source: src/InitTweak/GenInit.cc @ 30b65d8

aaron-thesisarm-ehcleanup-dtorsdeferred_resndemanglerenumforall-pointer-decayjacob/cs343-translationjenkins-sandboxnew-astnew-ast-unique-exprnew-envno_listpersistent-indexerresolv-newwith_gc
Last change on this file since 30b65d8 was 30b65d8, checked in by Rob Schluntz <rschlunt@…>, 6 years ago

always construct polymorphic types, substitute generic type parameters when resolving initializers

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1//
2// Cforall Version 1.0.0 Copyright (C) 2015 University of Waterloo
3//
4// The contents of this file are covered under the licence agreement in the
5// file "LICENCE" distributed with Cforall.
6//
7// GenInit.cc --
8//
9// Author           : Rob Schluntz
10// Created On       : Mon May 18 07:44:20 2015
11// Last Modified By : Rob Schluntz
12// Last Modified On : Fri May 13 11:37:48 2016
13// Update Count     : 166
14//
15
16#include <stack>
17#include <list>
18#include "GenInit.h"
19#include "InitTweak.h"
20#include "SynTree/Declaration.h"
21#include "SynTree/Type.h"
22#include "SynTree/Expression.h"
23#include "SynTree/Statement.h"
24#include "SynTree/Initializer.h"
25#include "SynTree/Mutator.h"
26#include "SymTab/Autogen.h"
27#include "SymTab/Mangler.h"
28#include "GenPoly/PolyMutator.h"
29#include "GenPoly/DeclMutator.h"
30#include "GenPoly/ScopedSet.h"
31#include "ResolvExpr/typeops.h"
32
33namespace InitTweak {
34        namespace {
35                const std::list<Label> noLabels;
36                const std::list<Expression *> noDesignators;
37        }
38
39        class ReturnFixer final : public GenPoly::PolyMutator {
40          public:
41                /// consistently allocates a temporary variable for the return value
42                /// of a function so that anything which the resolver decides can be constructed
43                /// into the return type of a function can be returned.
44                static void makeReturnTemp( std::list< Declaration * > &translationUnit );
45
46                ReturnFixer();
47
48                using GenPoly::PolyMutator::mutate;
49                virtual DeclarationWithType * mutate( FunctionDecl *functionDecl ) override;
50                virtual Statement * mutate( ReturnStmt * returnStmt ) override;
51
52          protected:
53                FunctionType * ftype;
54                UniqueName tempNamer;
55                std::string funcName;
56        };
57
58        class CtorDtor final : public GenPoly::PolyMutator {
59          public:
60                typedef GenPoly::PolyMutator Parent;
61                using Parent::mutate;
62                /// create constructor and destructor statements for object declarations.
63                /// the actual call statements will be added in after the resolver has run
64                /// so that the initializer expression is only removed if a constructor is found
65                /// and the same destructor call is inserted in all of the appropriate locations.
66                static void generateCtorDtor( std::list< Declaration * > &translationUnit );
67
68                virtual DeclarationWithType * mutate( ObjectDecl * ) override;
69                virtual DeclarationWithType * mutate( FunctionDecl *functionDecl ) override;
70                // should not traverse into any of these declarations to find objects
71                // that need to be constructed or destructed
72                virtual Declaration* mutate( StructDecl *aggregateDecl ) override;
73                virtual Declaration* mutate( UnionDecl *aggregateDecl ) override { return aggregateDecl; }
74                virtual Declaration* mutate( EnumDecl *aggregateDecl ) override { return aggregateDecl; }
75                virtual Declaration* mutate( TraitDecl *aggregateDecl ) override { return aggregateDecl; }
76                virtual TypeDecl* mutate( TypeDecl *typeDecl ) override { return typeDecl; }
77                virtual Declaration* mutate( TypedefDecl *typeDecl ) override { return typeDecl; }
78
79                virtual Type * mutate( FunctionType *funcType ) override { return funcType; }
80
81                virtual CompoundStmt * mutate( CompoundStmt * compoundStmt ) override;
82
83          private:
84                // set of mangled type names for which a constructor or destructor exists in the current scope.
85                // these types require a ConstructorInit node to be generated, anything else is a POD type and thus
86                // should not have a ConstructorInit generated.
87
88                bool isManaged( ObjectDecl * objDecl ) const ; // determine if object is managed
89                bool isManaged( Type * type ) const; // determine if type is managed
90                void handleDWT( DeclarationWithType * dwt ); // add type to managed if ctor/dtor
91                GenPoly::ScopedSet< std::string > managedTypes;
92                bool inFunction = false;
93        };
94
95        class HoistArrayDimension final : public GenPoly::DeclMutator {
96          public:
97                typedef GenPoly::DeclMutator Parent;
98
99                /// hoist dimension from array types in object declaration so that it uses a single
100                /// const variable of type size_t, so that side effecting array dimensions are only
101                /// computed once.
