Use generic array functions to setup the boilerplate to avoid logic duplication.

Use generic array functions to setup the boilerplate to avoid logic duplication.

Committed: https://code.google.com/p/v8/source/detail?r=13097

[Toon Verwaest, 2012-11-27 08:57:09]

PTAL

[danno, 2012-11-27 09:03:57]

Be careful with the performance of this. You've made parsing large array
literals much slower, please verify that you don't see a negative impact on the
Kraken benchmarks that have very large initial data sets declared in an array
literal.

https://codereview.chromium.org/11361281/diff/4001/src/parser.cc
File src/parser.cc (right):

https://codereview.chromium.org/11361281/diff/4001/src/parser.cc#newcode3726
src/parser.cc:3726: bool is_holey = false;
Can't you automatically track holiness through SetOwnElement? If you skip an
element, the array's elements kind should become holey.

https://codereview.chromium.org/11361281/diff/4001/src/parser.cc#newcode3739
src/parser.cc:3739: } else if (!boilerplate_value->IsTheHole()) {
You already know !boilerplate_value->IsTheHole() is true, since you checked
above.

https://codereview.chromium.org/11361281/diff/4001/src/parser.cc#newcode3758
src/parser.cc:3758: kind = is_holey ? GetHoleyElementsKind(kind) :
GetPackedElementsKind(kind);
Shouldn't be necessary, see above.

[Toon Verwaest, 2012-11-27 10:02:39]

I verified performance previously. Except for the usual flakes, it actually
slightly improves stanford-crypto-ccm; so probably there was a slight
inconsistency in previous parsing of int/double arrays.

https://codereview.chromium.org/11361281/diff/4001/src/parser.cc
File src/parser.cc (right):

https://codereview.chromium.org/11361281/diff/4001/src/parser.cc#newcode3726
src/parser.cc:3726: bool is_holey = false;
The reason is that I preallocate the full backing store. To do this properly, I
need to also set the length already. Otherwise, the conversion from smi to
double, or double to object, may cause the array to go into dictionary mode
since it looks sparse (when a large part of the array isn't filled in yet). Of
course, when I set the length to something larger than the values already
present, the type has to be HOLEY. Hence I have to keep track of holeyness by
hand.

On 2012/11/27 09:03:57, danno wrote:
> Can't you automatically track holiness through SetOwnElement? If you skip an
> element, the array's elements kind should become holey.

https://codereview.chromium.org/11361281/diff/4001/src/parser.cc#newcode3739
src/parser.cc:3739: } else if (!boilerplate_value->IsTheHole()) {
On 2012/11/27 09:03:57, danno wrote:
> You already know !boilerplate_value->IsTheHole() is true, since you checked
> above.

Done.

https://codereview.chromium.org/11361281/diff/4001/src/parser.cc#newcode3758
src/parser.cc:3758: kind = is_holey ? GetHoleyElementsKind(kind) :
GetPackedElementsKind(kind);
Unfortunately it is...

On 2012/11/27 09:03:57, danno wrote:
> Shouldn't be necessary, see above.

[danno, 2012-11-29 15:34:57]

lgtm