Changeset cce9429 for src/GenPoly/Box.cc

Timestamp:

Dec 13, 2016, 6:42:39 PM (6 years ago)

Author:

Rob Schluntz <rschlunt@…>

Branches:

ADT, aaron-thesis, arm-eh, 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:

1aa4b71

Parents:

31f379c

Message:

fix function return type in Validate and add single return decl, construct the return decl, fix polymorphic functions to use the return decl

File:

• src/GenPoly/Box.cc (modified) (13 diffs)

src/GenPoly/Box.cc

@@ -131 +131 @@
                         ScopedMap< std::string, DeclarationWithType* > adapters;     ///< Set of adapter functions in the current scope
 
+                        std::map< ApplicationExpr *, Expression * > retVals;
+
                         DeclarationWithType *retval;
-                        bool useRetval;
                         UniqueName tempNamer;
                 };
@@ -497 +498 @@
                 }
 
-                Pass1::Pass1() : useRetval( false ), tempNamer( "_temp" ) {}
+                Pass1::Pass1() : tempNamer( "_temp" ) {}
 
                 /// Returns T if the given declaration is a function with parameter (T*) for some TypeInstType T, NULL otherwise
@@ -667 +668 @@
 
                                 DeclarationWithType *oldRetval = retval;
-                                bool oldUseRetval = useRetval;
 
                                 // process polymorphic return value
-                                retval = 0;
-                                if ( isDynRet( functionDecl->get_functionType() ) && functionDecl->get_linkage() == LinkageSpec::Cforall ) {
+                                retval = nullptr;
+                                if ( isDynRet( functionDecl->get_functionType() ) && functionDecl->get_linkage() != LinkageSpec::C ) {
                                         retval = functionDecl->get_functionType()->get_returnVals().front();
 
@@ -700 +700 @@
                                         if ( adapters.find( mangleName ) == adapters.end() ) {
                                                 std::string adapterName = makeAdapterName( mangleName );
-                                                adapters.insert( std::pair< std::string, DeclarationWithType *>( mangleName, new ObjectDecl( adapterName, DeclarationNode::NoStorageClass, LinkageSpec::C, 0, new PointerType( Type::Qualifiers(), makeAdapterType( *funType, scopeTyVars ) ), 0 ) ) );
+                                                adapters.insert( std::pair< std::string, DeclarationWithType *>( mangleName, new ObjectDecl( adapterName, DeclarationNode::NoStorageClass, LinkageSpec::C, nullptr, new PointerType( Type::Qualifiers(), makeAdapterType( *funType, scopeTyVars ) ), nullptr ) ) );
                                         } // if
                                 } // for
@@ -712 +712 @@
                                 dtorOps.endScope();
                                 retval = oldRetval;
-                                useRetval = oldUseRetval;
                                 doEndScope();
                         } // if
@@ -724 +723 @@
 
                 Expression *Pass1::mutate( CommaExpr *commaExpr ) {
-                        bool oldUseRetval = useRetval;
-                        useRetval = false;
+                        // Attempting to find application expressions that were mutated by the copy constructor passes
+                        // to use an explicit return variable, so that the variable can be reused as a parameter to the
+                        // call rather than creating a new temp variable. Previously this step was an optimization, but
+                        // with the introduction of tuples and UniqueExprs, it is necessary to ensure that they use the same variable.
+                        // Essentially, looking for pattern: (x=f(...), x)
+                        // To compound the issue, the right side can be *x, etc. because of lvalue-returning functions
+                        if ( UntypedExpr * assign = dynamic_cast< UntypedExpr * >( commaExpr->get_arg1() ) ) {
+                                if ( InitTweak::isAssignment( InitTweak::getFunctionName( assign ) ) ) {
+                                        assert( assign->get_args().size() == 2 );
+                                        if ( ApplicationExpr * appExpr = dynamic_cast< ApplicationExpr * > ( assign->get_args().back() ) ) {
+                                                // first argument is assignable, so it must be an lvalue, so it should be legal to take its address.
+                                                retVals[appExpr] = assign->get_args().front();
+                                        }
+                                }
+                        }
+
                         commaExpr->set_arg1( maybeMutate( commaExpr->get_arg1(), *this ) );
-                        useRetval = oldUseRetval;
                         commaExpr->set_arg2( maybeMutate( commaExpr->get_arg2(), *this ) );
                         return commaExpr;
@@ -733 +745 @@
 
