A comparison of instruction sets for stack machines

Suppose you are approached by a computer designer who wants to select a machine architecture and instruction set that is desirable from a compiler writers standpoint. What would you recommend, and why? We give a limited answer to the above question. We focus on the computation of arithmetic expressions like a-b+c. When computing a-b we need different instructions depending on where a and b are to be found. On a programmable calculator for example, a or b may be on the stack, or stored in some memory register. We also need instructions that copy values from one place to another. Algorithms that generate code for arithmetic expressions tend to treat general purpose registers as a stack. Moreover, results about machines that perform all arithmetic in a hardware stack are directly applicable to machines with general purpose registers. We therefore start our study of instruction sets by looking at stack machines. We compare machines based on the number of instructions needed to compute a given expression. We then turn to algorithms that generate optimal programs for computing expressions on the various machines.