Abstract

the effects of head unification with the formal parameters ¯ x, given the abstract substitution ff describing the actual parameters, so as to obtain an initial abstract environment A 1 . 2. Let the abstract environment at the program point immediately before the literal q i (¯u i ) be denoted by A i , 1 i n. For i := 1 to n do: A 0 i := analyse call(q i ; A i ); A i+1 := extend abs env (A i ; A 0 i ); 3. Compute and return the abstract environment An+1 projected on the arguments in the head of the clause. A call to a procedure is analyzed by processing each clause for that procedure, in turn, as described above. For each clause, the analysis yields an abstract environment, and these can be "summarized"---for example, using the join operator t on ASub---to yield an abstract environment describing the substitutions that may be obtained when that call returns. In the following sections, we describe how the underlying analysis described above can be extended to detect situations ...

Citations