RFR: 8321278: C2: Partial peeling fails with assert "last_peel <- first_not_peeled" [v3]

[Tobias Hartmann]

On Fri, 22 Mar 2024 16:48:35 GMT, Roland Westrelin <roland at openjdk.org> wrote:

>> The assert fails because peeling happens at a single entry
>> `Region`. That `Region` only has a single input because other inputs
>> were found unreachable and removed by
>> `PhaseIdealLoop::Dominators()`. The fix I propose is to have
>> `PhaseIdealLoop::Dominators()` remove the `Region` and its `Phi`s
>> entirely in this case.
>
> Roland Westrelin has updated the pull request incrementally with one additional commit since the last revision:
> 
>   review

Looks good to me too.

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Marked as reviewed by thartmann (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/18353#pullrequestreview-1957586830