1727328 - Add fast path for PlainObject allocation

Status: RESOLVED FIXED

(Core :: JavaScript Engine, task, P3)

Description

[Jan de Mooij [:jandem]]

PlainObjects account for a large number of object allocations. We should move this out of the generic allocation code and add a fast path for all PlainObject allocations. This lets us cache the shape in the global for plain objects with default prototype.

This will also bypass the NewObjectCache for these allocations, getting us closer to removing it.

Comment 1

[Jan de Mooij [:jandem]]

Attachment: Bug 1727328 part 1 - Remove CopyTemplateObject. r?jonco!

Other callers were recently changed to call PlainObject::createWithShape instead.
We can also do that for the remaining caller and then remove CopyTemplateObject.

Drive-by change: assert we don't reuse dictionary shapes for new objects.

Comment 2

[Jan de Mooij [:jandem]]

Attachment: Bug 1727328 part 2 - Add functions for allocating PlainObjects. r?jonco!

• NewBuiltinClassInstance<PlainObject> => NewPlainObject
• NewObjectWithGivenProto<PlainObject> => NewPlainObjectWithProto

Depends on D123456

Comment 3

[Jan de Mooij [:jandem]]

Attachment: Bug 1727328 part 3 - Add functions for allocating PlainObjects with special AllocKinds. r?jonco!

Depends on D123457

Comment 4

[Jan de Mooij [:jandem]]

Attachment: Bug 1727328 part 4 - Use NewPlainObjectWithProto in CreateBlankProto. r?jonco!

Depends on D123458

Comment 5

[Jan de Mooij [:jandem]]

Attachment: Bug 1727328 part 5 - Remove GuessObjectGCKind. r?jonco!

Drive-by clean-up: GuessObjectGCKind(0) returns AllocKind::OBJECT4, this is
equivalent to NewObjectGCKind() that we already use elsewhere for this.

Depends on D123459

Comment 6

[Jan de Mooij [:jandem]]

Attachment: Bug 1727328 part 6 - Stop using the generic allocation code for PlainObject. r?jonco!

Depends on D123460

Comment 7

[Jan de Mooij [:jandem]]

Attachment: Bug 1727328 part 7 - Use cached shape for PlainObject with default prototype. r?jonco!

Because plain objects are created with different AllocKinds, we use an array of
shapes for this. A bit annoying but because plain objects are so common it's
probably worth handling all of them.

Depends on D123461

Comment 8

[Jan de Mooij [:jandem]]

Attachment: Bug 1727328 part 8 - Add a createWithShape overload that takes the AllocKind directly. r?jonco!

This is faster for callers that already know the AllocKind.

Depends on D123462

Comment 9

[Atila Butkovits]

https://hg.mozilla.org/mozilla-central/rev/c30a66b773cc
https://hg.mozilla.org/mozilla-central/rev/a513b36de59c
https://hg.mozilla.org/mozilla-central/rev/c893b5769016
https://hg.mozilla.org/mozilla-central/rev/6fdb51703983
https://hg.mozilla.org/mozilla-central/rev/9ad88ab90367
https://hg.mozilla.org/mozilla-central/rev/8fbf291d0412
https://hg.mozilla.org/mozilla-central/rev/02f18eaee023
https://hg.mozilla.org/mozilla-central/rev/6c26dce573db