I built this in 3 phases:
a) create a helper in the bootstrap VM to render the state of the stack.
b) interactively arrive at the right function (tools/stack_array.subx)
c) pull the final solution into the standard library (093stack_allocate.subx)
As the final layer says, this may not be the fastest approach for most
(or indeed any) Mu programs. Perhaps it's better on balance for the compiler
to just emit n/4 `push` instructions.
(I'm sure this solution can be optimized further.)
Kartik Agaram