[jdk26] RFR: 8374195: TestReplaceNarrowPhiWithBottomPhi fails on ppc64 platforms in (fast)debug

[Martin Doerr]

Clean backport of [JDK-8374195](https://bugs.openjdk.org/browse/JDK-8374195).

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Commit messages:
 - Backport e4e923a1ffc8ff059c983c7e9201d0ee3273482d

Changes: https://git.openjdk.org/jdk/pull/29162/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=29162&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8374195
  Stats: 2 lines in 1 file changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/29162.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29162/head:pull/29162

PR: https://git.openjdk.org/jdk/pull/29162