[Rev 01] RFR: 8238549: Add explicit cast to correct implementation type in VarHandle implementation methods

[Jorn Vernee]

On Thu, 6 Feb 2020 12:58:28 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

>> Hi,
>> as promised, I took a look into adding a bit more structure under our var handle implementations - more specifically, I've tweaked the signatures of the various implementation methods to take a plain VarHandle instead of a var handle implementation class.
>> 
>> This was tedious, but ultimately easy to do. Since, to do this in a complete way I also had to touch regular var handles (e.g. non-memory access ones), it seemed like a good idea to take an existing var handle test (VarHandleTestMethodTypeXYZ) and tweak it so that it tests all combinations of (adpated=yes/no, guards=yes/no). This revealed several issues in the adapter logic:
>> 
>> * first, varType() and coordinates() triggered a resolution of some of the underlying MH attached to the indirect handle - since this can fail with UOE, these methods could also fail spuriously with UOE which is wrong
>> 
>> * second, accessModeTypeUncached, in addition to the aforementioned problem, also had an issue in that it didn't make correct use of the direct handle target
>> 
>> * third, I realized that I did not update the lambda forms for var handle invokers to also call VarHandle::asDirect - this was causing issues when calling an adapted handle through the invoker
>> 
>> With these changes, all tests pass despite the extra layers of adaptation. So, in the end it turned out to be a fruitful bug hunt (thanks for the hint Paul!).
>> 
>> Cheers
>> Maurizio
> 
> The pull request has been updated with 1 additional commit.

Marked as reviewed by jvernee (Committer).

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PR: https://git.openjdk.java.net/panama-foreign/pull/6