Changeset 04b73b6 for src/Virtual/ExpandCasts.cc

Timestamp:

Jul 23, 2020, 3:37:05 PM (4 years ago)

Author:

Thierry Delisle <tdelisle@…>

Branches:

ADT, arm-eh, ast-experimental, enum, forall-pointer-decay, jacob/cs343-translation, master, new-ast, new-ast-unique-expr, pthread-emulation, qualifiedEnum

Children:

f4ec4a90

Parents:

f0c3120 (diff), e262b5e (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:

Merge branch 'master' of plg.uwaterloo.ca:software/cfa/cfa-cc

File:

• src/Virtual/ExpandCasts.cc (modified) (9 diffs)

src/Virtual/ExpandCasts.cc

@@ -10 +10 @@
 // Created On       : Mon Jul 24 13:59:00 2017
 // Last Modified By : Andrew Beach
-// Last Modified On : Tue May 26 14:37:00 2020
-// Update Count     : 2
+// Last Modified On : Tue Jul 22 10:04:00 2020
+// Update Count     : 3
 //
 
@@ -24 +24 @@
 #include "Common/PassVisitor.h"    // for PassVisitor
 #include "Common/SemanticError.h"  // for SemanticError
+#include "SymTab/Mangler.h"        // for mangleType
 #include "SynTree/Declaration.h"   // for ObjectDecl, StructDecl, FunctionDecl
 #include "SynTree/Expression.h"    // for VirtualCastExpr, CastExpr, Address...
@@ -31 +32 @@
 
 namespace Virtual {
+
+        // Indented until the new ast code gets added.
+
+        /// Maps virtual table types the instance for that type.
+        class VirtualTableMap final {
+                std::unordered_map<std::string, ObjectDecl *> vtable_instances;
+        public:
+                ObjectDecl * insert( ObjectDecl * vtableDecl ) {
+                        std::string const & mangledName = SymTab::Mangler::mangleType( vtableDecl->type );
+                        ObjectDecl *& value = vtable_instances[ mangledName ];
+                        if ( value ) {
+                                if ( vtableDecl->storageClasses.is_extern ) {
+                                        return nullptr;
+                                } else if ( ! value->storageClasses.is_extern ) {
+                                        return value;
+                                }
+                        }
+                        value = vtableDecl;
+                        return nullptr;
+                }
+
+                ObjectDecl * lookup( const Type * vtableType ) {
+                        std::string const & mangledName = SymTab::Mangler::mangleType( vtableType );
+                        const auto it = vtable_instances.find( mangledName );
+                        return ( vtable_instances.end() == it ) ? nullptr : it->second;
+                }
+        };
 
         /* Currently virtual depends on the rather brittle name matching between
@@ -39 +67 @@
          */
 
+        namespace {
+
         std::string get_vtable_name( std::string const & name ) {
                 return name + "_vtable";
@@ -53 +83 @@
         std::string get_vtable_inst_name_root( std::string const & name ) {
                 return get_vtable_name_root( name.substr(1, name.size() - 10 ) );
-        }
-
-        bool is_vtable_name( std::string const & name ) {
-                return (name.substr( name.size() - 7 ) == "_vtable" );
         }
 
@@ -64 +90 @@
         }
 
+        } // namespace
+
         class VirtualCastCore {
-        std::map<std::string, ObjectDecl *> vtable_instances;
-        FunctionDecl *vcast_decl;
-        StructDecl *pvt_decl;
+                VirtualTableMap vtable_instances;
+                FunctionDecl *vcast_decl;
+                StructDecl *pvt_decl;
 
                 Type * pointer_to_pvt(int level_of_indirection) {
@@ -107 +135 @@
         void VirtualCastCore::premutate( ObjectDecl * objectDecl ) {
                 if ( is_vtable_inst_name( objectDecl->get_name() ) ) {
-                        vtable_instances[objectDecl->get_name()] = objectDecl;
-                }
-        }
-
-        // Better error locations for generated casts.
-        static CodeLocation castLocation( VirtualCastExpr * castExpr ) {
+                        if ( ObjectDecl * existing = vtable_instances.insert( objectDecl ) ) {
+                                std::string msg = "Repeated instance of virtual table, original found at: ";
+                                msg += existing->location.filename;
+                                msg += ":" + toString( existing->location.first_line );
+                                SemanticError( objectDecl->location, msg );
+                        }
+                }
+        }
+
+        namespace {
+
+        /// Better error locations for generated casts.
+        CodeLocation castLocation( const VirtualCastExpr * castExpr ) {
                 if ( castExpr->location.isSet() ) {
                         return castExpr->location;
@@ -124 +159 @@
         }
 
