Procedure body

Q, the procedure body, is any nonempty list of assignment instructions, test instructions and CALL instructions, involving as variables only the formal parameters and local variables of the procedure, such that START Q STOP is a program scheme with CALLs. 

The example also gives selected parts of the computation for input n = 3 and k = 2. We enter instruction 3 with the IF test positive. Then we proceed as if a copy of the procedure body for FACT and the END statement were inserted just before instruction 4 of the main program. Notice that our definitions require a procedure definition to be, in effect, a single entry single exit subscheme so there is no ambiguity about where we enter the procedure or where we leave or where we go next, even if the main program were not a WHILE program (i.e., well-structured). 

Observe that the new statement first stores all global values which are not actual parameters Cy, ...,ym) on the pushdown store, then puts label Lq on top of the pushdown store, and finally lets the values of the actual parameters of the call, v, ...,vn, specify the formal parameters of procedure F, x,, ...,x the x. will be used as variables in the execution of F. Then con-trol passes to the start of the procedure body of F. When F is completed, label Lq r will be retrieved from the top of the store and a GOTO will pass control to the statement labeled by Lq. Then each actual parameter of the call, v, will be respecified by the final value of the corresponding formal parameter, x, of F, the other global variables will have their proper values restored from the pushdown store and control will return to , the statement originally following . ... 

There is only one procedure, which has formal parameters, ...,xn, LABEL and TOP. The first statement in the procedure body is ... 

We must consider the procedures to be subroutines or subprograms in the program. So we take each procedure body Qp and play the same game. To the entry point of Qp we attach inductive assertion pA and to the exit point we attach inductive assertion pB. We choose the other critical points to cut all cycles and to include all points directly before or directly after calls. We assign inductive assertions to critical points freely, except that for a call... 

After all this has been done, we apply the usual verification procedure to the main program and to each procedure body - constructing verification conditions and sending them to a THEOREM PROVER just as before. We claim that if all the verification conditions hold for the main program and all procedures, then the whole program is partially correct for A and B. ... 

Construct a recursion augmented scheme P without iteration (the main scheme and all procedure bodies are trees - no loops) and an interpretation I with domain the nonnegative integers and using only dyadic function,... 

Name the sections within the procedure body (for example, "Stripper Startup" or "Opening the Reactor Manway"). A number or letter can be assigned if desired. 

We use Predicated Code Blocks (PCB) to represent the control flow in the program. A predicated code block, (sg, Sn), consists of a conditional predicate So followed by a sequence of statements si,..., s . Conditional statements, while loops, and procedure bodies are represented by such code blocks, and a set of interconnected blocks represents the whole program. The code blocks are derived for these kinds of statements as follows ... 

Within a PCB the program flow is represented by the sequence of statements. For blocks representing while loops the represented flow is cyclic, with a back-edge from the last statement to the condition, whereas the flow represented by PCBs for conditional branches and non-recursive procedure bodies is acyclic. 

Program flow between PCBs can be represented by interfaces. These are graph edges that connect statements in different blocks s —> s is an interface if Si and s belong to different blocks B, B, and there is a possible direct flow of execution from Sj to s. Interfaces will connect blocks representing while and if statements to their parent blocks, and also procedure bodies to call sites. Since we consider structured code, there will always be a forward interface from parent to child block and a back interface in the reverse direction. We obtain the following possible interfaces connecting B and B (sq and sq are the conditions in B and B respectively) ... 

The PCB representation is easily extended to represent procedmes and procedure calls. Each procedure body is represented by a block. Interfaces coimect call sites with procedure body blocks from each call site a call interface reaches the entry point of the procedure, and a return interface connects the return statement with the call site. This is similar to how procedure calls are represented for CFGs [19]. An example is shown in Fig. 2. 

How will the call contribute to the slice of the procedure body of p7... 

This behavioural description requires the buffers contained within the BUFFERS block to enable and disable the input and output ports connecting die random sequence generator to die external bus. The code demonstrates another way of declaring and defining a procedure - bodi the procedure declaration and body are contained within the entity declarative part. 

A procedure is a subprogram that can receive and return any number of values. Like a function, it can consist of both a separate declaration and a body. When storing the procedure in a package, the procedure declaration is placed in the package declaration and die procedure body is stored in the package body. The syntax for both statements is ... 

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