git: ignore idea designer file

This was a tricky one. In order to call malloc the stack needs to be 16 byte aligned. GenASM up until this point was 8 byte aligned. This commit changes the code generation so that it is guaranteed that the stack is 16 byte aligned before visiting a child node. We need to do this before visiting *any* child node because we can not know whether somewhere downstream some child node calls malloc.

To make it possible for a visitor method to determine if it needs to align the stack it has to assume that the stack is currently aligned. This is the other reason we ensure that the stack is aligned before visiting any child node.

On top of that some visitor methods did not clean up after themselves. I am not sure why this did not result in segfaults already, but I changed the code so that each visitor method leaves the stack in the same state after completion.

.gitignore

@@ -16,4 +16,5 @@ src/main/antlr4/de/hsrm/compiler/Klang/.antlr
 
 # build output
 out
-src/test/test
+src/test/test
+/.idea/uiDesigner.xml

.idea/compiler.xml

@@ -10,7 +10,7 @@
       </profile>
     </annotationProcessing>
     <bytecodeTargetLevel>
-      <module name="klang" target="11" />
+      <module name="klang" target="17" />
     </bytecodeTargetLevel>
   </component>
 </project>

klang.iml

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <module org.jetbrains.idea.maven.project.MavenProjectsManager.isMavenModule="true" type="JAVA_MODULE" version="4">
-  <component name="NewModuleRootManager" LANGUAGE_LEVEL="JDK_11">
+  <component name="NewModuleRootManager" LANGUAGE_LEVEL="JDK_17">
     <output url="file://$MODULE_DIR$/target/classes" />
     <output-test url="file://$MODULE_DIR$/target/test-classes" />
     <content url="file://$MODULE_DIR$">

pom.xml

@@ -40,7 +40,7 @@
         <artifactId>maven-compiler-plugin</artifactId>
         <version>3.8.0</version>
         <configuration>
-          <release>11</release>
+          <release>17</release>
         </configuration>
       </plugin>
       <!-- Plugin to compile the g4 files ahead of the java files

src/main/java/de/hsrm/compiler/Klang/ContextAnalysis.java

@@ -8,10 +8,12 @@ import de.hsrm.compiler.Klang.nodes.loops.ForLoop;
 import de.hsrm.compiler.Klang.nodes.loops.WhileLoop;
 import de.hsrm.compiler.Klang.nodes.statements.*;
 import de.hsrm.compiler.Klang.types.Type;
+import org.antlr.v4.runtime.tree.TerminalNode;
 
 import java.util.*;
 
 public class ContextAnalysis extends KlangBaseVisitor<Node> {
+  Map<String, VariableDeclaration> params = new HashMap<>();
   Map<String, VariableDeclaration> vars = new HashMap<>();
   Map<String, FunctionDefinition> functionDefs;
   Map<String, StructDefinition> structDefs;
@@ -199,8 +201,8 @@ public class ContextAnalysis extends KlangBaseVisitor<Node> {
       throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
     }
 
-    if (vars.get(variableName) != null) {
+    if (vars.get(variableName) != null || params.get(variableName) != null) {
-      var error = "Redeclaration of variable with name \"" + variableName + "\".";
+      var error = "Redeclaration of variable or parameter with name \"" + variableName + "\".";
       throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
     }
 
@@ -236,31 +238,27 @@ public class ContextAnalysis extends KlangBaseVisitor<Node> {
 
   @Override
   public Node visitVariable_assignment(KlangParser.Variable_assignmentContext ctx) {
-    String name = ctx.IDENT().getText();
+    var name = ctx.IDENT().getText();
-    int line = ctx.start.getLine();
+    var line = ctx.start.getLine();
-    int col = ctx.start.getCharPositionInLine();
+    var col = ctx.start.getCharPositionInLine();
 
-    VariableDeclaration var = this.vars.get(name);
+    var variableOrParameter = getVariableOrParameter(name, line, col);
-    if (var == null) {
-      String error = "Variable with name \"" + name + "\" not defined.";
-      throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
-    }
 
     // Evaluate the expression
-    Expression expression = (Expression) this.visit(ctx.expression());
+    var expression = (Expression) visit(ctx.expression());
 
     // Make sure expression can be assigned to the variable
     try {
-      expression.type.combine(var.type);
+      expression.type.combine(variableOrParameter.type);
     } catch (Exception e) {
       throw new RuntimeException(Helper.getErrorPrefix(line, col) + e.getMessage());
     }
 
     // Since we assigned a value to this variable, we can consider it initialized
-    var.initialized = true;
+    variableOrParameter.initialized = true;
 
     // Create a new node and add the type of the expression to it
-    Node result = new VariableAssignment(name, expression);
+    var result = new VariableAssignment(name, expression);
     result.line = line;
     result.col = col;
     return result;
@@ -272,8 +270,7 @@ public class ContextAnalysis extends KlangBaseVisitor<Node> {
     ReturnStatement result = new ReturnStatement(expression);
 
     // Check if this expression is a tail recursion
-    if (expression instanceof FunctionCall) {
+    if (expression instanceof FunctionCall funCall) {
-      var funCall = (FunctionCall) expression;
       if (funCall.name.equals(this.currentFunctionDefinitionName)) {
         // Flag this function call
         funCall.isTailRecursive = true;
@@ -288,46 +285,24 @@ public class ContextAnalysis extends KlangBaseVisitor<Node> {
 
   @Override
   public Node visitField_assignment(KlangParser.Field_assignmentContext ctx) {
-    String varName = ctx.IDENT(0).getText();
+    var varName = ctx.IDENT(0).getText();
-    int line = ctx.start.getLine();
+    var line = ctx.start.getLine();
-    int col = ctx.start.getCharPositionInLine();
+    var col = ctx.start.getCharPositionInLine();
-    String[] path = new String[ctx.IDENT().size() - 1];
+    var path = createStructPath(ctx.IDENT());
 
-    for (int i = 1; i < ctx.IDENT().size(); i++) {
+    var variableOrParameter = getVariableOrParameter(varName, line, col);
-      path[i - 1] = ctx.IDENT(i).getText();
+    ensureReferencesStruct(variableOrParameter, line, col);
-    }
+    var fieldType = drillType(variableOrParameter, path, line, col);
 
