Steve Liao wrote:

> I would like to find out how other Harmony developers want to solve
> some basic JIT/VM interfacing.  One area is stack maps for precise
> enumeration of live object references. 

> Does anyone know how other open source JVMs do the above?

Jikes RVM's compilers (baseline & optimizing) produce machine code and 
metadata about the compiled method, which includes stack maps.  The 
compilers create the maps, which are associated with a runtime version of 
the method.   When a GC occurs, the GC stackwalker checks each stack frame 
to see who compiled it, and then asks the appropriate compiler auxiliary 
code to enumerate the references in that stack frame.  This is done by 
repeatedly calling this auxiliary code until it returns a sentinel 
signally "no more references".

I think this worked pretty well. 

Mike