1687335 - Remove padding from Chunk data structures

Status: RESOLVED FIXED

(Core :: JavaScript: GC, enhancement, P1)

Description

[Jon Coppeard (:jonco)]

There are a couple of instances of padding used in the Chunk data structures are are almost certainly there for historical reasons that aren't relevant any more. We should remove them.

Comment 1

[Jon Coppeard (:jonco)]

Attachment: Bug 1687335 - Remove padding from Chunk data structures r?sfink

Remove the unnecessary padding. This lets us have one more arena per chunk on 32 bit Android builds with the small chunk size.

Comment 2

[Jon Coppeard (:jonco)]

Attachment: Bug 1687335 - Remove chunk location field and use storebuffer pointer to determine which chunks are in the nursery r=sfink!,jandem!

The ChunkLocation field is not necessary because we can tell the different between nursery chunks and tenured heap chunks based on whether the storebuffer pointer is null or not. This patch removes the field.

Jan, is there any impact on the generated JIT code for doing it this way?

This allows us to get one more arena per chunk on 64 bit systems with the small chunk size.

Depends on D102392

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/64fc2e7b897a
Remove padding from Chunk data structures r=sfink
https://hg.mozilla.org/integration/autoland/rev/f13d6fb14d1e
Remove chunk location field and use storebuffer pointer to determine which chunks are in the nursery r=sfink,jandem

Comment 4

[Bogdan Tara[:bogdan_tara | bogdant]]

https://hg.mozilla.org/mozilla-central/rev/64fc2e7b897a
https://hg.mozilla.org/mozilla-central/rev/f13d6fb14d1e