source: src/InitTweak/GenInit.cc @ cce9429

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 cce9429 was cce9429, checked in by Rob Schluntz <rschlunt@…>, 5 years ago

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

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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                typedef GenPoly::PolyMutator Parent;
49                using Parent::mutate;
50                virtual DeclarationWithType * mutate( FunctionDecl *functionDecl ) override;
51                virtual Statement * mutate( ReturnStmt * returnStmt ) override;
52
53          protected:
54                FunctionType * ftype;
55                UniqueName tempNamer;
56                std::string funcName;
57        };
58
59        class CtorDtor final : public GenPoly::PolyMutator {
60          public:
61                typedef GenPoly::PolyMutator Parent;
62                using Parent::mutate;
63                /// create constructor and destructor statements for object declarations.
64                /// the actual call statements will be added in after the resolver has run
65                /// so that the initializer expression is only removed if a constructor is found
66                /// and the same destructor call is inserted in all of the appropriate locations.
67                static void generateCtorDtor( std::list< Declaration * > &translationUnit );
68
69                virtual DeclarationWithType * mutate( ObjectDecl * ) override;
70                virtual DeclarationWithType * mutate( FunctionDecl *functionDecl ) override;
71                // should not traverse into any of these declarations to find objects
72                // that need to be constructed or destructed
73                virtual Declaration* mutate( StructDecl *aggregateDecl ) override;
74                virtual Declaration* mutate( UnionDecl *aggregateDecl ) override { return aggregateDecl; }
75                virtual Declaration* mutate( EnumDecl *aggregateDecl ) override { return aggregateDecl; }
76                virtual Declaration* mutate( TraitDecl *aggregateDecl ) override { return aggregateDecl; }
77                virtual TypeDecl* mutate( TypeDecl *typeDecl ) override { return typeDecl; }
78                virtual Declaration* mutate( TypedefDecl *typeDecl ) override { return typeDecl; }
79
80                virtual Type * mutate( FunctionType *funcType ) override { return funcType; }
81
82                virtual CompoundStmt * mutate( CompoundStmt * compoundStmt ) override;
83
84          private:
85                // set of mangled type names for which a constructor or destructor exists in the current scope.
86                // these types require a ConstructorInit node to be generated, anything else is a POD type and thus
87                // should not have a ConstructorInit generated.
88
89                bool isManaged( ObjectDecl * objDecl ) const ; // determine if object is managed
90                bool isManaged( Type * type ) const; // determine if type is managed
91                void handleDWT( DeclarationWithType * dwt ); // add type to managed if ctor/dtor
92                GenPoly::ScopedSet< std::string > managedTypes;
93                bool inFunction = false;
94        };
95
96        class HoistArrayDimension final : public GenPoly::DeclMutator {
97          public:
98                typedef GenPoly::DeclMutator Parent;
99
100                /// hoist dimension from array types in object declaration so that it uses a single
101                /// const variable of type size_t, so that side effecting array dimensions are only
102                /// computed once.
