[jdk18] RFR: 8277447: Hotspot C1 compiler crashes on Kotlin suspend fun with loop

[Nils Eliasson]

On Thu, 16 Dec 2021 22:47:23 GMT, Igor Veresov <iveresov at openjdk.org> wrote:

> There are a bunch of problems with `BlockListBuilder::mark_loops()` and how it handles irreducible loops. It doesn't really seem to be explicitly designed to handle those, however, it does handle most. One shape emitted by the Kotlin compiler in this particular case gives it trouble.
> 
> The proper fix is to rewrite loop detection, detect irreducible loops, and switch off `SelectivePhiFunctions` is any are present. But given that we're close to the release, I'd like to add a bailout during phi insertion, and file an RFE to do the proper fix later.
> 
> I wrote a minimal test to demonstrate the issue.
> 
> Testing with hs-tier{1-7} is squeaky clean.

Looks good.

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Marked as reviewed by neliasso (Reviewer).

PR: https://git.openjdk.java.net/jdk18/pull/40