RFR: 8365570: C2 fails assert(false) failed: Unexpected node in SuperWord truncation: CastII [v3]

[Jasmine Karthikeyan]

> Hi all,
> This is a quick patch for the assert failure in superword truncation with CastII. I've added a check for all constraint cast nodes, and attached a reduced version of the fuzzer test. Thanks!

Jasmine Karthikeyan 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 four additional commits since the last revision:

 - Remove CompLevel.C2 from test
 - Merge branch 'master' into jdk-8365570
 - Update comment for constraint casts
 - Fix truncation assert for constraint casts

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/26827/files
  - new: https://git.openjdk.org/jdk/pull/26827/files/d6c81a9d..f433930e

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=26827&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=26827&range=01-02

  Stats: 600645 lines in 6681 files changed: 411649 ins; 119944 del; 69052 mod
  Patch: https://git.openjdk.org/jdk/pull/26827.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26827/head:pull/26827

PR: https://git.openjdk.org/jdk/pull/26827