1668332 - CacheIR: Optimize global name DOM getters like bareword `document`

Status: RESOLVED FIXED

(Core :: JavaScript Engine: JIT, enhancement, P1)

Description

[Tom S. (please needinfo tschuster)]

When doing something like document.getElementById in JS, the document lookup is actually a getter call on the global JS object (i.e, window). By using our existing support for DOM getters from bug 1664617, we automatically get a huge performance boost. document for example is a simple slot load using MGetDOMMember instead of an actual call.

The micro benchmark getElementById-1.html for example improves from 120ms to 70ms.

Comment 1

[Tom S. (please needinfo tschuster)]

Attachment: Bug 1668332 - Optimize global name DOM getters like bareword `document`. r?jandem

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/36503a9bb36d
Optimize global name DOM getters like bareword `document`. r=jandem

Comment 3

[Atila Butkovits]

https://hg.mozilla.org/mozilla-central/rev/36503a9bb36d

Comment 4

[Florin Strugariu [:Bebe]]

== Change summary for alert #27118 (as of Fri, 02 Oct 2020 16:36:58 GMT) ==

Improvements:

51% raptor-assorted-dom-firefox linux64-shippable-qr opt webrender 166.79 -> 81.58
50% raptor-assorted-dom-firefox linux64-shippable opt 162.80 -> 81.87

For up to date results, see: https://treeherder.mozilla.org/perf.html#/alerts?id=27118