-    // Get the referenced variable, make sure it is defined
+    // Visit the expression and make sure the type combines properly
-    var variableDef = this.vars.get(varName);
+    var expression = (Expression) visit(ctx.expression());
-    if (variableDef == null) {
-      String error = "Variable with name " + varName + " not defined.";
-      throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
-    }
-
-    // Make sure it references a struct
-    if (variableDef.type.isPrimitiveType()) {
-      String error = "Variable must reference a struct but references " + variableDef.type.getName() + ".";
-      throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
-    }
-
-    // Get the type of the result of this expression
-    String structName = variableDef.type.getName();
-    Type fieldType;
-    try {
-      fieldType = Helper.drillType(this.structDefs, structName, path, 0);
-    } catch (Exception e) {
-      throw new RuntimeException(Helper.getErrorPrefix(line, col) + e.getMessage());
-    }
-
-    // Get the expression and make sure the type combines properly
-    Expression expression = (Expression) this.visit(ctx.expression());
     try {
       fieldType.combine(expression.type);
     } catch (Exception e) {
       throw new RuntimeException(Helper.getErrorPrefix(line, col) + e.getMessage());
     }
 
-    Node result = new FieldAssignment(varName, structName, path, expression);
+    var result = new FieldAssignment(varName, variableOrParameter.type.getName(), path, expression);
     result.col = col;
     result.line = line;
     return result;
@@ -338,23 +313,17 @@ public class ContextAnalysis extends KlangBaseVisitor<Node> {
     var baseName = ctx.IDENT(0).getText();
     var line = ctx.start.getLine();
     var col = ctx.start.getCharPositionInLine();
-
+    var path = createStructPath(ctx.IDENT());
-    // Create a list of member names. This excludes
-    // the first entry as it is the base name.
-    var path = new ArrayList<String>();
-    for (int i = 1; i < ctx.IDENT().size(); i++) {
-      path.add(ctx.IDENT(i).getText());
-    }
 
     // Determine if the base name points to an enum or a variable
     var enumDef = enumDefs.get(baseName);
     if (enumDef != null) {
-      if (path.size() != 1) {
+      if (path.length != 1) {
         var error = "Illegal access to enum " + enumDef.name + ".";
         throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
       }
 
-      var enumValueName = path.get(0);
+      var enumValueName = path[0];
       var enumValue = Arrays.stream(enumDef.enums)
               .filter(e -> e.value.equals(enumValueName))
               .findFirst()
@@ -371,29 +340,11 @@ public class ContextAnalysis extends KlangBaseVisitor<Node> {
       return enumAccessExpression;
     }
 
-    // Get the referenced variable, make sure it is defined
+    var variableOrParameter = getVariableOrParameter(baseName, line, col);
-    var variableDef = vars.get(baseName);
+    ensureReferencesStruct(variableOrParameter, line, col);
-    if (variableDef == null) {
+    var resultType = drillType(variableOrParameter, path, line, col);
-      var error = "Variable with name " + baseName + " not defined.";
-      throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
-    }
 
-    // Make sure it references a struct
+    var memberAccessExpression = new MemberAccessExpression(baseName, variableOrParameter.type.getName(), path);
-    if (variableDef.type.isPrimitiveType()) {
-      var error = "Variable must reference a struct but references " + variableDef.type.getName() + ".";
-      throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
-    }
-
-    // Get the type of the result of this expression
-    var structName = variableDef.type.getName();
-    Type resultType;
-    try {
-      resultType = Helper.drillType(structDefs, structName, path.toArray(new String[0]), 0);
-    } catch (Exception e) {
-      throw new RuntimeException(Helper.getErrorPrefix(line, col) + e.getMessage());
-    }
-
-    var memberAccessExpression = new MemberAccessExpression(baseName, structName, path.toArray(new String[0]));
     memberAccessExpression.type = resultType;
     memberAccessExpression.line = line;
     memberAccessExpression.col = col;
@@ -711,24 +662,20 @@ public class ContextAnalysis extends KlangBaseVisitor<Node> {
 
   @Override
   public Node visitVariable(KlangParser.VariableContext ctx) {
-    String name = ctx.IDENT().getText();
+    var variableName = ctx.IDENT().getText();
-    int line = ctx.start.getLine();
+    var line = ctx.start.getLine();
-    int col = ctx.start.getCharPositionInLine();
+    var col = ctx.start.getCharPositionInLine();
 
-    VariableDeclaration var = this.vars.get(name);
+    var variableOrParameter = getVariableOrParameter(variableName, line, col);
-    if (var == null) {
-      String error = "Variable with name \"" + name + "\" not defined.";
-      throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
-    }
 
     // Make sure the variable has been initialized before it can be used
-    if (!var.initialized) {
+    if (!variableOrParameter.initialized) {
-      String error = "Variable with name \"" + name + "\" has not been initialized.";
+      var error = "Variable with name \"" + variableName + "\" has not been initialized.";
       throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
     }
 
-    Variable result = new Variable(ctx.IDENT().getText());
+    var result = new Variable(ctx.IDENT().getText());
-    result.type = var.type;
+    result.type = variableOrParameter.type;
     result.line = line;
     result.col = col;
     return result;
@@ -839,23 +786,23 @@ public class ContextAnalysis extends KlangBaseVisitor<Node> {
       throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
     }
 
-    // Create a new set for the variables of the current function
+    // Create a new set for the variables and parameters of the current function
     // this will be filled in the variable declaration visitor as well
     vars = new HashMap<>();
+    params = new HashMap<>();
+
 
-    // Process the parameter list by visiting every parameter in it
     var paramCount = ctx.params.parameter().size();
-    var params = new Parameter[paramCount];
+    var functionParameters = new Parameter[paramCount]; // the list of parameters that get passed to FunctionDefinition
     for (int i = 0; i < paramCount; i++) {
-      // Add the parameter to the list of parameters
+      functionParameters[i] = (Parameter) visit(ctx.params.parameter(i));
-      var param = (Parameter) visit(ctx.params.parameter(i));
-      params[i] = param;
 
-      // add the param as a variable
+      // add the param as a variable to the global parameter map so that
-      var var = new VariableDeclaration(param.name);
+      // child nodes can access them.
-      var.initialized = true; // parameters can always be considered initialized
+      var param = new VariableDeclaration(functionParameters[i].name);
-      var.type = param.type;
+      param.initialized = true; // parameters can always be considered initialized
-      vars.put(param.name, var);
+      param.type = functionParameters[i].type;
+      params.put(param.name, param);
     }
 
     // Visit the block, make sure that a return value is guaranteed
@@ -867,7 +814,7 @@ public class ContextAnalysis extends KlangBaseVisitor<Node> {
       throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
     }
 
-    var functionDef = new FunctionDefinition(name, params, (Block) block);
+    var functionDef = new FunctionDefinition(name, functionParameters, vars.values().toArray(new VariableDeclaration[0]), (Block) block);
     functionDef.type = returnType;
     functionDef.line = ctx.start.getLine();
     functionDef.col = ctx.start.getCharPositionInLine();
@@ -988,19 +935,52 @@ public class ContextAnalysis extends KlangBaseVisitor<Node> {
 
