[jdk17u-dev] RFR: 8303279: C2: crash in SubTypeCheckNode::sub() at IGVN split if

[Ben Taylor]

Backport is nearly clean, because https://bugs.openjdk.org/browse/JDK-8275201 has not been backported.
Only context lines in `src/hotspot/share/opto/subtypenode.cpp` differ, the assert itself is unmodified.

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Commit messages:
 - Backport caadad4fdc78799dab2d492dba9b9f74b22d036e

Changes: https://git.openjdk.org/jdk17u-dev/pull/1580/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=1580&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8303279
  Stats: 110 lines in 7 files changed: 94 ins; 4 del; 12 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/1580.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/1580/head:pull/1580

PR: https://git.openjdk.org/jdk17u-dev/pull/1580