[jdk17u-dev] RFR: 8276799: Implementation of JEP 422: Linux/RISC-V Port

[Fei Yang]

The RISC-V port was originally developed at Huawei Technologies, then integrated into OpenJDK 19.

The 17u version of the port has continued to be maintained in the openjdk/riscv-port-jdk17u repo later
and has been tested for several months. There are few changes to shared HotSpot code (mostly the main
one is C1 conditional move/branch support for RISC-V). As required by 17u maintainer, changes to shared
code has been kept to a minimum. Only enabling shared changes are incorporated and these changes are
properly guarded with macro RISCV. So this 17u port should not breaking existing code and, although it is
a large patch, finally integrating it into 17u upstream should be low risk.

Testing on linux-riscv64 platform:
- [x] Bootcycle (release build)
- [x] Tier1-4 tests (release build)
- [x] Benchmark workloads (Dacapo, SPECJbb2015, SPECJVM2008, Renaissance, etc.)

-------------

Commit messages:
 - 8305236: Some LoadLoad barriers in the interpreter are unnecessary after JDK-8220051
 - Merge remote-tracking branch 'upstream/master' into jep422-17u-backport
 - Merge remote-tracking branch 'upstream/master' into jep422-17u-backport
 - 8276799: Implementation of JEP 422: Linux/RISC-V Port

Changes: https://git.openjdk.org/jdk17u-dev/pull/1427/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=1427&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8276799
  Stats: 60287 lines in 188 files changed: 60152 ins; 43 del; 92 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/1427.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/1427/head:pull/1427

PR: https://git.openjdk.org/jdk17u-dev/pull/1427