[jdk21u-dev] RFR: 8328085: C2: Use after free in PhaseChaitin::Register_Allocate()

[Richard Reingruber]

Hi all,

This pull request contains a backport of commit https://github.com/openjdk/jdk/commit/93aa7e2fcf87c4dc62de4ea71be543ee677b11be.

The commit being backported was authored by Richard Reingruber on 21 Nov 2024 and was reviewed by Tobias Hartmann and Martin Doerr.

The original commit did not apply because the `TracePhase` constructor used above the removed line was changed.

The fix passed our CI testing: JTReg tests: tier1-4 of hotspot and jdk. All of Langtools and jaxp. JCK, SPECjvm2008, SPECjbb2015, Renaissance Suite, and SAP specific tests.
Testing was done with fastdebug builds on the main platforms and also on Linux/PPC64le and AIX.

Thanks, Richard.

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Commit messages:
 - 8328085: C2: Use after free in PhaseChaitin::Register_Allocate()

Changes: https://git.openjdk.org/jdk21u-dev/pull/1217/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=1217&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8328085
  Stats: 1 line in 1 file changed: 0 ins; 1 del; 0 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/1217.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/1217/head:pull/1217

PR: https://git.openjdk.org/jdk21u-dev/pull/1217