   @Override
   public Node visitDestroy_statement(KlangParser.Destroy_statementContext ctx) {
-    String name = ctx.IDENT().getText();
+    var varName = ctx.IDENT().getText();
-    int line = ctx.start.getLine();
+    var line = ctx.start.getLine();
-    int col = ctx.start.getCharPositionInLine();
+    var col = ctx.start.getCharPositionInLine();
-    
-    VariableDeclaration var = this.vars.get(name);
-    if (var == null) {
-      String error = "Variable with name \"" + name + "\" not defined.";
-      throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
-    }
 
-    Node result = new DestructorCall(name);
+    var variableOrParameter = getVariableOrParameter(varName, line, col);
+    ensureReferencesStruct(variableOrParameter, line, col);
+
+    var result = new DestructorCall(varName);
     result.line = line;
     result.col = col;
     return result;
   }
+
+  private VariableDeclaration getVariableOrParameter(String name, int line, int col) {
+    var variable = vars.get(name);
+    var parameter = params.get(name);
+    if (variable == null && parameter == null) {
+      var error = "Variable or parameter with name \"" + name + "\" not defined.";
+      throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
+    }
+
+    return variable != null ? variable : parameter;
+  }
+
+  private void ensureReferencesStruct(VariableDeclaration variableOrParameter, int line, int col) {
+    if (variableOrParameter.type.isPrimitiveType() || enumDefs.containsKey(variableOrParameter.type.getName())) {
+      var error = "Variable or parameter must reference a struct but references " + variableOrParameter.type.getName() + ".";
+      throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
+    }
+  }
+
+  private Type drillType(VariableDeclaration variableOrParameter, String[] path, int line, int col) {
+    try {
+      var structName = variableOrParameter.type.getName();
+      return Helper.drillType(structDefs, structName, path, 0);
+    } catch (Exception e) {
+      throw new RuntimeException(Helper.getErrorPrefix(line, col) + e.getMessage());
+    }
+  }
+
+  private String[] createStructPath(List<TerminalNode> identifiers) {
+    // Create a list of member names. This excludes the first entry as it is the base name.
+    var path = new String[identifiers.size() - 1];
+    for (int i = 1; i < identifiers.size(); i++) {
+      path[i - 1] = identifiers.get(i).getText();
+    }
+    return path;
+  }
 }

src/main/java/de/hsrm/compiler/Klang/GetDefinitions.java

@@ -210,7 +210,7 @@ public class GetDefinitions extends KlangBaseVisitor<Node> {
             parameters.put(paramName, parameter);
         }
 
-        var functionDef = new FunctionDefinition(funcName, parameters.values().toArray(new Parameter[0]), null);
+        var functionDef = new FunctionDefinition(funcName, parameters.values().toArray(new Parameter[0]), null, null);
         functionDef.type = Type.getByName(ctx.returnType.type().getText());
         functionDef.line = line;
         functionDef.col = col;

src/main/java/de/hsrm/compiler/Klang/asm/ASM.java

@@ -172,6 +172,10 @@ public class ASM {
     mnemonics.add(new Cqto());
   }
 
+  public void leave() {
+    mnemonics.add(new Leave());
+  }
+
   public void ret() {
     mnemonics.add(new Ret());
   }

src/main/java/de/hsrm/compiler/Klang/asm/mnemonics/Leave.java

@@ -0,0 +1,8 @@
+package de.hsrm.compiler.Klang.asm.mnemonics;
+
+public class Leave extends NoOperandMnemonic {
+    @Override
+    public String toAsm() {
+        return "leave";
+    }
+}

src/main/java/de/hsrm/compiler/Klang/nodes/FunctionDefinition.java

@@ -1,17 +1,20 @@
 package de.hsrm.compiler.Klang.nodes;
 
+import de.hsrm.compiler.Klang.nodes.statements.VariableDeclaration;
 import de.hsrm.compiler.Klang.visitors.Visitor;
 
 public class FunctionDefinition extends Node {
 
   public String name;
   public Parameter[] parameters;
+  public VariableDeclaration[] localVariables;
   public Block block;
 
-  public FunctionDefinition(String name, Parameter[] parameters, Block block) {
+  public FunctionDefinition(String name, Parameter[] parameters, VariableDeclaration[] localVariables, Block block) {
     this.name = name;
     this.parameters = parameters;
     this.block = block;
+    this.localVariables = localVariables;
   }
 
   @Override

src/main/java/de/hsrm/compiler/Klang/types/NamedType.java

@@ -1,11 +1,6 @@
 package de.hsrm.compiler.Klang.types;
 
 import de.hsrm.compiler.Klang.Value;
-import de.hsrm.compiler.Klang.nodes.EnumDefinition;
-import de.hsrm.compiler.Klang.nodes.FunctionDefinition;
-import de.hsrm.compiler.Klang.nodes.StructDefinition;
-
-import java.util.Map;
 
 public class NamedType extends Type {
     public String name;
@@ -21,7 +16,7 @@ public class NamedType extends Type {
 
     @Override
     public Type combine(Type that) {
-        if(this.equals(that)) {
+        if(this.equals(that) || (that instanceof NullType)) {
             return this;
         }
 
@@ -49,8 +44,7 @@ public class NamedType extends Type {
             return true;
         }
 
-        if (that instanceof NamedType) {
+        if (that instanceof NamedType thatType) {
-            var thatType = (NamedType) that;
             return getName().equals(thatType.getName());
         }
 

src/main/java/de/hsrm/compiler/Klang/visitors/EvalVisitor.java

@@ -10,6 +10,8 @@ import de.hsrm.compiler.Klang.nodes.loops.DoWhileLoop;
 import de.hsrm.compiler.Klang.nodes.loops.ForLoop;
 import de.hsrm.compiler.Klang.nodes.loops.WhileLoop;
 import de.hsrm.compiler.Klang.nodes.statements.*;
+import de.hsrm.compiler.Klang.types.NamedType;
+import de.hsrm.compiler.Klang.types.NullType;
 import de.hsrm.compiler.Klang.types.Type;
 
 public class EvalVisitor implements Visitor<Value> {
@@ -400,7 +402,7 @@ public class EvalVisitor implements Visitor<Value> {
   @Override
   public Value visit(Block e) {
     for (var stmt : e.statements) {
-      Value result = stmt.welcome(this);
+      var result = stmt.welcome(this);
       if (result != null) {
         return result;
       }
@@ -428,7 +430,7 @@ public class EvalVisitor implements Visitor<Value> {
     this.env = newEnv;
 
     // Execute
-    Value result = func.block.welcome(this);
+    var result = func.block.welcome(this);
 
