RFR: 8370774: Merge ModRefBarrierSet into CardTableBarrierSet

Tue Oct 28 09:28:15 UTC 2025

Merge a class into its sole subclass.

Many files are changed in this PR, and they can be largely divided into two groups, moving content of `ModRefBarrierSet` into `CardTableBarrierSet` (`src/hotspot/share/gc/`) and platform specific moving content of `ModRefBarrierSetAssembler` into `CardTableBarrierSetAssembler` (`src/hotspot/cpu/`).

Test: tier1-5 for x64 and aarch64; GHA

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Commit messages:
 - merge-barrier-set

Changes: https://git.openjdk.org/jdk/pull/28013/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=28013&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8370774
  Stats: 2066 lines in 60 files changed: 633 ins; 1368 del; 65 mod
  Patch: https://git.openjdk.org/jdk/pull/28013.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28013/head:pull/28013

PR: https://git.openjdk.org/jdk/pull/28013