102                static void hoistArrayDimension( std::list< Declaration * > & translationUnit );
103
104          private:
105                using Parent::mutate;
106
107                virtual DeclarationWithType * mutate( ObjectDecl * objectDecl ) override;
108                virtual DeclarationWithType * mutate( FunctionDecl *functionDecl ) override;
109                // should not traverse into any of these declarations to find objects
110                // that need to be constructed or destructed
111                virtual Declaration* mutate( StructDecl *aggregateDecl ) override { return aggregateDecl; }
112                virtual Declaration* mutate( UnionDecl *aggregateDecl ) override { return aggregateDecl; }
113                virtual Declaration* mutate( EnumDecl *aggregateDecl ) override { return aggregateDecl; }
114                virtual Declaration* mutate( TraitDecl *aggregateDecl ) override { return aggregateDecl; }
115                virtual TypeDecl* mutate( TypeDecl *typeDecl ) override { return typeDecl; }
116                virtual Declaration* mutate( TypedefDecl *typeDecl ) override { return typeDecl; }
117
118                virtual Type* mutate( FunctionType *funcType ) override { return funcType; }
119
120                void hoist( Type * type );
121
122                DeclarationNode::StorageClass storageclass = DeclarationNode::NoStorageClass;
123                bool inFunction = false;
124        };
125
126        void genInit( std::list< Declaration * > & translationUnit ) {
127                ReturnFixer::makeReturnTemp( translationUnit );
128                HoistArrayDimension::hoistArrayDimension( translationUnit );
129                CtorDtor::generateCtorDtor( translationUnit );
130        }
131
132        void ReturnFixer::makeReturnTemp( std::list< Declaration * > & translationUnit ) {
133                ReturnFixer fixer;
134                mutateAll( translationUnit, fixer );
135        }
136
137        ReturnFixer::ReturnFixer() : tempNamer( "_retVal" ) {}
138
139        Statement *ReturnFixer::mutate( ReturnStmt *returnStmt ) {
140                std::list< DeclarationWithType * > & returnVals = ftype->get_returnVals();
141                assert( returnVals.size() == 0 || returnVals.size() == 1 );
142                // hands off if the function returns an lvalue - we don't want to allocate a temporary if a variable's address
143                // is being returned
144                if ( returnStmt->get_expr() && returnVals.size() == 1 && funcName != "?=?" && ! returnVals.front()->get_type()->get_isLvalue() ) {
145                        // ensure return value is not destructed by explicitly creating
146                        // an empty SingleInit node wherein maybeConstruct is false
147                        ObjectDecl *newObj = new ObjectDecl( tempNamer.newName(), DeclarationNode::NoStorageClass, LinkageSpec::C, 0, returnVals.front()->get_type()->clone(), new ListInit( std::list<Initializer*>(), noDesignators, false ) );
148                        stmtsToAdd.push_back( new DeclStmt( noLabels, newObj ) );
149
150                        // and explicitly create the constructor expression separately
151                        UntypedExpr *construct = new UntypedExpr( new NameExpr( "?{}" ) );
152                        construct->get_args().push_back( new AddressExpr( new VariableExpr( newObj ) ) );
153                        construct->get_args().push_back( returnStmt->get_expr() );
154                        stmtsToAdd.push_back(new ExprStmt(noLabels, construct));
155
156                        returnStmt->set_expr( new VariableExpr( newObj ) );
157                } // if
158                return returnStmt;
159        }
160
161        DeclarationWithType* ReturnFixer::mutate( FunctionDecl *functionDecl ) {
162                // xxx - need to handle named return values - this pass may need to happen
163                // after resolution? the ordering is tricky because return statements must be
164                // constructed - the simplest way to do that (while also handling multiple
165                // returns) is to structure the returnVals into a tuple, as done here.
166                // however, if the tuple return value is structured before resolution,
167                // it's difficult to resolve named return values, since the name is lost
168                // in conversion to a tuple. this might be easiest to deal with
169                // after reference types are added, as it may then be possible to
170                // uniformly move named return values to the parameter list directly
171                ValueGuard< FunctionType * > oldFtype( ftype );
172                ValueGuard< std::string > oldFuncName( funcName );
173
174                ftype = functionDecl->get_functionType();
175                std::list< DeclarationWithType * > & retVals = ftype->get_returnVals();
176                if ( retVals.size() > 1 ) {
177                        TupleType * tupleType = safe_dynamic_cast< TupleType * >( ResolvExpr::extractResultType( ftype ) );
178                        ObjectDecl * newRet = new ObjectDecl( tempNamer.newName(), DeclarationNode::NoStorageClass, LinkageSpec::C, 0, tupleType, new ListInit( std::list<Initializer*>(), noDesignators, false ) );
179                        retVals.clear();
180                        retVals.push_back( newRet );
181                }
182                funcName = functionDecl->get_name();
183                DeclarationWithType * decl = Mutator::mutate( functionDecl );
184                return decl;
185        }
186
187        // precompute array dimension expression, because constructor generation may duplicate it,
188        // which would be incorrect if it is a side-effecting computation.
