RFR: 8266642: improve ResolvedMethodTable hash function [v9]

[Stefan Karlsson]

On Tue, 18 May 2021 11:39:04 GMT, Denghui Dong <ddong at openjdk.org> wrote:

>> JDK-8249719 has fixed the bad hash function problem, however, the performance problem still exists when there are a large number of classes with the same name.
>> Adding the address of the corresponding ClassLoaderData as a factor of hash can solve the problem.
>
> Denghui Dong has updated the pull request incrementally with one additional commit since the last revision:
> 
>   remote LogMinObjAlignmentInBytes

The identity_hash() changes look good.

FWIW, some allocators return 16 byte aligned memory chunks, so shifting by 3 might leave a non-set LSB. Maybe when fixing JDK-8267303, we should also consider if the shift should be 3 or 4.

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PR: https://git.openjdk.java.net/jdk/pull/3901