This stack thing is proving to be a real pig. The problem is that the stack for a method is set up in two parts. The caller allocates space for the method’s parameters and fills them in prior to calling the method entry, and the method entry then extends the stack to allow for any additional local variables. This is fine on i486 and amd64 (and I think sparc too) where you have free reign to set the stack pointer to whatever you want, but an absolute pain on ppc where the ABI dictates the stack be arranged in frames. (I think this means that the “stack pointer” on ppc is actually a frame pointer.) I thought I could get around this because the caller can look in the methodOop to see how many additional local variables are required; you’d just allocate them at the same time as the parameters (which are just the first however many local variables anyway). Except it turns out that the C++ interpreter can arbitrarily extend the stack too, to allocate space for monitors, so I still need to figure out a way to do it!