RFR: JDK-8302594: use-after-free in Node::destruct

Wed Feb 15 16:37:31 UTC 2023

Instrumenting Arena for ASan revealed some `use-after-free` behavior in C2. One of them is in `Node::destruct`, where the storage for `Node` is free'd and then fields are accessed. Thankfully none of the methods called allocate, but they could in the future. To resolve this, we move the calls to `Afree` to the end of `Node::destruct`.

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Commit messages:
 - use-after-free in Node::destruct

Changes: https://git.openjdk.org/jdk/pull/12577/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=12577&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8302594
  Stats: 44 lines in 1 file changed: 23 ins; 20 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/12577.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12577/head:pull/12577

PR: https://git.openjdk.org/jdk/pull/12577