[jdk17u-dev] RFR: 8287396: LIR_Opr::vreg_number() and data() can return negative number

[Goetz Lindenmaier]

I backport this for parity with 17.0.5-oracle.

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Commit messages:
 - Backport cdb476888a65b8ee2538f08b4b1dbb245874a262

Changes: https://git.openjdk.org/jdk17u-dev/pull/502/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=502&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8287396
  Stats: 8 lines in 1 file changed: 2 ins; 1 del; 5 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/502.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev pull/502/head:pull/502

PR: https://git.openjdk.org/jdk17u-dev/pull/502