JSArray::shiftCountWith* could be more efficient
https://bugs.webkit.org/show_bug.cgi?id=133011
Reviewed by Geoffrey Garen.
Source/JavaScriptCore:
Our current implementations of shiftCountWithAnyIndexingType and shiftCountWithArrayStorage
are scared of the presence of any holes in the array. We can mitigate this somewhat by enabling
them to correctly handle holes, thus avoiding the slowest of slow paths in most cases.
* runtime/ArrayStorage.h:
(JSC::ArrayStorage::indexingHeader):
(JSC::ArrayStorage::length):
(JSC::ArrayStorage::hasHoles):
* runtime/IndexingHeader.h:
(JSC::IndexingHeader::publicLength):
(JSC::IndexingHeader::from):
* runtime/JSArray.cpp:
(JSC::JSArray::shiftCountWithArrayStorage):
(JSC::JSArray::shiftCountWithAnyIndexingType):
(JSC::JSArray::unshiftCountWithArrayStorage):
* runtime/JSArray.h:
(JSC::JSArray::shiftCountForShift):
(JSC::JSArray::shiftCountForSplice):
(JSC::JSArray::shiftCount):
* runtime/Structure.cpp:
(JSC::Structure::holesRequireSpecialBehavior):
* runtime/Structure.h:
LayoutTests:
Added a performance regression test which tests the contiguous shift case. We're ~85% faster
on this microbenchmark with this patch.
Also added a bunch of tests for each permutation of contiguous/array storage with no holes, holes,
and holes that require special behavior (e.g. indexed properties in the prototype chain).
* js/array-storage-splice-holes-expected.txt: Added.
* js/array-storage-splice-holes-require-special-behavior-expected.txt: Added.
* js/array-storage-splice-holes-require-special-behavior.html: Added.
* js/array-storage-splice-holes.html: Added.
* js/array-storage-splice-no-holes-expected.txt: Added.
* js/array-storage-splice-no-holes.html: Added.
* js/contiguous-splice-holes-expected.txt: Added.
* js/contiguous-splice-holes-require-special-behavior-expected.txt: Added.
* js/contiguous-splice-holes-require-special-behavior.html: Added.
* js/contiguous-splice-holes.html: Added.
* js/contiguous-splice-no-holes-expected.txt: Added.
* js/contiguous-splice-no-holes.html: Added.
* js/regress/array-splice-contiguous-expected.txt: Added.
* js/regress/array-splice-contiguous.html: Added.
* js/regress/script-tests/array-splice-contiguous.js: Added.
(foo):
* js/script-tests/array-storage-splice-holes-require-special-behavior.js: Added.
* js/script-tests/array-storage-splice-holes.js: Added.
* js/script-tests/array-storage-splice-no-holes.js: Added.
* js/script-tests/contiguous-splice-holes-require-special-behavior.js: Added.
* js/script-tests/contiguous-splice-holes.js: Added.
* js/script-tests/contiguous-splice-no-holes.js: Added.
git-svn-id: http://svn.webkit.org/repository/webkit/trunk@169121 268f45cc-cd09-0410-ab3c-d52691b4dbfc
29 files changed
