RFR: 8327647: Occasional SIGSEGV in markWord::displaced_mark_helper() for SPECjvm2008 sunflow [v2]

[Matias Saavedra Silva]

> A misplaced memory barrier causes a very intermittent crash on on some aarch64 systems. This patch adds an appropriate LoadLoad barrier after a constant pool cache field entry is loaded. Verified with tier 1-5 tests.

Matias Saavedra Silva has updated the pull request incrementally with one additional commit since the last revision:

  Moved membar inside load_field_entry

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Changes:
  - all: https://git.openjdk.org/jdk/pull/18477/files
  - new: https://git.openjdk.org/jdk/pull/18477/files/60925369..4f976405

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=18477&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18477&range=00-01

  Stats: 26 lines in 5 files changed: 6 ins; 20 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/18477.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18477/head:pull/18477

PR: https://git.openjdk.org/jdk/pull/18477