[jdk17u-dev] RFR: 8287349: AArch64: Merge LDR instructions to improve C1 OSR performance

[Dmitry Chuyko]

Straightforward replacement to pair load-store instructions, applies cleanly.

Testing: jtreg tier1, tier2 on linux-aarch64.

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Commit messages:
 - Backport 08400f18badb23ea3d00282e8b71e76844398a67

Changes: https://git.openjdk.org/jdk17u-dev/pull/661/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=661&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8287349
  Stats: 3 lines in 1 file changed: 0 ins; 1 del; 2 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/661.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev pull/661/head:pull/661

PR: https://git.openjdk.org/jdk17u-dev/pull/661