rust-lang / rust-lang/rust

MC/DC LLVM 19 intrinsics changes

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A-LLVM C-enhancement F-coverage-mcdc T-compiler
Dominant language
Rust
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Description

In LLVM 19 some details about MC/DC changed, removing and updating some intrinsics:

I tried naively to remove the reference to the removed intrinsic https://github.com/rust-lang/rust/pull/126582, but that's incomplete. Will need more work to adapt to this it seems:

Contributor guide

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First steps

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  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reading the linked LLVM 19 commit and pull request, then inspect Rust's MC/DC intrinsic handling, including instrprof_mcdc_condbitmap_update. Done means adapting the implementation to the changed or removed LLVM intrinsics and confirming the relevant compiler tests pass.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
compilers
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
25/100

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