RFR: 8375657: RISC-V: Need to check size in SharedRuntime::is_wide_vector

[Dingli Zhang]

Hi,
Can you help to review this patch? Thanks!

Currently, we only check `UseRVV` flag in `SharedRuntime::is_wide_vector` on RISC-V platforms. This is not optimal when no vector instructions is used by the nmethod. In this case, the the input size parameter is zero. We should consider this case so that we choose the right sub in `SharedRuntime::get_poll_stub` when handling safepoint.

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Commit messages:
 - 8375657: RISC-V: Need to check size in SharedRuntime::is_wide_vector

Changes: https://git.openjdk.org/jdk/pull/29307/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=29307&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8375657
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/29307.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29307/head:pull/29307

PR: https://git.openjdk.org/jdk/pull/29307