...

compiler/NubLang/Generation/QBE/QBEGenerator.cs

@@ -8,6 +8,8 @@ namespace NubLang.Generation.QBE;
 
 public class QBEGenerator
 {
+    private const int PTR_SIZE = 8;
+
     private readonly QBEWriter _writer;
     private readonly List<DefinitionNode> _definitions;
     private readonly HashSet<StructTypeNode> _structTypes;
@@ -20,7 +22,6 @@ public class QBEGenerator
     private int _labelIndex;
     private int _cStringLiteralIndex;
     private int _stringLiteralIndex;
-    private bool _codeIsReachable = true;
 
     public QBEGenerator(List<DefinitionNode> definitions, HashSet<StructTypeNode> structTypes)
     {
@@ -39,7 +40,6 @@ public class QBEGenerator
         _labelIndex = 0;
         _cStringLiteralIndex = 0;
         _stringLiteralIndex = 0;
-        _codeIsReachable = true;
 
         _writer.Comment("========== Builtin functions ==========");
 
@@ -142,77 +142,125 @@ public class QBEGenerator
 
     private static string QBEAssign(TypeNode type)
     {
-        if (type.IsSimpleType(out var simpleType, out _))
+        return type switch
         {
-            return simpleType.StorageSize switch
+            IntTypeNode { Width: <= 32 } => "=w",
-            {
+            IntTypeNode { Width: 64 } => "=l",
-                StorageSize.I8 or StorageSize.U8 or StorageSize.I16 or StorageSize.U16 or StorageSize.I32 or StorageSize.U32 => "=w",
+            FloatTypeNode { Width: 32 } => "=s",
-                StorageSize.I64 or StorageSize.U64 => "=l",
+            FloatTypeNode { Width: 64 } => "=d",
-                StorageSize.F32 => "=s",
+            BoolTypeNode => "=w",
-                StorageSize.F64 => "=d",
+            PointerTypeNode => "=l",
-                _ => throw new ArgumentOutOfRangeException(nameof(simpleType.StorageSize))
+            FuncTypeNode => "=l",
+            CStringTypeNode => "=l",
+            StringTypeNode => "=l",
+            ArrayTypeNode => "=l",
+            StructTypeNode => throw new InvalidOperationException("Structs are not loaded/stored directly"),
+            VoidTypeNode => throw new InvalidOperationException("Void has no assignment"),
+            _ => throw new ArgumentOutOfRangeException(nameof(type), $"Unknown type {type.GetType()}")
         };
     }
 
-        return "=l";
-    }
-
     private void EmitStore(TypeNode type, string value, string destination)
     {
-        string store;
+        var store = type switch
-
-        if (type.IsSimpleType(out var simpleType, out _))
         {
-            store = simpleType.StorageSize switch
+            BoolTypeNode => "storeb",
-            {
+            IntTypeNode { Width: 8 } => "storeb",
-                StorageSize.I8 or StorageSize.U8 => "storeb",
+            IntTypeNode { Width: 16 } => "storeh",
-                StorageSize.I16 or StorageSize.U16 => "storeh",
+            IntTypeNode { Width: 32 } => "storew",
-                StorageSize.I32 or StorageSize.U32 => "storew",
+            IntTypeNode { Width: 64 } => "storel",
-                StorageSize.I64 or StorageSize.U64 => "storel",
+            FloatTypeNode { Width: 32 } => "stores",
-                StorageSize.F32 => "stores",
+            FloatTypeNode { Width: 64 } => "stored",
-                StorageSize.F64 => "stored",
+            PointerTypeNode => "storel",
-                _ => throw new ArgumentOutOfRangeException(nameof(simpleType.StorageSize))
+            FuncTypeNode => "storel",
+            CStringTypeNode => "storel",
+            StringTypeNode => "storel",
+            ArrayTypeNode => "storel",
+            StructTypeNode => throw new InvalidOperationException("Struct stores must use blit/memcpy"),
+            VoidTypeNode => throw new InvalidOperationException("Cannot store void"),
+            _ => throw new ArgumentOutOfRangeException(nameof(type), $"Unknown type {type.GetType()}")
         };
-        }
-        else
-        {
-            store = "storel";
-        }
 
         _writer.Indented($"{store} {value}, {destination}");
     }
 
     private string EmitLoad(TypeNode type, string from)
     {
-        string load;
+        string load = type switch
-
-        if (type.IsSimpleType(out var simpleType, out _))
         {
-            load = simpleType.StorageSize switch
+            BoolTypeNode => "loadub",
-            {
+            IntTypeNode { Signed: true, Width: 8 } => "loadsb",
-                StorageSize.I64 or StorageSize.U64 => "loadl",
+            IntTypeNode { Signed: true, Width: 16 } => "loadsh",
-                StorageSize.I32 or StorageSize.U32 => "loadw",
+            IntTypeNode { Signed: true, Width: 32 } => "loadw",
-                StorageSize.I16 => "loadsh",
+            IntTypeNode { Signed: true, Width: 64 } => "loadl",
-                StorageSize.I8 => "loadsb",
+            IntTypeNode { Signed: false, Width: 8 } => "loadsb",
-                StorageSize.U16 => "loaduh",
+            IntTypeNode { Signed: false, Width: 16 } => "loadsh",
-                StorageSize.U8 => "loadub",
+            IntTypeNode { Signed: false, Width: 32 } => "loadw",
-                StorageSize.F64 => "loadd",
+            IntTypeNode { Signed: false, Width: 64 } => "loadl",
-                StorageSize.F32 => "loads",
+            FloatTypeNode { Width: 32 } => "loads",
-                _ => throw new ArgumentOutOfRangeException(nameof(simpleType.StorageSize))
+            FloatTypeNode { Width: 64 } => "loadd",
+            PointerTypeNode => "loadl",
+            FuncTypeNode => "loadl",
+            CStringTypeNode => "loadl",
+            StringTypeNode => "loadl",
+            ArrayTypeNode => "loadl",
+            StructTypeNode => throw new InvalidOperationException("Struct loads must use blit/memcpy"),
+            VoidTypeNode => throw new InvalidOperationException("Cannot load void"),
+            _ => throw new ArgumentOutOfRangeException(nameof(type), $"Unknown type {type.GetType()}")
         };
-        }
-        else
-        {
-            load = "loadl";
-        }
 
