[jdk21u] RFR: 8314580: PhaseIdealLoop::transform_long_range_checks fails with assert "was tested before"

[Aleksey Shipilev]

Clean backport to improve C2 stability.

Additional testing:
 - [x] New regression test fails without fix, passes with it
 - [ ] Linux AArch64 server fastdebug, `tier1 tier2 tier3`

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Commit messages:
 - Backport 9def4538ab5456d689fd289bdef66fd1655773bc

Changes: https://git.openjdk.org/jdk21u/pull/316/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk21u&pr=316&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8314580
  Stats: 52 lines in 2 files changed: 46 ins; 4 del; 2 mod
  Patch: https://git.openjdk.org/jdk21u/pull/316.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u.git pull/316/head:pull/316

PR: https://git.openjdk.org/jdk21u/pull/316