JavaScriptCore:
2009-06-01 David Levin <[email protected]>
Reviewed by Darin Alder and Maciej Stachowiak.
Bug 26057: StringImpl should share buffers with UString.
https://bugs.webkit.org/show_bug.cgi?id=26057
- JavaScriptCore.exp:
- runtime/UString.cpp:
(JSC::UString::Rep::create):
(JSC::UString::BaseString::sharedBuffer): Only do the sharing when
the buffer exceeds a certain size. The size was tuned by running
various dom benchmarks with numbers ranging from 20 to 800 and finding
a place that seemed to do the best overall.
- runtime/UString.h:
WebCore:
2009-06-01 David Levin <[email protected]>
Reviewed by Darin Alder and Maciej Stachowiak.
Bug 26057: StringImpl should share buffers with UString.
https://bugs.webkit.org/show_bug.cgi?id=26057
This change results in the following performance improvements:
On http://www.hixie.ch/tests/adhoc/perf/dom/artificial/core/001.html
the time went from 78ms to 40ms for append (other times remained constant).
On http://www.hixie.ch/tests/adhoc/perf/dom/artificial/core/002.html,
the time went from 3900ms to 2600ms.
For http://dromaeo.com/?dom, the time for DomModification improved by ~6%.
Other tests in dom seemed to be faster across several runs but within the
margin of error (except DOM Attributes which was slightly ~1.5% worse).
Existing tests cover this code and there is no new functionality
that is exposed to test.
- platform/text/AtomicString.cpp:
(WebCore::AtomicString::add):
- platform/text/String.cpp:
(WebCore::String::String):
(WebCore::String::operator UString):
- platform/text/StringImpl.cpp:
(WebCore::StringImpl::StringImpl):
(WebCore::StringImpl::~StringImpl):
(WebCore::StringImpl::create): Consumes a shared buffer.
(WebCore::StringImpl::ustring): Shares the StringImpl's buffer with the UString.
(WebCore::StringImpl::sharedBuffer): Exposes the buffer that may be shared.
- platform/text/StringImpl.h:
(WebCore::StringImpl::hasTerminatingNullCharacter):
(WebCore::StringImpl::inTable):
(WebCore::StringImpl::setInTable): Converted the bools to be inside of PtrAndFlags
to avoid growing StringImpl in size.
