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

[Christian Hagedorn]

On Wed, 30 Aug 2023 14:39:11 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/multnode.cpp line 226:
> 
>> 224: 
>> 225:   // we need a ParsePredicate node for predicate reasons
>> 226:   if (reason != Deoptimization::Reason_none && !iff->is_ParsePredicate()) {
> 
> Unrelated to your change but this code doesn't seem to do what the comment says. `reason != Deoptimization::Reason_none` is not "predicate reasons". I think this needs to be cleaned up at some point.

You're right. I've had a look at all the usages if `is_uncommon_trap_if_pattern()` and it seems that we only use this method for `Reason_none. So, I think I can simplify this method. I can do it in this PR as I'm touching this code here.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/15449#discussion_r1310409215