         var into = TmpName();
-
         _writer.Indented($"{into} {QBEAssign(type)} {load} {from}");
-
         return into;
     }
 
+
+    private static string StructDefQBEType(TypeNode type)
+    {
+        return type switch
+        {
+            BoolTypeNode => "b",
+            IntTypeNode { Width: 8 } => "b",
+            IntTypeNode { Width: 16 } => "h",
+            IntTypeNode { Width: 32 } => "w",
+            IntTypeNode { Width: 64 } => "l",
+            FloatTypeNode { Width: 32 } => "s",
+            FloatTypeNode { Width: 64 } => "d",
+            PointerTypeNode => "l",
+            FuncTypeNode => "l",
+            CStringTypeNode => "l",
+            StringTypeNode => "l",
+            ArrayTypeNode => "l",
+            StructTypeNode st => StructTypeName(st.Module, st.Name),
+            VoidTypeNode => throw new InvalidOperationException("Void has no QBE type"),
+            _ => throw new ArgumentOutOfRangeException(nameof(type), $"Unknown type: {type.GetType()}")
+        };
+    }
+
+    private string FuncQBETypeName(TypeNode type)
+    {
+        return type switch
+        {
+            BoolTypeNode => "ub",
+            IntTypeNode { Signed: true, Width: 8 } => "sb",
+            IntTypeNode { Signed: true, Width: 16 } => "sh",
+            IntTypeNode { Signed: false, Width: 8 } => "ub",
+            IntTypeNode { Signed: false, Width: 16 } => "uh",
+            IntTypeNode { Width: 32 } => "w",
+            IntTypeNode { Width: 64 } => "l",
+            FloatTypeNode { Width: 32 } => "s",
+            FloatTypeNode { Width: 64 } => "d",
+            PointerTypeNode => "l",
+            FuncTypeNode => "l",
+            CStringTypeNode => "l",
+            StringTypeNode => "l",
+            ArrayTypeNode => "l",
+            StructTypeNode st => StructTypeName(st.Module, st.Name),
+            VoidTypeNode => throw new InvalidOperationException("Void has no QBE type"),
+            _ => throw new ArgumentOutOfRangeException(nameof(type), $"Unknown type: {type.GetType()}")
+        };
+    }
+
     private void EmitMemset(string destination, int value, string length)
     {
         _writer.Indented($"call $.memset(l {destination}, l {value}, l {length})");
@@ -250,107 +298,98 @@ public class QBEGenerator
 
     private void EmitCopyInto(ExpressionNode source, string destination)
     {
-        // Simple types are passed in registers and can therefore just be stored
+        if (source.Type.IsScalar)
-        if (source.Type.IsSimpleType(out var simpleType, out var complexType))
         {
-            var value = EmitExpression(source);
+            EmitStore(source.Type, EmitExpression(source), destination);
-            EmitStore(simpleType, value, destination);
             return;
         }
 
-        // Structs has known sizes at compile time
+        if (source.Type.IsValueType)
-        if (complexType is StructTypeNode)
         {
             var value = EmitExpression(source);
-            _writer.Indented($"blit {value}, {destination}, {SizeOf(complexType)}");
+            _writer.Indented($"blit {value}, {destination}, {SizeOf(source.Type)}");
+            return;
         }
-        // The rest of the complex types has unknown sizes
+
-        else
+        switch (source.Type)
+        {
+            case ArrayTypeNode arrayType:
             {
                 var value = EmitExpression(source);
-            var size = complexType switch
+                var size = EmitArraySizeInBytes(arrayType, value);
-            {
-                ArrayTypeNode arrayType => EmitArraySizeInBytes(arrayType, value),
-                CStringTypeNode => EmitCStringSizeInBytes(value),
-                StringTypeNode => EmitStringSizeInBytes(value),
-                _ => throw new ArgumentOutOfRangeException(nameof(source.Type))
-            };
-
                 var buffer = TmpName();
                 _writer.Indented($"{buffer} =l alloc8 {size}");
                 EmitMemcpy(value, buffer, size);
-            EmitStore(complexType, buffer, destination);
+                EmitStore(arrayType, buffer, destination);
+                return;
+            }
+            case CStringTypeNode:
+            {
+                var value = EmitExpression(source);
+                var size = EmitCStringSizeInBytes(value);
+                var buffer = TmpName();
+                _writer.Indented($"{buffer} =l alloc8 {size}");
+                EmitMemcpy(value, buffer, size);
+                EmitStore(source.Type, buffer, destination);
+                return;
+            }
+            case StringTypeNode:
+            {
+                var value = EmitExpression(source);
+                var size = EmitStringSizeInBytes(value);
+                var buffer = TmpName();
+                _writer.Indented($"{buffer} =l alloc8 {size}");
+                EmitMemcpy(value, buffer, size);
+                EmitStore(source.Type, buffer, destination);
+                return;
+            }
+            case VoidTypeNode:
+                throw new InvalidOperationException("Cannot copy void");
+            default:
+                throw new ArgumentOutOfRangeException(nameof(source.Type), $"Unknown type {source.Type}");
         }
     }
 
