RFR(XS): 8229236: CriticalJNINatives: dll handling should be done in native thread state

[Doerr, Martin]

Hi David,

thank you for reviewing.

> Okay. I'm not certain if this is really runtime code or compiler code,
> but it seems okay to me, so if Dean is okay with it then that's fine.
I would consider the lookup part to belong to runtime and the wrapper code generation to belong to compiler.
I've CC'ed hotspot-compiler-dev, but I think your reviews are sufficient.

> Aside: I'm wondering why ARM does not use this critical lookup
> functionality?
I was wondering, too. It's an optional functionality. I believe it's rarely used.

My answer to "Potentially unnecessarily" was a little short in my previous email.
With the latest webrev, the lookup is still unnecessarily done when somebody beat us after acquiring the lock.
But that's an unavoidable consequence of the decision to perform the lookup outside of the lock.
And it's unnecessarily done when the code cache is full and we can't allocate a BufferBlob.
I think these cases are ok.

Best regards,
Martin