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123 Commits

Author SHA1 Message Date
titzer@chromium.org
35490d82a9 Add OptimizedCodeList and DeoptimizedCodeList to native contexts. Both lists are weak. This makes it possible to find optimized code that is not referred to by any function, but still needs to be deoptimized. It obsoletes the weak deoptimizing code list in the deoptimizer data and generally simplifies the process of deoptimizing code. 
BUG=
R=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/23444029

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16530 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2013-09-04 13:53:24 +00:00
verwaest@chromium.org
04b5e7fa63 Replace HCheckPrototypeMaps by explicit map checks of constant values. 
R=danno@chromium.org

Review URL: https://chromiumcodereview.appspot.com/21065006

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16055 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2013-08-05 13:45:16 +00:00
hpayer@chromium.org
2bd5405dc2 Free slots buffer entries when tearing down the heap. 
BUG=
R=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/21216003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15973 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2013-07-31 07:17:03 +00:00
titzer@chromium.org
f612a29f8c Factor out common code from platform-specific deoptimization. Fix Deoptimizer not to need to partition functions, but revoke their code before patching, allowing deoptimizing_code_list to be removed from Code; Add DeoptimizeCodeList API to deoptimizer, which works on a ZoneList<Code*>. 
BUG=
R=mstarzinger@chromium.org, ulan@chromium.org

Review URL: https://codereview.chromium.org/19638014

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15854 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2013-07-24 11:12:17 +00:00
mstarzinger@chromium.org
ce81b0d3a8 ES6: Implement WeakSet 
WeakSets work similar to ordinary Sets but the value (which must be an
object) is held weakly.

This is available under --harmony-collections

BUG=v8:2785
R=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/19678023

Patch from Erik Arvidsson <arv@chromium.org>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15792 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2013-07-22 08:32:24 +00:00
hpayer@chromium.org
a3b856008b Use private field chunk_ 
R=hpayer@chromium.org

Review URL: https://codereview.chromium.org/19495002

Patch from HaiTao Feng <haitao.feng@intel.com>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15709 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2013-07-17 09:57:56 +00:00
hpayer@chromium.org
147163fc41 Added mark bit cell iterator. 
BUG=
R=mstarzinger@chromium.org, titzer@chromium.org

Review URL: https://codereview.chromium.org/19182002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15691 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2013-07-16 12:14:16 +00:00
hpayer@chromium.org
fba07ddd23 Perform new space evacuation based on marking bits. 
BUG=
R=titzer@chromium.org

Review URL: https://codereview.chromium.org/18531004

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15621 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2013-07-11 11:24:38 +00:00
ulan@chromium.org
74d147a25d Enable weak embedded maps in optimized code. 
If the top optimized code in call stack is at the point that does not support
deoptimization, then treat the maps in the code as strong pointers.

Note that other optimized code in call stack must support deoptimization
because of the call instruction with side-effects.

BUG=217858,v8:2073
R=mstarzinger@chromium.org

Review URL: https://chromiumcodereview.appspot.com/16955008

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15452 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2013-07-02 15:15:58 +00:00
danno@chromium.org
00709075ea Add DependentCode to PropertyCells 
R=mstarzinger@chromium.org, ulan@chromium.org

Review URL: https://codereview.chromium.org/17895004

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15341 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2013-06-26 16:17:12 +00:00
mstarzinger@chromium.org
b632a4be86 Deprecate one virtual marking visitor for mark-compact GC. 
R=hpayer@google.com

Review URL: https://codereview.chromium.org/17546005

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15286 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2013-06-24 12:39:02 +00:00
mstarzinger@chromium.org
be243df7ca Prevent excessive processing of weak maps while marking. 
This makes sure processing of Harmony weak maps is only triggerd twice
during a mark-compact collection. Note that the processing itself still
is a fix-point iteration with quadratic worst-case time.

R=hpayer@chromium.org
BUG=v8:2699

Review URL: https://codereview.chromium.org/16286018

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@14940 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2013-06-04 17:20:06 +00:00
mstarzinger@chromium.org
365b2eb91e Preserve optimized code map during GCs weakly. 
This change preserves the contents of optimized code maps during GCs but
treats the references in this cache weakly. It uses infrastructure from
code flushing to maintain a list of all caches.

R=hpayer@chromium.org

Review URL: https://codereview.chromium.org/14794007

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@14695 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2013-05-15 16:09:25 +00:00
svenpanne@chromium.org
e4e4447305 Pass Isolates explicitly in Deoptimizer-related code. 
Removed a few ancient useless ASSERTs on the way. Reduced the number of train wrecks.

