diff --git a/pkg/front_end/lib/src/fasta/builder/constructor_builder.dart b/pkg/front_end/lib/src/fasta/builder/constructor_builder.dart
index 76c675b7dc1..d478a6967f9 100644
--- a/pkg/front_end/lib/src/fasta/builder/constructor_builder.dart
+++ b/pkg/front_end/lib/src/fasta/builder/constructor_builder.dart
@@ -141,7 +141,7 @@ class ConstructorBuilderImpl extends FunctionBuilderImpl
       int charEndOffset,
       Member referenceFrom,
       [String nativeMethodName])
-      : _constructor = new Constructor(null,
+      : _constructor = new Constructor(new FunctionNode(null),
             name: new Name(name, compilationUnit.library),
             fileUri: compilationUnit.fileUri,
             reference: referenceFrom?.reference)
@@ -161,6 +161,8 @@ class ConstructorBuilderImpl extends FunctionBuilderImpl
   @override
   Member get invokeTarget => constructor;
 
+  FunctionNode get function => _constructor.function;
+
   @override
   Iterable<Member> get exportedMembers => [constructor];
 
@@ -202,8 +204,7 @@ class ConstructorBuilderImpl extends FunctionBuilderImpl
   @override
   Constructor build(SourceLibraryBuilder libraryBuilder) {
     if (!_hasBeenBuilt) {
-      _constructor.function = buildFunction(libraryBuilder);
-      _constructor.function.parent = _constructor;
+      buildFunction(libraryBuilder);
       _constructor.function.fileOffset = charOpenParenOffset;
       _constructor.function.fileEndOffset = _constructor.fileEndOffset;
       _constructor.function.typeParameters = const <TypeParameter>[];
@@ -263,10 +264,10 @@ class ConstructorBuilderImpl extends FunctionBuilderImpl
   }
 
   @override
-  FunctionNode buildFunction(SourceLibraryBuilder library) {
+  void buildFunction(SourceLibraryBuilder library) {
     // According to the specification §9.3 the return type of a constructor
     // function is its enclosing class.
-    FunctionNode functionNode = super.buildFunction(library);
+    super.buildFunction(library);
     ClassBuilder enclosingClassBuilder = parent;
     Class enclosingClass = enclosingClassBuilder.cls;
     List<DartType> typeParameterTypes = <DartType>[];
@@ -276,9 +277,8 @@ class ConstructorBuilderImpl extends FunctionBuilderImpl
           new TypeParameterType.withDefaultNullabilityForLibrary(
               typeParameter, library.library));
     }
-    functionNode.returnType = new InterfaceType(
+    function.returnType = new InterfaceType(
         enclosingClass, library.nonNullable, typeParameterTypes);
-    return functionNode;
   }
 
   @override
diff --git a/pkg/front_end/lib/src/fasta/builder/function_builder.dart b/pkg/front_end/lib/src/fasta/builder/function_builder.dart
index 15880c6cda1..7d11b18e6cf 100644
--- a/pkg/front_end/lib/src/fasta/builder/function_builder.dart
+++ b/pkg/front_end/lib/src/fasta/builder/function_builder.dart
@@ -293,9 +293,6 @@ abstract class FunctionBuilderImpl extends MemberBuilderImpl
   @override
   final String nativeMethodName;
 
-  @override
-  FunctionNode function;
-
   Statement bodyInternal;
 
   @override
@@ -308,18 +305,16 @@ abstract class FunctionBuilderImpl extends MemberBuilderImpl
 //      }
 //    }
     bodyInternal = newBody;
-    if (function != null) {
-      // A forwarding semi-stub is a method that is abstract in the source code,
-      // but which needs to have a forwarding stub body in order to ensure that
-      // covariance checks occur.  We don't want to replace the forwarding stub
-      // body with null.
-      TreeNode parent = function.parent;
-      if (!(newBody == null &&
-          parent is Procedure &&
-          parent.isForwardingSemiStub)) {
-        function.body = newBody;
-        newBody?.parent = function;
-      }
+    // A forwarding semi-stub is a method that is abstract in the source code,
+    // but which needs to have a forwarding stub body in order to ensure that
+    // covariance checks occur.  We don't want to replace the forwarding stub
+    // body with null.
+    TreeNode parent = function.parent;
+    if (!(newBody == null &&
+        parent is Procedure &&
+        parent.isForwardingSemiStub)) {
+      function.body = newBody;
+      newBody?.parent = function;
     }
   }
 
