RFR: 8347718: Unexpected NullPointerException in C2 compiled code due to ReduceAllocationMerges

Mon Jan 27 03:42:49 UTC 2025

Please, review this patch to fix an issue in reducing allocation merges used by Cmp nodes. The attached test case, adapted from the one attached to the JBS issue, can be used to reproduce the issue. The root of the problem was not properly checking the return value of `optimize_ptr_compare` against different Cmp mask predicates.

I tested this on OSX(ARM64) & Linux(Intel) tier1-4.

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Commit messages:
 - Fix RAM Cmp reduction.

Changes: https://git.openjdk.org/jdk/pull/23312/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=23312&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8347718
  Stats: 73 lines in 2 files changed: 71 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/23312.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23312/head:pull/23312

PR: https://git.openjdk.org/jdk/pull/23312