[JSC] Issue report (Jan 2017)

• The only bug we have reported for coco8 is still present in January 2017
• It is a VM bug that can be reproduced with pure javascript (w/o s8 environment)
• It has been found in all platforms we actually run using JavascriptCore (the javascript VM that Apple distributes in all iOS devices)

Details

• [E8] JavascriptCore parse issue
• [E8] Concecuences of the JSC parse issue while runnning coco8 applications
• [E8] References to webkit bug report (see long list in WebKit bugzilla)

Simple Javascript code to expose the bug

((function(){return ((function(){return ((function(){return ((function(){return 
((function(){return ((function(){return ((function(){return ((function(){return 
((function(){return ((function(){return ((function(){return ((function(){return 
((function(){return ((function(){return ((function(){return ((function(){return 
((function(){return ((function(){return ((function(){return ((function(){return 
(1);
})() + 1);})() + 1);})() + 1);})() + 1);
})() + 1);})() + 1);})() + 1);})() + 1);
})() + 1);})() + 1);})() + 1);})() + 1);
})() + 1);})() + 1);})() + 1);})() + 1);
})() + 1);})() + 1);})() + 1);})() + 1)

Conclusions

• The bug is closed, marked unsolved for now, until It is repaired the issue in the VM distributed by Apple in iOS devices
• Reccomendations
  1. avoid using JavascriptCore VM if possible
  2. force (preventive) full GC through JSC API to minimize crash during incremental GC