[Webkit-unassigned] [Bug 186916] New: zero assigned to variable instead of division calculation result

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=186916

            Bug ID: 186916
           Summary: zero assigned to variable instead of division
                    calculation result
           Product: WebKit
           Version: Safari 11
          Hardware: iPhone / iPad
                OS: iOS 11
            Status: NEW
          Severity: Normal
          Priority: P2
         Component: JavaScriptCore
          Assignee: webkit-unassigned at lists.webkit.org
          Reporter: d.lukashenko at triggre.com

We encounter issue when division calculation result assigned to variable results in variable having 0 value when it shouln't.

I've attached test html which demonstrates this issue (probably could be reduced to much smaller test case).
Steps to reproduce:
1. load page
2. in top left corner there will be canvas and you need to draw something using touch
3. click button
It will read image from canvas, calculate number of filled dots and divide by number of all dots to receive fill factor.
This operation performed 100 times and log attempts, when fill factor resulted in 0. For us it fails 5-6 first times. Note that divisor and divider populated properly and it is only result not saved properly to variable.
To repeat test you need to reload test page.

Environment details:
we can reproduce it on iOS 11.3-11.4 iPhone8/iPad
we cannot reproduce it on iOS 11.0 iPhone8

-- 
You are receiving this mail because:
You are the assignee for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.webkit.org/pipermail/webkit-unassigned/attachments/20180622/bfcfc753/attachment.html>