RFR: 8305637: Remove Opaque1 nodes for Parse Predicates and clean up useless predicate elimination [v2]

[Christian Hagedorn]

On Mon, 28 Aug 2023 14:55:25 GMT, Roland Westrelin <roland at openjdk.org> wrote:

>> Christian Hagedorn has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   remove hash_delete()
>
> src/hotspot/share/opto/loopPredicate.cpp line 314:
> 
>> 312:   assert(new_predicate_proj->is_IfTrue(), "the success projection of a Parse Predicate is a true projection");
>> 313:   ParsePredicateNode* parse_predicate = new_predicate_proj->in(0)->as_ParsePredicate();
>> 314:   _igvn.hash_delete(parse_predicate);
> 
> That looks strange. Wasn't the reason for the `hash_delete` in the previous version of the code that the `iff` was then modified. Is it still needed?

You're right. That `hash_delete()` is not needed anymore. Removed.

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PR Review Comment: https://git.openjdk.org/jdk/pull/15449#discussion_r1308358506