opt-dist: should we pass -Zincremental-verify-ich during builds?
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- Rust
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Description
I noticed that we are currently passing -Zincremental-verify-ich unconditionally:
This at minimum slows down that compilation, and likely also pollutes the profiling data with incorrect measurements (for actual users - perf.rlo would obviously be happy about it).
I'm not sure how much extra noise we'd see if we didn't do this though; the default is to verify 1/32 of the hashes which might mean that random-ish code sometimes get better PGO and sometimes worse. I'm also not sure how much benefit there is to not doing this.
cc @Kobzol
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Research direction
Start in collector/src/bin/rustc-fake.rs at lines 78-85 and inspect how -Zincremental-verify-ich is added during builds. Compare profiling and compilation measurements with the flag enabled and with the default verification behavior, including the potential variability described in the issue. Done means reaching and documenting a supported decision about whether opt-dist should pass the flag.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- rust
- Domain
- performance
- Issue type
- Refactor
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Quiet
- Clarity
- Needs clarification
- Newbie friendliness
- 38/100