RFR: 8315884: New Object to ObjectMonitor mapping [v3]

[Roman Kennke]

On Tue, 9 Jul 2024 20:43:06 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> Axel Boldt-Christmas has updated the pull request incrementally with two additional commits since the last revision:
>> 
>>  - Add JVMCI symbol exports
>>  - Revert "More graceful JVMCI VM option interaction"
>>    
>>    This reverts commit 2814350370cf142e130fe1d38610c646039f976d.
>
> src/hotspot/share/opto/library_call.cpp line 4620:
> 
>> 4618:       Node *unlocked_val      = _gvn.MakeConX(markWord::unlocked_value);
>> 4619:       Node *chk_unlocked      = _gvn.transform(new CmpXNode(lmasked_header, unlocked_val));
>> 4620:       Node *test_not_unlocked = _gvn.transform(new BoolNode(chk_unlocked, BoolTest::ne));
> 
> I don't really know what this does.  Someone from the c2 compiler group should look at this.

Yes, that looks correct. I'm familiar with this code because I messed with it in my attempts to implement compact identity hashcode in Lilliput2.

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PR Review Comment: https://git.openjdk.org/jdk/pull/20067#discussion_r1675699672