RFR: 8253644: C2: assert(skeleton_predicate_has_opaque(iff)) failed: unexpected [v2]

[Christian Hagedorn]

On Mon, 30 Nov 2020 18:12:54 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

>> Christian Hagedorn has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Add back accidentally removed execution of test2-5.
>
> Good.
> 
> I suggest to merge latest source and re-test again. I am concern that some Git testing failed.

> > Could that be improved? But as of the current implementation, the `Opaque4` node with its inputs is shared between a fast and a slow loop. So we could not remove the `Opaque4` node when either the fast or slow loop does not need it anymore while the other one does.
> 
> Right. Yes, I think it would make sense to remove the skeleton predicates that become useless. Anyway, your fix looks good to me.

Thanks for your careful review! I filed [JDK-8257498](https://bugs.openjdk.java.net/browse/JDK-8257498) to also eliminate useless skeleton predicates.

> Good.
> 
> I suggest to merge latest source and re-test again. I am concern that some Git testing failed.

Thanks for your review! Good idea, I will do that and start some more testing.

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PR: https://git.openjdk.java.net/jdk/pull/1448