1172943 - Use unboxed arrays for JSON and script literal arrays

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[Brian Hackett [Laid off!]]

Attachment: patch

It would be good to use unboxed arrays for JSON and script literal arrays (those in a JSOP_OBJECT).  The attached patch makes this change, which is pretty straightforward.  Copy on write arrays in a script are still always boxed.

Comment 1

[Jan de Mooij [:jandem]]

Comment on attachment 8617327 [details] [diff] [review]
patch

Review of attachment 8617327 [details] [diff] [review]:
-----------------------------------------------------------------

::: js/src/jsobj.cpp
@@ -1965,5 @@
>  template bool
>  js::XDRObjectLiteral(XDRState<XDR_DECODE>* xdr, MutableHandleObject obj);
>  
> -JSObject*
> -js::CloneObjectLiteral(JSContext* cx, HandleObject srcObj)

Nice.

::: js/src/vm/NativeObject.h
@@ +932,5 @@
> +            const Value& v = elements_[start + i];
> +            if (v.isObject() && IsInsideNursery(&v.toObject())) {
> +                JS::shadow::Runtime* shadowRuntime = shadowRuntimeFromMainThread();
> +                shadowRuntime->gcStoreBufferPtr()->putSlotFromAnyThread(this, HeapSlot::Element,
> +                                                                        start, count);

Hm you could narrow the range to start at |start + i|. Probably not worth it though.

::: js/src/vm/ObjectGroup.cpp
@@ +733,3 @@
>      {}
>  
> +    ArrayObjectKey(TypeSet::Type type)

Should be |explicit| now.

::: js/src/vm/ObjectGroup.h
@@ +593,5 @@
> +    // have any element type.
> +    static JSObject* newArrayObject(ExclusiveContext* cx, const Value* vp, size_t length,
> +                                    NewObjectKind newKind,
> +                                    bool copyOnWrite = false,
> +                                    bool forRest = false);

I think it'd be nice to use an enum instead of the 2 bools, as forRest and copyOnWrite can't be true at the same time (and then callers don't need the comments).

Comment 2

[Pulsebot]

https://hg.mozilla.org/integration/mozilla-inbound/rev/3a994e364343

Comment 3

[Phil Ringnalda (:philor)]

https://hg.mozilla.org/mozilla-central/rev/3a994e364343