Question regarding "native-compiled frame"

[Felix Yang]

On 7 September 2017 at 19:04, Andrew Dinn <adinn at redhat.com> wrote:

> On 07/09/17 11:35, Felix Yang wrote:
> >   Thanks for the reply.
> >   Then when will the last return statement of frame::sender got a chance
> to
> > be executed?
> >   As I see it, when JVM does something in safepoint state and need to
> > traverse Java thread stack, we never calculate the sender of a
> > native-compiled frame.
>
> It is possible for Java to call out into the JVM and then for the JVM to
> call back into Java. For example, when a class is loaded the JVM calls
> into Java to run the class initializer. This re-entry may happen
> multiple times.
>
> In that case a stack walk under the re-entry may find a Java start fame
> and it's parent frame will be the native frame where Java entered the VM.
>

Yes, that's the frame structure.


> Note that the native frame will always be returned by the call to
> sender_for_entry_frame(map). That method skips all the C frames between
> the Java entry frame and the native frame which exited Java.
>

True. And this is handled by the three IF statements of frame::sender
function.
It seems to me that the last return statement is not involved in the stack
walking process, isn't it?

Thanks for your help,
Felix