Reapplying r5147 (caching maps for slow case objects)....

Reapplying r5147 (caching maps for slow case objects).

r5147 wrongly assumed that a code cache for a slow case map is always empty.
This patch solves this: whenever we attempt to add a stub to a map's code cache 
we check that this map is cached. If it is we give the object its own copy
of the map and only then modify the map.


Committed: http://code.google.com/p/v8/source/detail?r=5342

[antonm, 2010-08-24 12:36:19]

LGTM

http://codereview.chromium.org/3134027/diff/1/9
File src/objects-debug.cc (right):

http://codereview.chromium.org/3134027/diff/1/9#newcode654
src/objects-debug.cc:654: ASSERT(instance_descriptors() ==
Heap::empty_descriptor_array());
minor cosmetic: maybe ASSERT_EQ is better.

http://codereview.chromium.org/3134027/diff/1/11
File src/objects.cc (right):

http://codereview.chromium.org/3134027/diff/1/11#newcode2102
src/objects.cc:2102: // Caching for global objects is not worth it (there too
few of them).
minor: there <are> too few of them

[Vladislav Kaznacheev, 2010-08-24 13:00:21]

http://codereview.chromium.org/3134027/diff/1/9
File src/objects-debug.cc (right):

http://codereview.chromium.org/3134027/diff/1/9#newcode654
src/objects-debug.cc:654: ASSERT(instance_descriptors() ==
Heap::empty_descriptor_array());
On 2010/08/24 12:36:20, antonm wrote:
> minor cosmetic: maybe ASSERT_EQ is better.

Done.

http://codereview.chromium.org/3134027/diff/1/11
File src/objects.cc (right):

http://codereview.chromium.org/3134027/diff/1/11#newcode2102
src/objects.cc:2102: // Caching for global objects is not worth it (there too
few of them).
On 2010/08/24 12:36:20, antonm wrote:
> minor: there <are> too few of them

Done.