     private string EmitCopy(ExpressionNode source)
     {
-        // Allowlist for types which are safe to not copy
+        if (source is RValueExpressionNode || source.Type.IsScalar)
-        if (source is ArrayInitializerNode or StructInitializerNode or LiteralNode)
         {
             return EmitExpression(source);
         }
 
-        // Simple types are passed in registers and therefore always copied
-        if (source.Type.IsSimpleType(out _, out var complexType))
-        {
-            return EmitExpression(source);
-        }
-
-        // For the rest, we figure out the size of the type and shallow copy them
         var value = EmitExpression(source);
         var destination = TmpName();
 
-        // Structs has known sizes at compile time
+        if (source.Type.IsValueType)
-        if (complexType is StructTypeNode)
         {
-            var size = SizeOf(complexType);
+            var size = SizeOf(source.Type);
             _writer.Indented($"{destination} =l alloc8 {size}");
             _writer.Indented($"blit {value}, {destination}, {size}");
-        }
-        // The rest of the complex types has unknown sizes
-        else
-        {
-            var size = complexType switch
-            {
-                ArrayTypeNode arrayType => EmitArraySizeInBytes(arrayType, value),
-                CStringTypeNode => EmitCStringSizeInBytes(value),
-                StringTypeNode => EmitStringSizeInBytes(value),
-                _ => throw new ArgumentOutOfRangeException(nameof(source.Type))
-            };
-
-            _writer.Indented($"{destination} =l alloc8 {size}");
-            EmitMemcpy(value, destination, size);
-        }
-
             return destination;
         }
 
-    // Utility to create QBE type names for function parameters and return types
+        switch (source.Type)
-    private string FuncQBETypeName(TypeNode type)
         {
-        if (type.IsSimpleType(out var simpleType, out var complexType))
+            case ArrayTypeNode arrayType:
-        {
+                var arraySize = EmitArraySizeInBytes(arrayType, value);
-            return simpleType.StorageSize switch
+                _writer.Indented($"{destination} =l alloc8 {arraySize}");
-            {
+                EmitMemcpy(value, destination, arraySize);
-                StorageSize.I64 or StorageSize.U64 => "l",
+                break;
-                StorageSize.I32 or StorageSize.U32 => "w",
+            case CStringTypeNode:
-                StorageSize.I16 => "sh",
+                var cstrSize = EmitCStringSizeInBytes(value);
-                StorageSize.I8 => "sb",
+                _writer.Indented($"{destination} =l alloc8 {cstrSize}");
-                StorageSize.U16 => "uh",
+                EmitMemcpy(value, destination, cstrSize);
-                StorageSize.U8 => "ub",
+                break;
-                StorageSize.F64 => "d",
+            case StringTypeNode:
-                StorageSize.F32 => "s",
+                var strSize = EmitStringSizeInBytes(value);
-                _ => throw new ArgumentOutOfRangeException()
+                _writer.Indented($"{destination} =l alloc8 {strSize}");
-            };
+                EmitMemcpy(value, destination, strSize);
+                break;
+            default:
+                throw new InvalidOperationException($"Cannot copy type {source.Type}");
         }
 
-        if (complexType is StructTypeNode structType)
+        return destination;
-        {
-            return StructTypeName(structType.Module, structType.Name);
-        }
-
-        return "l";
     }
 
     private void EmitStructType(StructTypeNode structType)
@@ -365,31 +404,6 @@ public class QBEGenerator
         }
 
         _writer.WriteLine(" }");
-        return;
-
-        string StructDefQBEType(TypeNode type)
-        {
-            if (type.IsSimpleType(out var simpleType, out var complexType))
-            {
-                return simpleType.StorageSize switch
-                {
-                    StorageSize.I64 or StorageSize.U64 => "l",
-                    StorageSize.I32 or StorageSize.U32 => "w",
-                    StorageSize.I16 or StorageSize.U16 => "h",
-                    StorageSize.I8 or StorageSize.U8 => "b",
-                    StorageSize.F64 => "d",
-                    StorageSize.F32 => "s",
-                    _ => throw new ArgumentOutOfRangeException()
-                };
-            }
-
-            if (complexType is StructTypeNode childStructType)
-            {
-                return StructTypeName(childStructType.Module, childStructType.Name);
-            }
-
-            return "l";
-        }
     }
 
     private void EmitStructDefinition(StructNode structDef)
@@ -477,12 +491,6 @@ public class QBEGenerator
 
         EmitBlock(funcDef.Body);
 
