1335862 - Implement mayResolve for arguments objects

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect, P2)

Description

[Tom S. (please needinfo tschuster)]

jQuery uses this pattern where they lookup 'nodeType' on everything you pass to it to check if it's a Node. Arguments objects are also used in such a way, but we don't attach property not found IC stubs, because arguments objects have a resolve function, but don't implement mayResolve. This should be an easy perf win.

Comment 1

[Tom S. (please needinfo tschuster)]

Attachment: Implement mayRresolve for arguments

I had a patch for this anyway, and I just saw this as an insignificant problem that showed up on Browsermark.

Comment 2

[Jan de Mooij [:jandem]]

Comment on attachment 8837215 [details] [diff] [review]
Implement mayRresolve for arguments

Review of attachment 8837215 [details] [diff] [review]:
-----------------------------------------------------------------

Good find.

::: js/src/vm/ArgumentsObject.cpp
@@ +436,5 @@
> +        return true;
> +
> +    JSAtom* atom = JSID_TO_ATOM(id);
> +    uint32_t index;
> +    if (atom->isIndex(&index))

obj_resolve actually only checks for JSID_IS_INT, probably because we don't support args length > JSID_INT_MAX/INT32_MAX.

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/b9ee87240799
Implement mayResolve for arguments objects. r=jandem

Comment 4

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/b9ee87240799