source: src/ResolvExpr/SpecCost.cc @ 0588d8c

//
// Cforall Version 1.0.0 Copyright (C) 2015 University of Waterloo
//
// The contents of this file are covered under the licence agreement in the
// file "LICENCE" distributed with Cforall.
//
// SpecCost.cc --
//
// Author           : Aaron B. Moss
// Created On       : Tue Oct 02 15:50:00 2018
// Last Modified By : Aaron B. Moss
// Last Modified On : Tue Oct 02 15:50:00 2018
// Update Count     : 1
//

#include <limits>
#include <list>

#include "Common/PassVisitor.h"
#include "SynTree/Declaration.h"
#include "SynTree/Expression.h"
#include "SynTree/Type.h"

namespace ResolvExpr {

        /// Counts specializations in a type
        class CountSpecs : public WithShortCircuiting, public WithVisitorRef<CountSpecs> {
                int count = -1;  ///< specialization count (-1 for none)

        public:
                int get_count() const { return count >= 0 ? count : 0; }

                // mark specialization of base type
                void postvisit(PointerType*) { if ( count >= 0 ) ++count; }

                // mark specialization of base type
                void postvisit(ArrayType*) { if ( count >= 0 ) ++count; }

                // mark specialization of base type
                void postvisit(ReferenceType*) { if ( count >= 0 ) ++count; }

        private:
                // takes minimum non-negative count over parameter/return list
                void takeminover( int& mincount, std::list<DeclarationWithType*>& dwts ) {
                        for ( DeclarationWithType* dwt : dwts ) {
                                count = -1;
                                maybeAccept( dwt->get_type(), *visitor );
                                if ( count != -1 && count < mincount ) mincount = count;
                        }
                }

        public:
                // take minimal specialization value over ->returnVals and ->parameters
                void previsit(FunctionType* fty) {
                        int mincount = std::numeric_limits<int>::max();
                        takeminover( mincount, fty->parameters );
                        takeminover( mincount, fty->returnVals );
                        // add another level to mincount if set
                        count = mincount < std::numeric_limits<int>::max() ? mincount + 1 : -1;
                        // already visited children
                        visit_children = false;
                }
        
        private:
                // returns minimum non-negative count + 1 over type parameters (-1 if none such)
                int minover( std::list<Expression*>& parms ) {
                        int mincount = std::numeric_limits<int>::max();
                        for ( Expression* parm : parms ) {
                                count = -1;
                                maybeAccept( parm->result, *visitor );
                                if ( count != -1 && count < mincount ) mincount = count;
                        }
                        return mincount < std::numeric_limits<int>::max() ? mincount + 1 : -1;
                }

        public:
                // look for polymorphic parameters
                void previsit(StructInstType* sty) {
                        count = minover( sty->parameters );
                        visit_children = false;
                }
                
                // look for polymorphic parameters
                void previsit(UnionInstType* uty) {
                        count = minover( uty->parameters );
                        visit_children = false;
                }

                // note polymorphic type (which may be specialized)
                // xxx - maybe account for open/closed type variables
                void postvisit(TypeInstType*) { count = 0; }

                // take minimal specialization over elements
                // xxx - maybe don't increment, tuple flattening doesn't necessarily specialize
                void previsit(TupleType* tty) {
                        int mincount = std::numeric_limits<int>::max();
                        for ( Type* ty : tty->types ) {
                                count = -1;
                                maybeAccept( ty, *visitor );
                                if ( count != -1 && count < mincount ) mincount = count;
                        }
                        count = mincount < std::numeric_limits<int>::max() ? mincount + 1 : -1;
                        visit_children = false;
                }
        };

        /// Returns the (negated) specialization cost for a given type
        int specCost( Type* ty ) {
                PassVisitor<CountSpecs> counter;
                maybeAccept( ty, *counter.pass.visitor );
                return counter.pass.get_count();
        }
} // namespace ResolvExpr

// Local Variables: //
// tab-width: 4 //
// mode: c++ //
// compile-command: "make install" //
// End: //