microsoft / microsoft/DirectXShaderCompiler
Segmentation fault (null deref) when missing patchconstantfunc in lib
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- C++
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Description
Description
When a hull shader is compiled with the wrong patchconstantfunc, it can yield to a segmentation fault when building with lib_ instead of hs_.
When building for hs_, we correctly get a patch constant function toto must be defined.
Steps to Reproduce
https://godbolt.org/z/bY3WKn6xz
// RUN: %dxc -T lib_6_6 %s
[patchconstantfunc("SubDToBezierConstantsHS")]
[outputtopology("triangle_cw")]
[outputcontrolpoints(16)]
void hs_main() { }
Environment
- DXC version: a11702ef0a393a9e0b78f982f9f0fa66d919c867
- Host Operating System: linux
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 running the Godbolt reproduction with dxc -T lib_6_6 and compare it with the hs_ target, which reports the missing patch constant function instead. Trace handling of the patchconstantfunc attribute in the lib_ path; done means the invalid shader produces a diagnostic rather than a segmentation fault.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- cpp, linux
- Domain
- compilers
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 38/100