@@ -342,9 +337,10 @@ abstract class FunctionBuilderImpl extends MemberBuilderImpl
   @override
   bool get isNative => nativeMethodName != null;
 
-  FunctionNode buildFunction(SourceLibraryBuilder library) {
-    assert(function == null);
-    FunctionNode result = new FunctionNode(body, asyncMarker: asyncModifier);
+  void buildFunction(SourceLibraryBuilder library) {
+    function.asyncMarker = asyncModifier;
+    function.body = body;
+    body?.parent = function;
     IncludesTypeParametersNonCovariantly needsCheckVisitor;
     if (!isConstructor && !isFactory && parent is ClassBuilder) {
       ClassBuilder enclosingClassBuilder = parent;
@@ -360,14 +356,14 @@ abstract class FunctionBuilderImpl extends MemberBuilderImpl
     if (typeVariables != null) {
       for (TypeVariableBuilder t in typeVariables) {
         TypeParameter parameter = t.parameter;
-        result.typeParameters.add(parameter);
+        function.typeParameters.add(parameter);
         if (needsCheckVisitor != null) {
           if (parameter.bound.accept(needsCheckVisitor)) {
             parameter.isGenericCovariantImpl = true;
           }
         }
       }
-      setParents(result.typeParameters, result);
+      setParents(function.typeParameters, function);
     }
     if (formals != null) {
       for (FormalParameterBuilder formal in formals) {
@@ -379,13 +375,13 @@ abstract class FunctionBuilderImpl extends MemberBuilderImpl
           }
         }
         if (formal.isNamed) {
-          result.namedParameters.add(parameter);
+          function.namedParameters.add(parameter);
         } else {
-          result.positionalParameters.add(parameter);
+          function.positionalParameters.add(parameter);
         }
-        parameter.parent = result;
+        parameter.parent = function;
         if (formal.isRequired) {
-          result.requiredParameterCount++;
+          function.requiredParameterCount++;
         }
 
         if (library.isNonNullableByDefault) {
@@ -409,14 +405,14 @@ abstract class FunctionBuilderImpl extends MemberBuilderImpl
       // assumes that parameters are built, even if illegal in number.
       VariableDeclaration parameter =
           new VariableDeclarationImpl("#synthetic", 0);
-      result.positionalParameters.clear();
-      result.positionalParameters.add(parameter);
-      parameter.parent = result;
-      result.namedParameters.clear();
-      result.requiredParameterCount = 1;
+      function.positionalParameters.clear();
+      function.positionalParameters.add(parameter);
+      parameter.parent = function;
+      function.namedParameters.clear();
+      function.requiredParameterCount = 1;
     }
     if (returnType != null) {
-      result.returnType = returnType.build(
+      function.returnType = returnType.build(
           library, null, !isConstructor && !isDeclarationInstanceMember);
     }
     if (!isConstructor && !isDeclarationInstanceMember) {
@@ -444,33 +440,32 @@ abstract class FunctionBuilderImpl extends MemberBuilderImpl
         }
 
