Bug 44037

Summary:

JSC: Move the static_cast into to(U)Int32 fast case

Product:

WebKit

Reporter:

Andreas Kling <kling>

Component:

JavaScriptCore

Assignee:

Nobody <webkit-unassigned>

Status:

RESOLVED FIXED

Severity:

Normal

CC:

commit-queue, ggaren, oliver

Priority:

Keywords:

Performance

Version:

528+ (Nightly build)

Hardware:

All

OS:

All

Attachments:

Description	Flags
Proposed patch	none

Andreas Kling

Reported 2010-08-15 13:48:00 PDT

Converting a double JSValue to an int32 (or uint32) is fairly expensive since it includes the overhead of calling to(U)Int32SlowCase. We could move the ideal case (static_cast<(u)int32_t> of double value within range) out of the slow case for a performance boost on conversion-heavy pages such as http://www.bel.fi/~alankila/plasma.html

Attachments
Proposed patch (3.64 KB, patch) 2010-08-15 13:53 PDT, Andreas Kling	no flags	Details Formatted Diff Diff
View All Add attachment proposed patch, testcase, etc.

Andreas Kling

Comment 1 2010-08-15 13:53:37 PDT

Created attachment 64453 [details] Proposed patch

Geoffrey Garen

Comment 2 2010-08-18 10:07:36 PDT

Comment on attachment 64453 [details] Proposed patch For changes that are likely to affect performance, we usually require a performance measurement. Please at least post SunSpider results with and without this patch, though I'd also be interested to see measurements of the website you mentioned.

Andreas Kling

Comment 3 2010-08-18 14:25:01 PDT

(In reply to comment #2) > (From update of attachment 64453 [details]) > Please at least post SunSpider results with and without this patch, though I'd also be interested to see measurements of the website you mentioned. Callgrind says: SunSpider is an amazing 0.0000072283% faster with this change. Results for the linked page are pretty much uninteresting until something is done about bug 43742.

Andreas Kling

Comment 4 2010-08-19 12:01:34 PDT

Comment on attachment 64453 [details] Proposed patch With the fix for 43742 landed, this patch yields a 1.6% speedup for the plasma demo - http://www.bel.fi/~alankila/plasma.html

Geoffrey Garen

Comment 5 2010-08-19 12:08:04 PDT

Comment on attachment 64453 [details] Proposed patch r=me

WebKit Commit Bot

Comment 6 2010-08-19 14:04:44 PDT

Comment on attachment 64453 [details] Proposed patch Clearing flags on attachment: 64453 Committed r65698: <http://trac.webkit.org/changeset/65698>

WebKit Commit Bot

Comment 7 2010-08-19 14:04:49 PDT

All reviewed patches have been landed. Closing bug.

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