[jdk21u] RFR: 8313262: C2: Sinking node may cause required cast to be dropped [v3]

[Aleksey Shipilev]

> Clean backport to fix recent JDK 21 backport regression.
> 
> Additional testing:
>  - [x] New test fails without the fix, passes with it
>  - [x] Linux x86_64 AArch64 `tier1 tier2 tier3`

Aleksey Shipilev 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 'master' into JDK-8313262-c2-sinking-node-cast
 - Merge branch 'master' into JDK-8313262-c2-sinking-node-cast
 - Backport 1cee3b9fd9720e7938029a6992460b9053e65e57

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

Changes:
  - all: https://git.openjdk.org/jdk21u/pull/99/files
  - new: https://git.openjdk.org/jdk21u/pull/99/files/6f95682e..8b42299c

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk21u&pr=99&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk21u&pr=99&range=01-02

  Stats: 103 lines in 19 files changed: 71 ins; 13 del; 19 mod
  Patch: https://git.openjdk.org/jdk21u/pull/99.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u.git pull/99/head:pull/99

PR: https://git.openjdk.org/jdk21u/pull/99