[riscv-port-jdk17u:riscv-port] RFR: 8294366: RISC-V: Partially mark out incompressible regions [v3]

[Xiaolin Zheng]

> One little difference: there is no `C2_MacroAssembler::emit_entry_barrier_stub` on JDK17.
> 
> Tested along with remaining patches, hotspot tier1~4 with fastdebug build.

Xiaolin Zheng has refreshed the contents of this pull request, and previous commits have been removed. Incremental views are not available. The pull request now contains one commit:

  8294366: RISC-V: Partially mark out incompressible regions
  
  Reviewed-by: fyang, yadongwang

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Changes:
  - all: https://git.openjdk.org/riscv-port-jdk17u/pull/28/files
  - new: https://git.openjdk.org/riscv-port-jdk17u/pull/28/files/b3f970ad..90f0054f

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=riscv-port-jdk17u&pr=28&range=02
 - incr: https://webrevs.openjdk.org/?repo=riscv-port-jdk17u&pr=28&range=01-02

  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/riscv-port-jdk17u/pull/28.diff
  Fetch: git fetch https://git.openjdk.org/riscv-port-jdk17u.git pull/28/head:pull/28

PR: https://git.openjdk.org/riscv-port-jdk17u/pull/28