RFR: 8258048: Placeholder hash code is the same as Dictionary hash code [v3]

[Lois Foltan]

On Wed, 16 Dec 2020 16:48:16 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> This change is a set of cleanups to the placeholders hashtable.  It moves the index calculation inside the hashtable.  It avoids using the placeholder hashcode because it's the same hashcode as the dictionary hashcode.  There are some asserts for this.
>> 
>> One of the find_class() functions is redundant to dictionary->find_class() so is removed.
>> 
>> Tested with tier1-6.
>
> Coleen Phillimore has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Fix or remove extraneous null checks.

Thank you for making suggested changes.  Looks good.
Lois

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Marked as reviewed by lfoltan (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/1789