BUG=v8:2487

Review URL: https://codereview.chromium.org/12917002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13965 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2013-03-18 13:57:49 +00:00
hpayer@chromium.org
fffadaf9ba Unlink evacuation candidates from list of pages before starting sweeper threads. 
Removed FinalizeSweeping().

BUG=

Review URL: https://codereview.chromium.org/12499004

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13886 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2013-03-08 14:41:21 +00:00
hpayer@chromium.org
80195113ab Wait for sweeper threads in EnsureSweeperProgress() only if the main thread finished its sweeping phase. 
BUG=

Review URL: https://codereview.chromium.org/12462002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13830 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2013-03-05 17:32:02 +00:00
mstarzinger@chromium.org
24abac9f02 Remove obsolete CodeFlusher debug code. 
R=hpayer@chromium.org

Review URL: https://codereview.chromium.org/12456002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13826 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2013-03-05 16:08:11 +00:00
rossberg@chromium.org
55f93b5532 Renamed "symbols" to "internalized strings" throughout the code base, 
in preparation of the introduction of ES6 'symbols' (aka private/unique names).

The SymbolTable became the StringTable. I also made sure to adapt all comments. The only remaining use of the term "symbol" (other than unrelated uses in the parser and such) is now 'NewSymbol' in the API and the 'V8.KeyedLoadGenericSymbol' counter, changing which might break embedders.

The one functional change in this CL is that I removed the former 'empty_string' constant, since it is redundant given the 'empty_symbol' constant that we also had (and both were used inconsistently).

R=yangguo@chromium.org
BUG=

Review URL: https://codereview.chromium.org/12210083

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13781 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2013-02-28 17:03:34 +00:00
svenpanne@chromium.org
54b4b1ecc2 Forced inlining of some GC-related methods. 
The selection of methods were driven by GCC's -Winline plus some benchmarking.
On ia32, the additional amount of code is roughly 63kB (= 0.07% of Chrome ;-).

BUG=v8:1607

Review URL: https://codereview.chromium.org/12338002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13710 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2013-02-21 14:02:52 +00:00
hpayer@chromium.org
ab3114df68 Release evacuation candidates after parallel sweeper threads completed. 
BUG=

Review URL: https://codereview.chromium.org/12082101

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13708 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2013-02-21 13:12:12 +00:00
ulan@chromium.org
3a1eca4242 Remove prototype checks for leaf maps in optimized code. 
Review URL: https://chromiumcodereview.appspot.com/12225099

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13697 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2013-02-20 11:49:54 +00:00
hpayer@chromium.org
37d88cca4e Move sweeping pending status field of concurrent sweepers to MarkCompactCollector. 
BUG=

Review URL: https://codereview.chromium.org/12261011

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13661 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2013-02-13 15:21:08 +00:00
hpayer@chromium.org
492396f2ab Fixed IsSweepingComplete and EnsureSweeperProgress helper functions. 
BUG=

Review URL: https://codereview.chromium.org/12177017

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13596 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2013-02-05 15:48:59 +00:00
ulan@chromium.org
744d61ebe7 Fix clearing of dead dependent codes and verify weak embedded maps on full GC. 
BUG=172488,172489
R=mstarzinger@chromium.org

Review URL: https://chromiumcodereview.appspot.com/12094036

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13584 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2013-02-04 10:56:50 +00:00
hpayer@chromium.org
7fe9f3b05c Added parallel marking threads. 
BUG=

Review URL: https://codereview.chromium.org/12047044

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13569 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2013-01-31 14:23:36 +00:00
hpayer@chromium.org
44caabb1cd Parallel and concurrent sweeping. 
Sweep old pointer space and old data space concurrently to the main mutator thread and in parallel.

BUG=

Review URL: https://codereview.chromium.org/11782028

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13552 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2013-01-30 12:19:32 +00:00
ulan@chromium.org
e6224d275f Make embedded maps in optimized code weak. 
Each map has a weak array of dependent codes, where the map tracks all the optimized codes that embed it.
Old space GC either clears the dead dependent codes from the array if the corresponding map is alive or deoptimizes the live dependent codes if the map is dead.

BUG=v8:2073
R=mstarzinger@chromium.org

Review URL: https://chromiumcodereview.appspot.com/11575007

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13490 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2013-01-24 11:55:05 +00:00
mstarzinger@chromium.org
90ec61152c Add sanity check to CodeFlusher::AddCandidate. 
R=hpayer@chromium.org
BUG=chromium:169209

Review URL: https://codereview.chromium.org/11887031

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13380 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2013-01-15 10:00:48 +00:00
mstarzinger@chromium.org
b93b2b98b8 Fix shared function info code replacement. 
This fixes a corner case when the unoptimized code for a shared function
info is replaced while the function is enqueued as a flushing candidate.
Since the link field is stored within the code object, the candidates
list got destroyed.

