RFR: 6312651: Compiler should only use verified interface types for optimization [v2]

[Vladimir Ivanov]

On Fri, 28 Oct 2022 15:35:38 GMT, Roland Westrelin <roland at openjdk.org> wrote:

>> This change is mostly the same I sent for review 3 years ago but was
>> never integrated:
>> 
>> https://mail.openjdk.org/pipermail/hotspot-compiler-dev/2019-May/033803.html
>> 
>> The main difference is that, in the meantime, I submitted a couple of
>> refactoring changes extracted from the 2019 patch:
>> 
>> 8266550: C2: mirror TypeOopPtr/TypeInstPtr/TypeAryPtr with TypeKlassPtr/TypeInstKlassPtr/TypeAryKlassPtr
>> 8275201: C2: hide klass() accessor from TypeOopPtr and typeKlassPtr subclasses
>> 
>> As a result, the current patch is much smaller (but still not small).
>> 
>> The implementation is otherwise largely the same as in the 2019
>> patch. I tried to remove some of the code duplication between the
>> TypeOopPtr and TypeKlassPtr hierarchies by having some of the logic
>> shared in template methods. In the 2019 patch, interfaces were trusted
>> when types were constructed and I had added code to drop interfaces
>> from a type where they couldn't be trusted. This new patch proceeds
>> the other way around: interfaces are not trusted when a type is
>> constructed and code that uses the type must explicitly request that
>> they are included (this was suggested as an improvement by Vladimir
>> Ivanov I think).
>
> Roland Westrelin has updated the pull request incrementally with one additional commit since the last revision:
> 
>   build fix

BTW will there still be a need in `CastPP` vs `CheckCastPP` dichotomy once the patch goes in?

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PR: https://git.openjdk.org/jdk/pull/10901