2025271 - Simplify DOMString.

Status: RESOLVED FIXED

(Core :: DOM: Bindings (WebIDL), enhancement)

Description

[Emilio Cobos Álvarez [:emilio]]

Split off from bug 2023628 since it's technically different. That way we can also land it separately.

Comment 1

[Emilio Cobos Álvarez [:emilio]]

Try: https://treeherder.mozilla.org/jobs?repo=try&landoCommitID=187490
SP3: https://perf.compare/compare-lando-results?baseLando=187463&newLando=187491&baseRepo=try&newRepo=try&framework=13
perf-reftest: https://perf.compare/compare-lando-results?baseLando=187391&newLando=187492&baseRepo=try&newRepo=try&framework=1

Comment 2

[Emilio Cobos Álvarez [:emilio]]

Attachment: Bug 2025271 - Simplify DOMString. r=smaug!,nika!

Make DOMString a regular nsAutoTString with some special methods for
performance in some hot getters. For that, we need to change a bit
nsTString:

• Support for unowned buffers: Owned buffers now are represented by
  STRINGBUFFER|OWNED flags, rather than REFCOUNTED.

• Inlining of the destructor: It showed up in profiles, it's also just
  a few instructions, so probably worth it. We could OOL the owned path
  I guess, if we wanted to.

• Inlinling and reordering of NonVoidStringToJsval. Old code had
  special DOMString path inline with [buffer, literal, copy] paths,
  then out of line code with [literal, buffer, copy]. Instead,
  consolidate everything in a [buffer, literal, copy] inline path.
  Do the same for UTF8/Latin1 strings too for consistency.

Comment 3

[Emilio Cobos Álvarez [:emilio]]

Attachment: Bug 2025271 - Simplify XMLHttpRequestStringSnapshot. r=nika!

Match GetAsJSString which just uses mData, this code is probably
leftover from bug 1484990.

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/fe182cca644b
https://hg.mozilla.org/integration/autoland/rev/5ad560d07305
Simplify DOMString. r=smaug,nika,extension-reviewers,core-sessionstore-reviewers,dom-worker-reviewers,robwu,asuth

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/e7068c87257b
https://hg.mozilla.org/integration/autoland/rev/b4ec12ebaa6f
Simplify XMLHttpRequestStringSnapshot. r=nika

Comment 6

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/5ad560d07305
https://hg.mozilla.org/mozilla-central/rev/b4ec12ebaa6f

Comment 7

[Mayank Bansal]

This increased the installer size on Windows-non-shippable by 93KB.

Comment 8

[Alex Finder]

(In reply to Pulsebot from comment #4)

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/fe182cca644b
https://hg.mozilla.org/integration/autoland/rev/5ad560d07305
Simplify DOMString.
r=smaug,nika,extension-reviewers,core-sessionstore-reviewers,dom-worker-
reviewers,robwu,asuth

Perfherder has detected a build_metrics performance change from push 5ad560d07305449e5126757d609577ba025f07c8.

No action is required from the author; this comment is provided for informational purposes only.

Improvement	Test	Platform	Options	Absolute values [old vs new]
2%	build times	windows2012-64-shippable	nightly taskcluster-projects/970387039909/machineTypes/c3d-standard-60-lssd	3,228.95 -> 3,161.25

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