1810299 - JS demo (https://www.fxhash.xyz/generative/slug/ascii-dun-gen ) is a lot slower in Nightly compared with Chrome

Status: RESOLVED FIXED

(Core :: JavaScript Engine, task, P3)

Description

[Mayank Bansal]

Go to https://www.fxhash.xyz/generative/slug/ascii-dun-gen
Click on the "Open" button. This will open the demo in a new tab
Change the Map size to 200
Ensure that the type of map is "Dungeon" (in the first drop down menu)
Click on generate

Nightly: https://share.firefox.dev/3iE6hnr
Chrome: https://share.firefox.dev/3W9vVOz

Comment 1

[Mayank Bansal]

Here is a profile with dungeon size as 500 : https://share.firefox.dev/3CNeXyG

Comment 2

[Jan de Mooij [:jandem]]

This is spending a lot of time under Ion's LessThan IC's slow path. My best guess is they're doing something weird, for example one side is undefined, but I'll take a look. It might be easy to support in CacheIR.

Comment 3

[André Bargull [:anba]]

I can upload some patches from last year which add support for Number/Int32/Boolean against Null/Undefined relational comparison. I've initially created them for IC failures in JetStream, but I didn't observe much real-world usage, so I never uploaded them for review:

• Part 1: https://hg.mozilla.org/try/rev/288879b5e177ab8a8f67cb69c2775b495432a63c
• Part 2: https://hg.mozilla.org/try/rev/ca289c4d046af674f205b6f00330476d3e02171b
• Part 3: https://hg.mozilla.org/try/rev/a95534c5da6f57a7cab35889797337465c687a79

Comment 4

[Jan de Mooij [:jandem]]

I added some logging to IonCompareIC::update and I only see hits for undefined < undefined... Do your patches handle that case too? JS code doing this is pretty broken, but if we can easily support this in the CacheIR generator it might not be too bad.

Comment 5

[André Bargull [:anba]]

No, Undefined x Undefined isn't supported by my patches, but it shouldn't be too hard to support it, too.

It's actually supported.

Comment 6

[André Bargull [:anba]]

Attachment: Bug 1810299 - Part 1: Move EmitGuardTo functions. r=jandem!

Move the functions in preparation for part two.

Comment 7

[André Bargull [:anba]]

Attachment: Bug 1810299 - Part 2: Handle more relational comparison for Number/Int32/Boolean against Null/Undefined. r=jandem!

Depends on D167131

Comment 8

[André Bargull [:anba]]

Attachment: Bug 1810299 - Part 3: Remove extra CacheIR code for relational comparison of Number x Undefined. r=jandem!

Instead emit a normal CompareDoubleResult instruction and for hot code let
GVN optimise the instruction to a constant.

Depends on D167132

Comment 9

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/a889cd33c920
Part 1: Move EmitGuardTo functions. r=jandem
https://hg.mozilla.org/integration/autoland/rev/098909b3b7ae
Part 2: Handle more relational comparison for Number/Int32/Boolean against Null/Undefined. r=jandem
https://hg.mozilla.org/integration/autoland/rev/869a971a4902
Part 3: Remove extra CacheIR code for relational comparison of Number x Undefined. r=jandem

Comment 10

[Serban Stanca [:SerbanS]]

https://hg.mozilla.org/mozilla-central/rev/a889cd33c920
https://hg.mozilla.org/mozilla-central/rev/098909b3b7ae
https://hg.mozilla.org/mozilla-central/rev/869a971a4902

Comment 11

[Mayank Bansal]

Profile from latest Nightly: https://share.firefox.dev/3wd3QLV
In my highly scientific testing of 2 samples, Nightly is comparable to Chrome now.