RFR: 8351844: C2 x64 AVX2 vpminmax assertion failure with equivalent inputs

[Jatin Bhateja]

Bug fix PR fixes an incorrect register equivalence in macro assembler. MaxV/MinV IR with equivalent inputs should ideally be removed from ideal graph before reaching to macro assembler. [JDK-8372797](https://bugs.openjdk.org/browse/JDK-8372797) is filed to add relevant identity transformations.

Best Regards,
Jatin

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Commit messages:
 - 8351844: C2 x64 AVX2 vpminmax assertion failure with equivalent inputs

Changes: https://git.openjdk.org/jdk/pull/28600/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=28600&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8351844
  Stats: 70 lines in 2 files changed: 68 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/28600.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28600/head:pull/28600

PR: https://git.openjdk.org/jdk/pull/28600