source: src/InitTweak/GenInit.cc @ 300d75b

aaron-thesisarm-ehcleanup-dtorsdeferred_resndemanglerjacob/cs343-translationjenkins-sandboxnew-astnew-ast-unique-exprnew-envno_listpersistent-indexerresolv-newwith_gc
Last change on this file since 300d75b was 300d75b, checked in by Rob Schluntz <rschlunt@…>, 4 years ago

Tighten the case where array dimension is hoisted

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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 : Peter A. Buhr
12// Last Modified On : Fri Mar 17 09:12:36 2017
13// Update Count     : 183
14//
15#include "GenInit.h"
16
17#include <stddef.h>                // for NULL
18#include <algorithm>               // for any_of
19#include <cassert>                 // for assert, strict_dynamic_cast, assertf
20#include <iterator>                // for back_inserter, inserter, back_inse...
21#include <list>                    // for _List_iterator, list
22
23#include "CodeGen/OperatorTable.h"
24#include "Common/PassVisitor.h"    // for PassVisitor, WithGuards, WithShort...
25#include "Common/SemanticError.h"  // for SemanticError
26#include "Common/UniqueName.h"     // for UniqueName
27#include "Common/utility.h"        // for ValueGuard, maybeClone
28#include "GenPoly/GenPoly.h"       // for getFunctionType, isPolyType
29#include "GenPoly/ScopedSet.h"     // for ScopedSet, ScopedSet<>::const_iter...
30#include "InitTweak.h"             // for isConstExpr, InitExpander, checkIn...
31#include "Parser/LinkageSpec.h"    // for isOverridable, C
32#include "ResolvExpr/Resolver.h"
33#include "SymTab/Autogen.h"        // for genImplicitCall, SizeType
34#include "SymTab/Mangler.h"        // for Mangler
35#include "SynTree/Declaration.h"   // for ObjectDecl, DeclarationWithType
36#include "SynTree/Expression.h"    // for VariableExpr, UntypedExpr, Address...
37#include "SynTree/Initializer.h"   // for ConstructorInit, SingleInit, Initi...
38#include "SynTree/Label.h"         // for Label
39#include "SynTree/Mutator.h"       // for mutateAll
40#include "SynTree/Statement.h"     // for CompoundStmt, ImplicitCtorDtorStmt
41#include "SynTree/Type.h"          // for Type, ArrayType, Type::Qualifiers
42#include "SynTree/Visitor.h"       // for acceptAll, maybeAccept
43#include "Tuples/Tuples.h"         // for maybeImpure
44
45namespace InitTweak {
46        namespace {
47                const std::list<Label> noLabels;
48                const std::list<Expression *> noDesignators;
49        }
50
51        struct ReturnFixer : public WithStmtsToAdd, public WithGuards {
52                /// consistently allocates a temporary variable for the return value
53                /// of a function so that anything which the resolver decides can be constructed
54                /// into the return type of a function can be returned.
55                static void makeReturnTemp( std::list< Declaration * > &translationUnit );
56
57                void premutate( FunctionDecl *functionDecl );
58                void premutate( ReturnStmt * returnStmt );
59
60          protected:
61                FunctionType * ftype = nullptr;
62                std::string funcName;
63        };
64
65        struct CtorDtor : public WithGuards, public WithShortCircuiting, public WithVisitorRef<CtorDtor>  {
66                /// create constructor and destructor statements for object declarations.
67                /// the actual call statements will be added in after the resolver has run
68                /// so that the initializer expression is only removed if a constructor is found
69                /// and the same destructor call is inserted in all of the appropriate locations.
70                static void generateCtorDtor( std::list< Declaration * > &translationUnit );
71
72                void previsit( ObjectDecl * );
73                void previsit( FunctionDecl *functionDecl );
74
75                // should not traverse into any of these declarations to find objects
76                // that need to be constructed or destructed
77                void previsit( StructDecl *aggregateDecl );
78                void previsit( AggregateDecl * ) { visit_children = false; }
79                void previsit( NamedTypeDecl * ) { visit_children = false; }
80                void previsit( FunctionType * ) { visit_children = false; }
81
82                void previsit( CompoundStmt * compoundStmt );
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                ManagedTypes managedTypes;
90                bool inFunction = false;
91        };
92
93        struct HoistArrayDimension final : public WithDeclsToAdd, public WithShortCircuiting, public WithGuards, public WithIndexer {
94                /// hoist dimension from array types in object declaration so that it uses a single
95                /// const variable of type size_t, so that side effecting array dimensions are only
96                /// computed once.
