1473682 - js --no-baseline should prevent JITs from being re-enabled

Status: NEW

(Core :: JavaScript Engine, enhancement, P3)

Description

[Steve Fink [:sfink] [:s:]]

Currently, if you run the JS shell with --no-baseline, neither baseline nor ion will run by default, but the script can turn them back on with setJitCompilerOption("baseline.enable", 1).

I thought msan was running into this (it doesn't work with JITted code), but at the moment I don't see anything unconditionally setting that option. (A fuzz test always could, of course.)

It is very possible that what I was seeing was the wasm jit being enabled rather than baseline or ion. I'm not sure if that's the same mechanism -- I don't see it in getJitCompilerOptions().

At any rate, we should have a --no-jit option that force-disables JITs and prevents them from being re-enabled. Or perhaps it should be options like --jit=0/1/never if we want to preserve the ability to set the current state without preventing further changes.

Comment 1

[Nicolas B. Pierron [:nbp] {away}]

Another simple option might be to disable "baseline.enable" under MSan, this would be a differential behaviour, but at least we should be able to run the tests.

Comment 2

[Jan de Mooij [:jandem]]

Another option is to have ./configure complain if you're using MSan but not using the none-backend or a simulator build.