1576356 - micro-optimize skip-ink rendering by using an autoarray for intercepts

Status: RESOLVED FIXED

(Core :: Layout: Text and Fonts, enhancement, P5)

Description

[Jonathan Kew [:jfkthame]]

Short underlined fragments will rarely involve more than a handful of intercepts, so we shouldn't need to heap-allocate an array for them in nsCSSRendering::PaintDecorationLine. Longer runs can have as many as a couple of hundred, but that's still reasonable to stack-allocate.

I instrumented the code to see how many intercepts were being collected when scrolling through a long Wikipedia article, with styles modified to underline all body text, and to move the underline up so that it touches all characters. Even then, only occasionally did the number of intercepts go above the mid-200's. In real-world cases it will typically be much smaller. So let's use an autoarray here.

Comment 1

[Jonathan Kew [:jfkthame]]

Attachment: Bug 1576356 - Use an AutoTArray to collect intercepts, to avoid heap allocation except in extreme cases. r=dholbert

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/4db791aec1af
Use an AutoTArray to collect intercepts, to avoid heap allocation except in extreme cases. r=dholbert

Comment 3

[Alexandru Michis [:malexandru]]

https://hg.mozilla.org/mozilla-central/rev/4db791aec1af