     // Das alte env wiederherstellen
     this.env = oldEnv;
@@ -502,12 +504,17 @@ public class EvalVisitor implements Visitor<Value> {
       struct.put(structDef.fields[i].name, arg);
     }
 
-    return new Value(struct);
+    var structValue = new Value(struct);
+    structValue.type = structDef.type;
+
+    return structValue;
   }
 
   @Override
   public Value visit(NullExpression e) {
-    return null;
+    var nullValue = new Value(null);
+    nullValue.type = new NullType();
+    return nullValue;
   }
 
   @Override

src/main/java/de/hsrm/compiler/Klang/visitors/GenASM.java

@@ -13,16 +13,16 @@ import de.hsrm.compiler.Klang.types.Type;
 import java.util.*;
 
 public class GenASM implements Visitor<Void> {
-  private class FloatWriter {
+  private static class FloatWriter {
-    private StringBuilder sb = new StringBuilder();
+    private final StringBuilder sb = new StringBuilder();
     private int id = -1;
 
     public String getFloat(double d) {
-      Long longBits = Double.doubleToRawLongBits(d);
+      long longBits = Double.doubleToRawLongBits(d);
-      String binary = Long.toBinaryString(longBits);
+      StringBuilder binary = new StringBuilder(Long.toBinaryString(longBits));
       int padCount = 64 - binary.length();
       while (padCount > 0) {
-        binary = "0" + binary;
+        binary.insert(0, "0");
         padCount--;
       }
       String upper = binary.substring(0, 32);
@@ -59,49 +59,19 @@ public class GenASM implements Visitor<Void> {
     }
   }
 
-  private ASM asm;
+  private final ASM asm;
-  private FloatWriter fw = new FloatWriter();
+  private final FloatWriter fw = new FloatWriter();
-  private String mainName;
+  private final String mainName;
+
   Map<String, Integer> env = new HashMap<>();
   Map<String, StructDefinition> structs;
-  Set<String> vars;
   String[] registers = { "%rdi", "%rsi", "%rdx", "%rcx", "%r8", "%r9" };
   String[] floatRegisters = { "%xmm0", "%xmm1", "%xmm2", "%xmm3", "%xmm4", "%xmm5", "%xmm6", "%xmm7" };
-  private int lCount = 0; // Invariant: lCount is used
-  private int currentFunctionStartLabel = 0;
-  private Parameter[] currentFunctionParams;
 
-  private boolean prepareRegisters(Expression lhs, Expression rhs) {
+  private int lCount = 0;
-    boolean lhsIsFloat = lhs.type.equals(Type.getFloatType());
+  private int currentFunctionStartLabel = 0;
-    boolean rhsIsFloat = rhs.type.equals(Type.getFloatType());
+  private long bytesToClearFromTheStack = 0;
-    if (lhsIsFloat && rhsIsFloat) {
+  private Parameter[] currentFunctionParams;
-      lhs.welcome(this);
-      asm.mov("sd", "%xmm0", "%xmm2");
-      rhs.welcome(this);
-      asm.mov("sd", "%xmm2", "%xmm0");
-      asm.mov("sd", "%xmm2", "%xmm0");
-      return true;
-    } else if (lhsIsFloat && !rhsIsFloat) {
-      lhs.welcome(this);
-      rhs.welcome(this);
-      asm.cvtsi2sd("%rax", "%xmm1");
-      return true;
-    } else if (!lhsIsFloat && rhsIsFloat) {
-      lhs.welcome(this);
-      asm.cvtsi2sd("%rax", "%xmm2");
-      rhs.welcome(this);
-      asm.mov("sd", "%xmm0", "%xmm1");
-      asm.mov("sd", "%xmm2", "%xmm0");
-      return true;
-    } else {
-      lhs.welcome(this);
-      asm.push("q", "%rax");
-      rhs.welcome(this);
-      asm.mov("q", "%rax", "%rbx");
-      asm.pop("q", "%rax");
-      return false;
-    }
-  }
 
   public GenASM(String mainName, Map<String, StructDefinition> structs) {
     this.mainName = mainName;
@@ -109,10 +79,6 @@ public class GenASM implements Visitor<Void> {
     this.asm = new ASM();
   }
 
-  public GenASM(Map<String, StructDefinition> structs) {
-    this("main", structs);
-  }
-
   public String toAsm() {
     return asm.toAsm();
   }
@@ -326,10 +292,19 @@ public class GenASM implements Visitor<Void> {
   @Override
   public Void visit(ModuloExpression e) {
     e.lhs.welcome(this);
+
+    // A single pushq brings the stack out of 16 byte alignment,
+    // so we need to increase the stack by another 8 bytes
+    asm.sub("q", "$8", "%rsp");
+
     asm.push("q", "%rax");
     e.rhs.welcome(this);
     asm.mov("q", "%rax", "%rbx");
     asm.pop("q", "%rax");
+
+    // Which we remove afterwards
+    asm.add("q", "$8", "%rsp");
+
     asm.cqto();
     asm.idiv("q", "%rbx");
     asm.mov("q", "%rdx", "%rax");
@@ -357,7 +332,7 @@ public class GenASM implements Visitor<Void> {
 
     // Werte LHS aus
     // Wenn LHS != 0 bedeutet das true
-    // also können wir direkt sagen dass das Ergebnis true ist
+    // also können wir direkt sagen, dass das Ergebnis true ist
     e.lhs.welcome(this);
     asm.cmp("q", 0, "%rax");
     asm.jne(lblTrue);
@@ -375,11 +350,11 @@ public class GenASM implements Visitor<Void> {
     asm.mov("q", 1, "%rax");
     asm.jmp(lblEnd);
 
-    // Die Expressoin wertet zu false aus
+    // Die Expression wertet zu false aus
     asm.label(lblFalse);
     asm.mov("q", 0, "%rax");
 
-    // Das hier ist das ende
+    // Das hier ist das Ende
     asm.label(lblEnd);
     return null;
   }
@@ -392,7 +367,7 @@ public class GenASM implements Visitor<Void> {
 
     // Werte LHS aus
     // Wenn LHS == 0, bedeutet das false
-    // also können wir direkt sagen dass das Ergebnis false ist
+    // also können wir direkt sagen, dass das Ergebnis false ist
     e.lhs.welcome(this);
     asm.cmp("q", 0, "%rax");
     asm.je(lblFalse);
@@ -410,11 +385,11 @@ public class GenASM implements Visitor<Void> {
     asm.mov("q", 1, "%rax");
     asm.jmp(lblEnd);
 
-    // Die Expressoin wertet zu false aus
+    // Die Expression wertet zu false aus
     asm.label(lblFalse);
     asm.mov("q", 0, "%rax");
 
