Caclulating operand stack size

Hello,


I am developing a stack-based virtual machine similar to the JVM.
Unfortunately, everytime I push or load something onto the operand
stack, I have to do this:


if(++SP == stackSize)
        growStack();


I would like to avoid this dynamic size check because it slows things
down. The JVM requires routines to specify a stack size limit as I
recall.


I *think* it is possible to statically calculate a stack size limit
using attribute grammars, but I'm not sure. For example:


Example expression and corresponding stack utilization:


1 - (2 + 3) * 4


          2 4 1
2 => 3 => 5 => 5 => 20 => 20 => -19


As can be seen, the stack size was never larger than 2. I was
wondering if a language can calculate this limit during an AST walk by
using attribute grammars?


Thanks,


MC.
[I'd think you could estimate an upper limit by walking the tree and
finding the depth of the deepest node. I suppose you could make the
depth attribute 1 for a leaf and 1+max(L,R) for an internal node. -John]

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