-        // Implicit return for void functions if no explicit return has been set
-        if (funcDef.Signature.ReturnType is VoidTypeNode && funcDef.Body.Statements.LastOrDefault() is not ReturnNode)
-        {
-            _writer.Indented("ret");
-        }
-
         _writer.WriteLine("}");
         _writer.NewLine();
     }
@@ -490,28 +498,23 @@ public class QBEGenerator
     private void EmitBlock(BlockNode block)
     {
         foreach (var statement in block.Statements)
-        {
-            if (_codeIsReachable)
         {
             EmitStatement(statement);
         }
     }
 
-        _codeIsReachable = true;
-    }
-
     private void EmitStatement(StatementNode statement)
     {
         switch (statement)
         {
             case AssignmentNode assignment:
-                EmitAssignment(assignment);
+                EmitCopyInto(assignment.Value, EmitAddressOf(assignment.Target));
                 break;
             case BreakNode:
-                EmitBreak();
+                _writer.Indented($"jmp {_breakLabels.Peek()}");
                 break;
             case ContinueNode:
-                EmitContinue();
+                _writer.Indented($"jmp {_continueLabels.Peek()}");
                 break;
             case IfNode ifStatement:
                 EmitIf(ifStatement);
@@ -536,23 +539,6 @@ public class QBEGenerator
         }
     }
 
-    private void EmitAssignment(AssignmentNode assignment)
-    {
-        EmitCopyInto(assignment.Value, EmitAddressOfLValue(assignment.Target));
-    }
-
-    private void EmitBreak()
-    {
-        _writer.Indented($"jmp {_breakLabels.Peek()}");
-        _codeIsReachable = false;
-    }
-
-    private void EmitContinue()
-    {
-        _writer.Indented($"jmp {_continueLabels.Peek()}");
-        _codeIsReachable = false;
-    }
-
     private void EmitIf(IfNode ifStatement)
     {
         var trueLabel = LabelName();
@@ -666,60 +652,47 @@ public class QBEGenerator
         _writer.WriteLine(endLabel);
     }
 
-    private string EmitExpression(ExpressionNode expression)
+    private string EmitExpression(ExpressionNode expr)
     {
-        return expression switch
+        return expr switch
         {
-            ArrayInitializerNode arrayInitializer => EmitArrayInitializer(arrayInitializer),
+            RValueExpressionNode rValue => EmitRValue(rValue),
-            StructInitializerNode structInitializer => EmitStructInitializer(structInitializer),
+            LValueExpressionNode lValue => EmitLValue(lValue),
-            AddressOfNode addressOf => EmitAddressOf(addressOf),
+            _ => throw new ArgumentOutOfRangeException(nameof(expr))
-            DereferenceNode dereference => EmitDereference(dereference),
-            BinaryExpressionNode binary => EmitBinaryExpression(binary),
-            FuncCallNode funcCall => EmitFuncCall(funcCall),
-            ConvertIntNode convertInt => EmitConvertInt(convertInt),
-            ConvertFloatNode convertFloat => EmitConvertFloat(convertFloat),
-            VariableIdentifierNode identifier => EmitVariableIdentifier(identifier),
-            FuncIdentifierNode funcIdentifier => EmitFuncIdentifier(funcIdentifier),
-            FuncParameterIdentifierNode funcParameterIdentifier => EmitParameterFuncIdentifier(funcParameterIdentifier),
-            LiteralNode literal => EmitLiteral(literal),
-            UnaryExpressionNode unaryExpression => EmitUnaryExpression(unaryExpression),
-            StructFieldAccessNode structFieldAccess => EmitStructFieldAccess(structFieldAccess),
-            StructFuncCallNode structFuncCall => EmitStructFuncCall(structFuncCall),
-            ArrayIndexAccessNode arrayIndex => EmitArrayIndexAccess(arrayIndex),
-            _ => throw new ArgumentOutOfRangeException(nameof(expression))
         };
     }
 
-    private string EmitFuncIdentifier(FuncIdentifierNode funcIdent)
+    private string EmitRValue(RValueExpressionNode rValue)
     {
-        return FuncName(funcIdent.Module, funcIdent.Name, funcIdent.ExternSymbol);
+        return rValue switch
+        {
+            AddressOfNode expr => EmitAddressOf(expr.LValue),
+            ArrayInitializerNode expr => EmitArrayInitializer(expr),
+            BinaryExpressionNode expr => EmitBinaryExpression(expr),
+            ConvertFloatNode expr => EmitConvertFloat(expr),
+            ConvertIntNode expr => EmitConvertInt(expr),
+            DereferenceNode expr => EmitLoad(expr.Type, EmitExpression(expr.Expression)),
+            FuncCallNode expr => EmitFuncCall(expr),
+            FuncIdentifierNode expr => FuncName(expr.Module, expr.Name, expr.ExternSymbol),
+            FuncParameterIdentifierNode expr => $"%{expr.Name}",
+            LiteralNode expr => EmitLiteral(expr),
+            StructFuncCallNode expr => EmitStructFuncCall(expr),
+            StructInitializerNode expr => EmitStructInitializer(expr),
+            UnaryExpressionNode expr => EmitUnaryExpression(expr),
+            _ => throw new ArgumentOutOfRangeException(nameof(rValue))
+        };
     }
 
-    private string EmitVariableIdentifier(VariableIdentifierNode variableIdent)
+    private string EmitLValue(LValueExpressionNode lValue)
     {
-        var address = EmitAddressOfVariableIdent(variableIdent);
+        var address = EmitAddressOf(lValue);
-        if (variableIdent.Type is StructTypeNode)
+
+        if (lValue.Type is { IsValueType: true, IsScalar: false })
         {
             return address;
         }
 