         Set<TypeParameter> set = typeParameters.toSet();
-        for (VariableDeclaration parameter in result.positionalParameters) {
+        for (VariableDeclaration parameter in function.positionalParameters) {
           if (containsTypeVariable(parameter.type, set)) {
             parameter.type = removeTypeVariables(parameter.type);
           }
         }
-        for (VariableDeclaration parameter in result.namedParameters) {
+        for (VariableDeclaration parameter in function.namedParameters) {
           if (containsTypeVariable(parameter.type, set)) {
             parameter.type = removeTypeVariables(parameter.type);
           }
         }
-        if (containsTypeVariable(result.returnType, set)) {
-          result.returnType = removeTypeVariables(result.returnType);
+        if (containsTypeVariable(function.returnType, set)) {
+          function.returnType = removeTypeVariables(function.returnType);
         }
       }
     }
     if (isExtensionInstanceMember) {
       ExtensionBuilder extensionBuilder = parent;
-      _extensionThis = result.positionalParameters.first;
+      _extensionThis = function.positionalParameters.first;
       if (extensionBuilder.typeParameters != null) {
         int count = extensionBuilder.typeParameters.length;
         _extensionTypeParameters = new List<TypeParameter>.filled(count, null);
         for (int index = 0; index < count; index++) {
-          _extensionTypeParameters[index] = result.typeParameters[index];
+          _extensionTypeParameters[index] = function.typeParameters[index];
         }
       }
     }
-    return function = result;
   }
 
   @override
diff --git a/pkg/front_end/lib/src/fasta/builder/procedure_builder.dart b/pkg/front_end/lib/src/fasta/builder/procedure_builder.dart
index 498826b12f4..087e96d54ce 100644
--- a/pkg/front_end/lib/src/fasta/builder/procedure_builder.dart
+++ b/pkg/front_end/lib/src/fasta/builder/procedure_builder.dart
@@ -107,15 +107,20 @@ abstract class ProcedureBuilderImpl extends FunctionBuilderImpl
         this.isExtensionInstanceMember = isInstanceMember && isExtensionMember,
         super(metadata, modifiers, returnType, name, typeVariables, formals,
             libraryBuilder, charOffset, nativeMethodName) {
-    _procedure = new Procedure(procedureNameScheme.getName(kind, name),
-        isExtensionInstanceMember ? ProcedureKind.Method : kind, null,
-        fileUri: libraryBuilder.fileUri, reference: procedureReference)
+    _procedure = new Procedure(
+        procedureNameScheme.getName(kind, name),
+        isExtensionInstanceMember ? ProcedureKind.Method : kind,
+        new FunctionNode(null),
+        fileUri: libraryBuilder.fileUri,
+        reference: procedureReference)
       ..startFileOffset = startCharOffset
       ..fileOffset = charOffset
       ..fileEndOffset = charEndOffset
       ..isNonNullableByDefault = libraryBuilder.isNonNullableByDefault;
   }
 
+  FunctionNode get function => _procedure.function;
+
   @override
   ProcedureBuilder get origin => actualOrigin ?? this;
 
@@ -136,11 +141,8 @@ abstract class ProcedureBuilderImpl extends FunctionBuilderImpl
   @override
   void set asyncModifier(AsyncMarker newModifier) {
     actualAsyncModifier = newModifier;
-    if (function != null) {
-      // No parent, it's an enum.
-      function.asyncMarker = actualAsyncModifier;
-      function.dartAsyncMarker = actualAsyncModifier;
-    }
+    function.asyncMarker = actualAsyncModifier;
+    function.dartAsyncMarker = actualAsyncModifier;
   }
 
   @override
@@ -266,7 +268,7 @@ class SourceProcedureBuilder extends ProcedureBuilderImpl {
       _extensionTearOff ??= new Procedure(
           procedureNameScheme.getName(ProcedureKind.Getter, name),
           ProcedureKind.Method,
-          null,
+          new FunctionNode(null),
           isStatic: true,
           isExtensionMember: true,
           reference: _tearOffReference)
@@ -379,8 +381,7 @@ class SourceProcedureBuilder extends ProcedureBuilderImpl {
 
