1781128 - Records have unnecessary initialized-length slot

Status: RESOLVED FIXED

(Core :: JavaScript Engine, task, P1)

Description

[Tim Chevalier]

Currently, Records have an internal slot that stores their length. This is unnecessary, since the value of that slot always equals the initialized length of the sorted keys array (another slot stored in records). It might be a minor optimization to cache the length rather than having to fetch the sorted keys array and then get its length, but right now we don't have any evidence that this helps significantly with performance.

I have a patch for this coming shortly.

Comment 1

[Tim Chevalier]

Attachment: Bug 1781128 - Remove INITIALIZED_LENGTH_FIELD slot for records

This slot is not necessary, as the initialized length can always be computed
from the sorted keys array.

Comment 2

[BugBot [:suhaib / :marco/ :calixte]]

There's a r+ patch which didn't land and no activity in this bug for 2 weeks.
:tjc, could you have a look please?
If you still have some work to do, you can add an action "Plan Changes" in Phabricator.
For more information, please visit auto_nag documentation.

Comment 3

[Tim Chevalier]

It's ready to land, I just didn't have a chance to nag somebody to land it. I asked on Matrix and hopefully someone will see it.

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/b4169f53b772
Remove INITIALIZED_LENGTH_FIELD slot for records r=jandem

Comment 5

[Atila Butkovits]

https://hg.mozilla.org/mozilla-central/rev/b4169f53b772