[lworld] RFR: 8372729: [lworld] Incorrect result of acmp with flat, nullable value class field [v2]

[Chen Liang]

> LayoutIteration is missing null markers. Added the test from tobias to SubstitutabilityTest.

Chen Liang has updated the pull request incrementally with one additional commit since the last revision:

  Need to add delta

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

Changes:
  - all: https://git.openjdk.org/valhalla/pull/1790/files
  - new: https://git.openjdk.org/valhalla/pull/1790/files/f5ddda7b..18e5c26f

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=valhalla&pr=1790&range=01
 - incr: https://webrevs.openjdk.org/?repo=valhalla&pr=1790&range=00-01

  Stats: 30 lines in 2 files changed: 21 ins; 3 del; 6 mod
  Patch: https://git.openjdk.org/valhalla/pull/1790.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1790/head:pull/1790

PR: https://git.openjdk.org/valhalla/pull/1790