[jdk23u] RFR: 8342014: RISC-V: ZStoreBarrierStubC2 clobbers rflags [v2]

[Gui Cao]

> Hi, The same issue also exists in the jdk23u. I would like to backport this to jdk23u. becasue jdk23u not have [JDK-8334060](https://bugs.openjdk.org/browse/JDK-8334060), so this backport is not clean. This is a risc-v specific change, risk is low.
> 
> # Testing
> - [ ]  Run tier1-3 tests on SOPHON SG2042 (release)

Gui Cao 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 two additional commits since the last revision:

 - Merge remote-tracking branch 'upstream/master' into backport-JDK-8342014
 - Backport 8342014: RISC-V: ZStoreBarrierStubC2 clobbers rflags

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

Changes:
  - all: https://git.openjdk.org/jdk23u/pull/176/files
  - new: https://git.openjdk.org/jdk23u/pull/176/files/3b2623c3..f2a69a79

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk23u&pr=176&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk23u&pr=176&range=00-01

  Stats: 3 lines in 1 file changed: 0 ins; 2 del; 1 mod
  Patch: https://git.openjdk.org/jdk23u/pull/176.diff
  Fetch: git fetch https://git.openjdk.org/jdk23u.git pull/176/head:pull/176

PR: https://git.openjdk.org/jdk23u/pull/176