[lworld] RFR: 8220710: [lworld] Improve propagation of nullability information

[Tobias Hartmann]

There are cases where C2 is not able to keep track of the fact that an inline type is never null. For example, after
explicit null checks and implicit receiver null checks on MyValue.ref.

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Commit messages:
 - 8220710: [lworld] Improve propagation of nullability information

Changes: https://git.openjdk.java.net/valhalla/pull/118/files
 Webrev: https://webrevs.openjdk.java.net/valhalla/118/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8220710
  Stats: 64 lines in 2 files changed: 64 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/valhalla/pull/118.diff
  Fetch: git fetch https://git.openjdk.java.net/valhalla pull/118/head:pull/118

PR: https://git.openjdk.java.net/valhalla/pull/118