[jdk17u] RFR: 8276927: [ppc64] Port shenandoahgc to linux on ppc64le

[Aleksey Shipilev]

On Thu, 18 Nov 2021 20:51:17 GMT, Martin Doerr <mdoerr at openjdk.org> wrote:

> Backport of 8276927: [PPC64] Port shenandoahgc to linux on ppc64le.
> Applies cleanly, but a trivial resolution is required: add additional parameter `, false /*unaligned*/` to `mem2reg` in `ShenandoahBarrierSetAssembler::gen_pre_barrier_stub`.
> This is needed because "8269672: C1: Remove unaligned move on all architectures" is not in 17u.

Looks fine. Since this is a new thing that slides into PPC code cleanly, we have a rather low risk of regressions. But it would be nice to have mainline tested a bit with this change, at least to make sure it does not break the builds.

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Marked as reviewed by shade (Reviewer).

PR: https://git.openjdk.java.net/jdk17u/pull/287