1149739 - Censor |performance| object in JS_MORE_DETERMINISTIC builds

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[Jesse Ruderman]

|performance.mozMemory| was added to the js shell in bug 1125412. Gary noticed that it trips up differential testing, when the fuzzer generates code like:

> print(JSON.stringify(this))
{ ... "mozMemory": { ... "gcBytes": 237568 ... } ... }

Where would be the best place to hide this information in JS_MORE_DETERMINISTIC builds? I'm thinking either:

A) Where the performance object is created
https://hg.mozilla.org/mozilla-central/file/18a8ea7c2c62/js/src/shell/js.cpp#l5650

B) Where the mozMemory object is populated
https://hg.mozilla.org/mozilla-central/file/18a8ea7c2c62/js/src/jsgc.cpp#l7245

Comment 1

[Gary Kwong [:gkw] [:nth10sd] (NOT official MoCo now)]

Steve worked on bug 1125412, adding needinfo? from him.

Comment 2

[Steve Fink [:sfink] [:s:]]

Attachment: Nerf performance.mozMemory ifdef JS_MORE_DETERMINISTIC

Yep, this was totally me. I'm not sure what the right place to cut this is, but I don't suppose it really matters. I was worried that making the JS::NewMemoryInfoObject call fail might mess up initialization without further fixes, and returning an empty object is a little odd because in my code, I feature-test the existence of performance.mozMemory. How about this?

Comment 3

[Terrence Cole [:terrence]]

Comment on attachment 8587617 [details] [diff] [review]
Nerf performance.mozMemory ifdef JS_MORE_DETERMINISTIC

Review of attachment 8587617 [details] [diff] [review]:
-----------------------------------------------------------------

wfm

Comment 4

[Steve Fink [:sfink] [:s:]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/1d672188b8aa

Comment 5

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/1d672188b8aa

Comment 6

[Steve Fink [:sfink] [:s:]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/ea7dabcd215e

Comment 7

[Phil Ringnalda (:philor)]

https://hg.mozilla.org/mozilla-central/rev/ea7dabcd215e