Bug 61306 - Is the YARR begin characters optimization still a win?
Summary: Is the YARR begin characters optimization still a win?
Alias: None
Product: WebKit
Classification: Unclassified
Component: JavaScriptCore (show other bugs)
Version: 528+ (Nightly build)
Hardware: Unspecified Unspecified
: P2 Normal
Assignee: Gavin Barraclough
Depends on:
Blocks: 45749 61129
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Reported: 2011-05-23 14:09 PDT by Gavin Barraclough
Modified: 2011-05-23 17:10 PDT (History)
2 users (show)

See Also:

The patch (17.70 KB, patch)
2011-05-23 16:34 PDT, Gavin Barraclough
ggaren: review+
Details | Formatted Diff | Diff

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Description Gavin Barraclough 2011-05-23 14:09:50 PDT
It looks like the benefit of this optimization may have been lost since the BOL optimizations went in ('once through' flag).

Disabling this optimization seems to have no impact on SunSpider performance, and I measure a 2% win on v8 w/ YARR interpreter by disabling.

If disabling will simplify the code, fix bugs & improve performance, than that is what we should do.

Do we have evidence that this is still a win?
Comment 1 Gavin Barraclough 2011-05-23 16:34:52 PDT
Created attachment 94517 [details]
The patch
Comment 2 Geoffrey Garen 2011-05-23 17:02:15 PDT
Comment on attachment 94517 [details]
The patch

Comment 3 Gavin Barraclough 2011-05-23 17:10:24 PDT
Removing this optimization for now in r87109, open to re-landing if we can demonstrate a significant performance win.