Changeset 22f94a4 for src/Virtual/ExpandCasts.cc

Timestamp:

Aug 11, 2020, 4:40:15 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:

0d070ca

Parents:

07d867b (diff), 129674b (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' into new-ast

File:

• src/Virtual/ExpandCasts.cc (modified) (10 diffs)

src/Virtual/ExpandCasts.cc

@@ -10 +10 @@
 // Created On       : Mon Jul 24 13:59:00 2017
 // Last Modified By : Andrew Beach
-// Last Modified On : Tus Aug  2 14:59:00 2017
-// Update Count     : 1
+// Last Modified On : Fri Jul 31 10:29:00 2020
+// Update Count     : 4
 //
 
@@ -18 +18 @@
 #include <cassert>                 // for assert, assertf
 #include <iterator>                // for back_inserter, inserter
-#include <map>                     // for map, _Rb_tree_iterator, map<>::ite...
 #include <string>                  // for string, allocator, operator==, ope...
-#include <utility>                 // for pair
 
 #include "Common/PassVisitor.h"    // for PassVisitor
+#include "Common/ScopedMap.h"      // for ScopedMap
 #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 +31 @@
 
 namespace Virtual {
+
+        // Indented until the new ast code gets added.
+
+        /// Maps virtual table types the instance for that type.
+        class VirtualTableMap final {
+                ScopedMap<std::string, ObjectDecl *> vtable_instances;
+        public:
+                void enterScope() {
+                        vtable_instances.beginScope();
+                }
+                void leaveScope() {
+                        vtable_instances.endScope();
+                }
+
+                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 +73 @@
          */
 
+        namespace {
+
         std::string get_vtable_name( std::string const & name ) {
                 return name + "_vtable";
@@ -53 +89 @@
         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 +96 @@
         }
 
+        } // namespace
+
         class VirtualCastCore {
-        std::map<std::string, ObjectDecl *> vtable_instances;
-        FunctionDecl *vcast_decl;
-        StructDecl *pvt_decl;
-
                 Type * pointer_to_pvt(int level_of_indirection) {
                         Type * type = new StructInstType(
@@ -80 +110 @@
         public:
                 VirtualCastCore() :
-                        vtable_instances(), vcast_decl( nullptr ), pvt_decl( nullptr )
+                        indexer(), vcast_decl( nullptr ), pvt_decl( nullptr )
                 {}
 
@@ -88 +118 @@
 
                 Expression * postmutate( VirtualCastExpr * castExpr );
+
+                VirtualTableMap indexer;
+        private:
+                FunctionDecl *vcast_decl;
+                StructDecl *pvt_decl;
         };
 
@@ -107 +142 @@
         void VirtualCastCore::premutate( ObjectDecl * objectDecl ) {
                 if ( is_vtable_inst_name( objectDecl->get_name() ) ) {
-                        vtable_instances[objectDecl->get_name()] = objectDecl;
-                }
-        }
+                        if ( ObjectDecl * existing = indexer.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;
+                } else if ( castExpr->arg->location.isSet() ) {
+                        return castExpr->arg->location;
+                } else if ( castExpr->result->location.isSet() ) {
+                        return castExpr->result->location;
+                } else {
+                        return CodeLocation();
+                }
+        }
+
+        [[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 );
 
-                // May only cast to a pointer or reference type.
-                // A earlier validation should give a syntax error, this is
-                // just to make sure errors don't creep during translation.
-                // Move to helper with more detailed error messages.
-                PointerType * target_type =
-                        dynamic_cast<PointerType *>( castExpr->get_result() );
-                assert( target_type );
-
-                StructInstType * target_struct =
-                        dynamic_cast<StructInstType *>( target_type->get_base() );
-                assert( target_struct );
-
-                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 ) {
-                        assertf( false, "virtual table instance not found." );
-                }
-                ObjectDecl * table = found->second;
+                const Type * vtable_type = getVirtualTableType( castExpr );
+                ObjectDecl * table = indexer.lookup( vtable_type );
+                if ( nullptr == table ) {
+                        SemanticError( castLocation( castExpr ),
+                                "Could not find virtual table instance." );
+                }
 
                 Expression * result = new CastExpr(
-                        //new ApplicationExpr(
-                                //new AddressExpr( new VariableExpr( vcast_decl ) ),
-                                //new CastExpr( new VariableExpr( vcast_decl ),
-                                //      new PointerType( noQualifiers,
-                                //              vcast_decl->get_type()->clone()
-                                //              )
-                                //      ),
                         new ApplicationExpr( VariableExpr::functionPointer( vcast_decl ), {
                                         new CastExpr(
@@ -163 +252 @@
                 castExpr->set_result( nullptr );
                 delete castExpr;
+                delete vtable_type;
                 return result;
         }