RFR: 8345178: RISC-V: Add gtests for narrow cmpxchg [v4]

[Robbin Ehn]

> Hi, please consider.
> 
> This adds tests of aligned narrow cmpxchg.
> 
> 
> Note: Google Test filter = *RiscV*
> [==========] Running 5 tests from 1 test suite.
> [----------] Global test environment set-up.
> [----------] 5 tests from RiscV
> ...
> [ RUN      ] RiscV.cmpxchg_int16_lr_sc_vm
> [       OK ] RiscV.cmpxchg_int16_lr_sc_vm (2 ms)
> [ RUN      ] RiscV.cmpxchg_int8_lr_sc_vm
> [       OK ] RiscV.cmpxchg_int8_lr_sc_vm (1 ms)
> [ RUN      ] RiscV.cmpxchg_int16_maybe_zacas_vm
> [       OK ] RiscV.cmpxchg_int16_maybe_zacas_vm (1 ms)
> [ RUN      ] RiscV.cmpxchg_int8_maybe_zacas_vm
> [       OK ] RiscV.cmpxchg_int8_maybe_zacas_vm (1 ms)
> [----------] 5 tests from RiscV (20831 ms total)
> 
> [----------] Global test environment tear-down
> [==========] 5 tests from 1 test suite ran. (20834 ms total)
> [  PASSED  ] 5 tests.
> 
> 
> Executed with -XX:+UnlockExperimentalVMOptions -XX:+UseZacas
> 
> Thanks, Robbin

Robbin Ehn has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains four commits:

 - Merge branch 'master' into narrow
 - Review comment
 - Remove CMF barrier
 - gtest narrow cmpxchg

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

Changes: https://git.openjdk.org/jdk/pull/22445/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=22445&range=03
  Stats: 81 lines in 1 file changed: 81 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/22445.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22445/head:pull/22445

PR: https://git.openjdk.org/jdk/pull/22445