RFR: 8301036: RISC-V: Factor out functions baseOffset & baseOffset32 from MacroAssembler [v3]

[Fei Yang]

> On RISC-V, functions baseOffset & baseOffset32 from MacroAssembler receive an Address in base_plus_offset mode. These two functions check the range of the offset, add it and base and put the result in a destination register. This duplicates function MacroAssembler::la in functionality. We could refactor this part moving the logic of Address legitimization into MacroAssembler::la and use this function instead.
> 
> Testing:
>   - [x] Bootcycle (release & fastdebug)
>   - [x] Tier1-4 (release)
>   - [x] Benchmarks: SPECjbb2015 (release)

Fei Yang has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains five additional commits since the last revision:

 - Fix
 - Merge branch 'master' into JDK-8301036
 - Comment
 - Merge branch 'master' into JDK-8301036
 - 8301036: RISC-V: Factor out functions baseOffset & baseOffset32 from MacroAssembler

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/12177/files
  - new: https://git.openjdk.org/jdk/pull/12177/files/c617b7f8..ff5de19c

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=12177&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=12177&range=01-02

  Stats: 3512 lines in 160 files changed: 1209 ins; 1045 del; 1258 mod
  Patch: https://git.openjdk.org/jdk/pull/12177.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12177/head:pull/12177

PR: https://git.openjdk.org/jdk/pull/12177