Changeset 67fa9f9 for src/ResolvExpr/AlternativeFinder.cc

Timestamp:

Jul 5, 2017, 10:50:22 AM (8 years ago)

Author:

Thierry Delisle <tdelisle@…>

Branches:

ADT, aaron-thesis, arm-eh, ast-experimental, cleanup-dtors, deferred_resn, demangler, enum, forall-pointer-decay, jacob/cs343-translation, jenkins-sandbox, master, new-ast, new-ast-unique-expr, new-env, no_list, persistent-indexer, pthread-emulation, qualifiedEnum, resolv-new, with_gc

Children:

0614d14

Parents:

11dbfe1 (diff), 307a732 (diff)
Note: this is a merge changeset, the changes displayed below correspond to the merge itself.
Use the (diff) links above to see all the changes relative to each parent.

Message:

Merge branch 'master' of plg.uwaterloo.ca:software/cfa/cfa-cc

File:

• src/ResolvExpr/AlternativeFinder.cc (modified) (4 diffs)

src/ResolvExpr/AlternativeFinder.cc

@@ -604 +604 @@
 //          )
                 SymTab::Indexer decls( indexer );
-                PRINT(
-                        std::cerr << "============= original indexer" << std::endl;
-                        indexer.print( std::cerr );
-                        std::cerr << "============= new indexer" << std::endl;
-                        decls.print( std::cerr );
-                )
+                // PRINT(
+                //      std::cerr << "============= original indexer" << std::endl;
+                //      indexer.print( std::cerr );
+                //      std::cerr << "============= new indexer" << std::endl;
+                //      decls.print( std::cerr );
+                // )
                 addToIndexer( have, decls );
                 AssertionSet newNeed;
@@ -809 +809 @@
         }
 
+        Expression * restructureCast( Expression * argExpr, Type * toType ) {
+                if ( argExpr->get_result()->size() > 1 && ! toType->isVoid() ) {
+                        // Argument expression is a tuple and the target type is not void. Cast each member of the tuple
+                        // to its corresponding target type, producing the tuple of those cast expressions. If there are
+                        // more components of the tuple than components in the target type, then excess components do not
+                        // come out in the result expression (but UniqueExprs ensure that side effects will still be done).
+                        if ( Tuples::maybeImpure( argExpr ) && ! dynamic_cast< UniqueExpr * >( argExpr ) ) {
+                                // expressions which may contain side effects require a single unique instance of the expression.
+                                argExpr = new UniqueExpr( argExpr );
+                        }
+                        std::list< Expression * > componentExprs;
+                        for ( unsigned int i = 0; i < toType->size(); i++ ) {
+                                // cast each component
+                                TupleIndexExpr * idx = new TupleIndexExpr( argExpr->clone(), i );
+                                componentExprs.push_back( restructureCast( idx, toType->getComponent( i ) ) );
+                        }
+                        delete argExpr;
+                        assert( componentExprs.size() > 0 );
+                        // produce the tuple of casts
+                        return new TupleExpr( componentExprs );
+                } else {
+                        // handle normally
+                        return new CastExpr( argExpr, toType->clone() );
+                }
+        }
+
         void AlternativeFinder::visit( CastExpr *castExpr ) {
                 Type *& toType = castExpr->get_result();
@@ -840 +866 @@
                                 thisCost += Cost( 0, 0, discardedValues );
 