103                static void hoistArrayDimension( std::list< Declaration * > & translationUnit );
104
105          private:
106                using Parent::mutate;
107
108                virtual DeclarationWithType * mutate( ObjectDecl * objectDecl ) override;
109                virtual DeclarationWithType * mutate( FunctionDecl *functionDecl ) override;
110                // should not traverse into any of these declarations to find objects
111                // that need to be constructed or destructed
112                virtual Declaration* mutate( StructDecl *aggregateDecl ) override { return aggregateDecl; }
113                virtual Declaration* mutate( UnionDecl *aggregateDecl ) override { return aggregateDecl; }
114                virtual Declaration* mutate( EnumDecl *aggregateDecl ) override { return aggregateDecl; }
115                virtual Declaration* mutate( TraitDecl *aggregateDecl ) override { return aggregateDecl; }
116                virtual TypeDecl* mutate( TypeDecl *typeDecl ) override { return typeDecl; }
117                virtual Declaration* mutate( TypedefDecl *typeDecl ) override { return typeDecl; }
118
119                virtual Type* mutate( FunctionType *funcType ) override { return funcType; }
120
121                void hoist( Type * type );
122
123                DeclarationNode::StorageClass storageclass = DeclarationNode::NoStorageClass;
124                bool inFunction = false;
125        };
126
127        void genInit( std::list< Declaration * > & translationUnit ) {
128                ReturnFixer::makeReturnTemp( translationUnit );
129                HoistArrayDimension::hoistArrayDimension( translationUnit );
130                CtorDtor::generateCtorDtor( translationUnit );
131        }
132
133        void ReturnFixer::makeReturnTemp( std::list< Declaration * > & translationUnit ) {
134                ReturnFixer fixer;
135                mutateAll( translationUnit, fixer );
136        }
137
138        ReturnFixer::ReturnFixer() : tempNamer( "_retVal" ) {}
139
140        Statement *ReturnFixer::mutate( ReturnStmt *returnStmt ) {
141                std::list< DeclarationWithType * > & returnVals = ftype->get_returnVals();
142                assert( returnVals.size() == 0 || returnVals.size() == 1 );
143                // hands off if the function returns an lvalue - we don't want to allocate a temporary if a variable's address
144                // is being returned
145                // Note: under the assumption that assignments return *this, checking for ?=? here is an optimization, since it shouldn't be necessary to copy construct `this`. This is a temporary optimization until reference types are added, at which point this should be removed, along with the analogous optimization in copy constructor generation.
146                if ( returnStmt->get_expr() && returnVals.size() == 1 && funcName != "?=?" && ! returnVals.front()->get_type()->get_isLvalue() ) {
147                        // explicitly construct the return value using the return expression and the retVal object
148                        assertf( returnVals.front()->get_name() != "", "Function %s has unnamed return value\n", funcName.c_str() );
149                        UntypedExpr *construct = new UntypedExpr( new NameExpr( "?{}" ) );
150                        construct->get_args().push_back( new AddressExpr( new VariableExpr( returnVals.front() ) ) );
151                        construct->get_args().push_back( returnStmt->get_expr() );
152                        stmtsToAdd.push_back(new ExprStmt(noLabels, construct));
153
154                        // return the retVal object
155                        returnStmt->set_expr( new VariableExpr( returnVals.front() ) );
156                } // if
157                return returnStmt;
158        }
159
160        DeclarationWithType* ReturnFixer::mutate( FunctionDecl *functionDecl ) {
161                ValueGuard< FunctionType * > oldFtype( ftype );
162                ValueGuard< std::string > oldFuncName( funcName );
163
164                ftype = functionDecl->get_functionType();
165                funcName = functionDecl->get_name();
166                return Parent::mutate( functionDecl );
167        }
168
169        // precompute array dimension expression, because constructor generation may duplicate it,
170        // which would be incorrect if it is a side-effecting computation.
171        void HoistArrayDimension::hoistArrayDimension( std::list< Declaration * > & translationUnit ) {
172                HoistArrayDimension hoister;
173                hoister.mutateDeclarationList( translationUnit );
174        }
175
176        DeclarationWithType * HoistArrayDimension::mutate( ObjectDecl * objectDecl ) {
177                storageclass = objectDecl->get_storageClass();
178                DeclarationWithType * temp = Parent::mutate( objectDecl );
179                hoist( objectDecl->get_type() );
180                storageclass = DeclarationNode::NoStorageClass;
181                return temp;
182        }
183
184        void HoistArrayDimension::hoist( Type * type ) {
185                // if in function, generate const size_t var
186                static UniqueName dimensionName( "_array_dim" );
187
188                // C doesn't allow variable sized arrays at global scope or for static variables,
189                // so don't hoist dimension.
