469351 - TM: loop with i<hColl.length slower with jit enabled

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[Dorus Peelen]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 6.0; nl; rv:1.9.0.4) Gecko/2008102920 Firefox/3.0.4
Build Identifier: Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.9.2a1pre) Gecko/20081212 Minefield/3.2a1pre 

As a follow up of bug 451974, here some more for loop problems.

Both 

for (var i=0; i<hColl.length; i++) { }

And

var i = 0; while (i < hColl.length) { i++; }


are 1.3x to 1.4x slower with JIT enabled then with JIT disabled. As i got the
idea these 2 problems are related, i put them in one bug for now.

Reproducible: Always

Comment 1

[Dorus Peelen]

Attachment: Somewhat minimized testcase

Comment 2

[Boris Zbarsky [:bzbarsky]]

We're aborting because of the DOM access here, but I'd still expect us to blacklist this....

Comment 3

[Damon Sicore (:damons)]

blocking1.9.1-

Comment 4

[Jan de Mooij [:jandem]]

This is about as fast as Chrome now. It's even faster with JM or JIT profiling disabled, I will file a follow up bug for that.

Comment 5

[Boris Zbarsky [:bzbarsky]]

Please post that followup bug number here?

Comment 6

[Boris Zbarsky [:bzbarsky]]

Ah, bug 606494.

Comment 7

[Jan de Mooij [:jandem]]

(In reply to comment #5)
> Please post that followup bug number here?

Sorry, will post it next time and block 467263 for perf bugs :)