RFR: 8295069: [PPC64] Performance regression after JDK-8290025 [v2]

[Martin Doerr]

> I have a proposal to mitigate the performance regression (see JBS issue) on PPC64 significantly. We get most of the performance back. Please review. May also be relevant for aarch64 which I haven't checked.
> I'm checking explicitly for GCs which are known to be safe. Maybe there is a better way to check this.

Martin Doerr has updated the pull request incrementally with one additional commit since the last revision:

  Implement like on aarch64.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/10632/files
  - new: https://git.openjdk.org/jdk/pull/10632/files/7c19cb17..99d133ba

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=10632&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=10632&range=00-01

  Stats: 17 lines in 5 files changed: 13 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/10632.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10632/head:pull/10632

PR: https://git.openjdk.org/jdk/pull/10632