R=hpayer@chromium.org
BUG=v8:169209
TEST=cctest/test-heap/Regress169209

Review URL: https://codereview.chromium.org/11818052

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13361 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2013-01-11 13:13:11 +00:00
mstarzinger@chromium.org
a4c4862ed8 Unify object groups iteration in global handles. 
This unifies the iteration logic of objects groups iteration in global
handles. The scavenger as well as mark-and-compact now rely on the same
underlying logic.

R=ulan@chromium.org

Review URL: https://codereview.chromium.org/11299248

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13128 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2012-12-04 10:23:43 +00:00
mstarzinger@chromium.org
3b291a0f48 Fix incremental marking to be off during heap snapshots. 
The heap snapshot generator uses the UnreachableObjectsFilter which in
turn messes with marking bits. This requires incremental marking to be
turned off while the snapshot is being generated.

R=verwaest@chromium.org
TEST=cctest/test-heap-profiler --stress-compaction

Review URL: https://codereview.chromium.org/11413183

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13066 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2012-11-27 13:18:55 +00:00
danno@chromium.org
bd4e114b8e Add code again to allow reclaiming old unexecuted functions. 
When code objects in the heap for FUNCTIONs and OPTIMIZED_FUNCTIONs are marked by the GC, their prologue is patched with a call to a stub that removes the patch. This allows the collector to quickly identify code objects that haven't been executed since the last full collection (they are the ones that sill contain the patch). The functionality is currently disabled, but can be activated by specifying the "--age-code".

R=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/10837037

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12898 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2012-11-08 12:18:11 +00:00
mstarzinger@chromium.org
8e7ae24b40 Fix disabling of code flusher while marking. 
This fixes a corner case when the code flusher is disabled while
incremental marking is running. The list of candidates needs to be
evicted to prevent list fragments without a head floating around.

R=ulan@chromium.org
BUG=chromium:159140

Review URL: https://codereview.chromium.org/11366136

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12894 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2012-11-08 10:26:50 +00:00
mstarzinger@chromium.org
014f00fa51 Fix code flusher to process weak function links. 
This fixes a corner case where weak function links of the code flushing
candidates list were destroyed by scavenges that happened during
incremental marking. Now those weak function links are updated while
scavenging happens.

R=ulan@chromium.org
TEST=cctest/test-heap/TestCodeFlushingIncrementalScavenge

Review URL: https://codereview.chromium.org/11271006

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12825 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2012-10-26 09:44:34 +00:00
mstarzinger@chromium.org
cee59bf522 Enable incremental code flushing. 
This enables code flushing even with incremental marking enabled and
fully shares the function link field in JSFunctions between candidates
for code flushing and the optimized functions list. If a candidate for
code flushing gets optimized, it will be evicted from the candidates
list.

R=ulan@chromium.org
BUG=v8:1609

Review URL: https://codereview.chromium.org/11140025

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12796 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2012-10-23 08:25:04 +00:00
mstarzinger@chromium.org
d9e3d35c07 Switch code flushing to use different JSFunction field. 
This is another preparation for incremental code flushing. Instead of
linking candidates using the code entry field, we use the next pointer
that is also used to link optimized functions together. Since we only
support flushing of unoptimized code, this field can be shared.

R=ulan@chromium.org
BUG=v8:1609

Review URL: https://codereview.chromium.org/11141023

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12734 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2012-10-15 14:43:57 +00:00
mstarzinger@chromium.org
bf85da7441 Move code flushing support into shared visitor. 
This is a first step towards incremental code flushing. The code
flushing support is now shared between full and incremental marking.
The code flusher itself is not yet activated in incremental mode and
will require some additional adaptations.

R=ulan@chromium.org
BUG=v8:1609

Review URL: https://codereview.chromium.org/11028016

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12714 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2012-10-12 12:41:29 +00:00
mvstanton@chromium.org
b3c0ed8245 Enable --verify-heap in release mode 
R=mstarzinger@chromium.org
BUG=v8:2120

Review URL: https://codereview.chromium.org/11118018

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12713 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2012-10-12 11:41:14 +00:00
verwaest@chromium.org
6e1bafc808 Revert "Allow partial scanning of large arrays in order to avoid" 
This reverts commit r12619.

BUG=

Review URL: https://chromiumcodereview.appspot.com/11029023

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12660 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2012-10-04 11:09:17 +00:00
mstarzinger@chromium.org
739c9f6f01 Fix slot recording of code target patches. 
This makes sure that we only record relocation slots for code target
patches that happen in marked objects. Unmarked ones might be visited
again, whereas marked ones are alive and will not be visited again.

