How to retrieve the receiver object of method call

[Peng Du]

I guess my current solution is not viable. The reason why I want to do 
it ad-hoc
is that there are some events that will happen in the entry of a method 
that I
have previously setup. They are not at the call sites. But, my analysis 
is on a
per instance basis since each instance carries some payload I allocated.

I used to cache the receiver objects to JavaThread when I see _invokeXXX 
bytecodes.
But when GC comes, it seems it would move this object away and cause 
SIGSEGV when
later I try to retrieve it. Besides, caching the receiver for every Java 
calls is
not efficient I guess.

Can you suggest some other approach? I can explain more what I am doing 
if that's
helps.

Thanks, Tom!

-Peng


On 04/08/2010 04:19 PM, Tom Rodriguez wrote:
> Well, you kind of have to look at the compiled frame as a set of vframes to get access to the locals unless you want to build it all yourself.  Basically you'd grab the PcDesc for the pc and look at the debug info to find the mapping from local 0 of the root of the compiled frame to some register or stack slot.  This requires having a proper RegisterMap and being at a pc that has debug info, which is pretty much only call sites.  If you want to be able to get it at arbitrary pcs then you are out of luck.
>
> Why can't you just arrange to grab the value you need directly instead of trying to get at it introspectively?
>
> tom
>