538729 - Consider backporting the byte-specialized canvas imagedata to 1.9.2.x

Status: RESOLVED WONTFIX

(Core :: JavaScript Engine, defect)

Description

[Boris Zbarsky [:bzbarsky]]

The work is pretty self-contained: custom quickstubs, typedarrays, and canvas 2d bits.  The impact is much faster canvas imagedata ops; speedups are 30% to 50% depending on testcase we've looked at, probably mostly from the better cache locality that we get with the 4x smaller imagedata.

This moves the needle from being at about safari-parity on most of these testcases (they've been slowly creeping faster in their dot-releases) to a lot faster.

Comment 1

[Vladimir Vukicevic [:vlad] [:vladv] (needinfo me, slow to respond)]

Added the relevant dependent bugs; we wouldn't need all of them, just fixes/changes to qsgen.py, and then the new code for typed arrays + the canvas 2d quickstubs.  We'd want to make sure that we don't expose the typed array constructors to web content, but that shouldn't be too hard.

Comment 2

[:Ms2ger (he/him; ⌚ UTC+1/+2)]

Do we still want to do this?

Comment 3

[Boris Zbarsky [:bzbarsky]]

There's no point; this would have helped to avoid being branded as slow 18 months ago, but now it's not like anyone cares the performance of 3.6.