R=ulan@chromium.org
BUG=chromium:152615,chromium:144230

Review URL: https://codereview.chromium.org/11040021

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12655 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2012-10-02 15:46:55 +00:00
erik.corry@gmail.com
aba09dcf2e Allow partial scanning of large arrays in order to avoid 
mark stack overflow.  This is a reland of r12609 -
https://chromiumcodereview.appspot.com/10959011 - but
this time VisitPointers has been fixed (it used to assume
that the first slot was on the first page of a large object).
Review URL: https://chromiumcodereview.appspot.com/10996018

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12619 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2012-09-26 12:17:24 +00:00
erik.corry@gmail.com
5547815daf Revert 12609 (Allow partial scanning of large arrays) 
due to crashes in unbox-double-arrays.js test.
Review URL: https://chromiumcodereview.appspot.com/10996017

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12610 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2012-09-26 08:55:19 +00:00
erik.corry@gmail.com
a54e007a95 Allow partial scanning of large arrays in order to avoid 
mark stack overflow.
Review URL: https://chromiumcodereview.appspot.com/10959011

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12609 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2012-09-26 08:33:15 +00:00
mstarzinger@chromium.org
3018b875b1 Integrate map marking into static marking visitor. 
This refactors the specialized marking of map contents to be done by the
static marking visitor shared between full and incremental marking. This
also fixes an issue where some maps weren't accounted for in the object
stats tracker. But more importantly, it simplifies the code base.

R=verwaest@chromium.org

Review URL: https://codereview.chromium.org/10919294

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12526 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2012-09-17 10:04:39 +00:00
erik.corry@gmail.com
1987542825 Fix invariant so that we cannot record relocation slots for 
white objects when compacting.  Add flag for incremental code
compaction.
Review URL: https://chromiumcodereview.appspot.com/10907174

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12483 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2012-09-11 14:01:39 +00:00
verwaest@chromium.org
d53de0590a Swapped transition array and descriptor array. 
Now a map points to a transition array which contains the descriptor array. The descriptor array is now immutable. The next step is to share the descriptor array with all back-pointed maps as long as there is a single line of extension. Maps that require a descriptor array but don't need transitions will still need a pseudo-empty transition array to contain the descriptor array.

Review URL: https://chromiumcodereview.appspot.com/10816005

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12298 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2012-08-13 08:43:16 +00:00
mstarzinger@chromium.org
81a43b5607 Make incremental marking clear ICs. 
This extends the existing clearing of ICs during GC to incremental
marking in order to prevent cross-context retention that would last
until the next non-incremental GC.

R=erik.corry@gmail.com
TEST=cctest/test-heap/IncrementalMarkingClears[Mono,Poly]morhpicIC

Review URL: https://chromiumcodereview.appspot.com/10831123

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12259 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2012-08-06 10:35:48 +00:00
mstarzinger@chromium.org
abede994d9 Refactor incremental marking to use static visitor. 
This is a refactoring only change that switches incremental marking to
use a static object visitor. It also shares the common code between the
non-incremental and the incremental marker. Sharing that would require
semantical changes will be done later.

R=verwaest@chromium.org

Review URL: https://chromiumcodereview.appspot.com/10816007

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12193 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2012-07-25 15:23:07 +00:00
verwaest@chromium.org
26afeb6ea5 Don't record elements transition slots since it will contain a map. 
Additionally removed unused code.

Review URL: https://chromiumcodereview.appspot.com/10802039

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12150 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2012-07-20 07:24:50 +00:00
verwaest@chromium.org
d7a5b7d5e2 Separating transitions from descriptors. 
In this design maps contain descriptor arrays, which in turn can contain transition arrays. If transitions are needed when no descriptor array is present, a descriptor array without real descriptors is inserted just so it can point at the transition array.

The transition array does not contain details about the field it transitions to. In order to weed out transitions to FIELDs from CONSTANT_FUNCTION (what used to be MAP_TRANSITION vs CONSTANT_TRANSITION), the transition needs to be followed and the details need to be looked up in the target map. CALLBACKS transitions are still easy to recognize since the transition targets are stored as an AccessorPair containing the maps, rather than the maps directly.

Currently AccessorPairs containing a transition and an accessor are shared between the descriptor array and the transition array. This simplifies lookup since we only have to look in one of both arrays. This will change in subsequent revisions, when descriptor arrays will become shared between multiple maps, since transitions cannot be shared.

Review URL: https://chromiumcodereview.appspot.com/10697015

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@11994 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
 2012-07-05 13:54:20 +00:00