1687602 - Optimize JSFunction allocation in Stencil

Status: RESOLVED FIXED

(Core :: JavaScript Engine, task, P1)

Description

[Ted Campbell [:tcampbell]]

For large JS files, we can have 10's of thousands of individual functions. Even with syntax parsing, we must allocate a JSFunction for each when we instantiate the CompilationStencil. Currently we use NewFunctionWithProto which is quite general purpose and involves many hashtable lookups for shape, group, etc. With stencil we allocate JSFunction in a single batch and nearly all of them have the same shape/group, so we should precompute the shape/group and add a fast path.

Netflix player code is an example that benefits noticeably from this. We can eliminate about 20% of Stencil instantiation time.

Comment 1

[Ted Campbell [:tcampbell]]

Attachment: Bug 1687602 - Optimize JSFunction allocation in Stencil. r?jandem!

Most parser-generated functions have the same prototype, initial-shape and
group and by caching those values we can speed up JSFunction allocation
significantly.

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/3f090cebbdd2
Optimize JSFunction allocation in Stencil. r=jandem

Comment 3

[Bogdan Tara[:bogdan_tara | bogdant]]

https://hg.mozilla.org/mozilla-central/rev/3f090cebbdd2