97                static void hoistArrayDimension( std::list< Declaration * > & translationUnit );
98
99                void premutate( ObjectDecl * objectDecl );
100                DeclarationWithType * postmutate( ObjectDecl * objectDecl );
101                void premutate( FunctionDecl *functionDecl );
102                // should not traverse into any of these declarations to find objects
103                // that need to be constructed or destructed
104                void premutate( AggregateDecl * ) { visit_children = false; }
105                void premutate( NamedTypeDecl * ) { visit_children = false; }
106                void premutate( FunctionType * ) { visit_children = false; }
107
108                // need this so that enumerators are added to the indexer, due to premutate(AggregateDecl *)
109                void premutate( EnumDecl * ) {}
110
111                void hoist( Type * type );
112
113                Type::StorageClasses storageClasses;
114                bool inFunction = false;
115        };
116
117        void genInit( std::list< Declaration * > & translationUnit ) {
118                fixReturnStatements( translationUnit );
119                HoistArrayDimension::hoistArrayDimension( translationUnit );
120                CtorDtor::generateCtorDtor( translationUnit );
121        }
122
123        void fixReturnStatements( std::list< Declaration * > & translationUnit ) {
124                PassVisitor<ReturnFixer> fixer;
125                mutateAll( translationUnit, fixer );
126        }
127
128        void ReturnFixer::premutate( ReturnStmt *returnStmt ) {
129                std::list< DeclarationWithType * > & returnVals = ftype->get_returnVals();
130                assert( returnVals.size() == 0 || returnVals.size() == 1 );
131                // hands off if the function returns a reference - we don't want to allocate a temporary if a variable's address
132                // is being returned
133                if ( returnStmt->expr && returnVals.size() == 1 && isConstructable( returnVals.front()->get_type() ) ) {
134                        // explicitly construct the return value using the return expression and the retVal object
135                        assertf( returnVals.front()->name != "", "Function %s has unnamed return value\n", funcName.c_str() );
136
137                        ObjectDecl * retVal = strict_dynamic_cast< ObjectDecl * >( returnVals.front() );
138                        if ( VariableExpr * varExpr = dynamic_cast< VariableExpr * >( returnStmt->expr ) ) {
139                                // return statement has already been mutated - don't need to do it again
140                                if ( varExpr->var == retVal ) return;
141                        }
142                        Statement * stmt = genCtorDtor( "?{}", retVal, returnStmt->expr );
143                        assertf( stmt, "ReturnFixer: genCtorDtor returned nullptr: %s / %s", toString( retVal ).c_str(), toString( returnStmt->expr ).c_str() );
144                        stmtsToAddBefore.push_back( stmt );
145
146                        // return the retVal object
147                        returnStmt->expr = new VariableExpr( returnVals.front() );
148                } // if
149        }
150
151        void ReturnFixer::premutate( FunctionDecl *functionDecl ) {
152                GuardValue( ftype );
153                GuardValue( funcName );
154
155                ftype = functionDecl->type;
156                funcName = functionDecl->name;
157        }
158
159        // precompute array dimension expression, because constructor generation may duplicate it,
160        // which would be incorrect if it is a side-effecting computation.
161        void HoistArrayDimension::hoistArrayDimension( std::list< Declaration * > & translationUnit ) {
162                PassVisitor<HoistArrayDimension> hoister;
163                mutateAll( translationUnit, hoister );
164        }
165
166        void HoistArrayDimension::premutate( ObjectDecl * objectDecl ) {
167                GuardValue( storageClasses );
168                storageClasses = objectDecl->get_storageClasses();
169        }
170
171        DeclarationWithType * HoistArrayDimension::postmutate( ObjectDecl * objectDecl ) {
172                hoist( objectDecl->get_type() );
173                return objectDecl;
174        }
175
176        void HoistArrayDimension::hoist( Type * type ) {
177                // if in function, generate const size_t var
178                static UniqueName dimensionName( "_array_dim" );
179
180                // C doesn't allow variable sized arrays at global scope or for static variables, so don't hoist dimension.
181                if ( ! inFunction ) return;
182                if ( storageClasses.is_static ) return;
183
184                if ( ArrayType * arrayType = dynamic_cast< ArrayType * >( type ) ) {
185                        if ( ! arrayType->get_dimension() ) return; // xxx - recursive call to hoist?
