[lworld] RFR: 8332387: [lworld] monitorenter on value class instances must throw IdentityException instead of IllegalMonitorStateException

[Frederic Parain]

On Thu, 23 May 2024 13:42:33 GMT, Dan Heidinga <heidinga at openjdk.org> wrote:

>> Change the exception thrown by monitorenter when attempted on an instance of a value class.
>> Monitorexit is not changed according to some discussions about the JVMS changes (it still throws IllegalMonitorStateException).
>> 
>> Tested with Mach5, tier1-3.
>> 
>> Fred
>
> src/hotspot/share/c1/c1_LIR.cpp line 841:
> 
>> 839: 
>> 840:       do_stub(opLock->_stub);
>> 841:       do_stub(opLock->_throw_ie_stub);
> 
> Does `_throw_ie_stub` apply to both `lir_lock` & 'lir_unlock`?  I thought only `monitorenter` was being changed.

When creating a LIR_OpLock for lir_unlock (in LIR_List::unlock_object(), c1_LIR.cpp:1576), no stub is provided so _throw_ie_stub is null. And do_stub() does nothing if the pointer passed in argument is null.
Did I miss something?

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PR Review Comment: https://git.openjdk.org/valhalla/pull/1108#discussion_r1612064611