JS execution very slow when debugging on DEBUG builds

RESOLVED FIXED in mozilla22

Status

()

RESOLVED FIXED
6 years ago
6 years ago

People

(Reporter: jimb, Unassigned)

Tracking

Trunk
mozilla22
Points:
---

Firefox Tracking Flags

(Not tracked)

Details

Attachments

(1 attachment)

(Reporter)

Description

6 years ago
Created attachment 726971 [details] [diff] [review]
Remove assertions that make us horribly slow when debugging JS in a DEBUG build.

Bug 848665 was that JS ran very, very slowly when a debugger was enabled: 
Debugger::slowPathOnEnterFrame constructed a ScriptFrameIter instance every
time we entered a JS function or did an eval; and that constructor calls (JaegerMonkey's) ExpandAllInlineFrames, which is very expensive.

The fix for 848665 addresses the problem, but still constructs a ScriptFrameIter in DEBUG builds, for an assertion. This means that the performance problem persists in DEBUG builds. Since we need Debugger to work in DEBUG builds, too, I think those assertions should be removed; they're too expensive.
Attachment #726971 - Flags: review?(jdemooij)

Updated

6 years ago
Attachment #726971 - Flags: review?(jdemooij) → review+

Comment 1

6 years ago
https://hg.mozilla.org/mozilla-central/rev/3232196cb95d
Status: NEW → RESOLVED
Last Resolved: 6 years ago
Resolution: --- → FIXED
Target Milestone: --- → mozilla22
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