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PreserveImportsExportsJS fuzzer: Handle crashes and function ids#8648

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kripken merged 2 commits into
WebAssembly:mainfrom
kripken:fuzz.pjs.funcid
Apr 28, 2026
Merged

PreserveImportsExportsJS fuzzer: Handle crashes and function ids#8648
kripken merged 2 commits into
WebAssembly:mainfrom
kripken:fuzz.pjs.funcid

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@kripken

@kripken kripken commented Apr 27, 2026

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  1. Report VM errors as failures (rather than see they still occur after opts).
  2. Ignore function ID differences in logging.
@kripken kripken requested a review from a team as a code owner April 27, 2026 17:00
@kripken kripken requested review from aheejin and removed request for a team April 27, 2026 17:00
Comment thread scripts/fuzz_opt.py
Comment on lines +2222 to +2224
# VM crashes are actual issues we want to find.
if '(core dumped)' in out or 'Received signal' in out or '== C stack trace ==' in out or '== JS stack trace ==' in out:
raise Exception(f"VM crash:\n\n{out}")

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Why is this different than in other fuzz handlers?

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Our normal JS is very careful to swallow and log any JS errors. The return code of the process is always 0.

Here we are running JS that is itself a fuzz testcase, and might error.

@kripken kripken merged commit af1dd5b into WebAssembly:main Apr 28, 2026
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@kripken kripken deleted the fuzz.pjs.funcid branch April 28, 2026 17:21
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