RFR: 8319373: Serial: Refactor dirty cards scanning during Young GC

Fri Nov 3 12:43:19 UTC 2023

Reading the new code directly is probably easier. The structure is quite similar to its counterpart in Parallel.

It's mostly perf-neutral, except when dirty cards are scarce. Using `card_scan.java` in [JDK-8310031](https://bugs.openjdk.org/browse/JDK-8310031), I observed ~40% reduction in young-gc pause time with `stride = 32 * 64`.

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Commit messages:
 - s1-young-gc

Changes: https://git.openjdk.org/jdk/pull/16492/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16492&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8319373
  Stats: 470 lines in 4 files changed: 187 ins; 270 del; 13 mod
  Patch: https://git.openjdk.org/jdk/pull/16492.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16492/head:pull/16492

PR: https://git.openjdk.org/jdk/pull/16492