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Bitset optimization

A rule is bitset optimizable, if all incoming edges to the target node of an assigned edge are implemented by bitsets. If so, for the rule bitset operations are generated; otherwise normal object-based code generation is used.

The following rule is bitset optimizable, if we suppose that EC_DSAVE_OUT, EC_DSAVE_IN, and EC_TRANSP are implemented as SETF(Stmt). The rule test graphs is a directed acyclic graphs, all assigned edges are added in forward direction, and all edges incoming to the target node of the assigned edge s are have bitset functors..

$\begin{examplefoot}EC_DSAFE_IN(Block,Expr) :- EC_TRANSP(Block,Expr), EC_DSAFE_OUT(Block,Expr); \end{examplefoot}$

The generated code is

$\begin{verblines}for (_onceindex = 1; _onceindex > 0; _onceindex--) { /* path t... ... [Block]-EC_TRANSP->[Expr] */ } /* end of rule fake for-loop */ \end{verblines}$

Uwe Assmann
1998-12-22