RFR(M): 8227680: FastJNIAccessors: Check for JVMTI field access event requests at runtime

[Doerr, Martin]

Hi Erik,

adding Andrew and Aleksey.

> The new webrev looks good.
Thanks.

> Note though the following though... it looks like the AArch64 code
> doesn't do appropriate fencing if the field is volatile.
I agree. I was not aware of JDK-8179954 (https://bugs.openjdk.java.net/browse/JDK-8179954).

My new aarch64 proposal:
http://cr.openjdk.java.net/~mdoerr/8227680_FastJNIAccessors/webrev.02/

Note: All platforms were tested except arm (32 bit). I could also return (address)-1 if JvmtiExport::can_post_field_access() in case nobody wants this for arm.

Best regards,
Martin