[jdk25u-dev] RFR: 8376572: RISC-V: Interpreter: Load array index as signed int

[Fei Yang]

Hi all,

This pull request contains a backport of commit [3a327577](https://github.com/openjdk/jdk/commit/3a32757743b459902aa97092d95eb9b0cb3099d6) from the [openjdk/jdk](https://git.openjdk.org/jdk) repository.

The commit being backported was authored by Feilong Jiang on 2 Feb 2026 and was reviewed by Fei Yang and Dingli Zhang.

Thanks!

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Commit messages:
 - Backport 3a32757743b459902aa97092d95eb9b0cb3099d6

Changes: https://git.openjdk.org/jdk25u-dev/pull/216/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk25u-dev&pr=216&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8376572
  Stats: 6 lines in 1 file changed: 0 ins; 1 del; 5 mod
  Patch: https://git.openjdk.org/jdk25u-dev/pull/216.diff
  Fetch: git fetch https://git.openjdk.org/jdk25u-dev.git pull/216/head:pull/216

PR: https://git.openjdk.org/jdk25u-dev/pull/216