microsoft / microsoft/DirectXShaderCompiler
[SPIR-V] debug info omits scope necessary for for-loops
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- Dominant language
- C++
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Description
Description
When outputting NS100 debug info, SpirvEmitter currently skips a lexical scope that coincides with the '(' and ')' of the for loop. This leads to confusing debug info.
Steps to Reproduce
https://godbolt.org/z/Pfe5zcPTb
Actual Behavior
%65 = OpExtInst %void %1 DebugLexicalBlock %42 %uint_11 %uint_1 %62
%66 = OpExtInst %void %1 DebugLexicalBlock %42 %uint_15 %uint_33 %65
Both 'i' variables have the same lexical block.
An examination of LLVM reveals that this can be solved by considering the for-loop controls to be a DebugLexicalScope.
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 SpirvEmitter and reproduce the issue using the linked Godbolt example. Compare the emitted NS100 debug information with LLVM's treatment of for-loop controls as a DebugLexicalScope. Done means the two variables receive distinct lexical blocks and the confusing debug output is corrected.
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
- Quiet
- Clarity
- Mostly clear
- Newbie friendliness
- 52/100