RFR: 8308000: add PopFrame support for virtual threads

[Chris Plummer]

On Tue, 16 May 2023 08:12:21 GMT, Serguei Spitsyn <sspitsyn at openjdk.org> wrote:

> This enhancement adds `PopFrame` support for virtual threads. The spec defines minimal support that the JVMTI `PopFrame` can be used for a virtual thread suspended an an event. 
> Actually, the `PopFrame` can supports suspended and mounted virtual threads. 
> 
> CSR (approved): https://bugs.openjdk.org/browse/JDK-8308001: add PopFrame support for virtual threads
> 
> Testing:
> New test was developed: `serviceability/vthread/PopFrameTest`.
> Submitted mach5 tiers 1-6 are good.
> TBD: rerun mach5 tiers 1-6 at the end of review again if necessary.

Your changes will cause `test/hotspot/jtreg/vmTestbase/nsk/jdi/ThreadReference/popFrames/popframes001` to fail since it was previously modified to expect OpaqueFrameException for virtual threads. You'll need to problem list it until I can fix it with my JDWP/JDI changes.

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PR Comment: https://git.openjdk.org/jdk/pull/14002#issuecomment-1550156643