1622854 - Use mozilla::HashMap for the JS holder map

Status: RESOLVED FIXED

(Core :: XPCOM, task)

Description

[Jon Coppeard (:jonco)]

The comments in mfbt/HashTable.h say this is a lot faster than PLDHashTable so we should probably use it for the JS holders map.

This is in preparation for hopefully figuring out how we can split up the JS holders by zone.

Comment 1

[Eric Rahm [:erahm]]

I think we improved that situation. Nathan, is that right?

Comment 2

[Nathan Froyd [:froydnj]]

(In reply to Eric Rahm [:erahm] from comment #1)

I think we improved that situation. Nathan, is that right?

We improved the situation as far as memory usage is concerned, but mozilla::HashMap is almost certainly going to be faster because it (potentially) inlines everything due to being template-based. Maybe LTO + PGO winds up doing some sort of code-splitting + inlining across the calls-through-function-pointers that PLDHashTable requires, I dunno.

Comment 3

[Eric Rahm [:erahm]]

Okay well from a fission memshrink point of view lets not blow up memory usage.

Comment 4

[Jon Coppeard (:jonco)]

Attachment: Bug 1622854 - Factor out the JS holder map into a separate class r?mccr8

Comment 5

[Jon Coppeard (:jonco)]

Attachment: Bug 1622854 - Switch JSHolderMap to use HashMap r?mccr8

Depends on D67017

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/4da09b513bb1
Factor out the JS holder map into a separate class r=mccr8
https://hg.mozilla.org/integration/autoland/rev/15d4e5e5fd14
Switch JSHolderMap to use HashMap r=mccr8

Comment 7

[Andreea Pavel [:apavel]]

https://hg.mozilla.org/mozilla-central/rev/4da09b513bb1
https://hg.mozilla.org/mozilla-central/rev/15d4e5e5fd14