Changeset 2a301ff for src/InitTweak/GenInit.cc

Timestamp:

Aug 31, 2023, 11:31:15 PM (2 years ago)

Author:

JiadaL <j82liang@…>

Branches:

master

Children:

950c58e

Parents:

92355883 (diff), 686912c (diff)
Note: this is a merge changeset, the changes displayed below correspond to the merge itself.
Use the (diff) links above to see all the changes relative to each parent.

Message:

Resolve conflict

File:

• src/InitTweak/GenInit.cc (modified) (1 diff)

src/InitTweak/GenInit.cc

@@ -300 +300 @@
 
 #       warning Remove the _New suffix after the conversion is complete.
+
+        // Outer pass finds declarations, for their type could wrap a type that needs hoisting
         struct HoistArrayDimension_NoResolve_New final :
                         public ast::WithDeclsToAdd<>, public ast::WithShortCircuiting,
                         public ast::WithGuards, public ast::WithConstTranslationUnit,
-                        public ast::WithVisitorRef<HoistArrayDimension_NoResolve_New> {
-                void previsit( const ast::ObjectDecl * decl );
-                const ast::DeclWithType * postvisit( const ast::ObjectDecl * decl );
-                // Do not look for objects inside there declarations (and type).
-                void previsit( const ast::AggregateDecl * ) { visit_children = false; }
-                void previsit( const ast::NamedTypeDecl * ) { visit_children = false; }
-                void previsit( const ast::FunctionType * ) { visit_children = false; }
-
-                const ast::Type * hoist( const ast::Type * type );
+                        public ast::WithVisitorRef<HoistArrayDimension_NoResolve_New>,
+                        public ast::WithSymbolTableX<ast::SymbolTable::ErrorDetection::IgnoreErrors> {
+
+                // Inner pass looks within a type, for a part that depends on an expression
+                struct HoistDimsFromTypes final :
+                                public ast::WithShortCircuiting, public ast::WithGuards {
+
+                        HoistArrayDimension_NoResolve_New * outer;
+                        HoistDimsFromTypes( HoistArrayDimension_NoResolve_New * outer ) : outer(outer) {}
+
+                        // Only intended for visiting through types.
+                        // Tolerate, and short-circuit at, the dimension expression of an array type.
+                        //    (We'll operate on the dimension expression of an array type directly
+                        //    from the parent type, not by visiting through it)
+                        // Look inside type exprs.
+                        void previsit( const ast::Node * ) {
+                                assert( false && "unsupported node type" );
+                        };
+                        const ast::Expr * allowedExpr = nullptr;
+                        void previsit( const ast::Type * ) {
+                                GuardValue( allowedExpr ) = nullptr;
+                        }
+                        void previsit( const ast::ArrayType * t ) {
+                                GuardValue( allowedExpr ) = t->dimension.get();
+                        }
+                        void previsit( const ast::PointerType * t ) {
+                                GuardValue( allowedExpr ) = t->dimension.get();
+                        }
+                        void previsit( const ast::TypeofType * t ) {
+                                GuardValue( allowedExpr ) = t->expr.get();
+                        }
+                        void previsit( const ast::Expr * e ) {
+                                assert( e == allowedExpr &&
+                                    "only expecting to visit exprs that are dimension exprs or typeof(-) inner exprs" );
+
+                                // Skip the tolerated expressions
+                                visit_children = false;
+                        }
+                        void previsit( const ast::TypeExpr * ) {}
+
+                        const ast::Type * postvisit(
+                                        const ast::ArrayType * arrayType ) {
+                                static UniqueName dimensionName( "_array_dim" );
+
+                                if ( nullptr == arrayType->dimension ) {  // if no dimension is given, don't presume to invent one
+                                        return arrayType;
+                                }
+
+                                // find size_t; use it as the type for a dim expr
+                                ast::ptr<ast::Type> dimType = outer->transUnit().global.sizeType;
+                                assert( dimType );
+                                add_qualifiers( dimType, ast::CV::Qualifiers( ast::CV::Const ) );
+
+                                // Special-case handling: leave the user's dimension expression alone
+                                // - requires the user to have followed a careful convention
+                                // - may apply to extremely simple applications, but only as windfall
+                                // - users of advanced applications will be following the convention on purpose
+                                // - CFA maintainers must protect the criteria against leaving too much alone
+
+                                // Actual leave-alone cases following are conservative approximations of "cannot vary"
+
+                                // Leave alone: literals and enum constants
+                                if ( dynamic_cast< const ast::ConstantExpr * >( arrayType->dimension.get() ) ) {
+                                        return arrayType;
+                                }
+
+                                // Leave alone: direct use of an object declared to be const
+                                const ast::NameExpr * dimn = dynamic_cast< const ast::NameExpr * >( arrayType->dimension.get() );
+                                if ( dimn ) {
+                                        std::vector<ast::SymbolTable::IdData> dimnDefs = outer->symtab.lookupId( dimn->name );
+                                        if ( dimnDefs.size() == 1 ) {
+                                                const ast::DeclWithType * dimnDef = dimnDefs[0].id.get();
+                                                assert( dimnDef && "symbol table binds a name to nothing" );
+                                                const ast::ObjectDecl * dimOb = dynamic_cast< const ast::ObjectDecl * >( dimnDef );
+                                                if( dimOb ) {
+                                                        const ast::Type * dimTy = dimOb->type.get();
+                                                        assert( dimTy && "object declaration bearing no type" );
+                                                        // must not hoist some: size_t
+                                                        // must hoist all: pointers and references
+                                                        // the analysis is conservative; BasicType is a simple approximation
+                                                        if ( dynamic_cast< const ast::BasicType * >( dimTy ) ||
+                                                             dynamic_cast< const ast::SueInstType<ast::EnumDecl> * >( dimTy ) ) {
+                                                                if ( dimTy->is_const() ) {
+                                                                        // The dimension is certainly re-evaluable, giving the same answer each time.
+                                                                        // Our user might be hoping to write the array type in multiple places, having them unify.
+                                                                        // Leave the type alone.
+
+                                                                        // We believe the new criterion leaves less alone than the old criterion.
+                                                                        // Thus, the old criterion should have left the current case alone.
+                                                                        // Catch cases that weren't thought through.
+                                                                        assert( !Tuples::maybeImpure( arrayType->dimension ) );
+
+                                                                        return arrayType;
+                                                                }
+                                                        };
+                                                }
+                                        }
+                                }
+
+                                // Leave alone: any sizeof expression (answer cannot vary during current lexical scope)
+                                const ast::SizeofExpr * sz = dynamic_cast< const ast::SizeofExpr * >( arrayType->dimension.get() );
+                                if ( sz ) {
+                                        return arrayType;
+                                }
+
+                                // General-case handling: change the array-type's dim expr (hoist the user-given content out of the type)
+                                // - always safe
+                                // - user-unnoticeable in common applications (benign noise in -CFA output)
+                                // - may annoy a responsible user of advanced applications (but they can work around)
+                                // - protects against misusing advanced features
+                                //
+                                // The hoist, by example, is:
+                                // FROM USER:  float a[ rand() ];
+                                // TO GCC:     const size_t __len_of_a = rand(); float a[ __len_of_a ];
+
+                                ast::ObjectDecl * arrayDimension = new ast::ObjectDecl(
+                                        arrayType->dimension->location,
+                                        dimensionName.newName(),
+                                        dimType,
+                                        new ast::SingleInit(
+                                                arrayType->dimension->location,
+                                                arrayType->dimension
+                                        )
+                                );
+
+                                ast::ArrayType * mutType = ast::mutate( arrayType );
+                                mutType->dimension = new ast::VariableExpr(
+                                                arrayDimension->location, arrayDimension );
+                                outer->declsToAddBefore.push_back( arrayDimension );
+
+                                return mutType;
+                        }  // postvisit( const ast::ArrayType * )
+                }; // struct HoistDimsFromTypes
 
