Function subclasses did not have function properties installed (name, prototype, etc.).
Now when an instance of a Function subclass is created it gets initial map that corresponds
to the language mode of the function body. The language mode dependent maps are cached as
special transitions on initial map of the subclass constructor.
BUG=v8:4597, v8:3101, v8:3330
LOG=Y
Review URL: https://codereview.chromium.org/1510753005
Cr-Commit-Position: refs/heads/master@{#32764}
Reason for revert:
Broken canary. Trying to find out root cause.
Original issue's description:
> Introduce instance type for transition arrays.
>
> The motivation is to allow specialized marking visitor for transition arrays and collect all transition array in a list for post-processing in ClearNonLiveReferences.
>
> BUG=chromium:554488
> LOG=NO
>
> Committed: https://crrev.com/026095a3c7932573e1810b8064ec3008ed696601
> Cr-Commit-Position: refs/heads/master@{#32396}
TBR=mlippautz@chromium.org,jkummerow@chromium.org,ulan@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=chromium:554488
Review URL: https://codereview.chromium.org/1483003002
Cr-Commit-Position: refs/heads/master@{#32404}
The motivation is to allow specialized marking visitor for transition arrays and collect all transition array in a list for post-processing in ClearNonLiveReferences.
BUG=chromium:554488
LOG=NO
Review URL: https://codereview.chromium.org/1480873003
Cr-Commit-Position: refs/heads/master@{#32396}
This enables linter checking for "readability/namespace" violations
during presubmit and instead marks the few known exceptions that we
allow explicitly.
R=bmeurer@chromium.org
Review URL: https://codereview.chromium.org/1371083003
Cr-Commit-Position: refs/heads/master@{#31019}
Original issue: https://codereview.chromium.org/980573002/
Simple transitions are now stored in a map's "transitions" field (as a WeakCell wrapping the target map); full TransitionArrays are used when that's not sufficient.
To encapsulate these storage format implementation details, functions for manipulating and querying transitions have been refactored to be static functions on the TransitionArray class, and take maps as inputs.
Review URL: https://codereview.chromium.org/988703002
Cr-Commit-Position: refs/heads/master@{#27044}
Reason for revert:
x64 test failures
Original issue's description:
> Simplify and compact transitions storage
>
> Simple transitions are now stored in a map's "transitions" field (as a WeakCell wrapping the target map); full TransitionArrays are used when that's not sufficient.
> To encapsulate these storage format implementation details, functions for manipulating and querying transitions have been refactored to be static functions on the TransitionArray class, and take maps as inputs.
>
> Committed: https://crrev.com/45fbef7f2252fce10634931cb103ccc1fc95ae6a
> Cr-Commit-Position: refs/heads/master@{#27029}
TBR=verwaest@chromium.org,ulan@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
Review URL: https://codereview.chromium.org/982143002
Cr-Commit-Position: refs/heads/master@{#27030}
Simple transitions are now stored in a map's "transitions" field (as a WeakCell wrapping the target map); full TransitionArrays are used when that's not sufficient.
To encapsulate these storage format implementation details, functions for manipulating and querying transitions have been refactored to be static functions on the TransitionArray class, and take maps as inputs.
Review URL: https://codereview.chromium.org/980573002
Cr-Commit-Position: refs/heads/master@{#27029}
They both now run fast (due to utilizing transitions instead of always
creating new maps) and sealed or non-extensible objects can stay in
fast mode after transitioning.
This almost entirely reuses the code for transitioning objects
frozen by Object.freeze(), with the added benefit of freeing
up a bit on the map (we no longer keep track of frozen-ness,
as that bit wasn't used for anything interesting).
BUG=v8:3662,chromium:115960
LOG=y
Review URL: https://codereview.chromium.org/776143005
Cr-Commit-Position: refs/heads/master@{#25759}
Revert "Fix for an assertion failure in Map::FindTransitionToField(...). Appeared after r25136."
This revert is made in order to revert r25099 which potentially causes renderer hangs.
R=verwaest@chromium.org
Review URL: https://codereview.chromium.org/722873004
Cr-Commit-Position: refs/heads/master@{#25332}
Each time a transition is added to a hidden class, the whole
transitions array must be copied, which causes poor performance
in some circumstances. This change limits the maximum size of
the transition array, avoiding this behavior in the pathological
case. For example, this improves the performance of the EtchMark
benchmark by nearly 60%.
BUG=v8:3616
LOG=
R=verwaest@chromium.org, svenpanne@chromium.org
Review URL: https://codereview.chromium.org/635883003
Patch from Kevin M. McCormick <mckev@amazon.com>.
