RFR: 8297445: PPC64: Represent Registers as values

Tue Nov 22 18:19:44 UTC 2022

The recent Register implementation uses wild pointer (including null pointer) dereferences which exhibit undefined behavior. We should migrate away from pointer-based representation of Register values as it was done for x86 ([JDK-8292153](https://bugs.openjdk.org/browse/JDK-8292153)). Problems exist when trying to build with GCC 11 ([JDK-8297426](https://bugs.openjdk.org/browse/JDK-8297426)).

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Commit messages:
 - 8297445: PPC64: Represent Registers as values

Changes: https://git.openjdk.org/jdk/pull/11297/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=11297&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8297445
  Stats: 814 lines in 13 files changed: 163 ins; 429 del; 222 mod
  Patch: https://git.openjdk.org/jdk/pull/11297.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11297/head:pull/11297

PR: https://git.openjdk.org/jdk/pull/11297