RFR: 8330145: Serial: Refactor SerialHeap::scan_evacuated_objs [v2]

[Albert Mingkun Yang]

> Simple refactoring to extract oop-scanning logic from generation.

Albert Mingkun Yang has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains four additional commits since the last revision:

 - Merge branch 'master' into s1-scan-evac-obj
 - review
 - Merge branch 'master' into s1-scan-evac-obj
 - s1-scan-evac-obj

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/18750/files
  - new: https://git.openjdk.org/jdk/pull/18750/files/f206380f..eb7a3665

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=18750&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18750&range=00-01

  Stats: 24073 lines in 410 files changed: 10675 ins; 11892 del; 1506 mod
  Patch: https://git.openjdk.org/jdk/pull/18750.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18750/head:pull/18750

PR: https://git.openjdk.org/jdk/pull/18750