RFR: 8343747: C2: TestReplicateAtConv.java crashes with -XX:MaxVectorSize=8 [v2]

[Roland Westrelin]

> Crash occurs when attempting to create a `Replicate` node that's input
> to a `VectorCast` node (for a `ConvL2I`) that's not supported by the
> platform (when run with `MaxVectorSize=8`). I think the pack for the
> `VectorCast` should be filtered out earlier as not implemented and I
> propose adding a test to `VectorCastNode::implemented()` for the type
> of its input to handle that corner case.

Roland Westrelin has updated the pull request incrementally with one additional commit since the last revision:

  review

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/22442/files
  - new: https://git.openjdk.org/jdk/pull/22442/files/ecc9a7b7..faacb5d7

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=22442&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=22442&range=00-01

  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/22442.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22442/head:pull/22442

PR: https://git.openjdk.org/jdk/pull/22442