source: src/InitTweak/GenInit.cc @ 9facf3b

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 9facf3b was 9facf3b, checked in by Rob Schluntz <rschlunt@…>, 5 years ago

update generation of return variables and the affected test outputs

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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                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() {}
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                // 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.
145                if ( returnStmt->get_expr() && returnVals.size() == 1 && funcName != "?=?" && ! returnVals.front()->get_type()->get_isLvalue() ) {
146                        // explicitly construct the return value using the return expression and the retVal object
147                        assertf( returnVals.front()->get_name() != "", "Function %s has unnamed return value\n", funcName.c_str() );
148                        UntypedExpr *construct = new UntypedExpr( new NameExpr( "?{}" ) );
149                        construct->get_args().push_back( new AddressExpr( new VariableExpr( returnVals.front() ) ) );
150                        construct->get_args().push_back( returnStmt->get_expr() );
151                        stmtsToAdd.push_back(new ExprStmt(noLabels, construct));
152
153                        // return the retVal object
154                        returnStmt->set_expr( new VariableExpr( returnVals.front() ) );
155                } // if
156                return returnStmt;
157        }
158
159        DeclarationWithType* ReturnFixer::mutate( FunctionDecl *functionDecl ) {
160                ValueGuard< FunctionType * > oldFtype( ftype );
161                ValueGuard< std::string > oldFuncName( funcName );
162
163                ftype = functionDecl->get_functionType();
164                funcName = functionDecl->get_name();
165                return Parent::mutate( functionDecl );
166        }
167
168        // precompute array dimension expression, because constructor generation may duplicate it,
169        // which would be incorrect if it is a side-effecting computation.
170        void HoistArrayDimension::hoistArrayDimension( std::list< Declaration * > & translationUnit ) {
171                HoistArrayDimension hoister;
172                hoister.mutateDeclarationList( translationUnit );
173        }
174
175        DeclarationWithType * HoistArrayDimension::mutate( ObjectDecl * objectDecl ) {
176                storageclass = objectDecl->get_storageClass();
177                DeclarationWithType * temp = Parent::mutate( objectDecl );
178                hoist( objectDecl->get_type() );
179                storageclass = DeclarationNode::NoStorageClass;
180                return temp;
181        }
182
183        void HoistArrayDimension::hoist( Type * type ) {
184                // if in function, generate const size_t var
185                static UniqueName dimensionName( "_array_dim" );
186
187                // C doesn't allow variable sized arrays at global scope or for static variables,
188                // so don't hoist dimension.
189                if ( ! inFunction ) return;
190                if ( storageclass == DeclarationNode::Static ) return;
191
192                if ( ArrayType * arrayType = dynamic_cast< ArrayType * >( type ) ) {
193                        if ( ! arrayType->get_dimension() ) return; // xxx - recursive call to hoist?
194
195                        // don't need to hoist dimension if it's a constexpr - only need to if there's potential
196                        // for side effects.
197                        if ( isConstExpr( arrayType->get_dimension() ) ) return;
198
199                        ObjectDecl * arrayDimension = new ObjectDecl( dimensionName.newName(), storageclass, LinkageSpec::C, 0, SymTab::SizeType->clone(), new SingleInit( arrayType->get_dimension() ) );
200                        arrayDimension->get_type()->set_isConst( true );
201
202                        arrayType->set_dimension( new VariableExpr( arrayDimension ) );
203                        addDeclaration( arrayDimension );
204
205                        hoist( arrayType->get_base() );
206                        return;
207                }
208        }
209
210        DeclarationWithType * HoistArrayDimension::mutate( FunctionDecl *functionDecl ) {
211                ValueGuard< bool > oldInFunc( inFunction );
212                inFunction = true;
213                DeclarationWithType * decl = Parent::mutate( functionDecl );
214                return decl;
215        }
216
217        void CtorDtor::generateCtorDtor( std::list< Declaration * > & translationUnit ) {
218                CtorDtor ctordtor;
219                mutateAll( translationUnit, ctordtor );
220        }
221
222        bool CtorDtor::isManaged( Type * type ) const {
223                if ( TupleType * tupleType = dynamic_cast< TupleType * > ( type ) ) {
224                        // tuple is also managed if any of its components are managed
225                        if ( std::any_of( tupleType->get_types().begin(), tupleType->get_types().end(), [&](Type * type) { return isManaged( type ); }) ) {
226                                return true;
227                        }
228                }
229                // 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)
230                return managedTypes.find( SymTab::Mangler::mangle( type ) ) != managedTypes.end() || GenPoly::isPolyType( type );
231        }
232
233        bool CtorDtor::isManaged( ObjectDecl * objDecl ) const {
234                Type * type = objDecl->get_type();
235                while ( ArrayType * at = dynamic_cast< ArrayType * >( type ) ) {
236                        type = at->get_base();
237                }
238                return isManaged( type );
239        }
240
241        void CtorDtor::handleDWT( DeclarationWithType * dwt ) {
242                // if this function is a user-defined constructor or destructor, mark down the type as "managed"
243                if ( ! LinkageSpec::isOverridable( dwt->get_linkage() ) && isCtorDtor( dwt->get_name() ) ) {
