Optimization of some packed array cases.

Optimization of some packed array cases.

R=jkummerow@chromium.org
TEST=slight improvement in 3d-morph

Committed: https://code.google.com/p/v8/source/detail?r=11777

[Jakob Kummerow, 2012-06-12 12:50:43]

LGTM.

I don't like how CopySmiToDoubleElements(), CopyPackedSmiToDoubleElements() and
CopyObjectToDoubleElements() share what feels like 90% of their code, but their
differences are such that I don't see an element way to unify them more :-/

https://chromiumcodereview.appspot.com/10538104/diff/5001/src/elements.cc
File src/elements.cc (right):

https://chromiumcodereview.appspot.com/10538104/diff/5001/src/elements.cc#new...
src/elements.cc:379: to_end = to_start + copy_size;
I have a suspicion that the Windows compiler might wish for a
static_cast<uint32_t>(copy_size) here (and again below).

https://chromiumcodereview.appspot.com/10538104/diff/5001/src/elements.cc#new...
src/elements.cc:425: if (hole_or_object == the_hole) {
Why this change? Is it faster?

https://chromiumcodereview.appspot.com/10538104/diff/5001/src/elements.cc#new...
src/elements.cc:625: bool is_packed = FLAG_packed_arrays &&
Another unnecessary FLAG check.

https://chromiumcodereview.appspot.com/10538104/diff/5001/src/objects.cc
File src/objects.cc (right):

https://chromiumcodereview.appspot.com/10538104/diff/5001/src/objects.cc#newc...
src/objects.cc:10026: if (FLAG_packed_arrays && IsJSArray()) {
This flag check isn't necessary, as we can't have PACKED elements kinds without
the flag anyway. Same below.

[danno, 2012-06-12 15:38:14]

landed

http://codereview.chromium.org/10538104/diff/5001/src/elements.cc
File src/elements.cc (right):

http://codereview.chromium.org/10538104/diff/5001/src/elements.cc#newcode379
src/elements.cc:379: to_end = to_start + copy_size;
On 2012/06/12 12:50:44, Jakob wrote:
> I have a suspicion that the Windows compiler might wish for a
> static_cast<uint32_t>(copy_size) here (and again below).

Done.

http://codereview.chromium.org/10538104/diff/5001/src/elements.cc#newcode425
src/elements.cc:425: if (hole_or_object == the_hole) {
Yes :-) 
On 2012/06/12 12:50:44, Jakob wrote:
> Why this change? Is it faster?

http://codereview.chromium.org/10538104/diff/5001/src/elements.cc#newcode625
src/elements.cc:625: bool is_packed = FLAG_packed_arrays &&
On 2012/06/12 12:50:44, Jakob wrote:
> Another unnecessary FLAG check.

Done.

http://codereview.chromium.org/10538104/diff/5001/src/objects.cc
File src/objects.cc (right):

http://codereview.chromium.org/10538104/diff/5001/src/objects.cc#newcode10026
src/objects.cc:10026: if (FLAG_packed_arrays && IsJSArray()) {
On 2012/06/12 12:50:44, Jakob wrote:
> This flag check isn't necessary, as we can't have PACKED elements kinds
without
> the flag anyway. Same below.

Done.