                 Expression *Pass1::mutate( ConditionalExpr *condExpr ) {
-                        bool oldUseRetval = useRetval;
-                        useRetval = false;
                         condExpr->set_arg1( maybeMutate( condExpr->get_arg1(), *this ) );
-                        useRetval = oldUseRetval;
                         condExpr->set_arg2( maybeMutate( condExpr->get_arg2(), *this ) );
                         condExpr->set_arg3( maybeMutate( condExpr->get_arg3(), *this ) );
@@ -783 +792 @@
                                         } else {
                                                 // xxx - should this be an assertion?
-                                                throw SemanticError( "unbound type variable: " + tyParm->first + " in application ", appExpr );
+                                                std::string x = env ? toString( *env ) : "missing env";
+                                                throw SemanticError( x + "\n" + "unbound type variable: " + tyParm->first + " in application ", appExpr );
                                         } // if
                                 } // if
@@ -819 +829 @@
                 Expression *Pass1::addRetParam( ApplicationExpr *appExpr, FunctionType *function, Type *retType, std::list< Expression *>::iterator &arg ) {
                         // Create temporary to hold return value of polymorphic function and produce that temporary as a result
-                        // using a comma expression.  Possibly change comma expression into statement expression "{}" for multiple
-                        // return values.
+                        // using a comma expression.
                         assert( retType );
-                        ObjectDecl *newObj = makeTemporary( retType->clone() );
-                        Expression *paramExpr = new VariableExpr( newObj );
+
+                        Expression * paramExpr = nullptr;
+                        // try to use existing return value parameter if it exists, otherwise create a new temporary
+                        if ( retVals.count( appExpr ) ) {
+                                paramExpr = retVals[appExpr]->clone();
+                        } else {
+                                ObjectDecl *newObj = makeTemporary( retType->clone() );
+                                paramExpr = new VariableExpr( newObj );
+                        }
+                        Expression * retExpr = paramExpr->clone();
 
                         // If the type of the temporary is not polymorphic, box temporary by taking its address;
                         // otherwise the temporary is already boxed and can be used directly.
-                        if ( ! isPolyType( newObj->get_type(), scopeTyVars, env ) ) {
+                        if ( ! isPolyType( paramExpr->get_result(), scopeTyVars, env ) ) {
                                 paramExpr = new AddressExpr( paramExpr );
                         } // if
@@ -833 +850 @@
                         arg++;
                         // Build a comma expression to call the function and emulate a normal return.
-                        CommaExpr *commaExpr = new CommaExpr( appExpr, new VariableExpr( newObj ) );
+                        CommaExpr *commaExpr = new CommaExpr( appExpr, retExpr );
                         commaExpr->set_env( appExpr->get_env() );
                         appExpr->set_env( 0 );
@@ -851 +868 @@
                                 Type *concrete = env->lookup( typeInst->get_name() );
                                 if ( concrete == 0 ) {
-                                        throw SemanticError( "Unbound type variable " + typeInst->get_name() + " in ", appExpr );
+                                        // xxx - should this be an assertion?
+                                        std::string x = env ? toString( *env ) : "missing env";
+                                        throw SemanticError( x + "\n" + "Unbound type variable " + typeInst->get_name() + " in ", appExpr );
                                 } // if
                                 return concrete;
@@ -1259 +1278 @@
                         // }
                         // std::cerr << "\n";
-                        bool oldUseRetval = useRetval;
-                        useRetval = false;
                         appExpr->get_function()->acceptMutator( *this );
                         mutateAll( appExpr->get_args(), *this );
-                        useRetval = oldUseRetval;
 
                         assert( appExpr->get_function()->has_result() );
@@ -1545 +1561 @@
                 }
 
+                /// determines if `pref` is a prefix of `str`
+                bool isPrefix( const std::string & str, const std::string & pref ) {
+                        if ( pref.size() > str.size() ) return false;
+                        auto its = std::mismatch( pref.begin(), pref.end(), str.begin() );
+                        return its.first == pref.end();
+                }
+
                 DeclarationWithType * Pass2::mutate( FunctionDecl *functionDecl ) {
-                        return handleDecl( functionDecl, functionDecl->get_functionType() );
+                        if ( ! LinkageSpec::isBuiltin( functionDecl->get_linkage() ) ) {
+                                // std::cerr << "mutating function: " << functionDecl->get_name() << std::endl;
+                        }
+                        functionDecl = safe_dynamic_cast< FunctionDecl * > ( handleDecl( functionDecl, functionDecl->get_functionType() ) );
+                        FunctionType * ftype = functionDecl->get_functionType();
+                        if ( ! ftype->get_returnVals().empty() && functionDecl->get_statements() ) {
+                                if ( functionDecl->get_name() != "?=?" && ! isPrefix( functionDecl->get_name(), "_thunk" ) ) { // xxx - remove check for ?=? once reference types are in; remove check for prefix once thunks properly use ctor/dtors
+                                        assert( ftype->get_returnVals().size() == 1 );
+                                        DeclarationWithType * retval = ftype->get_returnVals().front();
+                                        if ( retval->get_name() == "" ) {
+                                                retval->set_name( "_retval" );
+                                        }
+                                        functionDecl->get_statements()->get_kids().push_front( new DeclStmt( noLabels, retval ) );
+                                        DeclarationWithType * newRet = retval->clone(); // for ownership purposes
+                                        ftype->get_returnVals().front() = newRet;
+                                }
+                        }
+                        return functionDecl;
                 }