186
187                        // need to resolve array dimensions in order to accurately determine if constexpr
188                        ResolvExpr::findSingleExpression( arrayType->dimension, SymTab::SizeType->clone(), indexer );
189                        // don't need to hoist dimension if it's definitely pure - only need to if there's potential for side effects.
190                        if ( ! Tuples::maybeImpure( arrayType->dimension ) ) return;
191
192                        ObjectDecl * arrayDimension = new ObjectDecl( dimensionName.newName(), storageClasses, LinkageSpec::C, 0, SymTab::SizeType->clone(), new SingleInit( arrayType->get_dimension() ) );
193                        arrayDimension->get_type()->set_const( true );
194
195                        arrayType->set_dimension( new VariableExpr( arrayDimension ) );
196                        declsToAddBefore.push_back( arrayDimension );
197
198                        hoist( arrayType->get_base() );
199                        return;
200                }
201        }
202
203        void HoistArrayDimension::premutate( FunctionDecl * ) {
204                GuardValue( inFunction );
205                inFunction = true;
206        }
207
208        void CtorDtor::generateCtorDtor( std::list< Declaration * > & translationUnit ) {
209                PassVisitor<CtorDtor> ctordtor;
210                acceptAll( translationUnit, ctordtor );
211        }
212
213        bool ManagedTypes::isManaged( Type * type ) const {
214                // references are never constructed
215                if ( dynamic_cast< ReferenceType * >( type ) ) return false;
216                // need to clear and reset qualifiers when determining if a type is managed
217                ValueGuard< Type::Qualifiers > qualifiers( type->get_qualifiers() );
218                type->get_qualifiers() = Type::Qualifiers();
219                if ( TupleType * tupleType = dynamic_cast< TupleType * > ( type ) ) {
220                        // tuple is also managed if any of its components are managed
221                        if ( std::any_of( tupleType->types.begin(), tupleType->types.end(), [&](Type * type) { return isManaged( type ); }) ) {
222                                return true;
223                        }
224                }
225                // 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)
226                return managedTypes.find( SymTab::Mangler::mangleConcrete( type ) ) != managedTypes.end() || GenPoly::isPolyType( type );
227        }
228
229        bool ManagedTypes::isManaged( ObjectDecl * objDecl ) const {
230                Type * type = objDecl->get_type();
231                while ( ArrayType * at = dynamic_cast< ArrayType * >( type ) ) {
232                        type = at->get_base();
233                }
234                return isManaged( type );
235        }
236
237        void ManagedTypes::handleDWT( DeclarationWithType * dwt ) {
238                // if this function is a user-defined constructor or destructor, mark down the type as "managed"
239                if ( ! LinkageSpec::isOverridable( dwt->get_linkage() ) && CodeGen::isCtorDtor( dwt->get_name() ) ) {
240                        std::list< DeclarationWithType * > & params = GenPoly::getFunctionType( dwt->get_type() )->get_parameters();
241                        assert( ! params.empty() );
242                        Type * type = InitTweak::getPointerBase( params.front()->get_type() );
243                        assert( type );
244                        managedTypes.insert( SymTab::Mangler::mangleConcrete( type ) );
245                }
246        }
247
248        void ManagedTypes::handleStruct( StructDecl * aggregateDecl ) {
249                // don't construct members, but need to take note if there is a managed member,
250                // because that means that this type is also managed
251                for ( Declaration * member : aggregateDecl->get_members() ) {
252                        if ( ObjectDecl * field = dynamic_cast< ObjectDecl * >( member ) ) {
253                                if ( isManaged( field ) ) {
254                                        // generic parameters should not play a role in determining whether a generic type is constructed - construct all generic types, so that
255                                        // polymorphic constructors make generic types managed types
256                                        StructInstType inst( Type::Qualifiers(), aggregateDecl );
257                                        managedTypes.insert( SymTab::Mangler::mangleConcrete( &inst ) );
258                                        break;
259                                }
260                        }
261                }
262        }
263
264        void ManagedTypes::beginScope() { managedTypes.beginScope(); }
265        void ManagedTypes::endScope() { managedTypes.endScope(); }
266
267        ImplicitCtorDtorStmt * genCtorDtor( const std::string & fname, ObjectDecl * objDecl, Expression * arg ) {
268                // call into genImplicitCall from Autogen.h to generate calls to ctor/dtor
269                assertf( objDecl, "genCtorDtor passed null objDecl" );
