WebAssembly / WebAssembly/binaryen
Parse bug with extra non-nullable br_on_cast values
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- Dominant language
- WebAssembly
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Description
(module
(type $s (struct))
(func (param $s (ref $s)) (result (ref $s) (ref $s))
local.get $s
local.get $s
br_on_cast 0 (ref $s) (ref $s)
)
)
[wasm-validator error in function 0] unexpected false: non-nullable local's sets must dominate gets
Looks like we're not setting up the scratch locals quite right. It doesn't look like we're properly preserving exact results, either.
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 provided module through Binaryen's WebAssembly validator and trace how br_on_cast handles its extra non-nullable values. Inspect the scratch-local setup and result preservation described in the report; done means the repro validates without the dominance error and preserves the exact results.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- wasm
- Domain
- compilers
- Issue type
- Bug
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Quiet
- Clarity
- Mostly clear
- Newbie friendliness
- 54/100