[jdk17u-dev] RFR: 8271579: G1: Move copy before CAS in do_copy_to_survivor_space

[Dmitry Chuyko]

Small change in G1 with good performance effect. Original patch applies cleanly.

Testing: jtreg tier1 & gc (aarch64 build).

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Commit messages:
 - Backport d874e9616f80324a53f3c8866ce500e55dfa308f

Changes: https://git.openjdk.java.net/jdk17u-dev/pull/42/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk17u-dev&pr=42&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8271579
  Stats: 13 lines in 1 file changed: 1 ins; 11 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk17u-dev/pull/42.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk17u-dev pull/42/head:pull/42

PR: https://git.openjdk.java.net/jdk17u-dev/pull/42