[lworld] Handling of missing ValueTypes attributes (original) (raw)

Ioi Lam ioi.lam at oracle.com
Mon Jul 9 22:44:24 UTC 2018

In lworld, how are we suppose to handle cases where the ValueTypes attribute should have been there for a classfile, but is missing?

E.g.,

  class MyHack {       Point getPoint() {           if (onceInAWhile) {               return Point.makePoint(1, 2);           } else {               return null;           }       }   }

Normally, Point will be included in MyHack's ValueTypes attribute, and the Point class will be aggressively loaded. So we'd know for sure that getPoint returns a ValueType.

However, someone can write this class by hand and omit the ValueTypes attribute. In that case, I think the program's output should be the same as if the ValueTypes attribute had been present, although performance may differ (slower, more heap allocations, etc).

Is this understanding correct?

Thanks

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