1592102 - Do Bytecode Emission without Allocating Scopes

Status: RESOLVED FIXED

(Core :: JavaScript Engine, task, P1)

Description

[Matthew Gaudet (he/him) [:mgaudet]]

Scopes are one of the types allocated during BytecodeEmission that need to be deferred.

Following in the footsteps of Bug 1585718 we need to avoid allocating these Scopes during bytecode emission, leaving them until JSScript::fullyInitFromEmitter (which later can be turned into a main-thread merge step).

Comment 1

[Matthew Gaudet (he/him) [:mgaudet]]

Attachment: Bug 1592102 - Hoist ScopeKind into own header r?tcampbell

Avoids future circular include issues.

Comment 2

[Matthew Gaudet (he/him) [:mgaudet]]

Attachment: Bug 1592102 - Refactor Scope allocation paths to support code sharing r?tcampbell

Depends on D51909

Comment 3

[Matthew Gaudet (he/him) [:mgaudet]]

Attachment: Bug 1592102 - Introduce AbstractScope r?tcampbell

In preparation for deferring the allocation of Scopes to the end of bytecode
emission, we introduce ScopeProvider, which is a facade class for use within
the BytecodeEmitter. This class allows asking the same set of queries that are
asked of Scopes, but when we defer the allocation of Scopes, we may not choose
to answer the queries with a Scope, instead using a (to be implemented)
ScopeCreationData.

Depends on D51910

Comment 4

[Matthew Gaudet (he/him) [:mgaudet]]

Attachment: Bug 1592102 - Defer allocation of Scopes r?tcampbell

Defer the allocation of Scopes by implementing ScopeCreationData and family.
The idea is that we do not reify a GC allocated scope until
JSScript::fullyInitFromEmitter (the goal being to eventually move that onto
main thread).

Depends on D51911

Comment 5

[Matthew Gaudet (he/him) [:mgaudet]]

Performance testing shows these changes (combined with those in Bug 1592103) appear to have no impact on our metrics when disabled, and also no impact when enabled

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/325e83234dd5
Hoist ScopeKind into own header r=tcampbell
https://hg.mozilla.org/integration/autoland/rev/351c88e680a3
Refactor Scope allocation paths to support code sharing r=tcampbell
https://hg.mozilla.org/integration/autoland/rev/0f59860a21ef
Introduce AbstractScope r=tcampbell

Comment 7

[Matthew Gaudet (he/him) [:mgaudet]]

Marking leave open, as only preliminary patches are landing today.

Comment 8

[Dorel Luca [:dluca]]

https://hg.mozilla.org/mozilla-central/rev/325e83234dd5
https://hg.mozilla.org/mozilla-central/rev/351c88e680a3
https://hg.mozilla.org/mozilla-central/rev/0f59860a21ef

Comment 9

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/47592189b305
Defer allocation of Scopes r=tcampbell

Comment 10

[Noemi Erli[:noemi_erli]]

https://hg.mozilla.org/mozilla-central/rev/47592189b305