Bug 16738

Summary: Collector block offset could be stored as an cell offset instead of a byte offset
Product: WebKit Reporter: Henry Mason <hmason>
Component: JavaScriptCoreAssignee: Nobody <webkit-unassigned>
Status: RESOLVED FIXED    
Severity: Normal    
Priority: P2    
Version: 528+ (Nightly build)   
Hardware: Mac   
OS: All   
Attachments:
Description Flags
Cell offset usage mjs: review+

Henry Mason
Reported 2008-01-04 23:23:26 PST
Contrary to comments in the code to the contrary, storing the "next" field as a byte offset rather than a cell offset seems to be hurting performance. Both shark and timing tests with SunSpider show a small performance gain by switching to cell offsets. As an added bonus, using cell offsets eliminates a lot of somewhat ugly casting.
Attachments
Cell offset usage (2.49 KB, patch)
2008-01-04 23:27 PST, Henry Mason 		mjs: review+
DetailsFormatted DiffDiff
View All Add attachment proposed patch, testcase, etc.
Henry Mason
Comment 1 2008-01-04 23:27:15 PST
Created attachment 18284 [details] Cell offset usage
Maciej Stachowiak
Comment 2 2008-01-04 23:28:16 PST
Comment on attachment 18284 [details] Cell offset usage r=me
Maciej Stachowiak
Comment 3 2008-01-04 23:36:04 PST
Henry requests that anyone landing this patch should verify that it is a speedup since it is a little mysterious why.
Mark Rowe (bdash)
Comment 4 2008-01-05 00:26:28 PST
Landed in r29195. My testing showed this was a 0.4% speedup.
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