723985 - Implement 'use moz::forceInterpreter' directive to prevent JITting

Status: RESOLVED INACTIVE

(Core :: JavaScript Engine, defect)

Description

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

For testing, I've always wanted a way to force the mode in which a given script is compiled (without affecting other scripts.)

For my stackwalking work, it turns out that I need js::Interpret to run all the way through once before I can properly identify its address range. If I run in "mjit always" mode, there's no straightforward way to ensure that this happens before I start to try to walk the stack.

The most convenient way I could think of to do this would be to add something similar to 'use strict'. So I did.

I called it 'use moz::forceInterpreter'. It's a kinda hacky language change, and I haven't discussed it with anybody, but it seems to be working for my tests.

Any feedback welcome.

Obviously, this would need to be implemented for IonMonkey as well.

Comment 1

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

Attachment: Implement 'use moz::forceInterpret' directive to prevent JITting

Comment 2

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

Whoops, you can see my ambivalence about the exact string to use. forceInterpret vs forceInterpreter.

Comment 3

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

dmandelin suggested 'use nojit'