Any::isNull check

Paul Benedict pbenedict at
Wed Dec 16 15:45:25 UTC 2015

Yes, HotSpot is really good at that. I agree. However, my point is there's
no reason in even carrying around the dead bytecode in the class file. With
lots of these if() checks, the class file can surely shrink if the compiler
gets some additional smarts.


On Wed, Dec 16, 2015 at 9:42 AM, Brian Goetz <brian.goetz at> wrote:

> HotSpot is *really* good at eliminating dead code based on type profiles.
> On 12/16/2015 10:38 AM, Paul Benedict wrote:
>> When a method is specialized for values, Any::isNull can only return
>> "false", which means if(Any.isNull(o)) can only ever have one outcome --
>> the other code branch can be discarded by the compiler. I know it's too
>> early to talk about optimizations :-) but will javac be smart enough to
>> recognize this optimization? Is it on your list for the future?
>> Cheers,
>> Paul

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