-    // Das hier ist das ende
+    // Das hier ist das Ende
     asm.label(lblEnd);
     return null;
   }
@@ -424,9 +399,9 @@ public class GenASM implements Visitor<Void> {
     int lblFalse = ++lCount;
     int lblEnd = ++lCount;
 
-    // Werte LHS aus
+    // Werte LHS aus.
-    // Wenn LHS != 0 bedeutet das true, also jumpe zum false Teil
+    // Wenn LHS != 0 bedeutet das true, also springe zum false Teil.
-    // Wenn nicht, falle durch zum true Teil
+    // Wenn nicht, falle durch zum true Teil.
     e.lhs.welcome(this);
     asm.cmp("q", 0, "%rax");
     asm.jne(lblFalse);
@@ -551,8 +526,15 @@ public class GenASM implements Visitor<Void> {
   @Override
   public Void visit(ReturnStatement e) {
     e.expression.welcome(this);
-    asm.mov("q", "%rbp", "%rsp");
+
-    asm.pop("q", "%rbp");
+    // The ReturnStatement visitor is kindly removing the
+    // stack space that was allocated by the FunctionDefinition
+    // before executing the function body.
+    if (bytesToClearFromTheStack > 0) {
+      asm.add("q", "$" + bytesToClearFromTheStack, "%rsp");
+    }
+
+    asm.leave();
     asm.ret();
     return null;
   }
@@ -574,32 +556,27 @@ public class GenASM implements Visitor<Void> {
       e.name = "main_by_user";
     }
 
-    int lblStart = ++lCount;
+    var lblStart = ++lCount;
-    this.currentFunctionStartLabel = lblStart;
+    currentFunctionStartLabel = lblStart;
-    this.currentFunctionParams = e.parameters;
+    currentFunctionParams = e.parameters;
     asm.functionHead(e.name);
     asm.push("q", "%rbp");
     asm.mov("q", "%rsp", "%rbp");
     asm.label(lblStart);
 
-    // hole die anzahl der lokalen variablen
+    // Create a new environment
-    this.vars = new TreeSet<String>();
+    env = new HashMap<>();
-    HashMap<String, Type> types = new HashMap<String, Type>();
-    GetVars getvars = new GetVars(vars, types);
-    getvars.visit(e);
 
-    // Erzeuge ein environment
+    // Remember the offsets of the arguments that were placed on the stack.
-    this.env = new HashMap<String, Integer>();
+    var offset = 16; // Variables that were passed via the stack are located above our BSP
+    var ri = 0;
+    var fi = 0;
 
-    // Merke dir die offsets der parameter, die direkt auf den stack gelegt wurden
+    // Add arguments that were passed via the stack to the environment
-    int offset = 16; // Per Stack übergebene Parameter liegen über unserem BSP
-    int ri = 0;
-    int fi = 0;
-    // Per stack übergebene variablen in env registrieren
     var registerParameters = new ArrayList<Parameter>();
     for (int i = 0; i < e.parameters.length; i++) {
       if (e.parameters[i].type.equals(Type.getFloatType())) {
-        if (fi >= this.floatRegisters.length) {
+        if (fi >= floatRegisters.length) {
           // parameter is on stack already
           env.put(e.parameters[i].name, offset);
           offset += 8;
@@ -609,7 +586,7 @@ public class GenASM implements Visitor<Void> {
           fi++;
         }
       } else {
-        if (ri >= this.registers.length) {
+        if (ri >= registers.length) {
           // parameter is on stack already
           env.put(e.parameters[i].name, offset);
           offset += 8;
@@ -624,29 +601,58 @@ public class GenASM implements Visitor<Void> {
     offset = 0;
     ri = 0;
     fi = 0;
+
+    // Push arguments that were passed via registers onto the stack
+    // and add them to the environment.
     for (var param: registerParameters) {
       if (param.type.equals(Type.getFloatType())) {
-        asm.mov("q", this.floatRegisters[fi], "%rax");
+        asm.mov("q", floatRegisters[fi], "%rax");
         asm.push("q", "%rax");
         offset -= 8;
-        this.env.put(param.name, offset); // negative, liegt unter aktuellem BP
+        env.put(param.name, offset); // negative, liegt unter aktuellem BP
         fi++;
       } else {
-        asm.push("q", this.registers[ri]);
+        asm.push("q", registers[ri]);
         offset -= 8;
-        this.env.put(param.name, offset); // negative, liegt unter aktuellem BP
+        env.put(param.name, offset); // negative, liegt unter aktuellem BP
         ri++;
       }
     }
 
-    // Reserviere Platz auf dem Stack für jede lokale variable
+    // Reserve memory on the stack for the local variables.
-    for (String lok_var : vars) {
+    if (e.localVariables.length > 0) {
-      offset -= 8;
+      // Each variable is at most 8 bytes in size.
-      asm.push("q", 0);
+      asm.sub("q", "$" + (8 * e.localVariables.length), "%rsp");
-      this.env.put(lok_var, offset);
+
+      // Save the offsets (they are relative to rbp)
+      for (var localVariable : e.localVariables) {
+        offset -= 8;
+        env.put(localVariable.name, offset);
+      }
+    }
+
+    // Check the stack alignment and correct if necessary
+    // The padding needs to happen after the register parameters
+    // and local variables were pushed to the stack because otherwise
+    // the relative offsets to rbp will be wrong.
+    if ((registerParameters.size() + e.localVariables.length) % 2 != 0) {
+      // Since each variable is 8 bytes and the stack is 16 byte aligned
+      // we need to add 8 bytes to the stack to make it aligned
+      // if there is an odd number of parameters and local variables.
+      asm.sub("q", "$8", "%rsp");
     }
 
     e.block.welcome(this);
+
+    // I need to clear the stack here so that the top most element is the old rbp that
+    // ret uses to return to the caller but code that gets generated here will never be
+    // reached since the block node is guaranteed to contain a return node that results
+    // in a ret command being executed before this code would be reached.
+    // As a workaround (and a dirty, dirty hack) I indicate to the return node visitor
+    // how many bytes need to be cleared from the stack.
+    var wasStackPadded = (registerParameters.size() + e.localVariables.length) % 2 != 0;
+    bytesToClearFromTheStack = 8L * (registerParameters.size() + e.localVariables.length + (wasStackPadded ? 1 : 0));
+
     return null;
   }
 
@@ -665,7 +671,7 @@ public class GenASM implements Visitor<Void> {
         asm.push("q", "%rax");
       }
 
-      // push args into local var locations, last arg is ontop of the stack
+      // push args into local var locations, last arg is on top of the stack
       for (int i = e.arguments.length - 1; i >= 0; i--) {
         asm.pop("q", this.env.get(this.currentFunctionParams[i].name) + "(%rbp)");
       }
@@ -674,6 +680,9 @@ public class GenASM implements Visitor<Void> {
       return null;
     }
 