-        return EmitLoad(variableIdent.Type, address);
+        return EmitLoad(lValue.Type, address);
-    }
-
-    private string EmitParameterFuncIdentifier(FuncParameterIdentifierNode funcParameterIdent)
-    {
-        return "%" + funcParameterIdent.Name;
-    }
-
-    private string EmitArrayIndexAccess(ArrayIndexAccessNode arrayIndexAccess)
-    {
-        var address = EmitAddressOfArrayIndexAccess(arrayIndexAccess);
-        if (arrayIndexAccess.Type is StructTypeNode)
-        {
-            return address;
-        }
-
-        return EmitLoad(arrayIndexAccess.Type, address);
     }
 
     private string EmitArrayInitializer(ArrayInitializerNode arrayInitializer)
@@ -743,30 +716,14 @@ public class QBEGenerator
         return arrayPointer;
     }
 
-    private string EmitDereference(DereferenceNode dereference)
+    private string EmitAddressOf(LValueExpressionNode lval)
     {
-        var address = EmitExpression(dereference.Expression);
+        return lval switch
-        if (dereference.Type is StructTypeNode)
-        {
-            return address;
-        }
-
-        return EmitLoad(dereference.Type, address);
-    }
-
-    private string EmitAddressOf(AddressOfNode addressOf)
-    {
-        return EmitAddressOfLValue(addressOf.LValue);
-    }
-
-    private string EmitAddressOfLValue(LValueExpressionNode addressOf)
-    {
-        return addressOf switch
         {
             ArrayIndexAccessNode arrayIndexAccess => EmitAddressOfArrayIndexAccess(arrayIndexAccess),
             StructFieldAccessNode structFieldAccess => EmitAddressOfStructFieldAccess(structFieldAccess),
-            VariableIdentifierNode variableIdent => EmitAddressOfVariableIdent(variableIdent),
+            VariableIdentifierNode variableIdent => $"%{variableIdent.Name}",
-            _ => throw new ArgumentOutOfRangeException(nameof(addressOf))
+            _ => throw new ArgumentOutOfRangeException(nameof(lval))
         };
     }
 
@@ -794,11 +751,6 @@ public class QBEGenerator
         return address;
     }
 
-    private string EmitAddressOfVariableIdent(VariableIdentifierNode variableIdent)
-    {
-        return "%" + variableIdent.Name;
-    }
-
     private string EmitBinaryExpression(BinaryExpressionNode binaryExpression)
     {
         var left = EmitExpression(binaryExpression.Left);
@@ -1116,17 +1068,6 @@ public class QBEGenerator
         throw new NotSupportedException($"Unary operator {unaryExpression.Operator} for type {unaryExpression.Operand.Type} not supported");
     }
 
-    private string EmitStructFieldAccess(StructFieldAccessNode structFieldAccess)
-    {
-        var address = EmitAddressOfStructFieldAccess(structFieldAccess);
-        if (structFieldAccess.Type is StructTypeNode)
-        {
-            return address;
-        }
-
-        return EmitLoad(structFieldAccess.Type, address);
-    }
-
     private string EmitStructFuncCall(StructFuncCallNode structFuncCall)
     {
         var func = StructFuncName(structFuncCall.StructType.Module, structFuncCall.StructType.Name, structFuncCall.Name);
@@ -1236,19 +1177,16 @@ public class QBEGenerator
     {
         return type switch
         {
-            SimpleTypeNode simple => simple.StorageSize switch
+            IntTypeNode intType => intType.Width / 8,
-            {
+            FloatTypeNode fType => fType.Width / 8,
-                StorageSize.Void => 0,
+            BoolTypeNode => 1,
-                StorageSize.I8 or StorageSize.U8 => 1,
+            PointerTypeNode => PTR_SIZE,
-                StorageSize.I16 or StorageSize.U16 => 2,
+            FuncTypeNode => PTR_SIZE,
-                StorageSize.I32 or StorageSize.U32 or StorageSize.F32 => 4,
-                StorageSize.I64 or StorageSize.U64 or StorageSize.F64 => 8,
-                _ => throw new ArgumentOutOfRangeException(nameof(type), $"Unknown storage size: {simple.StorageSize}")
-            },
-            CStringTypeNode => 8,
-            StringTypeNode => 8,
-            ArrayTypeNode => 8,
             StructTypeNode structType => CalculateStructSize(structType),
+            VoidTypeNode => throw new InvalidOperationException("Void type has no size"),
+            CStringTypeNode => PTR_SIZE,
+            StringTypeNode => PTR_SIZE,
+            ArrayTypeNode => PTR_SIZE,
             _ => throw new ArgumentOutOfRangeException(nameof(type), $"Unknown type: {type.GetType()}")
         };
     }
@@ -1272,23 +1210,21 @@ public class QBEGenerator
     {
         return type switch
         {
-            SimpleTypeNode simple => simple.StorageSize switch
+            IntTypeNode intType => intType.Width / 8,
-            {
+            FloatTypeNode fType => fType.Width / 8,
-                StorageSize.Void => 1,
+            BoolTypeNode => 1,
-                StorageSize.I8 or StorageSize.U8 => 1,
+            PointerTypeNode => PTR_SIZE,
-                StorageSize.I16 or StorageSize.U16 => 2,
+            FuncTypeNode => PTR_SIZE,
-                StorageSize.I32 or StorageSize.U32 or StorageSize.F32 => 4,
+            StructTypeNode st => CalculateStructAlignment(st),
-                StorageSize.I64 or StorageSize.U64 or StorageSize.F64 => 8,
+            CStringTypeNode => PTR_SIZE,
-                _ => throw new ArgumentOutOfRangeException(nameof(type), $"Unknown storage size: {simple.StorageSize}")
+            StringTypeNode => PTR_SIZE,
-            },
+            ArrayTypeNode => PTR_SIZE,
-            CStringTypeNode => 8,
+            VoidTypeNode => throw new InvalidOperationException("Void has no alignment"),
-            StringTypeNode => 8,
-            ArrayTypeNode => 8,
-            StructTypeNode structType => CalculateStructAlignment(structType),
             _ => throw new ArgumentOutOfRangeException(nameof(type), $"Unknown type: {type.GetType()}")
         };
     }
 