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24857 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This is preparatory work for reordering the transition tree. Since elements transitions will be at the root of the transition tree, runtime access to them is slow since we have to walk the transition tree backwards first. Hence remove the optimization that promoted them to a special field, requiring a pointer (mostly NULL) in every non-simple transition array.
R=titzer@chromium.org
Review URL: https://chromiumcodereview.appspot.com/21228002
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15993 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Since symbols and strings share a common representation, most of this change is about consistently replacing 'String' with 'Name' in all places where property names are expected. In particular, no new logic at all is necessary for maps, property dictionaries, or transitions. :) The only places where an actual case distinction is needed have to do with generated type checks, and with conversions of names to strings (especially in logger and profiler).
Left in some TODOs wrt to the API: interceptors and native getters don't accept symbols as property names yet, because that would require extending the external v8.h.
(Baseline CL: https://codereview.chromium.org/12296026/)
R=verwaest@chromium.org,mstarzinger@chromium.org
BUG=v8:2158
Review URL: https://codereview.chromium.org/12330012
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13811 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This CL adds multiple things:
Transition arrays do not directly point at their descriptor array anymore, but rather do so via an indirect pointer (a JSGlobalPropertyCell).
An ownership bit is added to maps indicating whether it owns its own descriptor array or not.
Maps owning a descriptor array can pass on ownership if a transition from that map is generated; but only if the descriptor array stays exactly the same; or if a descriptor is added.
Maps that don't have ownership get ownership back if their direct child to which ownership was passed is cleared in ClearNonLiveTransitions.
To detect which descriptors in an array are valid, each map knows its own NumberOfOwnDescriptors. Since the descriptors are sorted in order of addition, if we search and find a descriptor with index bigger than this number, it is not valid for the given map.
We currently still build up an enumeration cache (although this may disappear). The enumeration cache is always built for the entire descriptor array, even if not all descriptors are owned by the map. Once a descriptor array has an enumeration cache for a given map; this invariant will always be true, even if the descriptor array was extended. The extended array will inherit the enumeration cache from the smaller descriptor array. If a map with more descriptors needs an enumeration cache, it's EnumLength will still be set to invalid, so it will have to recompute the enumeration cache. This new cache will also be valid for smaller maps since they have their own enumlength; and use this to loop over the cache. If the EnumLength is still invalid, but there is already a cache present that is big enough; we just initialize the EnumLength field for the map.
When we apply ClearNonLiveTransitions and descriptor ownership is passed back to a parent map, the descriptor array is trimmed in-place and resorted. At the same time, the enumeration cache is trimmed in-place.
Only transition arrays contain descriptor arrays. If we transition to a map and pass ownership of the descriptor array along, the child map will not store the descriptor array it owns. Rather its parent will keep the pointer. So for every leaf-map, we find the descriptor array by following the back pointer, reading out the transition array, and fetching the descriptor array from the JSGlobalPropertyCell. If a map has a transition array, we fetch it from there. If a map has undefined as its back-pointer and has no transition array; it is considered to have an empty descriptor array.
When we modify properties, we cannot share the descriptor array. To accommodate this, the child map will get its own transition array; even if there are not necessarily any transitions leaving from the child map. This is necessary since it's the only way to store its own descriptor array.
Review URL: https://chromiumcodereview.appspot.com/10909007
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12492 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
The order by name is maintained as secondary order by using unused bits in the property details.
This is preliminary work towards sharing descriptors arrays.
The change allows us
- to get rid of the LastAdded bits in the map, binding it to the number of valid descriptors for the given map
- to avoid resorting by enumeration index to create the cache
- (maybe in the future, depending on performance) to get rid of the enumeration cache altogether.
Although generally the number_of_descriptors equals the NumberOfOwnDescriptors in the current version, this is preliminary work towards sharing descriptors, where maps may have more descriptors than are valid for the map.
Review URL: https://chromiumcodereview.appspot.com/10879013
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12385 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
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
AccessorPair related transitions are now also stored as single map links, simplifying the code that handles transitions. AccessorPairs can now be shared between descriptor arrays, since they can only be mutated after another transition anyway; during which the pair is copied before writing.
Review URL: https://chromiumcodereview.appspot.com/10784014
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12097 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
The LastAdded points to the descriptor that was last added to the array. From the descriptor we can deduce the NextEnumerationIndex. This allows us to quickly find the property that we are transitioning to, which is necessary for transition-intensive code, eg JSON parsing.
Review URL: https://chromiumcodereview.appspot.com/10695120
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12042 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
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