189        void HoistArrayDimension::hoistArrayDimension( std::list< Declaration * > & translationUnit ) {
190                HoistArrayDimension hoister;
191                hoister.mutateDeclarationList( translationUnit );
192        }
193
194        DeclarationWithType * HoistArrayDimension::mutate( ObjectDecl * objectDecl ) {
195                storageclass = objectDecl->get_storageClass();
196                DeclarationWithType * temp = Parent::mutate( objectDecl );
197                hoist( objectDecl->get_type() );
198                storageclass = DeclarationNode::NoStorageClass;
199                return temp;
200        }
201
202        void HoistArrayDimension::hoist( Type * type ) {
203                // if in function, generate const size_t var
204                static UniqueName dimensionName( "_array_dim" );
205
206                // C doesn't allow variable sized arrays at global scope or for static variables,
207                // so don't hoist dimension.
208                if ( ! inFunction ) return;
209                if ( storageclass == DeclarationNode::Static ) return;
210
211                if ( ArrayType * arrayType = dynamic_cast< ArrayType * >( type ) ) {
212                        if ( ! arrayType->get_dimension() ) return; // xxx - recursive call to hoist?
213
214                        // don't need to hoist dimension if it's a constexpr - only need to if there's potential
215                        // for side effects.
216                        if ( isConstExpr( arrayType->get_dimension() ) ) return;
217
218                        ObjectDecl * arrayDimension = new ObjectDecl( dimensionName.newName(), storageclass, LinkageSpec::C, 0, SymTab::SizeType->clone(), new SingleInit( arrayType->get_dimension() ) );
219                        arrayDimension->get_type()->set_isConst( true );
220
221                        arrayType->set_dimension( new VariableExpr( arrayDimension ) );
222                        addDeclaration( arrayDimension );
223
224                        hoist( arrayType->get_base() );
225                        return;
226                }
227        }
228
229        DeclarationWithType * HoistArrayDimension::mutate( FunctionDecl *functionDecl ) {
230                ValueGuard< bool > oldInFunc( inFunction );
231                inFunction = true;
232                DeclarationWithType * decl = Parent::mutate( functionDecl );
233                return decl;
234        }
235
236        void CtorDtor::generateCtorDtor( std::list< Declaration * > & translationUnit ) {
237                CtorDtor ctordtor;
238                mutateAll( translationUnit, ctordtor );
239        }
240
241        bool CtorDtor::isManaged( Type * type ) const {
242                if ( TupleType * tupleType = dynamic_cast< TupleType * > ( type ) ) {
243                        // tuple is also managed if any of its components are managed
244                        if ( std::any_of( tupleType->get_types().begin(), tupleType->get_types().end(), [&](Type * type) { return isManaged( type ); }) ) {
245                                return true;
246                        }
247                }
248                // a type is managed if it appears in the map of known managed types, or if it contains any polymorphism (is a type variable or generic type containing a type variable)
249                return managedTypes.find( SymTab::Mangler::mangle( type ) ) != managedTypes.end() || GenPoly::isPolyType( type );
250        }
251
252        bool CtorDtor::isManaged( ObjectDecl * objDecl ) const {
253                Type * type = objDecl->get_type();
254                while ( ArrayType * at = dynamic_cast< ArrayType * >( type ) ) {
255                        type = at->get_base();
256                }
257                return isManaged( type );
258        }
259
260        void CtorDtor::handleDWT( DeclarationWithType * dwt ) {
261                // if this function is a user-defined constructor or destructor, mark down the type as "managed"
262                if ( ! LinkageSpec::isOverridable( dwt->get_linkage() ) && isCtorDtor( dwt->get_name() ) ) {
263                        std::list< DeclarationWithType * > & params = GenPoly::getFunctionType( dwt->get_type() )->get_parameters();
264                        assert( ! params.empty() );
265                        PointerType * type = safe_dynamic_cast< PointerType * >( params.front()->get_type() );
266                        managedTypes.insert( SymTab::Mangler::mangle( type->get_base() ) );
267                }
268        }
269
270        ConstructorInit * genCtorInit( ObjectDecl * objDecl ) {
271                // call into genImplicitCall from Autogen.h to generate calls to ctor/dtor
272                // for each constructable object
273                std::list< Statement * > ctor;
274                std::list< Statement * > dtor;
275
276                InitExpander srcParam( objDecl->get_init() );
277                InitExpander nullParam( (Initializer *)NULL );
278                SymTab::genImplicitCall( srcParam, new VariableExpr( objDecl ), "?{}", back_inserter( ctor ), objDecl );
279                SymTab::genImplicitCall( nullParam, new VariableExpr( objDecl ), "^?{}", front_inserter( dtor ), objDecl, false );
280
281                // Currently genImplicitCall produces a single Statement - a CompoundStmt
282                // which  wraps everything that needs to happen. As such, it's technically
283                // possible to use a Statement ** in the above calls, but this is inherently
284                // unsafe, so instead we take the slightly less efficient route, but will be
285                // immediately informed if somehow the above assumption is broken. In this case,
286                // we could always wrap the list of statements at this point with a CompoundStmt,
287                // but it seems reasonable at the moment for this to be done by genImplicitCall
288                // itself. It is possible that genImplicitCall produces no statements (e.g. if
289                // an array type does not have a dimension). In this case, it's fine to ignore
290                // the object for the purposes of construction.
