1636357 - Cleanup the cascade iterator.

Status: RESOLVED FIXED

(Core :: CSS Parsing and Computation, defect, P3)

Comment 1

[Emilio Cobos Álvarez (:emilio)]

Attachment: Bug 1636357 - Clean up cascade rule iteration. r=#style

The current API was pretty awkward as a result of two things:

• Not being able to create empty iterators for smallbitvec.
• We used to call the F function multiple times, but turns out that
  collecting the declarations in a SmallVec was a perf win.

So clean this up so that it looks more similar to other APIs. This
needs a smallbitvec patch which is up for review in
https://github.com/servo/smallbitvec/pull/24, but I figured I'd submit
the Gecko patch anyways.

This is a bit more code, but hopefully easier to understand (and also hopefully
easier to optimize).

The motivation for this work is that I plan to investigate rebasing / landing
https://github.com/servo/servo/pull/20151, and I don't want more instantiations
of apply_declarations and such.

Comment 2

[Emilio Cobos Álvarez (:emilio)]

Attachment: Bug 1636357 - Update smallbitvec. r=#style

This is needed for the next patch.

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/5c1f0ed14851
Update smallbitvec. r=jwatt

Comment 4

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/5c1f0ed14851

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/1b82eac309f6
Clean up cascade rule iteration. r=nordzilla

Comment 6

[Emilio Cobos Álvarez (:emilio)]

Err, wat

Comment 7

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/1b82eac309f6

Comment 8

[Alexandru Ionescu (needinfo me) [:alexandrui]]

== Change summary for alert #25914 (as of Wed, 13 May 2020 03:39:31 GMT) ==

Improvements:

18% perf_reftest style-attr-1.html windows10-64-shippable-qr opt e10s stylo 3.73 -> 3.05
17% perf_reftest style-attr-1.html windows7-32-shippable opt e10s stylo 3.18 -> 2.63
16% perf_reftest style-attr-1.html windows10-64-shippable opt e10s stylo 3.62 -> 3.03
16% perf_reftest_singletons style-attr-1.html windows10-64-shippable-qr opt e10s stylo 3.87 -> 3.26
14% perf_reftest_singletons style-attr-1.html windows7-32-shippable opt e10s stylo 3.27 -> 2.82
13% perf_reftest_singletons style-attr-1.html linux64-shippable opt e10s stylo 3.51 -> 3.05
13% perf_reftest_singletons style-attr-1.html linux64-shippable-qr opt e10s stylo 3.51 -> 3.07
12% perf_reftest style-attr-1.html linux64-shippable opt e10s stylo 3.19 -> 2.80
12% perf_reftest style-attr-1.html linux64-shippable opt e10s stylo 3.24 -> 2.86
5% perf_reftest_singletons link-style-cache-1.html macosx1014-64-shippable opt e10s stylo 1,307.85 -> 1,240.25
4% displaylist_mutate linux64-shippable-qr opt e10s stylo 3,481.40 -> 3,326.76

For up to date results, see: https://treeherder.mozilla.org/perf.html#/alerts?id=25914

Comment 9

[Emilio Cobos Álvarez (:emilio)]

Nice