RFR: 8361140: Missing OptimizePtrCompare check in ConnectionGraph::reduce_phi_on_cmp [v2]

[Guanqiang Han]

On Thu, 10 Jul 2025 12:50:03 GMT, Christian Hagedorn <chagedorn at openjdk.org> wrote:

>> Guanqiang Han 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 three additional commits since the last revision:
>> 
>>  - update modification and add regression test
>>  - Merge remote-tracking branch 'upstream/master' into 8361140
>>  - 8361140: Missing OptimizePtrCompare check in ConnectionGraph::reduce_phi_on_cmp
>>    
>>    When running with `-XX:-OptimizePtrCompare` (which disables pointer comparison optimization), the compiler may hit an assertion failure in debug builds because `optimize_ptr_compare` is still being called. This violates the intended usage of the flag and leads to unexpected crashes.
>>    
>>    This patch adds an early return to `reduce_phi_on_cmp` when `OptimizePtrCompare` is false. Since the optimization relies on `optimize_ptr_compare` for static reasoning about comparisons, there's no benefit in proceeding with `reduce_phi_on_cmp` when this support is disabled.
>
> Thanks for the update! I have some follow-up comments.

hi @chhagedorn ，thanks a lot for your detailed and thoughtful review. I'm still learning more about this area, and your feedback has been a great help. I've updated the PR based on your suggestions . Please feel free to let me know if anything else needs improvement.

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PR Comment: https://git.openjdk.org/jdk/pull/26125#issuecomment-3057725959