RFR: 8256392: C2: Various Node cleanups [v2]

[Nils Eliasson]

On Tue, 17 Nov 2020 09:28:19 GMT, Claes Redestad <redestad at openjdk.org> wrote:

>> - Unused methods:
>>  Node::walk, walk_, nop, lookup, rpop
>>  Node_Array::reset, sort
>> - Disallowing 0 as values to OptoNodeListSize and OptoBlockListSize can simplify some logic: e.g., Node_Array::_max > 0 becomes an invariant (with reset unused and removed)
>
> Claes Redestad has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Add back Node::lookup: used by ppc

Looks good.

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Marked as reviewed by neliasso (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/1223