With a short search in the logs I found optimizations for at least operator+, but didn't search further:
http://trac.webkit.org/changeset/86330 https://bugs.webkit.org/show_bug.cgi?id=58420 Greetings, Dirk On Sep 4, 2012, at 4:31 PM, Adam Barth <[email protected]> wrote: > Do you have a proposal for how that would work and/or a link to the > previous discussion? > > Adam > > > On Tue, Sep 4, 2012 at 4:27 PM, Dirk Schulze <[email protected]> wrote: >> I thought we had efforts to make String::operator+= use StringBuilder >> somehow? I can remember that we had a discussion on webkit-dev and >> definitely on bugzilla about improving String::operator+= instead of >> replacing it with StringBuilder. >> >> Greetings, >> Dirk >> >> On Sep 4, 2012, at 4:22 PM, Adam Barth <[email protected]> wrote: >> >>> As part of the work to deploy efficient string patterns [1] throughout >>> WebKit, Benjamin and I noticed a bunch of very inefficient code that >>> uses operator+= with Strings: >>> >>> String foo; >>> for (...) >>> foo += [...]; >>> return foo; >>> >>> This pattern is particularly inefficient because += mallocs an >>> entirely new buffer for the result and copies the the string into the >>> new buffer. That means that this pattern makes O(n) calls to malloc >>> and does O(n^2) work. A more efficient pattern is to use >>> StringBuilder: >>> >>> StringBuilder foo; >>> for (...) >>> foo.append([...]); >>> return foo.toString(); >>> >>> I'm in the process of going through WebCore and removing all callers >>> of WTF::String::operator+=. Once that's complete, my plan is to >>> remove WTF::String::operator+= from WTFString.h. Hopefully that will >>> nudge contributors and reviewers towards more efficient string >>> patterns. >>> >>> Removing operator+= will likely require changes to a number of >>> port-specific files. I'll do my best to remove these, but I might >>> need some help from maintainers of individual ports. If you're >>> interested in helping out, please let me know. >>> >>> Many thanks, >>> Adam >>> >>> [1] http://trac.webkit.org/wiki/EfficientStrings >>> _______________________________________________ >>> webkit-dev mailing list >>> [email protected] >>> http://lists.webkit.org/mailman/listinfo/webkit-dev >> > _______________________________________________ > webkit-dev mailing list > [email protected] > http://lists.webkit.org/mailman/listinfo/webkit-dev _______________________________________________ webkit-dev mailing list [email protected] http://lists.webkit.org/mailman/listinfo/webkit-dev