                 ast::Storage::Classes storageClasses;
+                void previsit(
+                                const ast::ObjectDecl * decl ) {
+                        GuardValue( storageClasses ) = decl->storage;
+                }
+
+                const ast::DeclWithType * postvisit(
+                                const ast::ObjectDecl * objectDecl ) {
+
+                        if ( !isInFunction() || storageClasses.is_static ) {
+                                return objectDecl;
+                        }
+
+                        const ast::Type * mid = objectDecl->type;
+
+                        ast::Pass<HoistDimsFromTypes> hoist{this};
+                        const ast::Type * result = mid->accept( hoist );
+
+                        return mutate_field( objectDecl, &ast::ObjectDecl::type, result );
+                }
         };
 
-        void HoistArrayDimension_NoResolve_New::previsit(
-                        const ast::ObjectDecl * decl ) {
-                GuardValue( storageClasses ) = decl->storage;
-        }
-
-        const ast::DeclWithType * HoistArrayDimension_NoResolve_New::postvisit(
-                        const ast::ObjectDecl * objectDecl ) {
-                return mutate_field( objectDecl, &ast::ObjectDecl::type,
-                                hoist( objectDecl->type ) );
-        }
-
-        const ast::Type * HoistArrayDimension_NoResolve_New::hoist(
-                        const ast::Type * type ) {
-                static UniqueName dimensionName( "_array_dim" );
-
-                if ( !isInFunction() || storageClasses.is_static ) {
-                        return type;
-                }
-
-                if ( auto arrayType = dynamic_cast< const ast::ArrayType * >( type ) ) {
-                        if ( nullptr == arrayType->dimension ) {
-                                return type;
-                        }
-
-                        if ( !Tuples::maybeImpure( arrayType->dimension ) ) {
-                                return type;
-                        }
-
-                        ast::ptr<ast::Type> dimType = transUnit().global.sizeType;
-                        assert( dimType );
-                        add_qualifiers( dimType, ast::CV::Qualifiers( ast::CV::Const ) );
-
-                        ast::ObjectDecl * arrayDimension = new ast::ObjectDecl(
-                                arrayType->dimension->location,
-                                dimensionName.newName(),
-                                dimType,
-                                new ast::SingleInit(
-                                        arrayType->dimension->location,
-                                        arrayType->dimension
-                                )
-                        );
-
-                        ast::ArrayType * mutType = ast::mutate( arrayType );
-                        mutType->dimension = new ast::VariableExpr(
-                                        arrayDimension->location, arrayDimension );
-                        declsToAddBefore.push_back( arrayDimension );
-
-                        mutType->base = hoist( mutType->base );
-                        return mutType;
-                }
-                return type;
-        }
+
+
 
         struct ReturnFixer_New final :