1906778 - Fakespot addon appears to spend a ton of time in non-ion path (Blinterp)

Status: RESOLVED DUPLICATE of bug 1827188

(Core :: JavaScript Engine, enhancement, P3)

Description

[Mayank Bansal]

1. Add fakespot extension to Firefox Nightly desktop browser
2. Go to https://prettier.io/playground
   From the left-pane, select the following :
   parser = Babel (should be default)
   Debug = "Show input" only. (UNCHECK "Show AST")
3. Paste the attached sample text into the input pane

AR:https://share.firefox.dev/3zwFjWR

ER:
Even when triggered, the extension should take the fast ionmonkey path inside the Javascript engine. So it appears that the JS code inside the extension is using some pattern that ionmonkey cannot handle.
My naive thought is that the time is being spent in regexp and the Blinterp time shown is a know issue/limitation with the profiler.

cc: iain, canaltinova.

Comment 1

[Mayank Bansal]

Attachment: about:support

Comment 2

[Mayank Bansal]

Attachment: Sample text file (source code of d3.js)

Comment 3

[Mayank Bansal]

Feel free to WONTFIX or dupe to existing bugs.

Comment 4

[Jan de Mooij [:jandem]]

We're spending most time in unsymbolicated frames under RegExp_prototype_Exec (for RegExp.prototype.exec). Maybe some slow regular expressions.

Comment 5

[Mayank Bansal]

This may end up being a dupe of bug 1827188

Comment 6

[Iain Ireland [:iain]]

I confirm that this is a profiler interface quirk, not an optimization problem. These regexps are being compiled to native code, which is the highest tier available for regexps. Given the Fakespot code, this is what we expect to see.