RFR: 8331711: G1 doesn't need pre write barrier for stores from new allocated objects

[Liang Mao]

The pre-write barrier of G1 is used to capture the object disconnected from the marking graph which could be unmarked aka *white* and stored into *black* objects then break tri-color invariance. But references in new allocated objects are created in object initialization after marking start and never could be white. So we don't need pre-write barrier for stores from new allocated objects. The same mechanism is also used for barrier eliminantion in GenZGC.

Additional testing:
 - [x] Linux aarch64 server release/fastdebug, test/hotspot/jtreg/gc with +UseG1GC
 - [x] Run several iterations of SPECjbb2015 with aggressively frequent concurrent mark

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Commit messages:
 - 8331711: G1 doesn't need pre write barrier for stores from new allocated objects

Changes: https://git.openjdk.org/jdk/pull/19098/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=19098&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8331711
  Stats: 7 lines in 1 file changed: 6 ins; 1 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/19098.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19098/head:pull/19098

PR: https://git.openjdk.org/jdk/pull/19098