1762584 - Store private brand as a data-property

Status: RESOLVED FIXED

(Core :: JavaScript Engine, enhancement)

Description

[André Bargull [:anba]]

The current private brand implementation uses an accessor property to save a slot. This optimisation no longer applies after bug 1700052, because accessor properties are now also stored in slots.

Using a data property for the private brand allows to use the existing optimisations for initialising data properties, which makes initialising classes which use a private brand significantly faster.

Comment 1

[André Bargull [:anba]]

Attachment: Bug 1762584 - Part 1: Store private brand in a data-property. r=mgaudet!

The previous accessor property based solution no longer applies after bug 1700052.

Comment 2

[André Bargull [:anba]]

Attachment: Bug 1762584 - Part 2: Don't emit private-brand reinit checks for non-derived class constructors. r=mgaudet!

Private brands can't be installed multiple times in non-derived class
constructors, so we can omit this check in base class constructors. This check
can already be optimised away in Warp, so this only saves a bit of bytecode
size.

Depends on D142676

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/8dbbf5328ef3
Part 1: Store private brand in a data-property. r=mgaudet
https://hg.mozilla.org/integration/autoland/rev/44bdb3be6aa9
Part 2: Don't emit private-brand reinit checks for non-derived class constructors. r=mgaudet

Comment 4

[Narcis Beleuzu [:NarcisB]]

https://hg.mozilla.org/mozilla-central/rev/8dbbf5328ef3
https://hg.mozilla.org/mozilla-central/rev/44bdb3be6aa9