Procedure Call and Return

This chapter discusses the design of code fragments which support procedure call and return in both recursive and non-recursive programming languages. To aid the discussion in later chapters it includes a model of procedure call and return based on the notion of a procedure activation record. A procedure activation is a special case of a ‘micro-process1’, and the same model can explain the operation of languages such as SIMULA 67 whose control structures are not restricted to simple procedure call and return. It also helps to explain how restrictions on the use of data and procedures in the source language can allow restricted (and therefore less costly) implementations of the general procedure call and return mechanism. The mechanism of procedure call and return in FORTRAN is briefly discussed: then I concentrate on the mechanisms of stack handling which are required to implement procedure call and return in a recursive language on a conventional object machine.