1349148 - Improve performance of megamorphic stubs

Status: NEW

(Core :: JavaScript Engine: JIT, enhancement, P3)

Description

[Jan de Mooij [:jandem]]

Some random ideas to consider/investigate:

* We could add a 1-entry cache to ShapeTable (both for hits and misses).

* We create a ShapeTable when there are more than 11 entries (ShapeTable::MIN_ENTRIES) but we should measure what the best value is for this nowadays. Since bug 1314569 we can purge ShapeTables on GC so we could be a bit more eager.

* Maybe when the number of entries is small, it would be faster for ShapeTable to store an array of {id, Shape*}.

* We could add a global cache/HashTable to avoid looking at each object on the proto chain.

Comment 1

[Jan de Mooij [:jandem]]

* We should also check how common ShapeTable hash collisions are.

Comment 2

[Sylvestre Ledru [:Sylvestre]]

Moving to p3 because no activity for at least 1 year(s).
See https://github.com/mozilla/bug-handling/blob/master/policy/triage-bugzilla.md#how-do-you-triage for more information

Comment 3

[Denis Palmeiro [:denispal]]

I can do some of these measurements, especially since I have the instrumentation already setup from bug 1384808.