Re: Mixing native code and bytecode

[Andrew Haley <aph at redhat dot com>]

Jerome Roussel writes:
 > 
 > I am looking for information about the way GCJ mix native code and
 > bytecode. I know that the bytecode is interpreted so now I am trying to
 > understand the interface used to "switch" from native to bytecode and
 > from bytecode to native. 
 > 
 > For instance, when -findirect-dispatch is used, a vtable needs to be
 > filled for each native class, but what happens if one method is
 > inherited from a parent class which is in bytecode form. This is the
 > kind of question I am trying to understand about the implementation
 > internals.  

The part you perhaps don't know about is the libffi invocation
interface.  This is the "magic bullet" that allows you to construct on
the fly a native code thunk to interpreted code.  More explanation at
ftp://gcc.gnu.org/pub/gcc/summit/2004/GCJ%20New%20ABI.pdf

 > The possibility to mix native code and bytecode is very powerful so
 > I thought that some papers would explain the mechanism but I
 > haven't found anything on that matter. If you have a link to such a
 > paper, a documentation or to some specific source files in GCC to
 > look at, I would be very grateful.

Let us know if there's anything more you need.

Andrew.