190                if ( ! inFunction ) return;
191                if ( storageclass == DeclarationNode::Static ) return;
192
193                if ( ArrayType * arrayType = dynamic_cast< ArrayType * >( type ) ) {
194                        if ( ! arrayType->get_dimension() ) return; // xxx - recursive call to hoist?
195
196                        // don't need to hoist dimension if it's a constexpr - only need to if there's potential
197                        // for side effects.
198                        if ( isConstExpr( arrayType->get_dimension() ) ) return;
199
200                        ObjectDecl * arrayDimension = new ObjectDecl( dimensionName.newName(), storageclass, LinkageSpec::C, 0, SymTab::SizeType->clone(), new SingleInit( arrayType->get_dimension() ) );
201                        arrayDimension->get_type()->set_isConst( true );
202
203                        arrayType->set_dimension( new VariableExpr( arrayDimension ) );
204                        addDeclaration( arrayDimension );
205
206                        hoist( arrayType->get_base() );
207                        return;
208                }
209        }
210
211        DeclarationWithType * HoistArrayDimension::mutate( FunctionDecl *functionDecl ) {
212                ValueGuard< bool > oldInFunc( inFunction );
213                inFunction = true;
214                DeclarationWithType * decl = Parent::mutate( functionDecl );
215                return decl;
216        }
217
218        void CtorDtor::generateCtorDtor( std::list< Declaration * > & translationUnit ) {
219                CtorDtor ctordtor;
220                mutateAll( translationUnit, ctordtor );
221        }
222
223        bool CtorDtor::isManaged( Type * type ) const {
224                if ( TupleType * tupleType = dynamic_cast< TupleType * > ( type ) ) {
225                        // tuple is also managed if any of its components are managed
226                        if ( std::any_of( tupleType->get_types().begin(), tupleType->get_types().end(), [&](Type * type) { return isManaged( type ); }) ) {
227                                return true;
228                        }
229                }
230                // 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)
231                return managedTypes.find( SymTab::Mangler::mangle( type ) ) != managedTypes.end() || GenPoly::isPolyType( type );
232        }
233
234        bool CtorDtor::isManaged( ObjectDecl * objDecl ) const {
235                Type * type = objDecl->get_type();
236                while ( ArrayType * at = dynamic_cast< ArrayType * >( type ) ) {
237                        type = at->get_base();
238                }
239                return isManaged( type );
240        }
241
242        void CtorDtor::handleDWT( DeclarationWithType * dwt ) {
243                // if this function is a user-defined constructor or destructor, mark down the type as "managed"
244                if ( ! LinkageSpec::isOverridable( dwt->get_linkage() ) && isCtorDtor( dwt->get_name() ) ) {
245                        std::list< DeclarationWithType * > & params = GenPoly::getFunctionType( dwt->get_type() )->get_parameters();
246                        assert( ! params.empty() );
247                        PointerType * type = safe_dynamic_cast< PointerType * >( params.front()->get_type() );
248                        managedTypes.insert( SymTab::Mangler::mangle( type->get_base() ) );
249                }
250        }
251
252        ConstructorInit * genCtorInit( ObjectDecl * objDecl ) {
253                // call into genImplicitCall from Autogen.h to generate calls to ctor/dtor
254                // for each constructable object
255                std::list< Statement * > ctor;
256                std::list< Statement * > dtor;
257
258                InitExpander srcParam( objDecl->get_init() );
259                InitExpander nullParam( (Initializer *)NULL );
260                SymTab::genImplicitCall( srcParam, new VariableExpr( objDecl ), "?{}", back_inserter( ctor ), objDecl );
261                SymTab::genImplicitCall( nullParam, new VariableExpr( objDecl ), "^?{}", front_inserter( dtor ), objDecl, false );
262
263                // Currently genImplicitCall produces a single Statement - a CompoundStmt
264                // which  wraps everything that needs to happen. As such, it's technically
265                // possible to use a Statement ** in the above calls, but this is inherently
266                // unsafe, so instead we take the slightly less efficient route, but will be
267                // immediately informed if somehow the above assumption is broken. In this case,
268                // we could always wrap the list of statements at this point with a CompoundStmt,
269                // but it seems reasonable at the moment for this to be done by genImplicitCall
270                // itself. It is possible that genImplicitCall produces no statements (e.g. if
271                // an array type does not have a dimension). In this case, it's fine to ignore
272                // the object for the purposes of construction.
