Return descriptor ownership after TrimDescriptorArray to allow resharing of descriptor arrays

Return descriptor ownership after TrimDescriptorArray to allow resharing of descriptor arrays

BUG=None
R=mstarzinger@chromium.org

Committed: http://code.google.com/p/v8/source/detail?r=17237

[rmcilroy, 2013-10-14 17:49:44]

This was an idea Toon had.  It seems to saves ~3KB (every little helps...) on
descriptor arrays for Octane and doesn't cost any performance.

PTAL.

[Michael Starzinger, 2013-10-16 09:34:06]

LGTM after one comment is addressed.

https://codereview.chromium.org/27197002/diff/1/src/objects.cc
File src/objects.cc (right):

https://codereview.chromium.org/27197002/diff/1/src/objects.cc#newcode9250
src/objects.cc:9250: map->set_owns_descriptors(true);
nit: Can we hoist this out of this helper into Map::ClearNonLiveTransitions()?
Otherwise the semantics of TrimDescriptorArray get blurred and it magically does
other things.

[rmcilroy, 2013-10-16 10:44:00]

Thanks Michael. Could you please land for me?

https://codereview.chromium.org/27197002/diff/1/src/objects.cc
File src/objects.cc (right):

https://codereview.chromium.org/27197002/diff/1/src/objects.cc#newcode9250
src/objects.cc:9250: map->set_owns_descriptors(true);
On 2013/10/16 09:34:06, Michael Starzinger wrote:
> nit: Can we hoist this out of this helper into Map::ClearNonLiveTransitions()?
> Otherwise the semantics of TrimDescriptorArray get blurred and it magically
does
> other things.

Makes sense, done.

[Michael Starzinger, 2013-10-16 11:17:44]

Committed patchset #2 manually as r17237 (presubmit successful).

[Michael Starzinger, 2013-10-16 11:18:49]

Landed. Had to make minor adjustments to make it actually compile.

[rmcilroy, 2013-10-16 11:25:30]

On 2013/10/16 11:18:49, Michael Starzinger wrote:
> Landed. Had to make minor adjustments to make it actually compile.

Opps, sorry.  Thanks for making the change.