+
     private static int CalculateStructAlignment(StructTypeNode structType)
     {
         var maxAlignment = 1;
@@ -1307,26 +1243,27 @@ public class QBEGenerator
         return (offset + alignment - 1) & ~(alignment - 1);
     }
 
-    private static int OffsetOf(StructTypeNode structDef, string member)
+    private static int OffsetOf(StructTypeNode type, string member)
     {
         var offset = 0;
 
-        foreach (var field in structDef.Fields)
+        foreach (var field in type.Fields)
         {
+            var fieldAlignment = AlignmentOf(field.Type);
+            offset = AlignTo(offset, fieldAlignment);
+
             if (field.Name == member)
             {
                 return offset;
             }
 
-            var fieldAlignment = AlignmentOf(field.Type);
-
-            offset = AlignTo(offset, fieldAlignment);
             offset += SizeOf(field.Type);
         }
 
         throw new UnreachableException($"Member '{member}' not found in struct");
     }
 
+
     private string TmpName()
     {
         return $"%.t{++_tmpIndex}";

compiler/NubLang/TypeChecking/Node/ExpressionNode.cs

@@ -32,7 +32,7 @@ public enum BinaryOperator
 
 public abstract record ExpressionNode(TypeNode Type) : Node;
 
-public abstract record LValueExpressionNode(TypeNode Type) : RValueExpressionNode(Type);
+public abstract record LValueExpressionNode(TypeNode Type) : ExpressionNode(Type);
 
 public abstract record RValueExpressionNode(TypeNode Type) : ExpressionNode(Type);
 

compiler/NubLang/TypeChecking/Node/Node.cs

@@ -3,5 +3,3 @@
 public abstract record Node;
 
 public record BlockNode(List<StatementNode> Statements) : Node;
-
-public record TypedSyntaxTree(List<DefinitionNode> Definitions);

compiler/NubLang/TypeChecking/Node/StatementNode.cs

@@ -1,6 +1,6 @@
 namespace NubLang.TypeChecking.Node;
 
-public record StatementNode : Node;
+public abstract record StatementNode : Node;
 
 public record StatementExpressionNode(ExpressionNode Expression) : StatementNode;
 

compiler/NubLang/TypeChecking/Node/TypeNode.cs

@@ -1,31 +1,13 @@
-using System.Diagnostics.CodeAnalysis;
+namespace NubLang.TypeChecking.Node;
-
-namespace NubLang.TypeChecking.Node;
 
 public abstract class TypeNode : IEquatable<TypeNode>
 {
-    public bool IsSimpleType([NotNullWhen(true)] out SimpleTypeNode? simpleType, [NotNullWhen(false)] out ComplexTypeNode? complexType)
+    public abstract bool IsValueType { get; }
-    {
+    public abstract bool IsScalar { get; }
-        if (this is SimpleTypeNode st)
-        {
-            complexType = null;
-            simpleType = st;
-            return true;
-        }
-
-        if (this is ComplexTypeNode ct)
-        {
-            complexType = ct;
-            simpleType = null;
-            return false;
-        }
-
-        throw new ArgumentException($"Type {this} is not a simple type nor a complex type");
-    }
 
     public override bool Equals(object? obj) => obj is TypeNode other && Equals(other);
-
     public abstract bool Equals(TypeNode? other);
+
     public abstract override int GetHashCode();
     public abstract override string ToString();
 
@@ -33,90 +15,71 @@ public abstract class TypeNode : IEquatable<TypeNode>
     public static bool operator !=(TypeNode? left, TypeNode? right) => !Equals(left, right);
 }
 
-public enum StorageSize
+public class VoidTypeNode : TypeNode
 {
-    Void,
+    public override bool IsValueType => false;
-    I8,
+    public override bool IsScalar => false;
-    I16,
+
-    I32,
+    public override string ToString() => "void";
-    I64,
+    public override bool Equals(TypeNode? other) => other is VoidTypeNode;
-    U8,
+    public override int GetHashCode() => HashCode.Combine(typeof(VoidTypeNode));
-    U16,
-    U32,
-    U64,
-    F32,
-    F64
 }
 
-public abstract class SimpleTypeNode : TypeNode
+public sealed class IntTypeNode(bool signed, int width) : TypeNode
 {
-    public abstract StorageSize StorageSize { get; }
+    public override bool IsValueType => true;
-}
+    public override bool IsScalar => true;
 
