[lworld] RFR: 8377680: [lworld] [BACKOUT] Improve acmp expansion

Wed Feb 11 17:05:38 UTC 2026

Hi,

This PR backs out the changes in #2066. While the failure is due to the dead `MergeMemNode` not collected by igvn, investigating the issue reveals to me that with `-XX:+StressReflectiveCode`, `GraphKit::gen_checkcast` can buffer the `InlineTypeNode`. This is unexpected as the code in `InlineTypeNode::emit_substitutability_check` does not expect the expansion to generate new memory nodes.

Please review, thanks a lot.

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Commit messages:
 - Revert "8377414: [lworld] Improve acmp expansion"

Changes: https://git.openjdk.org/valhalla/pull/2080/files
  Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=2080&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8377680
  Stats: 571 lines in 7 files changed: 91 ins; 377 del; 103 mod
  Patch: https://git.openjdk.org/valhalla/pull/2080.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/2080/head:pull/2080

PR: https://git.openjdk.org/valhalla/pull/2080