[11] RFR(XS): 8198826: -XX:+VerifyStack fails with fatal error: ExceptionMark constructor expects no pending exceptions (original) (raw)

David Holmes david.holmes at oracle.com
Thu Mar 1 11:53:37 UTC 2018

On 1/03/2018 8:38 PM, Tobias Hartmann wrote:

Hi David,

On 01.03.2018 11:11, David Holmes wrote: Interesting - does that mean you have to roll back everything that happened since the allocation point ??? No, besides the general JVM state, C2 compiled code also keeps track of the state of scalarized objects to be able to reconstruct them at safepoints, i.e., when deoptimization could happen (see 'SafePointScalarObjectNode').

But if the allocation fails you don't have the ability to reconstruct the object ?? The OOME must appear to happen at the point at which the object should have been allocated, and nothing that happens after that point can be seen to have happened.

Looks okay. My only thought is whether the PEM should be across the full scope of the VerifyStack logic (as you have it) or whether it should only wrap the code you know has the ExceptionMark? I guess as this is a JRTLEAF function we don't expect anything else to generate exceptions, so the placement shouldn't really matter. The ExceptionMark is in OopMapCache::computeoneoopmap() which is called from two locations in the VerifyStack scope. A more narrow scope would be inside the for-loop and I think we would like to avoid that. And yes, we don't expect anything else to generate an exception (the PEM actually guards against that).

Ok.

Thanks, David

Thanks, Tobias

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