[lworld] RFR: 8355397: [lworld] Parse::array_load fails with "array can't be flat" assert [v2]

[Quan Anh Mai]

> Hi,
> 
> The issue here is that `InstanceKlass::flat_array` is too strict and it rejects any class that is atomic and has more than 1 field. I remove the unnecessary restrictions and rename the method to `maybe_flat_in_array` to illustrate the functionality in a clearer manner.
> 
> Please kindly review, thanks a lot.

Quan Anh Mai 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 three additional commits since the last revision:

 - Merge branch 'lworld' into flatinarray
 - add tests
 - fix InstanceKlass::flat_array

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

Changes:
  - all: https://git.openjdk.org/valhalla/pull/1446/files
  - new: https://git.openjdk.org/valhalla/pull/1446/files/fcfd9334..55e444a6

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=valhalla&pr=1446&range=01
 - incr: https://webrevs.openjdk.org/?repo=valhalla&pr=1446&range=00-01

  Stats: 304 lines in 6 files changed: 278 ins; 2 del; 24 mod
  Patch: https://git.openjdk.org/valhalla/pull/1446.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1446/head:pull/1446

PR: https://git.openjdk.org/valhalla/pull/1446