1439788 - Having performance.now added to spidermonkey's shell would help with perf diagnosis

Status: RESOLVED FIXED

(Core :: JavaScript Engine, enhancement, P5)

Description

[Jeff Griffiths (:canuckistani) (:⚡︎)]

Spidermonkey and V8 can have different performance characteristics, and access to performance apis in the shell might make certain kinds of investigations more convenient:

"[I wanted to sprinkle performance.now() but SpiderMonkey shell apparently does not support it.]"

See http://mrale.ph/blog/2018/02/03/maybe-you-dont-need-rust-to-speed-up-your-js.html

Comment 1

[Jan de Mooij [:jandem]]

We have dateNow in the shell; we could rename/alias it.

Comment 2

[Tooru Fujisawa [:arai]]

Required code changes are following:
  1. Define `performance` object in the shell global
  2. Define `now` property to the `performance` object, with the same value as `dateNow` [1][2]

Bug 1118158 would be a good example, which added `console.log` [3][4][5].

You'll need basic knowledge of C++, and be able to build and test SpiderMonkey shell [6][7].

A skilled first-time contributor should be able to finish this in a month.  Leave comments / questions here, or ask me (:arai) in IRC [8] #introduction or #jsapi channels.

[1] https://searchfox.org/mozilla-central/rev/47cb352984bac15c476dcd75f8360f902673cb98/js/src/shell/js.cpp#6848-6850
[2] https://searchfox.org/mozilla-central/rev/47cb352984bac15c476dcd75f8360f902673cb98/js/src/shell/js.cpp#2274-2281
[3] https://hg.mozilla.org/mozilla-central/rev/58d6a621d9626547407708b7c78cf5dbf1fa935a
[4] https://searchfox.org/mozilla-central/rev/47cb352984bac15c476dcd75f8360f902673cb98/js/src/shell/js.cpp#7387-7402
[5] https://searchfox.org/mozilla-central/rev/47cb352984bac15c476dcd75f8360f902673cb98/js/src/shell/js.cpp#8305-8306
[6] https://developer.mozilla.org/en-US/docs/Mozilla/Projects/SpiderMonkey/Build_Documentation
[7] https://developer.mozilla.org/en-US/docs/Simple_Firefox_build
[8] https://wiki.mozilla.org/index.php?title=IRC

Comment 3

[Dhi Aurrahman]

Hi Tooru, may I take this bug?

Comment 4

[Dhi Aurrahman]

Attachment: Add performance.now() function to JS shell

Comment 5

[Tooru Fujisawa [:arai]]

Comment on attachment 8955760 [details] [diff] [review]
Add performance.now() function to JS shell

Review of attachment 8955760 [details] [diff] [review]:
-----------------------------------------------------------------

Thank you for taking this :)
Looks great!

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/c59eff0e8209
Add performance.now() function to JS shell. r=arai

Comment 7

[Narcis Beleuzu [:NarcisB]]

https://hg.mozilla.org/mozilla-central/rev/c59eff0e8209