   @override
   Procedure build(SourceLibraryBuilder libraryBuilder) {
-    _procedure.function = buildFunction(libraryBuilder);
-    _procedure.function.parent = _procedure;
+    buildFunction(libraryBuilder);
     _procedure.function.fileOffset = charOpenParenOffset;
     _procedure.function.fileEndOffset = _procedure.fileEndOffset;
     _procedure.isAbstract = isAbstract;
@@ -747,8 +748,7 @@ class RedirectingFactoryBuilder extends ProcedureBuilderImpl {
 
   @override
   Procedure build(SourceLibraryBuilder libraryBuilder) {
-    _procedure.function = buildFunction(libraryBuilder);
-    _procedure.function.parent = _procedure;
+    buildFunction(libraryBuilder);
     _procedure.function.fileOffset = charOpenParenOffset;
     _procedure.function.fileEndOffset = _procedure.fileEndOffset;
     _procedure.isAbstract = isAbstract;
diff --git a/pkg/front_end/lib/src/fasta/kernel/body_builder.dart b/pkg/front_end/lib/src/fasta/kernel/body_builder.dart
index 50db82b756d..1f26ed0385b 100644
--- a/pkg/front_end/lib/src/fasta/kernel/body_builder.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/body_builder.dart
@@ -4999,8 +4999,8 @@ class BodyBuilder extends ScopeListener<JumpTarget>
     }
     push(new FunctionDeclarationImpl(
         variable,
-        // The function node is created later.
-        null)
+        // The real function node is created later.
+        dummyFunctionNode)
       ..fileOffset = beginToken.charOffset);
     declareVariable(variable, scope.parent);
   }
diff --git a/pkg/front_end/lib/src/fasta/kernel/member_covariance.dart b/pkg/front_end/lib/src/fasta/kernel/member_covariance.dart
index b33dbcd7881..03c89ce7268 100644
--- a/pkg/front_end/lib/src/fasta/kernel/member_covariance.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/member_covariance.dart
@@ -95,7 +95,7 @@ class Covariance {
   /// Computes the covariance for the [setter].
   factory Covariance.fromSetter(Procedure setter) {
     int covariance =
-        covarianceFromParameter(setter.function!.positionalParameters.first);
+        covarianceFromParameter(setter.function.positionalParameters.first);
     if (covariance == 0) {
       return const Covariance.empty();
     }
@@ -104,7 +104,7 @@ class Covariance {
 
   /// Computes the covariance for the [procedure].
   factory Covariance.fromMethod(Procedure procedure) {
-    FunctionNode function = procedure.function!;
+    FunctionNode function = procedure.function;
     List<int>? positionalParameters;
     if (function.positionalParameters.isNotEmpty) {
       for (int index = 0;
@@ -269,7 +269,7 @@ class Covariance {
   void applyCovariance(Member member) {
     if (isEmpty) return;
     if (member is Procedure) {
-      FunctionNode function = member.function!;
+      FunctionNode function = member.function;
       List<int>? positionalParameters = _positionalParameters;
       if (positionalParameters != null) {
         for (int index = 0; index < positionalParameters.length; index++) {
diff --git a/pkg/kernel/binary.md b/pkg/kernel/binary.md
index b5948984f75..20ee23e0296 100644
--- a/pkg/kernel/binary.md
+++ b/pkg/kernel/binary.md
@@ -147,7 +147,7 @@ type CanonicalName {
 
 type ComponentFile {
   UInt32 magic = 0x90ABCDEF;
-  UInt32 formatVersion = 60;
+  UInt32 formatVersion = 61;
   Byte[10] shortSdkHash;
   List<String> problemsAsJson; // Described in problems.md.
   Library[] libraries;
@@ -425,8 +425,7 @@ type Procedure extends Member {
   Name name;
   List<Expression> annotations;
   MemberReference stubTarget; // May be NullReference.
-  // Can only be absent if abstract, but tag is there anyway.
-  Option<FunctionNode> function;
+  FunctionNode function;
 }
 
 type RedirectingFactoryConstructor extends Member {
diff --git a/pkg/kernel/lib/ast.dart b/pkg/kernel/lib/ast.dart
index a81d28faaa4..9e1ce0fe631 100644
--- a/pkg/kernel/lib/ast.dart
+++ b/pkg/kernel/lib/ast.dart
@@ -1988,9 +1988,8 @@ class Constructor extends Member {
 
   int flags = 0;
 
