[jdk26] RFR: 8351889: C2 crash: assertion failed: Base pointers must match (addp 344) [v2]

[Roland Westrelin]

> Hi all,
> 
> This pull request contains a backport of commit [ad29642d](https://github.com/openjdk/jdk/commit/ad29642d8f4e8e0fb1223b14b85ab7841d7b1b51) from the [openjdk/jdk](https://git.openjdk.org/jdk) repository.
> 
> The commit being backported was authored by Roland Westrelin on 15 Dec 2025 and was reviewed by Roberto Castañeda Lozano and Emanuel Peter.
> 
> Thanks!

Roland Westrelin has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains two additional commits since the last revision:

 - Merge branch 'jdk26' into backport-rwestrel-ad29642d-jdk26
 - Backport ad29642d8f4e8e0fb1223b14b85ab7841d7b1b51

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/28893/files
  - new: https://git.openjdk.org/jdk/pull/28893/files/ff20d122..acd2913c

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=28893&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=28893&range=00-01

  Stats: 1087 lines in 32 files changed: 746 ins; 238 del; 103 mod
  Patch: https://git.openjdk.org/jdk/pull/28893.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28893/head:pull/28893

PR: https://git.openjdk.org/jdk/pull/28893