In-place trimming of descriptor array when appending callbacks.

In-place trimming of descriptor array when appending callbacks.

Committed: https://code.google.com/p/v8/source/detail?r=12184

[Toon Verwaest, 2012-07-25 10:59:43]

PTAL.

[Michael Starzinger, 2012-07-25 11:09:06]

LGTM (with a few nits).

https://chromiumcodereview.appspot.com/10830005/diff/1/src/objects.cc
File src/objects.cc (right):

https://chromiumcodereview.appspot.com/10830005/diff/1/src/objects.cc#newcode...
src/objects.cc:2109: enum RightTrimPhase { FROM_GC, FROM_MUTATOR };
Let's call that RightTrimMode or something like that.

https://chromiumcodereview.appspot.com/10830005/diff/1/src/objects.cc#newcode...
src/objects.cc:2120: template<RightTrimPhase trim_phase>
Let's call that trim_mode.

https://chromiumcodereview.appspot.com/10830005/diff/1/src/objects.cc#newcode...
src/objects.cc:2221: int new_array_size =
DescriptorArray::SizeFor(new_number_of_descriptors);
Nice catch.

https://chromiumcodereview.appspot.com/10830005/diff/1/src/objects.h
File src/objects.h (right):

https://chromiumcodereview.appspot.com/10830005/diff/1/src/objects.h#newcode4971
src/objects.h:4971: Handle<Object> descriptors);
Empty new-line after the declaration.

[Vyacheslav Egorov (Google), 2012-07-25 12:04:21]

drive by comment

https://chromiumcodereview.appspot.com/10830005/diff/1/src/objects.cc
File src/objects.cc (right):

https://chromiumcodereview.appspot.com/10830005/diff/1/src/objects.cc#newcode...
src/objects.cc:2123: // For now this trick is only applied to fixed arrays in
new and paged space.
this comment makes no sense for trimming from the _right_ (that is from the
end).