922172 - Add redimension method for typed objects

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[Niko Matsakis [:nmatsakis]]

Redimensioning arrays means dividing up the elements in distinct ways (e.g., converting a 10xT array into a 5x2xT array). It is a simpler form of casting that is quite useful for parallelism, and -- unlike going all the way to a byte array -- safe even with object or other reference types. The `redimension()` method is proposed for typed objects spec (though not yet in wiki)

Comment 1

[Niko Matsakis [:nmatsakis]]

Attachment: Bug922172.diff

Comment 2

[Niko Matsakis [:nmatsakis]]

Attachment: Bug922172.diff

Accidentally included old version of patch file.

Comment 3

[Till Schneidereit [:till]]

Comment on attachment 824850 [details] [diff] [review]
Bug922172.diff

Review of attachment 824850 [details] [diff] [review]:
-----------------------------------------------------------------

This is very nice. r=me with nits addressed, a license header added to the test file and a test added for redimensioning an array containing references.

::: js/src/builtin/TypedObject.js
@@ +461,5 @@
> +    newElementType = newElementType.elementType;
> +  }
> +
> +  // Check that the total number of elements does not change.
> +  if (oldElementCount !== newElementCount)

Nit: braces for multiline then content. Here and below.

@@ +463,5 @@
> +
> +  // Check that the total number of elements does not change.
> +  if (oldElementCount !== newElementCount)
> +    ThrowError(JSMSG_TYPEDOBJECT_HANDLE_BAD_ARGS,
> +               1,

Personally, I'd not put this on its own line. Up to you, though.

Comment 4

[Niko Matsakis [:nmatsakis]]

Till -- arrays of references are not supported until bug 898359 lands, but I'll add a test in that case.

Comment 5

[Niko Matsakis [:nmatsakis]]

Or rather, I can add a test as part of that bug.

Comment 6

[Niko Matsakis [:nmatsakis]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/660ff870ffa7

Try run: https://tbpl.mozilla.org/?tree=Try&rev=ad8fccfc779f

Comment 7

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/660ff870ffa7