Jan de Mooij [:jandem] Assignee
	Description • 9 years ago

Right now in ArgumentsObject::create, we have to do two lookups for the initial shape and the ObjectGroup. This is slow.

This patch stores a weak pointer to a template object for normal and strict arguments objects in JSCompartment. Then when we allocate an arguments object we can avoid the shape/group lookup if the compartment has a template object.

It improves the micro-benchmark in bug 1175466 from 172 ms to 98 ms (on top of the patch in that bug).

	Brian Hackett [Laid off!]
	Comment 1 • 9 years ago

Comment on attachment 8623659 [details] [diff] [review]
Patch

Review of attachment 8623659 [details] [diff] [review]:
-----------------------------------------------------------------

::: js/src/vm/ArgumentsObject.cpp
@@ +184,5 @@
> +
> +ArgumentsObject*
> +JSCompartment::getOrCreateArgumentsTemplateObject(JSContext* cx, bool strict)
> +{
> +    ArgumentsObject* obj = strict ? strictArgumentsTemplate_ : normalArgumentsTemplate_;

If this was a ReadBarriered<ArgumentsObject*>& you could avoid the second branch on |strict| below I think.

	Pulsebot
	Comment 2 • 9 years ago

https://hg.mozilla.org/integration/mozilla-inbound/rev/bdbeef387598

	Phil Ringnalda (:philor)
	Comment 3 • 9 years ago

https://hg.mozilla.org/mozilla-central/rev/bdbeef387598