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
This makes back pointers in the map transition tree explicit by having
accurate back pointers throughout the lifetime of maps instead of
establishing and destroying back pointers before and after each marking
phase. This is a prerequisite for being able to clear map transitions
during incremental marking.
R=vegorov@chromium.org
BUG=v8:1465
Review URL: https://chromiumcodereview.appspot.com/10381053
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@11528 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This simple refactoring makes it very clear that clearing non-live transitions
actually consists of 2 quite separate things. Things would even be nicer if the
prototype transitions were represented by a separate data structure instead of
reusing FixedArray in an interesting way once again.
As an additional bonus, this CL makes it possible to read each of the methods in
question on a 30" screen without scrolling!
Review URL: https://chromiumcodereview.appspot.com/9169045
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10501 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This refactoring (almost) gets rid of the requirement to get the target
object address for an object pointer embedded in code objects. This is
not possible on MIPS as pointers are encoded using two instructions. All
usages of RelocInfo::target_object_address() are (almost) obsoleted by
this change. The serializer still uses it, so MIPS will not yet work
with snapshots turned on.
R=danno@chromium.org,vegorov@chromium.org
Review URL: http://codereview.chromium.org/8245007
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@9597 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
All slots that were recorded on these objects during incremental marking should be ignored as they are no longer valid.
To filter such invalidated slots out during slots buffers iteration we set all markbits under the invalidated code object to 1 after the code space was swept and before slots buffers are processed.
R=erik.corry@gmail.com
BUG=v8:1713
TEST=test/mjsunit/regress/regress-1713.js
Review URL: http://codereview.chromium.org/7983045
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@9402 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
The "live bytes" count is *really* a "marked black" count - i.e., the count of bytes *known* to be live.
Fix aggravating bug on X64 where assembler code used a value that was off
by a factor of 2^31.
Ensure that sweeping clears live-bytes. Added other missing increments.
Added print statements to trace live-byte modifications, under a flag.
Still a few cases of undercounting left.
(New issue to merge from GC branch to bleeding_edge)
Review URL: http://codereview.chromium.org/7970009
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@9338 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
That could improve chances for commit success as currently,
if we moved free pages out of order, we cannot shrink spaces.
However, when we experience problems commiting from space back, we should
use most of resources at our disposal.
Also get rid of currently unused parameter to DeallocateFunction.
Review URL: http://codereview.chromium.org/3260001
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5372 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
the code object's instructions.
This allows us to find a code object using just the pc. This approach
uses a cache (PcToCodeCache) to make sure we don't continuously have
to iterate heap pages.
This change eliminates the need for cooking and uncooking of stack frames.
Review URL: http://codereview.chromium.org/3226014
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5369 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
- New сardmarking write barrier handles large objects and normal objects in a similar fashion (no more additional space for pointer tracking is required, no conditional branches in WB code).
- Changes to enable oldspaces iteration without maps decoding:
-- layout change for FixedArrays: length is stored as a smis (initial patch by
Kevin Millikin)
-- layout change for SharedFunctionInfo: integer fields are stored as smi on
arm, ia32 and rearranged on x64.
-- layout change for String: meaning of LSB bit is fliped (1 now means hash not
computed); on x64 padding is added.
-- layout of maps is _not_ changed. Map space is currently iterated in a special
way.
Review URL: http://codereview.chromium.org/2144006
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4715 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
-- layout change for FixedArrays: length is stored as a smis (initial patch by Kevin Millikin)
-- layout change for SharedFunctionInfo: integer fields are stored as smi on arm, ia32 and rearranged on x64.
-- layout change for String: meaning of LSB bit is fliped (1 now means hash not computed); on x64 padding is added.
-- layout of maps is _not_ changed. Map space is currently iterated in a special way.
- Cardmarking write barrier. New barrier handles large objects and normal objects in a similar fashion (no more additional space for pointer tracking is required, no conditional branches in WB code).
Review URL: http://codereview.chromium.org/2101002
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4685 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