291                assert( ctor.size() == dtor.size() && ctor.size() <= 1 );
292                if ( ctor.size() == 1 ) {
293                        // need to remember init expression, in case no ctors exist
294                        // if ctor does exist, want to use ctor expression instead of init
295                        // push this decision to the resolver
296                        assert( dynamic_cast< ImplicitCtorDtorStmt * > ( ctor.front() ) && dynamic_cast< ImplicitCtorDtorStmt * > ( dtor.front() ) );
297                        return new ConstructorInit( ctor.front(), dtor.front(), objDecl->get_init() );
298                }
299                return nullptr;
300        }
301
302        DeclarationWithType * CtorDtor::mutate( ObjectDecl * objDecl ) {
303                handleDWT( objDecl );
304                // hands off if @=, extern, builtin, etc.
305                // if global but initializer is not constexpr, always try to construct, since this is not legal C
306                if ( ( tryConstruct( objDecl ) && isManaged( objDecl ) ) || (! inFunction && ! isConstExpr( objDecl->get_init() ) ) ) {
307                        // constructed objects cannot be designated
308                        if ( isDesignated( objDecl->get_init() ) ) throw SemanticError( "Cannot include designations in the initializer for a managed Object. If this is really what you want, then initialize with @=.", objDecl );
309                        // constructed objects should not have initializers nested too deeply
310                        if ( ! checkInitDepth( objDecl ) ) throw SemanticError( "Managed object's initializer is too deep ", objDecl );
311
312                        objDecl->set_init( genCtorInit( objDecl ) );
313                }
314                return Parent::mutate( objDecl );
315        }
316
317        DeclarationWithType * CtorDtor::mutate( FunctionDecl *functionDecl ) {
318                ValueGuard< bool > oldInFunc = inFunction;
319                inFunction = true;
320
321                handleDWT( functionDecl );
322
323                managedTypes.beginScope();
324                // go through assertions and recursively add seen ctor/dtors
325                for ( auto & tyDecl : functionDecl->get_functionType()->get_forall() ) {
326                        for ( DeclarationWithType *& assertion : tyDecl->get_assertions() ) {
327                                assertion = assertion->acceptMutator( *this );
328                        }
329                }
330                // parameters should not be constructed and destructed, so don't mutate FunctionType
331                mutateAll( functionDecl->get_oldDecls(), *this );
332                functionDecl->set_statements( maybeMutate( functionDecl->get_statements(), *this ) );
333
334                managedTypes.endScope();
335                return functionDecl;
336        }
337
338        Declaration* CtorDtor::mutate( StructDecl *aggregateDecl ) {
339                // don't construct members, but need to take note if there is a managed member,
340                // because that means that this type is also managed
341                for ( Declaration * member : aggregateDecl->get_members() ) {
342                        if ( ObjectDecl * field = dynamic_cast< ObjectDecl * >( member ) ) {
343                                if ( isManaged( field ) ) {
344                                        managedTypes.insert( SymTab::Mangler::mangle( aggregateDecl ) );
345                                        break;
346                                }
347                        }
348                }
349                return aggregateDecl;
350        }
351
352        CompoundStmt * CtorDtor::mutate( CompoundStmt * compoundStmt ) {
353                managedTypes.beginScope();
354                CompoundStmt * stmt = Parent::mutate( compoundStmt );
355                managedTypes.endScope();
356                return stmt;
357        }
358
359} // namespace InitTweak
360
361// Local Variables: //
362// tab-width: 4 //
363// mode: c++ //
364// compile-command: "make install" //
365// End: //
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