[jdk20] RFR: 8298225: [AIX] Disable PPC64LE continuations on AIX

[Martin Doerr]

On Thu, 8 Dec 2022 18:56:10 GMT, Tyler Steele <tsteele at openjdk.org> wrote:

> This small change adds an import to ppc.ad to allow it to find Contiuations::enabled, and sets VMContinuations to false on AIX.
> 
> Thanks to @TheRealMDoerr for suggestions to a previous version of this PR.

Ok, switching it off for AIX makes sense for JDK 20. Do you know what's wrong on that OS? I believe there's not much missing. I recommend trying test/jdk/java/lang/Thread/virtual/stress tests and debugging it on linux PPC64 Big Endian. Maybe the frame header size is the problem which could cause GC to look at the wrong fields for example.
(But, you can integrate this fix and continue in JDK 21.)

src/hotspot/cpu/ppc/ppc.ad line 14378:

> 14376: 
> 14377: source %{
> 14378:   #include "runtime/continuation.hpp"

I usually avoid spaces in front of preprocessor directives. But, I guess it's no longer problematic with recent compilers.

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Marked as reviewed by mdoerr (Reviewer).

PR: https://git.openjdk.org/jdk20/pull/4