-                                Expression * argExpr = i->expr->clone();
-                                if ( argExpr->get_result()->size() > 1 && ! castExpr->get_result()->isVoid() ) {
-                                        // Argument expression is a tuple and the target type is not void. Cast each member of the tuple
-                                        // to its corresponding target type, producing the tuple of those cast expressions. If there are
-                                        // more components of the tuple than components in the target type, then excess components do not
-                                        // come out in the result expression (but UniqueExprs ensure that side effects will still be done).
-                                        if ( Tuples::maybeImpure( argExpr ) && ! dynamic_cast< UniqueExpr * >( argExpr ) ) {
-                                                // expressions which may contain side effects require a single unique instance of the expression.
-                                                argExpr = new UniqueExpr( argExpr );
-                                        }
-                                        std::list< Expression * > componentExprs;
-                                        for ( unsigned int i = 0; i < castExpr->get_result()->size(); i++ ) {
-                                                // cast each component
-                                                TupleIndexExpr * idx = new TupleIndexExpr( argExpr->clone(), i );
-                                                componentExprs.push_back( new CastExpr( idx, castExpr->get_result()->getComponent( i )->clone() ) );
-                                        }
-                                        delete argExpr;
-                                        assert( componentExprs.size() > 0 );
-                                        // produce the tuple of casts
-                                        candidates.push_back( Alternative( new TupleExpr( componentExprs ), i->env, i->cost, thisCost ) );
-                                } else {
-                                        // handle normally
-                                        candidates.push_back( Alternative( new CastExpr( argExpr->clone(), toType->clone() ), i->env, i->cost, thisCost ) );
-                                }
+                                candidates.push_back( Alternative( restructureCast( i->expr->clone(), toType ), i->env, i->cost, thisCost ) );
                         } // if
                 } // for
@@ -1182 +1185 @@
         }
 
+        void AlternativeFinder::visit( UntypedInitExpr *initExpr ) {
+                // handle each option like a cast
+                AltList candidates;
+                PRINT( std::cerr << "untyped init expr: " << initExpr << std::endl; )
+                // O(N^2) checks of d-types with e-types
+                for ( InitAlternative & initAlt : initExpr->get_initAlts() ) {
+                        Type * toType = resolveTypeof( initAlt.type, indexer );
+                        SymTab::validateType( toType, &indexer );
+                        adjustExprType( toType, env, indexer );
+                        // Ideally the call to findWithAdjustment could be moved out of the loop, but unfortunately it currently has to occur inside or else
+                        // polymorphic return types are not properly bound to the initialization type, since return type variables are only open for the duration of resolving
+                        // the UntypedExpr. This is only actually an issue in initialization contexts that allow more than one possible initialization type, but it is still suboptimal.
+                        AlternativeFinder finder( indexer, env );
+                        finder.targetType = toType;
+                        finder.findWithAdjustment( initExpr->get_expr() );
+                        for ( Alternative & alt : finder.get_alternatives() ) {
+                                TypeEnvironment newEnv( alt.env );
+                                AssertionSet needAssertions, haveAssertions;
+                                OpenVarSet openVars;  // find things in env that don't have a "representative type" and claim those are open vars?
+                                PRINT( std::cerr << "  @ " << toType << " " << initAlt.designation << std::endl; )
+                                // It's possible that a cast can throw away some values in a multiply-valued expression.  (An example is a
+                                // cast-to-void, which casts from one value to zero.)  Figure out the prefix of the subexpression results
+                                // that are cast directly.  The candidate is invalid if it has fewer results than there are types to cast
+                                // to.
+                                int discardedValues = alt.expr->get_result()->size() - toType->size();
+                                if ( discardedValues < 0 ) continue;
+                                // xxx - may need to go into tuple types and extract relevant types and use unifyList. Note that currently, this does not
+                                // allow casting a tuple to an atomic type (e.g. (int)([1, 2, 3]))
+                                // unification run for side-effects
+                                unify( toType, alt.expr->get_result(), newEnv, needAssertions, haveAssertions, openVars, indexer ); // xxx - do some inspecting on this line... why isn't result bound to initAlt.type??
+
+                                Cost thisCost = castCost( alt.expr->get_result(), toType, indexer, newEnv );
+                                if ( thisCost != Cost::infinity ) {
+                                        // count one safe conversion for each value that is thrown away
+                                        thisCost += Cost( 0, 0, discardedValues );
+                                        candidates.push_back( Alternative( new InitExpr( restructureCast( alt.expr->clone(), toType ), initAlt.designation->clone() ), newEnv, alt.cost, thisCost ) );
+                                }
+                        }
+                }
+
+                // findMinCost selects the alternatives with the lowest "cost" members, but has the side effect of copying the
+                // cvtCost member to the cost member (since the old cost is now irrelevant).  Thus, calling findMinCost twice
+                // selects first based on argument cost, then on conversion cost.
+                AltList minArgCost;
+                findMinCost( candidates.begin(), candidates.end(), std::back_inserter( minArgCost ) );
+                findMinCost( minArgCost.begin(), minArgCost.end(), std::back_inserter( alternatives ) );
+        }
 } // namespace ResolvExpr