500876 - Find the largest classes in Gecko

Status: RESOLVED WONTFIX

(Developer Infrastructure :: Source Code Analysis, enhancement)

Description

[Jesse Ruderman]

Pav is pretty sure that identifying the largest classes (in terms of sizeof) would lead us to some easy perf optimizations.

Comment 1

[(dormant account)]

this seems like a variant of bug 492185. I'm not sure what you'll do once you find a big class(ie pretty much any class in editor/).

Comment 2

[Benjamin Smedberg]

especially since most of the largest classes are singletons or otherwise pretty uninteresting

Comment 3

[Stuart Parmenter]

i think having it be visible how big classes are would be helpful for people, and might lead us to spotting some useful information.

Comment 4

[georgi - hopefully not receiving bugspam]

can gdb's sizeof() be trusted for this, are these true:

(gdb) p sizeof(nsDOMClassInfo)
$4 = 40
(gdb) p sizeof(nsCAutoString)
$5 = 96
(gdb) p sizeof(JSRuntime)
$6 = 2256

if these are true, gdb script can be created and then parsed.

Comment 5

[Nathan Froyd [:froydnj]]

We're not going to write a static analysis for this; if somebody is super-motivated, they can script gdb or write a dwarf groveller along the lines of comment 4.