273                assert( ctor.size() == dtor.size() && ctor.size() <= 1 );
274                if ( ctor.size() == 1 ) {
275                        // need to remember init expression, in case no ctors exist
276                        // if ctor does exist, want to use ctor expression instead of init
277                        // push this decision to the resolver
278                        assert( dynamic_cast< ImplicitCtorDtorStmt * > ( ctor.front() ) && dynamic_cast< ImplicitCtorDtorStmt * > ( dtor.front() ) );
279                        return new ConstructorInit( ctor.front(), dtor.front(), objDecl->get_init() );
280                }
281                return nullptr;
282        }
283
284        DeclarationWithType * CtorDtor::mutate( ObjectDecl * objDecl ) {
285                handleDWT( objDecl );
286                // hands off if @=, extern, builtin, etc.
287                // if global but initializer is not constexpr, always try to construct, since this is not legal C
288                if ( ( tryConstruct( objDecl ) && isManaged( objDecl ) ) || (! inFunction && ! isConstExpr( objDecl->get_init() ) ) ) {
289                        // constructed objects cannot be designated
290                        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 );
291                        // constructed objects should not have initializers nested too deeply
292                        if ( ! checkInitDepth( objDecl ) ) throw SemanticError( "Managed object's initializer is too deep ", objDecl );
293
294                        objDecl->set_init( genCtorInit( objDecl ) );
295                }
296                return Parent::mutate( objDecl );
297        }
298
299        DeclarationWithType * CtorDtor::mutate( FunctionDecl *functionDecl ) {
300                ValueGuard< bool > oldInFunc = inFunction;
301                inFunction = true;
302
303                handleDWT( functionDecl );
304
305                managedTypes.beginScope();
306                // go through assertions and recursively add seen ctor/dtors
307                for ( auto & tyDecl : functionDecl->get_functionType()->get_forall() ) {
308                        for ( DeclarationWithType *& assertion : tyDecl->get_assertions() ) {
309                                assertion = assertion->acceptMutator( *this );
310                        }
311                }
312                // parameters should not be constructed and destructed, so don't mutate FunctionType
313                mutateAll( functionDecl->get_oldDecls(), *this );
314                functionDecl->set_statements( maybeMutate( functionDecl->get_statements(), *this ) );
315
316                managedTypes.endScope();
317                return functionDecl;
318        }
319
320        Declaration* CtorDtor::mutate( StructDecl *aggregateDecl ) {
321                // don't construct members, but need to take note if there is a managed member,
322                // because that means that this type is also managed
323                for ( Declaration * member : aggregateDecl->get_members() ) {
324                        if ( ObjectDecl * field = dynamic_cast< ObjectDecl * >( member ) ) {
325                                if ( isManaged( field ) ) {
326                                        managedTypes.insert( SymTab::Mangler::mangle( aggregateDecl ) );
327                                        break;
328                                }
329                        }
330                }
331                return aggregateDecl;
332        }
333
334        CompoundStmt * CtorDtor::mutate( CompoundStmt * compoundStmt ) {
335                managedTypes.beginScope();
336                CompoundStmt * stmt = Parent::mutate( compoundStmt );
337                managedTypes.endScope();
338                return stmt;
339        }
340
341} // namespace InitTweak
342
343// Local Variables: //
344// tab-width: 4 //
345// mode: c++ //
346// compile-command: "make install" //
347// End: //
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