RFR: 8345178: RISC-V: Add gtests for narrow cmpxchg

[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

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

Commit messages:
 - gtest narrow cmpxchg

Changes: https://git.openjdk.org/jdk/pull/22445/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=22445&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8345178
  Stats: 87 lines in 1 file changed: 87 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