RFR: 8295110: RISC-V: Mark out relocations as incompressible [v7]

[Xiaolin Zheng]

> This patch marks all relocations incompressible as pre-discussions at [1] and converts instructions to their 2-byte compressible counterparts as much as possible when UseRVC is enabled.
> 
> Chaining PR #10421.
> 
> 1. Code size reduction rate: about ~17% now after this patch under RVC, meaning if there's a piece of code of 1000 bytes, it may shrink to 830 bytes when RVC is enabled. [2]
> 2. Performance: conservatively no regressions observed. [3]
> 
> The overloaded `relocate()` methods hide `IncompressibleRegion`s inside, to exclude instructions used at relocations from being compressed.
> 
> 
> Having tested several times hotspot tier1~tier4; Testing another turn on board.
> 
> 
> 
> [1] https://mail.openjdk.org/pipermail/riscv-port-dev/2022-September/000615.html
> [2] https://mail.openjdk.org/pipermail/riscv-port-dev/2022-September/000633.html
> [3] https://mail.openjdk.org/pipermail/riscv-port-dev/2022-October/000656.html

Xiaolin Zheng has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains eight commits:

 - Merge remote-tracking branch 'jdk20/master' into riscv-rvc-checkin-second-half-part
 - Merge branch 'master' into riscv-rvc-checkin-second-half-part
 - Keep aligning int32_t style
 - remove a dummy line, and a simple polish by the way
 - swap the order
 - Change the style as to comments
 - [7] Blacklist mode
 - [6] RVC: IncompressibleRegions for relocations

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Changes: https://git.openjdk.org/jdk/pull/10643/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10643&range=06
  Stats: 312 lines in 12 files changed: 148 ins; 3 del; 161 mod
  Patch: https://git.openjdk.org/jdk/pull/10643.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10643/head:pull/10643

PR: https://git.openjdk.org/jdk/pull/10643