+        [[noreturn]] void castError( const VirtualCastExpr * castExpr, std::string const & message ) {
+                SemanticError( castLocation( castExpr ), message );
+        }
+
+        /// Get the virtual table type used in a virtual cast.
+        Type * getVirtualTableType( const VirtualCastExpr * castExpr ) {
+                const Type * objectType;
+                if ( auto target = dynamic_cast<const PointerType *>( castExpr->result ) ) {
+                        objectType = target->base;
+                } else if ( auto target = dynamic_cast<const ReferenceType *>( castExpr->result ) ) {
+                        objectType = target->base;
+                } else {
+                        castError( castExpr, "Virtual cast type must be a pointer or reference type." );
+                }
+                assert( objectType );
+
+                const StructInstType * structType = dynamic_cast<const StructInstType *>( objectType );
+                if ( nullptr == structType ) {
+                        castError( castExpr, "Virtual cast type must refer to a structure type." );
+                }
+                const StructDecl * structDecl = structType->baseStruct;
+                assert( structDecl );
+
+                const ObjectDecl * fieldDecl = nullptr;
+                if ( 0 < structDecl->members.size() ) {
+                        const Declaration * memberDecl = structDecl->members.front();
+                        assert( memberDecl );
+                        fieldDecl = dynamic_cast<const ObjectDecl *>( memberDecl );
+                        if ( fieldDecl && fieldDecl->name != "virtual_table" ) {
+                                fieldDecl = nullptr;
+                        }
+                }
+                if ( nullptr == fieldDecl ) {
+                        castError( castExpr, "Virtual cast type must have a leading virtual_table field." );
+                }
+                const PointerType * fieldType = dynamic_cast<const PointerType *>( fieldDecl->type );
+                if ( nullptr == fieldType ) {
+                        castError( castExpr, "Virtual cast type virtual_table field is not a pointer." );
+                }
+                assert( fieldType->base );
+                auto virtualStructType = dynamic_cast<const StructInstType *>( fieldType->base );
+                assert( virtualStructType );
+
+                // Here is the type, but if it is polymorphic it will have lost information.
+                // (Always a clone so that it may always be deleted.)
+                StructInstType * virtualType = virtualStructType->clone();
+                if ( ! structType->parameters.empty() ) {
+                        deleteAll( virtualType->parameters );
+                        virtualType->parameters.clear();
+                        cloneAll( structType->parameters, virtualType->parameters );
+                }
+                return virtualType;
+        }
+
+        } // namespace
+
         Expression * VirtualCastCore::postmutate( VirtualCastExpr * castExpr ) {
-                assertf( castExpr->get_result(), "Virtual Cast target not found before expansion." );
+                assertf( castExpr->result, "Virtual Cast target not found before expansion." );
 
                 assert( vcast_decl );
                 assert( pvt_decl );
 
-                // Get the base type of the pointer/reference.
-                Type * base;
-                Type * result_type = castExpr->result;
-                if ( PointerType * target = dynamic_cast<PointerType *>( result_type ) ) {
-                        base = target->base;
-                } else if ( ReferenceType * target = dynamic_cast<ReferenceType *>( result_type ) ) {
-                        base = target->base;
-                } else {
+                const Type * vtable_type = getVirtualTableType( castExpr );
+                ObjectDecl * table = vtable_instances.lookup( vtable_type );
+                if ( nullptr == table ) {
                         SemanticError( castLocation( castExpr ),
-                                "Virtual cast type must be a pointer or reference type." );
-                }
-
-                StructInstType * target_struct = dynamic_cast<StructInstType *>( base );
-                if ( nullptr == target_struct ) {
-                        SemanticError( castLocation( castExpr ),
-                                "Virtual cast type must refer to a structure type." );
-                }
-                StructDecl * target_decl = target_struct->get_baseStruct();
-
-                std::map<std::string, ObjectDecl *>::iterator found =
-                        vtable_instances.find( get_vtable_inst_name( target_decl->get_name() ) );
-                if ( vtable_instances.end() == found ) {
-                        SemanticError( castLocation( castExpr ),
-                                "Virtual cast type does not have a virtual table instance." );
-                }
-                ObjectDecl * table = found->second;
+                                "Could not find virtual table instance." );
+                }
 
                 Expression * result = new CastExpr(
@@ -174 +245 @@
                 castExpr->set_result( nullptr );
                 delete castExpr;
+                delete vtable_type;
                 return result;
         }