RFR: 8361140: Missing OptimizePtrCompare check in ConnectionGraph::reduce_phi_on_cmp [v3]

[Guanqiang Han]

On Thu, 10 Jul 2025 17:17:04 GMT, Cesar Soares Lucas <cslucas 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 five additional commits since the last revision:
>> 
>>  - update regression test
>>  - Merge remote-tracking branch 'upstream/master' into 8361140
>>  - 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.
>
> test/hotspot/jtreg/compiler/c2/TestReducePhiOnCmpWithNoOptPtrCompare.java line 47:
> 
>> 45:     @Run(test = {"testReducePhiOnCmp_C2"})
>> 46:     public void runner(RunInfo info) {
>> 47:         invocations++;
> 
> I don't think you need this variable anymroe.

hi @JohnTortugo , Thanks for the feedback! I overlooked a small detail, I've fixed it now. Let me know if there's anything else.

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PR Review Comment: https://git.openjdk.org/jdk/pull/26125#discussion_r2199100535