-#region Simple types
-
-public class IntTypeNode(bool signed, int width) : SimpleTypeNode
-{
     public bool Signed { get; } = signed;
     public int Width { get; } = width;
 
-    public override StorageSize StorageSize => Signed switch
-    {
-        true => Width switch
-        {
-            8 => StorageSize.I8,
-            16 => StorageSize.I16,
-            32 => StorageSize.I32,
-            64 => StorageSize.I64,
-            _ => throw new ArgumentOutOfRangeException(nameof(Width))
-        },
-        false => Width switch
-        {
-            8 => StorageSize.U8,
-            16 => StorageSize.U16,
-            32 => StorageSize.U32,
-            64 => StorageSize.U64,
-            _ => throw new ArgumentOutOfRangeException(nameof(Width))
-        }
-    };
-
     public override string ToString() => $"{(Signed ? "i" : "u")}{Width}";
     public override bool Equals(TypeNode? other) => other is IntTypeNode @int && @int.Width == Width && @int.Signed == Signed;
     public override int GetHashCode() => HashCode.Combine(typeof(IntTypeNode), Signed, Width);
 }
 
-public class FloatTypeNode(int width) : SimpleTypeNode
+public sealed class FloatTypeNode(int width) : TypeNode
 {
+    public override bool IsValueType => true;
+    public override bool IsScalar => true;
+
     public int Width { get; } = width;
 
-    public override StorageSize StorageSize => Width switch
-    {
-        32 => StorageSize.F32,
-        64 => StorageSize.F64,
-        _ => throw new ArgumentOutOfRangeException(nameof(Width))
-    };
-
     public override string ToString() => $"f{Width}";
-    public override bool Equals(TypeNode? other) => other is FloatTypeNode @int && @int.Width == Width;
+    public override bool Equals(TypeNode? other) => other is FloatTypeNode @float && @float.Width == Width;
     public override int GetHashCode() => HashCode.Combine(typeof(FloatTypeNode), Width);
 }
 
-public class BoolTypeNode : SimpleTypeNode
+public class BoolTypeNode : TypeNode
 {
-    public override StorageSize StorageSize => StorageSize.U8;
+    public override bool IsValueType => true;
+    public override bool IsScalar => true;
 
     public override string ToString() => "bool";
     public override bool Equals(TypeNode? other) => other is BoolTypeNode;
     public override int GetHashCode() => HashCode.Combine(typeof(BoolTypeNode));
 }
 
-public class FuncTypeNode(List<TypeNode> parameters, TypeNode returnType) : SimpleTypeNode
+public sealed class PointerTypeNode(TypeNode baseType) : TypeNode
 {
+    public override bool IsValueType => true;
+    public override bool IsScalar => true;
+
+    public TypeNode BaseType { get; } = baseType;
+
+    public override string ToString() => "^" + BaseType;
+    public override bool Equals(TypeNode? other) => other is PointerTypeNode pointer && BaseType.Equals(pointer.BaseType);
+    public override int GetHashCode() => HashCode.Combine(typeof(PointerTypeNode), BaseType);
+}
+
+public class FuncTypeNode(List<TypeNode> parameters, TypeNode returnType) : TypeNode
+{
+    public override bool IsValueType => true;
+    public override bool IsScalar => true;
+
     public List<TypeNode> Parameters { get; } = parameters;
     public TypeNode ReturnType { get; } = returnType;
 
-    public override StorageSize StorageSize => StorageSize.U64;
-
     public override string ToString() => $"func({string.Join(", ", Parameters)}): {ReturnType}";
     public override bool Equals(TypeNode? other) => other is FuncTypeNode func && ReturnType.Equals(func.ReturnType) && Parameters.SequenceEqual(func.Parameters);
 
@@ -134,44 +97,19 @@ public class FuncTypeNode(List<TypeNode> parameters, TypeNode returnType) : Simp
     }
 }
 
-public class PointerTypeNode(TypeNode baseType) : SimpleTypeNode
+public class StructTypeNode(string module, string name, List<StructTypeField> fields, List<StructTypeFunc> functions) : TypeNode
 {
-    public TypeNode BaseType { get; } = baseType;
+    public override bool IsValueType => true;
+    public override bool IsScalar => false;
 
-    public override StorageSize StorageSize => StorageSize.U64;
+    public string Module { get; } = module;
+    public string Name { get; } = name;
+    public List<StructTypeField> Fields { get; set; } = fields;
+    public List<StructTypeFunc> Functions { get; set; } = functions;
 
-    public override string ToString() => "^" + BaseType;
+    public override string ToString() => Name;
-    public override bool Equals(TypeNode? other) => other is PointerTypeNode pointer && BaseType.Equals(pointer.BaseType);
+    public override bool Equals(TypeNode? other) => other is StructTypeNode structType && Name == structType.Name && Module == structType.Module;
-    public override int GetHashCode() => HashCode.Combine(typeof(PointerTypeNode), BaseType);
+    public override int GetHashCode() => HashCode.Combine(typeof(StructTypeNode), Name);
-}
-
-public class VoidTypeNode : SimpleTypeNode
-{
-    public override StorageSize StorageSize => StorageSize.Void;
-
-    public override string ToString() => "void";
-    public override bool Equals(TypeNode? other) => other is VoidTypeNode;
-    public override int GetHashCode() => HashCode.Combine(typeof(VoidTypeNode));
-}
-
-#endregion
-
-public abstract class ComplexTypeNode : TypeNode;
-
-#region Complex types
-
-public class CStringTypeNode : ComplexTypeNode
-{
-    public override string ToString() => "cstring";
-    public override bool Equals(TypeNode? other) => other is CStringTypeNode;
-    public override int GetHashCode() => HashCode.Combine(typeof(CStringTypeNode));
-}
-
-public class StringTypeNode : ComplexTypeNode
-{
-    public override string ToString() => "string";
-    public override bool Equals(TypeNode? other) => other is StringTypeNode;
-    public override int GetHashCode() => HashCode.Combine(typeof(StringTypeNode));
 }
 
