RFC (S) 8140483: Atomic*FieldUpdaters final fields should be trusted

[Aleksey Shipilev]

On 10/27/2015 02:52 AM, Vitaly Davidovich wrote:
> In this particular case, A*FU is doing obj.getClass() == tclass as a
> cheaper check than what fullCheck() does, which is
> tclass.isInstance(obj).  However, theoretically speaking, if A*FU op is
> inlined into an instance method where `this` is passed, it should be
> able to determine at JIT time whether `this` is tclass or subtype of
> it.  Then that whole type check could be removed.

Yes, I get that. It may be profitable to check Class.isInstance, instead
of the exact match, so that subclasses are also acceptable. And it
indeed does help to eliminate the type check.

Thanks,
-Aleksey


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