244                        std::list< DeclarationWithType * > & params = GenPoly::getFunctionType( dwt->get_type() )->get_parameters();
245                        assert( ! params.empty() );
246                        PointerType * type = safe_dynamic_cast< PointerType * >( params.front()->get_type() );
247                        managedTypes.insert( SymTab::Mangler::mangle( type->get_base() ) );
248                }
249        }
250
251        ConstructorInit * genCtorInit( ObjectDecl * objDecl ) {
252                // call into genImplicitCall from Autogen.h to generate calls to ctor/dtor
253                // for each constructable object
254                std::list< Statement * > ctor;
255                std::list< Statement * > dtor;
256
257                InitExpander srcParam( objDecl->get_init() );
258                InitExpander nullParam( (Initializer *)NULL );
259                SymTab::genImplicitCall( srcParam, new VariableExpr( objDecl ), "?{}", back_inserter( ctor ), objDecl );
260                SymTab::genImplicitCall( nullParam, new VariableExpr( objDecl ), "^?{}", front_inserter( dtor ), objDecl, false );
261
262                // Currently genImplicitCall produces a single Statement - a CompoundStmt
263                // which  wraps everything that needs to happen. As such, it's technically
264                // possible to use a Statement ** in the above calls, but this is inherently
265                // unsafe, so instead we take the slightly less efficient route, but will be
266                // immediately informed if somehow the above assumption is broken. In this case,
267                // we could always wrap the list of statements at this point with a CompoundStmt,
268                // but it seems reasonable at the moment for this to be done by genImplicitCall
269                // itself. It is possible that genImplicitCall produces no statements (e.g. if
270                // an array type does not have a dimension). In this case, it's fine to ignore
271                // the object for the purposes of construction.
272                assert( ctor.size() == dtor.size() && ctor.size() <= 1 );
273                if ( ctor.size() == 1 ) {
274                        // need to remember init expression, in case no ctors exist
275                        // if ctor does exist, want to use ctor expression instead of init
276                        // push this decision to the resolver
277                        assert( dynamic_cast< ImplicitCtorDtorStmt * > ( ctor.front() ) && dynamic_cast< ImplicitCtorDtorStmt * > ( dtor.front() ) );
278                        return new ConstructorInit( ctor.front(), dtor.front(), objDecl->get_init() );
279                }
280                return nullptr;
281        }
282
283        DeclarationWithType * CtorDtor::mutate( ObjectDecl * objDecl ) {
284                handleDWT( objDecl );
285                // hands off if @=, extern, builtin, etc.
286                // if global but initializer is not constexpr, always try to construct, since this is not legal C
287                if ( ( tryConstruct( objDecl ) && isManaged( objDecl ) ) || (! inFunction && ! isConstExpr( objDecl->get_init() ) ) ) {
288                        // constructed objects cannot be designated
289                        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 );
290                        // constructed objects should not have initializers nested too deeply
291                        if ( ! checkInitDepth( objDecl ) ) throw SemanticError( "Managed object's initializer is too deep ", objDecl );
292
293                        objDecl->set_init( genCtorInit( objDecl ) );
294                }
295                return Parent::mutate( objDecl );
296        }
297
298        DeclarationWithType * CtorDtor::mutate( FunctionDecl *functionDecl ) {
299                ValueGuard< bool > oldInFunc = inFunction;
300                inFunction = true;
301
302                handleDWT( functionDecl );
303
304                managedTypes.beginScope();
305                // go through assertions and recursively add seen ctor/dtors
306                for ( auto & tyDecl : functionDecl->get_functionType()->get_forall() ) {
307                        for ( DeclarationWithType *& assertion : tyDecl->get_assertions() ) {
308                                assertion = assertion->acceptMutator( *this );
309                        }
310                }
311                // parameters should not be constructed and destructed, so don't mutate FunctionType
312                mutateAll( functionDecl->get_oldDecls(), *this );
313                functionDecl->set_statements( maybeMutate( functionDecl->get_statements(), *this ) );
314
315                managedTypes.endScope();
316                return functionDecl;
317        }
318
319        Declaration* CtorDtor::mutate( StructDecl *aggregateDecl ) {
320                // don't construct members, but need to take note if there is a managed member,
321                // because that means that this type is also managed
322                for ( Declaration * member : aggregateDecl->get_members() ) {
323                        if ( ObjectDecl * field = dynamic_cast< ObjectDecl * >( member ) ) {
324                                if ( isManaged( field ) ) {
325                                        managedTypes.insert( SymTab::Mangler::mangle( aggregateDecl ) );
326                                        break;
327                                }
328                        }
329                }
330                return aggregateDecl;
331        }
332
333        CompoundStmt * CtorDtor::mutate( CompoundStmt * compoundStmt ) {
334                managedTypes.beginScope();
335                CompoundStmt * stmt = Parent::mutate( compoundStmt );
336                managedTypes.endScope();
337                return stmt;
338        }
339
340} // namespace InitTweak
341
342// Local Variables: //
343// tab-width: 4 //
344// mode: c++ //
345// compile-command: "make install" //
346// End: //
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