270                std::list< Statement * > stmts;
271                InitExpander srcParam( maybeClone( arg ) );
272                SymTab::genImplicitCall( srcParam, new VariableExpr( objDecl ), fname, back_inserter( stmts ), objDecl );
273                assert( stmts.size() <= 1 );
274                return stmts.size() == 1 ? strict_dynamic_cast< ImplicitCtorDtorStmt * >( stmts.front() ) : nullptr;
275        }
276
277        ConstructorInit * genCtorInit( ObjectDecl * objDecl ) {
278                // call into genImplicitCall from Autogen.h to generate calls to ctor/dtor
279                // for each constructable object
280                std::list< Statement * > ctor;
281                std::list< Statement * > dtor;
282
283                InitExpander srcParam( objDecl->get_init() );
284                InitExpander nullParam( (Initializer *)NULL );
285                SymTab::genImplicitCall( srcParam, new VariableExpr( objDecl ), "?{}", back_inserter( ctor ), objDecl );
286                SymTab::genImplicitCall( nullParam, new VariableExpr( objDecl ), "^?{}", front_inserter( dtor ), objDecl, false );
287
288                // Currently genImplicitCall produces a single Statement - a CompoundStmt
289                // which  wraps everything that needs to happen. As such, it's technically
290                // possible to use a Statement ** in the above calls, but this is inherently
291                // unsafe, so instead we take the slightly less efficient route, but will be
292                // immediately informed if somehow the above assumption is broken. In this case,
293                // we could always wrap the list of statements at this point with a CompoundStmt,
294                // but it seems reasonable at the moment for this to be done by genImplicitCall
295                // itself. It is possible that genImplicitCall produces no statements (e.g. if
296                // an array type does not have a dimension). In this case, it's fine to ignore
297                // the object for the purposes of construction.
298                assert( ctor.size() == dtor.size() && ctor.size() <= 1 );
299                if ( ctor.size() == 1 ) {
300                        // need to remember init expression, in case no ctors exist
301                        // if ctor does exist, want to use ctor expression instead of init
302                        // push this decision to the resolver
303                        assert( dynamic_cast< ImplicitCtorDtorStmt * > ( ctor.front() ) && dynamic_cast< ImplicitCtorDtorStmt * > ( dtor.front() ) );
304                        return new ConstructorInit( ctor.front(), dtor.front(), objDecl->get_init() );
305                }
306                return nullptr;
307        }
308
309        void CtorDtor::previsit( ObjectDecl * objDecl ) {
310                managedTypes.handleDWT( objDecl );
311                // hands off if @=, extern, builtin, etc.
312                // even if unmanaged, try to construct global or static if initializer is not constexpr, since this is not legal C
313                if ( tryConstruct( objDecl ) && ( managedTypes.isManaged( objDecl ) || ((! inFunction || objDecl->get_storageClasses().is_static ) && ! isConstExpr( objDecl->get_init() ) ) ) ) {
314                        // constructed objects cannot be designated
315                        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 @=.\n", objDecl );
316                        // constructed objects should not have initializers nested too deeply
317                        if ( ! checkInitDepth( objDecl ) ) throw SemanticError( "Managed object's initializer is too deep ", objDecl );
318
319                        objDecl->set_init( genCtorInit( objDecl ) );
320                }
321        }
322
323        void CtorDtor::previsit( FunctionDecl *functionDecl ) {
324                visit_children = false;  // do not try and construct parameters or forall parameters
325                GuardValue( inFunction );
326                inFunction = true;
327
328                managedTypes.handleDWT( functionDecl );
329
330                GuardScope( managedTypes );
331                // go through assertions and recursively add seen ctor/dtors
332                for ( auto & tyDecl : functionDecl->get_functionType()->get_forall() ) {
333                        for ( DeclarationWithType *& assertion : tyDecl->get_assertions() ) {
334                                managedTypes.handleDWT( assertion );
335                        }
336                }
337
338                maybeAccept( functionDecl->get_statements(), *visitor );
339        }
340
341        void CtorDtor::previsit( StructDecl *aggregateDecl ) {
342                visit_children = false; // do not try to construct and destruct aggregate members
343
344                managedTypes.handleStruct( aggregateDecl );
345        }
346
347        void CtorDtor::previsit( CompoundStmt * ) {
348                GuardScope( managedTypes );
349        }
350} // namespace InitTweak
351
352// Local Variables: //
353// tab-width: 4 //
354// mode: c++ //
355// compile-command: "make install" //
356// End: //
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