2062076 - Bail out of a SelectorMap when no rule in it can match the element's local name

Status: ASSIGNED

(Core :: CSS Parsing and Computation, enhancement)

Comment 1

[Mayank Bansal]

Attachment: WIP: Bug 2062076 - Bail out of a SelectorMap when no rule in it can match the element's local name. r=#firefox-style-system-reviewers

Every ::before/::after rule in the UA sheets requires one of q, img, input,
option or optgroup, so matching those pseudos for anything else walks every
bucket of that map for nothing. Accumulate a bloom of the local names a map
requires as rules are inserted, and check it before the bucket lookups.

The filter is only as good as its weakest rule: one selector that can match any
local name saturates the whole map, which is the common case for author sheets.

Comment 2

[Mayank Bansal]

sp3 perfcompare: https://perf.compare/compare-results?baseRev=5474eb9b8c54cbe0e8c949a84931608468fde391&baseRepo=try&newRev=68f5b1031ea476aef165ecbcd99f0fcb91d462ff&newRepo=try&framework=13&filter_significance=significant&filter_status=improvement%2Cregression

try debug: https://treeherder.mozilla.org/jobs?repo=try&revision=801eb6fe6bf21fe5836de0dcb3fda2fccb831ef3
try opt: https://treeherder.mozilla.org/jobs?repo=try&revision=4ad876d7f8023c3b920b469a6946402bac0f2108

Comment 3

[Mayank Bansal]

Looks to be perf neutral on SP3: https://perf.compare/compare-results?baseRev=c405c8c654a322da888a1669cc7eb9b35e6de48e&baseRepo=try&newRev=3edebf6035adae62ce561c9150eee4006044926b&newRepo=try&framework=13