The number of inobject properties used to be derived from the number
of this property assignments in the constructor (and increased by 2 to
allow for properties added later). This very often leads to wasted inobject
slots.
This patch reclaims some of the unused inobject space by the following method:
- for each constructor function the first several objects are allocated using the initial
("generous) instance size estimation (this is called 'tracking phase').
- during the tracking phase map transitions are tracked and actual property counts are collected.
- at the end of the tracking phase instance sizes in the maps are decreased if necessary
(starting with the function's initial map and traversing the transition tree).
- all further allocation use more realistic instance size estimation.
Shrinking generously allocated objects without costly heap traversal is made possible
by initializing their inobject properties with one_pointer_filler_map (instead of undefined).
The initial slack for the generous allocation is increased from 2 to 6 which really helps some tests.
Review URL: http://codereview.chromium.org/3329019
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5510 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
The collector class automatically expands to hold the values added to it,
like a List, but doesn't ensure that the backing store is contiguous, which
allows it to avoid copying back and forth as the buffer grows.
This is in preparation for identifyng identical symbols during preparsing.
Review URL: http://codereview.chromium.org/3181036
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5325 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Object model changes
----------------------------------------
New fixed_cow_array_map is used for the elements array of a JSObject
to mark it as COW. The JSObject's map and other fields are not
affected. The JSObject's map still has the "fast elements" bit set. It
means we can do only the receiver map check in keyed loads and the
receiver and the elements map checks in keyed stores. So introducing
COW arrays doesn't hurt performance of these operations. But note that
the elements map check is necessary in all mutating operations because
the "has fast elements" bit now means "has fast elements for reading".
EnsureWritableFastElements can be used in runtime functions to perform
the necessary lazy copying.
Generated code changes
----------------------------------------
Generic keyed load is updated to only do the receiver map check (this
could have been done earlier). FastCloneShallowArrayStub now has two
modes: clone elements and use COW elements. AssertFastElements macro
is added to check the elements when necessary. The custom call IC
generators for Array.prototype.{push,pop} are updated to avoid going
to the slow case (and patching the IC) when calling the builtin should
work.
COW enablement
----------------------------------------
Currently we only put shallow and simple literal arrays in the COW
mode. This is done by the parser.
Review URL: http://codereview.chromium.org/3144002
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5275 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
in allowing more flexible compilation and to simplify builtins lookup.
This changes a number of places where code objects are assigned to
SharedFunctionInfo objects to also assign this code object to the
JSFunction. In addition, the code flushing is changed slightly to
accomodate this (we need to flush the code from functions pointing to
SharedFunctionInfo objects that has already been flushed).
Review URL: http://codereview.chromium.org/3120006
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5233 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Please note that we do not implement correctly the setting of caller
and arguments on the returned objects, since we already have these
properties on function objects (and they are non-configurable).
Also corrects indention in DefineOwnProperty.
Review URL: http://codereview.chromium.org/3046010
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5124 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
The caching code used to require that all keys in the literal were symbol strings
in order to be able to cache object literal maps.
Relaxed this requirement to allow array indices as well (as in { "1": "one", two: "two" }).
Changed the way 'number_of_properties' is calculated so that redundant property slots are not
allocated for array indices.
Review URL: http://codereview.chromium.org/2858064
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5114 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
The static ScopeInfo members moved into this class.
The new class is named ScopeInfoObject which I am not proud of,
better ideas are very welcome.
Also got rid of the sentinels in the serialized scope info which saves 3 words per function
and is not slower.
Review URL: http://codereview.chromium.org/2908009
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5067 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
to the runtime will both patch in the more specialized binary op
stub and calculate the answer. This eliminates the need to call
both the rest of the binary op and the patching runtime call. The
runtime routines are altered to be more agressive in returning
Smis so we don't get spurious heap numbers as inputs to binary ops
while we are patching the binary op ICs.
Review URL: http://codereview.chromium.org/2843049
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5026 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
A potential issue with this change is creating lots of maps when
objects flip between fast/slow elements modes. We could add special
transitions to avoid this. Yet testing this on our benchmarks, gmail,
and wave seems to indicate that this is not a real problem.
Review URL: http://codereview.chromium.org/2870018
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4941 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
If a two-byte string only contains ascii characters, then we can save
memory when flattening a cons string containing it. Similarly we can
use this in Array.prototype.join implementation. To track this a new
bit is added to instance type. This bit is used as a hint in generated
code and in runtime functions.
To enable testing a new V8 extension is added controlled by
--expose-externalize-string flag.
Review URL: http://codereview.chromium.org/2762008
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4894 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
With the change in r4820 all return statements are now breakable like any statement, so stepping will stop before the return statement actually returning from a function. With this change the position when breaking in the function return (after executing the return statement) will be the actual end of the function. At this point the return value is available as it saved to the stack by the debug break at return handling. Added information on the actual value returned from the function to the debugger.
Review URL: http://codereview.chromium.org/2783002
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4835 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
perform a context lookup in the runtime system for the 'eval'
function. Instead load the 'eval' function from the global context in
generated code if it is not shadowed.
Will port to other platforms as a separate change.
Review URL: http://codereview.chromium.org/2666001
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4794 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This fix adds support for retriving a property descriptor on elements. The
new version supports both fast and slow case elements. In the fast case
we always default configurable, writable, enumerable to true (we don't have
PropertyDetails for fast elements).
A few new tests are added to get-own-property-descriptor.js, I will
add a lot more to object-define-property when I add support for indices in
Object.defineProperty.
Review URL: http://codereview.chromium.org/2278002
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4738 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
NumberToUint32 that I was trying to use maps -0 to +0 (as desired) but
also maps +/-Infinity to +0, which made +/-Infinity a valid string
index. I fixed it by introducing a new runtime function with the right
semantics.
TEST=LayoutTests/fast/js/char-at.html,mjsunit/string-charat.js
Review URL: http://codereview.chromium.org/2223003
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4734 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
registration of external references in Proxy objects).
I moved the declaration of the two functions to stub-cache.h
because with all the types they use it's hard to declare them
anywhere else. But the actual definition is still in runtime.cc
near to the place where they are used.
Review URL: http://codereview.chromium.org/1079012
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4231 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