+    // This holds the indices into the arguments array for
+    // arguments that need to be passed to the callee via the stack
+    var stackIndices = new ArrayList<Integer>();
 
     if (e.arguments.length > 0) {
       // Mapping arguments index -> xmm registers index
@@ -684,9 +693,6 @@ public class GenASM implements Visitor<Void> {
       int[] rIdxs = new int[this.registers.length];
       int ri = -1;
 
-      // Mapping arguments index -> stack
-      ArrayList<Integer> stackIdxs = new ArrayList<Integer>();
-
       // Go through arguments
       // sort them into the memory regions they go when being passed to functions
       for (int i = 0; i < e.arguments.length; i++) {
@@ -698,7 +704,7 @@ public class GenASM implements Visitor<Void> {
             xmmIdxs[fi] = i;
           } else {
             // Float onto stack
-            stackIdxs.add(i);
+            stackIndices.add(i);
           }
         } else {
           if (ri < this.registers.length - 1) {
@@ -707,14 +713,39 @@ public class GenASM implements Visitor<Void> {
             rIdxs[ri] = i;
           } else {
             // bool/int onto stack
-            stackIdxs.add(i);
+            stackIndices.add(i);
           }
         }
       }
 
-      // Welcome the arguments in order, push everything onto the stack
+      // Make sure that the stack is aligned after all arguments
-      for (var arg : e.arguments) {
+      // have been pushed onto the stack. Keep in mind that we
+      // may remove the top n elements from our stack so they form
+      // the base of the callee's stack.
+      if ((e.arguments.length - stackIndices.size()) % 2 != 0) {
+        asm.sub("q", "$8", "%rsp");
+      }
+
+      // Welcome the arguments in order, push everything onto the stack.
+      // We can assume that we are currently 16 byte aligned which holds
+      // true until after the result of the first argument is pushed onto
+      // the stack. After that we have to pad the stack for every argument
+      // to ensure that the stack is aligned before welcoming the argument.
+      // We get rid of the padding directly after welcome() to
+      // "tightly pack" the arguments on the stack. This way the usual
+      // 8 byte offsets are kept intact.
+      for (int i = 0; i < e.arguments.length; i++) {
+        if (i % 2 == 0) {
+          asm.sub("q", "$8", "%rsp");
+        }
+
+        var arg = e.arguments[i];
         arg.welcome(this);
+
+        if (i % 2 == 0) {
+          asm.add("q", "$8", "%rsp");
+        }
+
         if (arg.type.equals(Type.getFloatType())) {
           asm.mov("q", "%xmm0", "%rax");
           asm.push("q", "%rax");
@@ -737,22 +768,38 @@ public class GenASM implements Visitor<Void> {
         asm.mov("q", rspOffset, "%rsp", this.registers[i]);
       }
 
-      // Move everything else from a higher stack position to our stack frame start
+      // Reorder the remaining n arguments that did not fit in a register,
+      // so that the remaining n arguments occupy the last n spots on our current stack
+      // This does not manipulate the stack in any way. It just reorders it.
       int stackStartOffset = ((e.arguments.length) * 8);
-      for (int i = stackIdxs.size() - 1; i >= 0; i--) {
+      for (int i = stackIndices.size() - 1; i >= 0; i--) {
         stackStartOffset -= 8;
-        int indexInArguments = stackIdxs.get(i);
+        int indexInArguments = stackIndices.get(i);
         int rspOffset = (((e.arguments.length - indexInArguments) - 1) * 8);
         asm.mov("q", rspOffset, "%rsp", "%rax");
         asm.mov("q", "%rax", stackStartOffset, "%rsp");
       }
 
-      // Rescue RSP
+      // The top n elements of the stack prepared in the step earlier will now become
-      asm.add("q", stackStartOffset, "%rsp");
+      // the base of the callee's stack by shrinking the stack by the size of the
+      // n arguments that did not fit in registers.
+      // This must only be done if there were any arguments that did not fit in the registers.
+      if (!stackIndices.isEmpty()) {
+        asm.add("q", stackStartOffset, "%rsp");
+      }
     }
 
     // We rename a function name if it is "main"
-    asm.call(e.name.equals("main") ? "main_by_user": e.name);
+    var mainName = e.name.equals("main") ? "main_by_user": e.name;
+    asm.call(mainName);
+
+    // Remove the arguments that remained on the stack and the stack padding if there was any
+    var wasStackPadded = (e.arguments.length - stackIndices.size()) % 2 != 0;
+    var bytesToRemove = 8 * (e.arguments.length - stackIndices.size() + (wasStackPadded ? 1 : 0));
+    if (bytesToRemove > 0) {
+      asm.add("q", "$" + bytesToRemove, "%rsp");
+    }
+
     return null;
   }
 
@@ -840,10 +887,29 @@ public class GenASM implements Visitor<Void> {
 
   @Override
   public Void visit(ConstructorCall e) {
+    // Make sure the stack is aligned before calling malloc
+    if (e.args.length % 2 != 0) {
+      // an odd number of arguments means we called pushq an odd number of times
+      // which results in an unaligned stack. Subtract 8 from the stack pointer to
+      // re-align the stack
+      asm.sub("q", "$8", "%rsp");
+    }
+
     // push arguments onto the stack
-    for (var arg: e.args) {
+    for (int i = 0; i < e.args.length; i++) {
+
+      // if you want to know why this is done go and read visit(FunctionCall)
+      if (i % 2 != 0) {
+        asm.sub("q", "$8", "%rsp");
+      }
+
+      var arg = e.args[i];
       arg.welcome(this);
 
+      if (i % 2 != 0) {
+        asm.add("q", "$8", "%rsp");
+      }
+
       // move float values from xmm0 to rax first
       if (arg.type.equals(Type.getFloatType())) {
         asm.mov("q", "%xmm0", "%rax");
@@ -857,11 +923,16 @@ public class GenASM implements Visitor<Void> {
     asm.mov("l", Helper.getFieldSizeBytes(structDef), "%edi");
     asm.call("malloc@PLT");
 
-    // push args into struct memory, last arg is ontop of the stack
+    // push args into struct memory, last arg is on top of the stack
     for (int i = e.args.length - 1; i >= 0; i--) {
       asm.pop("q", Helper.getFieldOffset(structDef, i) + "(%rax)");
     }
 
+    // Get rid of the stack alignment if there was any
+    if (e.args.length % 2 != 0) {
+      asm.add("q", "$8", "%rsp");
+    }
+
     return null;
   }
 
@@ -886,7 +957,7 @@ public class GenASM implements Visitor<Void> {
 
     e.expression.welcome(this);
 
