RFR: 8370502: C2: segfault while adding node to IGVN worklist [v5]

[Kerem Kat]

On Wed, 3 Dec 2025 00:04:53 GMT, Dean Long <dlong at openjdk.org> wrote:

>> Kerem Kat 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 10 additional commits since the last revision:
>> 
>>  - Merge branch 'master' into fix-c2-segfault-unlocknode
>>  - address comments
>>  - fix rename
>>  - rename test file
>>  - Merge branch 'master' into fix-c2-segfault-unlocknode
>>  - fix test spacing
>>  - Update src/hotspot/share/opto/macro.cpp
>>    
>>    Co-authored-by: Manuel Hässig <manuel at haessig.org>
>>  - Update src/hotspot/share/opto/macro.cpp
>>    
>>    Co-authored-by: Manuel Hässig <manuel at haessig.org>
>>  - copyright format fix?
>>  - 8370502: C2: segfault while adding node to IGVN worklist
>
> Yes, it would be good to know if expand_lock_node() also needs a null check.  I was assuming the lock and unlock node shapes were basically the same, but now I see that the shapes are different for some reason.  The LockNode gets a FastLockNode edge early, while the UnlockNode creates its FastUnlockNode late.  I failed to get expand_lock_node() to crash with -XX:+StressMacroExpansion but that doesn't mean there isn't the same problem there.

Now that the holiday season is over, could I get a review @dean-long, @mhaessig, @eme64?

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PR Comment: https://git.openjdk.org/jdk/pull/28432#issuecomment-3744217399