1626907 - InitFromBailout uses a heap GCVector for small vector startFrameFormals

Status: RESOLVED FIXED

(Core :: JavaScript Engine: JIT, enhancement, P1)

Description

[Christian Holler (:decoder)]

In js/src/jit/BaselineBailouts.cpp the InitFromBailout receives a MutableHandle<GCVector<Value>> startFrameFormals which forces a heap allocation as soon as this vector is used. According to my measurements on tests and in fuzzing, in almost all cases where this vector is actually populated, it remains small (up to 4 elements mostly), so using a StackGCVector is probably more effective here.

Comment 1

[Christian Holler (:decoder)]

Attachment: Bug 1626907 - Use a StackGCVector for startFrameFormals in baseline bailout. r?jandem

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/e85c1126616d
Use a StackGCVector for startFrameFormals in baseline bailout. r=jandem

Comment 3

[Andrei Ciure[:aciure]]

https://hg.mozilla.org/mozilla-central/rev/e85c1126616d