RFR: 8261957: [PPC64] Support for Concurrent Thread-Stack Processing

[Lutz Schmidt]

On Fri, 5 Mar 2021 09:58:35 GMT, Martin Doerr <mdoerr at openjdk.org> wrote:

> I'd like to support Concurrent Thread-Stack Processing on PPC64. This will be needed by ShenandoahGC and zGC when implemented. Maybe for other purposes in the future, too.
> I'm using conditional trap instructions by default, so we don't need the extra stubs unless -XX:-UseSIGTRAP is used.
> 
> Original change: https://github.com/openjdk/jdk/commit/b9873e18

The changes look good to me. 
I had only one minor suggestion. It's your choice to accept or disregard it. 
Thank you for contributing this enhancement!

src/hotspot/cpu/ppc/macroAssembler_ppc.cpp line 3069:

> 3067:       fp = R0;
> 3068:       ld(fp, _abi0(callers_sp), R1_SP);
> 3069:     }

You could move this block down into the else path, preceding the cmpld()

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Marked as reviewed by lucy (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/2841