+2011-01-28 Eric Seidel <eric@webkit.org>
+
+ Reviewed by Darin Adler.
+
+ HTML5 TreeBuilder regressed a Peacekeeper DOM test by 40%
+ https://bugs.webkit.org/show_bug.cgi?id=48719
+
+ It's unclear exactly what the Peacekeeper benchmark is testing,
+ because I haven't found a way to run it myself.
+
+ However, I constructed a benchmark which shows at least one possible slow point.
+ The HTML5 spec talks about creating a new document for every time we use
+ the fragment parsing algorithm. Document() it turns out, it a huge bloated
+ mess, and the constructor and destructor do a huge amount of work.
+ To avoid constructing (or destructing) documents for each innerHTML call,
+ this patch adds a shared dummy document used by all innerHTML calls.
+
+ This patch brings us from 7x slower than Safari 5 on tiny-innerHTML
+ to only 1.5x slower than Safari 5. I'm sure there is more work to do here.
+
+ Saving a shared Document like this is error prone. Currently
+ DummyDocumentFactory::releaseDocument() calls removeAllChildren()
+ in an attempt to clear the Document's state. However it's possible
+ that that call is not sufficient and we'll have future bugs here.
+
+ * html/parser/HTMLTreeBuilder.cpp:
+ (WebCore::DummyDocumentFactory::createDummyDocument):
+ (WebCore::DummyDocumentFactory::releaseDocument):
+ (WebCore::HTMLTreeBuilder::FragmentParsingContext::FragmentParsingContext):
+ (WebCore::HTMLTreeBuilder::FragmentParsingContext::document):
+ (WebCore::HTMLTreeBuilder::FragmentParsingContext::finished):
+ * html/parser/HTMLTreeBuilder.h:
+
git://git.webkit.org / WebKit.git / blobdiff