On Tuesday 2009-02-24 14:51 -0500, Boris Zbarsky wrote: > I've been doing a bit of profiling of frame construction, and trying to > figure out ways to optimize all the pseudo-style probing we do right now > (for :before/:after content, for first-line and first-letter, etc). That > stuff takes up up to 25% of frame construction time; the value is lower > if more complicated CSS is used on the page, of course. > > Some thoughts that could use sanity-checking: > > 1) Instead of putting all the pseudo-element rules into a single linked > list per ruleprocessor, we could actually create a separate rulehash per > pseudo-element, or at least for before/after/first-line/first-letter. > Then within this rulehash we hash rules as we normally would. This > means, for example, that when probing ::before we don't have to do > SelectorMatches on all the UA ::before rules we have and can instead > just check against the ones that matter (usually none).
Separating pseudo-element rules would be useful for other things, such as fixing IsPseudoElement to distinguish between :before (a pseudo-element) and \:before (an element); see https://bugzilla.mozilla.org/show_bug.cgi?id=475216#c1 . But that requires distinguishing through even more of the process. Maybe we could somehow have one rule hash for every pseudo-element for which we actually have rules? That could avoid getting too bloated (since in many cases there are no pseudo-element rules). > 2) In RuleHash::EnumerateAllRules, check entry counts on the tables > before doing lookups. Lookups are not that cheap with pldhash, and > often enough the tables are completely empty (e.g. in the UA level the > id table is empty; in the user level most of the tables are empty by > default, etc). Seems reasonable. > 3) Perhaps combine the rule processor data for the "main" style > resolution and the pseudo-probing, since the latter just uses the same > data with the additional pseudo-tag tossed in. Makes sense if it's easy; I haven't looked at how much code it would require changing. -David -- L. David Baron http://dbaron.org/ Mozilla Corporation http://www.mozilla.com/ _______________________________________________ dev-tech-layout mailing list [email protected] https://lists.mozilla.org/listinfo/dev-tech-layout
