microsoft / microsoft/DirectXShaderCompiler
No bounds check on matrix access in type constructor
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- C++
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Description
Description
I noticed that there seems to be no bounds check on matrix access when it is wrapped in a type constructor.
Steps to Reproduce
https://shader-playground.timjones.io/0aaa9f3162e186ce4ce9da1926b93a40
float4x4 M;
float4 PSMain() : SV_TARGET
{
return float4(M[8]);
}
Actual Behavior
I was expecting a compilation error on the out of bounds access M[8]. If I remove the redundant float4() type constructor, it yields a compilation error as expected.
Environment
Shader playground. Trunk (2024-04-29).
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 by reproducing the shader-playground example with the HLSL expression M[8] wrapped in float4(), then compare it with the direct M[8] form. Trace the compiler handling of matrix indexing and type-constructor expressions, and identify the relevant regression-test location. Done means the wrapped out-of-bounds access produces the expected compilation error without changing the valid case.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- cpp
- Domain
- compilers
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100