-    // Move it from xmm0 rax if its a flaot
+    // Move it from xmm0 rax if it's a float
     if (e.expression.type.equals(Type.getFloatType())) {
       asm.mov("q", "%xmm0", "%rax");
     }
@@ -904,11 +975,49 @@ public class GenASM implements Visitor<Void> {
       asm.mov("q",  Helper.getFieldOffset(structDef, e.path[i]), "%rax", "%rax");
     }
 
-    // pop the expression that is ontop of the stack into the field of the struct that has to be updated
+    // pop the expression that is on top of the stack into the field of the struct that has to be updated
     asm.pop("q", Helper.getFieldOffset(structDef, fieldNameToUpdate) + "(%rax)");
     asm.mov("q", 0 , "%rax"); // clear rax since an assignment has no result
 
     return null;
   }
 
+  private boolean prepareRegisters(Expression lhs, Expression rhs) {
+    boolean lhsIsFloat = lhs.type.equals(Type.getFloatType());
+    boolean rhsIsFloat = rhs.type.equals(Type.getFloatType());
+    if (lhsIsFloat && rhsIsFloat) {
+      lhs.welcome(this);
+      asm.mov("sd", "%xmm0", "%xmm2");
+      rhs.welcome(this);
+      asm.mov("sd", "%xmm2", "%xmm0");
+      asm.mov("sd", "%xmm2", "%xmm0");
+      return true;
+    } else if (lhsIsFloat) {
+      lhs.welcome(this);
+      rhs.welcome(this);
+      asm.cvtsi2sd("%rax", "%xmm1");
+      return true;
+    } else if (rhsIsFloat) {
+      lhs.welcome(this);
+      asm.cvtsi2sd("%rax", "%xmm2");
+      rhs.welcome(this);
+      asm.mov("sd", "%xmm0", "%xmm1");
+      asm.mov("sd", "%xmm2", "%xmm0");
+      return true;
+    } else {
+      lhs.welcome(this);
+      // A single pushq brings the stack out of 16 byte alignment,
+      // so we need to increase the stack by another 8 bytes
+      asm.sub("q", "$8", "%rsp");
+
+      asm.push("q", "%rax");
+      rhs.welcome(this);
+      asm.mov("q", "%rax", "%rbx");
+      asm.pop("q", "%rax");
+
+      // Which we remove afterwards
+      asm.add("q", "$8", "%rsp");
+      return false;
+    }
+  }
 }

src/test/java/DestroyStatementTest.java

@@ -17,6 +17,6 @@ public class DestroyStatementTest {
         ContextAnalysis ctxAnal = new ContextAnalysis(funcs, structs, enums);
         
         Exception e = assertThrows(RuntimeException.class, () -> ctxAnal.visit(tree));
-        assertEquals("Error in line 1:45 Variable with name \"x\" not defined.", e.getMessage());
+        assertEquals("Error in line 1:45 Variable or parameter with name \"x\" not defined.", e.getMessage());
     }
 }

src/test/java/FieldAssignmentTest.java

@@ -17,7 +17,7 @@ public class FieldAssignmentTest {
         ContextAnalysis ctxAnal = new ContextAnalysis(funcs, structs, enums);
         
         Exception e = assertThrows(RuntimeException.class, () -> ctxAnal.visit(tree));
-        assertEquals("Error in line 1:46 Variable with name str not defined.", e.getMessage());
+        assertEquals("Error in line 1:46 Variable or parameter with name \"str\" not defined.", e.getMessage());
     }
 
     @Test
@@ -29,6 +29,6 @@ public class FieldAssignmentTest {
         ContextAnalysis ctxAnal = new ContextAnalysis(funcs, structs, enums);
         
         Exception e = assertThrows(RuntimeException.class, () -> ctxAnal.visit(tree));
-        assertEquals("Error in line 1:62 Variable must reference a struct but references int.", e.getMessage());
+        assertEquals("Error in line 1:62 Variable or parameter must reference a struct but references int.", e.getMessage());
     }
 }

src/test/java/FunctionDefinitionTest.java

@@ -92,4 +92,28 @@ public class FunctionDefinitionTest {
         var e = assertThrows(RuntimeException.class, () -> ctxAnal.visit(tree));
         assertEquals("Error in line 1:31 Parameter name Bar duplicates an enum of the same name.", e.getMessage());
     }
+
+    @Test
+    void shouldResetVariablesAndParameterEnvironment() {
+        // given
+        var tree = Helper.prepareParser("""
+                function foo(x: int): int {
+                  return 1;
+                }
+                function bar(): int {
+                  let x: int = 0;
+                  return x;
+                }
+                                
+                bar();
+                """);
+        var ctxAnal = new ContextAnalysis(
+                Helper.getFuncs(tree),
+                Helper.getStructs(tree),
+                Helper.getEnums(tree)
+        );
+
+        // when / then
+        assertDoesNotThrow(() -> ctxAnal.visit(tree));
+    }
 }

src/test/java/NaughtTest.java

@@ -0,0 +1,72 @@
+import de.hsrm.compiler.Klang.ContextAnalysis;
+import org.antlr.v4.runtime.tree.ParseTree;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+public class NaughtTest {
+    @Test
+    void shouldBeComparableToStruct() {
+        ParseTree tree = Helper.prepareParser("""
+                    struct bar { a: int; }
+                    
+                    function foo(): int {
+                        let a: bar = create bar(1);
+                        if (a == naught) {
+                            return -1;
+                        }
+                        return 1;
+                    }
+                    
+                    foo();
+                """);
+        var ctxAnal = new ContextAnalysis(
+                Helper.getFuncs(tree),
+                Helper.getStructs(tree),
+                Helper.getEnums(tree)
+        );
+
+        assertDoesNotThrow(() -> ctxAnal.visit(tree));
+    }
+
+    @Test
+    void shouldBeAssignableToStruct() {
+        ParseTree tree = Helper.prepareParser("""
+                    struct bar { a: int; }
+                    
+                    function foo(): int {
+                        let a: bar = naught;
+                        return 1;
+                    }
+                    
+                    foo();
+                """);
+        var ctxAnal = new ContextAnalysis(
+                Helper.getFuncs(tree),
+                Helper.getStructs(tree),
+                Helper.getEnums(tree)
+        );
+
+        assertDoesNotThrow(() -> ctxAnal.visit(tree));
+    }
+
+    @Test
+    void shouldBeReturnable() {
+        ParseTree tree = Helper.prepareParser("""
+                    struct bar { a: int; }
+                    
+                    function foo(): bar {
+                        return naught;
+                    }
+                    
+                    foo();
+                """);
+        var ctxAnal = new ContextAnalysis(
+                Helper.getFuncs(tree),
+                Helper.getStructs(tree),
+                Helper.getEnums(tree)
+        );
+
+        assertDoesNotThrow(() -> ctxAnal.visit(tree));
+    }
+}

src/test/java/StructFieldAccessTest.java

@@ -16,7 +16,7 @@ public class StructFieldAccessTest {
         ContextAnalysis ctxAnal = new ContextAnalysis(funcs, structs, enums);
         
