RFR: 8265132 : C2 compilation fails with assert "missing precedence edge" [v4]

[Jamsheed Mohammed C M]

On Thu, 17 Jun 2021 19:22:02 GMT, Dean Long <dlong at openjdk.org> wrote:

>> AFAIU reinit is ok. it is not reinitialized as it holds unique value.
>> https://github.com/openjdk/jdk/blob/master/src/hotspot/share/opto/block.hpp#L214
>
> I took another look, and it looks safe, but I'm concerned that it will cause raise_LCA_above_marks to do more work.  Don't you think there might be a performance impact?  Have you measured performance?
> 
> I still don't understand what inconsistency state this tries to solve, or how it solves it.

raise_LCA_above_marks checks and marks visited bits from LCA and  move upward. i am trying to be safe by clearing visited bits where we don't use calculated LCA. marking visited and not used cases only get impacted.
Only performance issue is explicit clearing logic i guess.

Inconsistency  is marking visited and not using the newly computed LCA. but yes inconsistency can never happen as all the cases are computed by this time. and new store interfering  the loads can seldom come. but i was trying to be safe.

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PR: https://git.openjdk.java.net/jdk/pull/4200