RFR: 8320649: C2: Optimize scoped values [v7]

[Emanuel Peter]

On Thu, 8 Feb 2024 09:32:43 GMT, Roland Westrelin <roland at openjdk.org> wrote:

>> src/hotspot/share/gc/shared/c2/barrierSetC2.hpp line 190:
>> 
>>> 188: class C2OptAccess: public C2Access {
>>> 189:   PhaseGVN& _gvn;
>>> 190:   Node* _mem;
>> 
>> Hmm. It is a little strange to have a `_mem` node that is not even a `MemNode*`. What types are expected here?
>
> `_mem` is some node that carry memory state. `MemNode` is not the super type of all nodes that modify memory state. It's not even a super type of some of the nodes that modify memory state (`LoadNode` doesn't). Such a super type doesn't exist.

Ok. Fair enough.

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PR Review Comment: https://git.openjdk.org/jdk/pull/16966#discussion_r1482738268