writing two different bytecode parts at the same time

Hi all,

I am currently experimenting in Groovy with a special way of compiling 
expressions. One way is the classic way, the other is more or less java 
style static compilation. Since I want to switch between them at runtime 
and express it completely in bytecode I have currently a small problem.

So for example I would compile

void foo(int x) {
   x++
}

into something like this

if !fastpath GOTO slowpath
   ILAOD 1
   IINC
   ISTORE
slowpath:
   x' = box(x)
   x' = x'.next()
   x  = unbox(x)

I hope you guys forgive me for using some shortcuts here, but it should 
give away the idea

Currently I can switch the compiler to do either the one thing or the 
other, but I would like to do both at the same time. Ideally I would 
like to do that with two method visitors on the same method. Then I 
could do (not real API, I know):

mv1.visitInsn(ILOAD, 1)

mv2.visitInsn(ILOAD, 1)
mv2.visitMethodcall(SBA.box(I)Object)

to handle loading x in the fast path (mv1) and loading x in the slow 
path (mv2). That means I can handle both ways while handling the x in 
x++ and have not to duplicate the my AST, or revisit it.

So basically I would like to be able to define a label and have one 
method visitor write after it, while another one can write before it. Or 
a way to somehow jump

Is there anything slightly like that in th asm lib I can use?

bye Jochen

-- 
Jochen "blackdrag" Theodorou
The Groovy Project Tech Lead (http://groovy.codehaus.org)
http://blackdragsview.blogspot.com/

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