompiler
SplitDouble producing transposed output in DXIL
Nobody has claimed this yet.
- Dominant language
- C++
- Stars
- 3.7k
- Forks
- 900
- Avg merge
- 2d 11h
- Merged PRs (30d)
- 44
Description
Description
DXIL lowering of splitdouble writes the output matrices in column-major flat order while consuming the input row-major, producing transposed low/high matrices.
Steps to Reproduce
https://hlsl.godbolt.org/z/rd18nG95x
Actual Behavior
https://hlsl.godbolt.org/z/rd18nG95x, line 40 of DXIL should be:
call void @dx.op.rawBufferStore.i32(i32 140, %dx.types.Handle %Lows_UAV_structbuf, i32 0, i32 0, i32 %5, i32 %7, i32 %9, i32 %11, i8 15, i32 4), !dbg !119
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start with the linked hlsl.godbolt.org reproduction and inspect the DXIL lowering path for splitdouble. Compare the generated stores around line 40 with the expected rawBufferStore call shown in the issue. Done means the low/high matrices are emitted in the correct row-major order without transposition.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- cpp
- Domain
- compilers, computer-graphics
- Issue type
- Bug
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Quiet
- Clarity
- Mostly clear
- Newbie friendliness
- 52/100