RFR: 8255400: Shenandoah: C2 failures after JDK-8255000

[Roman Kennke]

On Mon, 2 Nov 2020 09:51:01 GMT, Roland Westrelin <roland at openjdk.org> wrote:

> At barrier expansion time, the IR graph may contain a Halt node whose
> control is a region. In that case, code that wires raw memory creates
> a memory Phi at the region. But that Phi has no use because the Halt
> node doesn't consume any memory. That dead Phi causes the assert to
> trigger. I propose some adjustments so a Phi is not created in that
> case.

Looks good to me! Thank you!

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Marked as reviewed by rkennke (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/1000