         Exception e = assertThrows(RuntimeException.class, () -> ctxAnal.visit(tree));
-        assertEquals("Error in line 1:53 Variable with name str not defined.", e.getMessage());
+        assertEquals("Error in line 1:53 Variable or parameter with name \"str\" not defined.", e.getMessage());
     }
 
     @Test
@@ -28,6 +28,6 @@ public class StructFieldAccessTest {
         ContextAnalysis ctxAnal = new ContextAnalysis(funcs, structs, enums);
         
         Exception e = assertThrows(RuntimeException.class, () -> ctxAnal.visit(tree));
-        assertEquals("Error in line 1:69 Variable must reference a struct but references int.", e.getMessage());
+        assertEquals("Error in line 1:69 Variable or parameter must reference a struct but references int.", e.getMessage());
     }
 }

src/test/java/VariableAssignmentTest.java

@@ -17,6 +17,6 @@ public class VariableAssignmentTest {
         ContextAnalysis ctxAnal = new ContextAnalysis(funcs, structs, enums);
         
         Exception e = assertThrows(RuntimeException.class, () -> ctxAnal.visit(tree));
-        assertEquals("Error in line 1:22 Variable with name \"x\" not defined.", e.getMessage());
+        assertEquals("Error in line 1:22 Variable or parameter with name \"x\" not defined.", e.getMessage());
     }
 }

src/test/java/VariableDeclarationTest.java

@@ -89,7 +89,7 @@ public class VariableDeclarationTest {
 
         // when / then
         var e = assertThrows(RuntimeException.class, () -> ctxAnal.visit(tree));
-        assertEquals("Error in line 1:34 Redeclaration of variable with name \"x\".", e.getMessage());
+        assertEquals("Error in line 1:34 Redeclaration of variable or parameter with name \"x\".", e.getMessage());
     }
 
     @Test

src/test/java/VariableTest.java

@@ -17,7 +17,7 @@ public class VariableTest {
         ContextAnalysis ctxAnal = new ContextAnalysis(funcs, structs, enums);
         
         Exception e = assertThrows(RuntimeException.class, () -> ctxAnal.visit(tree));
-        assertEquals("Error in line 1:29 Variable with name \"x\" not defined.", e.getMessage());
+        assertEquals("Error in line 1:29 Variable or parameter with name \"x\" not defined.", e.getMessage());
     }
 
     @Test

src/test/struct/struct.c

@@ -94,6 +94,11 @@ int testStructCreation() {
   struct_testExpected_l("init inner field a", 20, resultRec->b->a);
   struct_testExpected_s("init inner field b", NULL, resultRec->b->b);
 
+  // The result of this test is always 1 because if the tests fail
+  // a segmentation fault occurs.
+  long alignmentResult = isStackAlignedBeforeFunctionCall();
+  struct_testExpected_l("stack alignment before malloc", 1, alignmentResult);
+
   free(resultRec);
   free(innerStruct);
 }

src/test/struct/struct.h

@@ -28,4 +28,6 @@ long getStructFieldRecA(struct testStructRec *t);
 struct testStructRec *getStructFieldRecB(struct testStructRec *t);
 
 struct testStructRec *setStructFieldRecA(struct testStructRec *t, long a);
-struct testStructRec *setStructFieldRecB(struct testStructRec *t, struct testStructRec *b);
+struct testStructRec *setStructFieldRecB(struct testStructRec *t, struct testStructRec *b);
+
+long isStackAlignedBeforeFunctionCall();

src/test/test.k

@@ -555,6 +555,72 @@ function getTestStructRec(a: int, b: testStructRec): testStructRec {
   return create testStructRec(a, b);
 }
 
+struct evenFieldsStruct {
+  a: int;
+  b: int;
+}
+
+struct oddFieldsStruct {
+  a: int;
+  b: int;
+  c: int;
+}
+
+function stackAlignmentTestInternal1(): oddFieldsStruct {
+  // an odd amount of constructor parameters could lead to an unaligned stack
+  // which results in a segmentation fault when calling malloc
+  return create oddFieldsStruct(1, 1, 1);
+}
+
+function stackAlignmentTestInternal2(): evenFieldsStruct {
+  // an odd amount of local variables could lead to an unaligned stack
+  // which results in a segmentation fault when calling malloc
+  let a: evenFieldsStruct = create evenFieldsStruct(1, 1);
+  return a;
+}
+
+function stackAlignmentTestInternal3(a: int): evenFieldsStruct {
+  // an odd amount of function parameters could lead to an unaligned stack
+  // which results in a segmentation fault when calling malloc
+  return create evenFieldsStruct(1, 1);
+}
+
+function stackAlignmentTestInternal4(a: int): evenFieldsStruct {
+  // if (function parameters + local variables + constructor parameters) is odd
+  // then this could lead to an unaligned stack
+  // which results in a segmentation faul when calling malloc
+  let b: int = 0;
+  let c: int = 0;
+  return create evenFieldsStruct(1, 1);
+}
+
+function stackAlignmentTestInternal5(a: int, b: int): evenFieldsStruct {
+  // if (function parameters + local variables + constructor parameters) is odd
+  // then this could lead to an unaligned stack
+  // which results in a segmentation faul when calling malloc
+  let c: int = 0;
+  return create evenFieldsStruct(1, 1);
+}
+
+function stackAlignmentTestInternal6(a: int, b: int): oddFieldsStruct {
+  // if (function parameters + local variables + constructor parameters) is odd
+  // then this could lead to an unaligned stack
+  // which results in a segmentation faul when calling malloc
+  let c: int = 0;
+  let d: int = 0;
+  return create oddFieldsStruct(1, 1, 1);
+}
+
+function isStackAlignedBeforeFunctionCall(): int {
+  let a: oddFieldsStruct = stackAlignmentTestInternal1();
+  let b: evenFieldsStruct = stackAlignmentTestInternal2();
+  let c: evenFieldsStruct = stackAlignmentTestInternal3(1);
+  let d: evenFieldsStruct = stackAlignmentTestInternal4(1);
+  let e: evenFieldsStruct = stackAlignmentTestInternal5(1, 1);
+  let f: oddFieldsStruct = stackAlignmentTestInternal6(1, 1);
+  return 1;
+}
+
 function getStructFieldA(t: testStruct): int {
   return t.a;
 }