Bug 34462

Summary:

Fix a bug that Math.round() returns incorrect results for huge integers

Product:

WebKit

Reporter:

Kent Tamura <tkent>

Component:

JavaScriptCore

Assignee:

Nobody <webkit-unassigned>

Status:

RESOLVED FIXED

Severity:

Normal

CC:

darin

Priority:

Version:

528+ (Nightly build)

Hardware:

All

OS:

All

Attachments:

Description	Flags
Patch	darin: review+

Kent Tamura

Reported 2010-02-01 19:37:14 PST

Fix a bug that Math.round() retunrs incorrect results for huge integers

Attachments
Patch (3.64 KB, patch) 2010-02-01 19:38 PST, Kent Tamura	darin: review+	Details Formatted Diff Diff
View All Add attachment proposed patch, testcase, etc.

Kent Tamura

Comment 1 2010-02-01 19:38:48 PST

Created attachment 47901 [details] Patch

Darin Adler

Comment 2 2010-02-01 19:46:59 PST

Comment on attachment 47901 [details] Patch How about this instead? - if (signbit(arg) && arg >= -0.5) - return jsNumber(exec, -0.0); - return jsNumber(exec, floor(arg + 0.5)); + double integer = ceil(arg); + return jsNumber(exec, integer - (integer - arg > 0.5));

Darin Adler

Comment 3 2010-02-01 19:47:56 PST

Comment on attachment 47901 [details] Patch Patch seems fine. But you should consider my patch with ceil that avoids the need for the separate if statement. You could use ? : instead of the way I did it. Or use my code exactly as is (as long as it passes your tests).

Darin Adler

Comment 4 2010-02-01 19:48:58 PST

Would be nice to have tests cases for the maximum and minimum double values as well to make sure they don't turn into infinity when rounded.

Kent Tamura

Comment 5 2010-02-01 20:51:16 PST

Thank you for the quick review. Ok, I followed the proposed code, and add test cases for minimum/maximum values. Landed as r54197 and r54198.

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