 public class StructTypeField(string name, TypeNode type, bool hasDefaultValue)
@@ -187,26 +125,34 @@ public class StructTypeFunc(string name, FuncTypeNode type)
     public FuncTypeNode Type { get; } = type;
 }
 
-public class StructTypeNode(string module, string name, List<StructTypeField> fields, List<StructTypeFunc> functions) : ComplexTypeNode
+public class CStringTypeNode : TypeNode
 {
-    public string Module { get; } = module;
+    public override bool IsValueType => false;
-    public string Name { get; } = name;
+    public override bool IsScalar => false;
-    public List<StructTypeField> Fields { get; set; } = fields;
-    public List<StructTypeFunc> Functions { get; set; } = functions;
 
-    public override string ToString() => Name;
+    public override string ToString() => "cstring";
-    public override bool Equals(TypeNode? other) => other is StructTypeNode structType && Name == structType.Name && Module == structType.Module;
+    public override bool Equals(TypeNode? other) => other is CStringTypeNode;
-    public override int GetHashCode() => HashCode.Combine(typeof(StructTypeNode), Name);
+    public override int GetHashCode() => HashCode.Combine(typeof(CStringTypeNode));
 }
 
-public class ArrayTypeNode(TypeNode elementType) : ComplexTypeNode
+public class StringTypeNode : TypeNode
 {
+    public override bool IsValueType => false;
+    public override bool IsScalar => false;
+
+    public override string ToString() => "string";
+    public override bool Equals(TypeNode? other) => other is StringTypeNode;
+    public override int GetHashCode() => HashCode.Combine(typeof(StringTypeNode));
+}
+
+public class ArrayTypeNode(TypeNode elementType) : TypeNode
+{
+    public override bool IsValueType => false;
+    public override bool IsScalar => false;
+
     public TypeNode ElementType { get; } = elementType;
 
     public override string ToString() => "[]" + ElementType;
-
     public override bool Equals(TypeNode? other) => other is ArrayTypeNode array && ElementType.Equals(array.ElementType);
     public override int GetHashCode() => HashCode.Combine(typeof(ArrayTypeNode), ElementType);
 }
-
-#endregion

compiler/NubLang/TypeChecking/TypeChecker.cs

@@ -117,15 +117,25 @@ public sealed class TypeChecker
             scope.Declare(new Identifier(parameter.Name, ResolveType(parameter.Type), IdentifierKind.FunctionParameter));
         }
 
+        var signature = CheckFuncSignature(node.Signature);
+
         BlockNode? body = null;
         if (node.Body != null)
         {
-            _funcReturnTypes.Push(ResolveType(node.Signature.ReturnType));
+            _funcReturnTypes.Push(signature.ReturnType);
+
             body = CheckBlock(node.Body, scope);
+
+            // Insert implicit return for void functions
+            if (signature.ReturnType is VoidTypeNode && body.Statements.LastOrDefault() is not ReturnNode)
+            {
+                body.Statements.Add(new ReturnNode(Optional<ExpressionNode>.Empty()));
+            }
+
             _funcReturnTypes.Pop();
         }
 
-        return new FuncNode(_syntaxTree.Metadata.ModuleName, node.Name, node.ExternSymbol, CheckFuncSignature(node.Signature), body);
+        return new FuncNode(_syntaxTree.Metadata.ModuleName, node.Name, node.ExternSymbol, signature, body);
     }
 
     private StatementNode CheckStatement(StatementSyntax node)
@@ -715,9 +725,29 @@ public sealed class TypeChecker
 
         _scopes.Push(scope ?? Scope.SubScope());
 
+        var reachable = true;
+        var warnedUnreachable = false;
+
         foreach (var statement in node.Statements)
         {
-            statements.Add(CheckStatement(statement));
+            var checkedStatement = CheckStatement(statement);
+
+            if (reachable)
+            {
+                statements.Add(checkedStatement);
+                if (checkedStatement is ReturnNode or BreakNode or ContinueNode)
+                {
+                    reachable = false;
+                }
+            }
+            else
+            {
+                if (!warnedUnreachable)
+                {
+                    Diagnostics.Add(Diagnostic.Warning("Statement is unreachable").At(statement).Build());
+                    warnedUnreachable = true;
+                }
+            }
         }
 
         _scopes.Pop();

example/src/main.nub

@@ -2,6 +2,11 @@ module "main"
 
 extern "puts" func puts(text: cstring)
 
+struct Human
+{
+    name: cstring
+}
+
 extern "main" func main(args: []cstring): i64
 {
     let x = [2]cstring
@@ -14,5 +19,16 @@ extern "main" func main(args: []cstring): i64
         puts(u)
     }
 
+    let me: Human = {
+        name = "test"
+    }
+
+    puts(me.name)
+
     return 0
 }
+
+
+func test()
+{
+}