-  // TODO(johnniwinther): Make this non-nullable.
   @override
-  FunctionNode? function;
+  FunctionNode function;
 
   List<Initializer> initializers;
 
@@ -2004,8 +2003,10 @@ class Constructor extends Member {
       Uri? fileUri,
       Reference? reference})
       : this.initializers = initializers ?? <Initializer>[],
+        // ignore: unnecessary_null_comparison
+        assert(function != null),
         super(name, fileUri, reference) {
-    function?.parent = this;
+    function.parent = this;
     setParents(this.initializers, this);
     this.isConst = isConst;
     this.isExternal = isExternal;
@@ -2082,16 +2083,17 @@ class Constructor extends Member {
     visitList(annotations, v);
     name.accept(v);
     visitList(initializers, v);
-    function?.accept(v);
+    function.accept(v);
   }
 
   @override
   void transformChildren(Transformer v) {
     v.transformList(annotations, this);
     v.transformList(initializers, this);
+    // ignore: unnecessary_null_comparison
     if (function != null) {
-      function = v.transform(function!);
-      function?.parent = this;
+      function = v.transform(function);
+      function.parent = this;
     }
   }
 
@@ -2099,9 +2101,10 @@ class Constructor extends Member {
   void transformOrRemoveChildren(RemovingTransformer v) {
     v.transformExpressionList(annotations, this);
     v.transformInitializerList(initializers, this);
+    // ignore: unnecessary_null_comparison
     if (function != null) {
-      function = v.transformOrRemove(function!, dummyFunctionNode);
-      function?.parent = this;
+      function = v.transform(function);
+      function.parent = this;
     }
   }
 
@@ -2504,16 +2507,15 @@ class Procedure extends Member {
   final ProcedureKind kind;
   int flags = 0;
 
-  // TODO(johnniwinther): Make this non-nullable.
   @override
-  FunctionNode? function;
+  FunctionNode function;
 
   // The function node's body might be lazily loaded, meaning that this value
   // might not be set correctly yet. Make sure the body is loaded before
   // returning anything.
   @override
   int get transformerFlags {
-    function?.body;
+    function.body;
     return super.transformerFlags;
   }
 
@@ -2522,7 +2524,7 @@ class Procedure extends Member {
   // body now and only set the value afterwards.
   @override
   void set transformerFlags(int newValue) {
-    function?.body;
+    function.body;
     super.transformerFlags = newValue;
   }
 
@@ -2536,7 +2538,7 @@ class Procedure extends Member {
   ProcedureStubKind stubKind;
   Reference? stubTargetReference;
 
-  Procedure(Name name, ProcedureKind kind, FunctionNode? function,
+  Procedure(Name name, ProcedureKind kind, FunctionNode function,
       {bool isAbstract: false,
       bool isStatic: false,
       bool isExternal: false,
@@ -2576,15 +2578,17 @@ class Procedure extends Member {
       this.stubTargetReference})
       // ignore: unnecessary_null_comparison
       : assert(kind != null),
+        // ignore: unnecessary_null_comparison
+        assert(function != null),
         super(name, fileUri, reference) {
-    function?.parent = this;
+    function.parent = this;
     this.isAbstract = isAbstract;
     this.isStatic = isStatic;
     this.isExternal = isExternal;
     this.isConst = isConst;
     this.isExtensionMember = isExtensionMember;
     this.isSynthetic = isSynthetic;
-    this.transformerFlags = transformerFlags;
+    setTransformerFlagsWithoutLazyLoading(transformerFlags);
     assert(!(isMemberSignature && stubTargetReference == null),
         "No member signature origin for member signature $this.");
     assert(
@@ -2753,38 +2757,40 @@ class Procedure extends Member {
   void visitChildren(Visitor v) {
     visitList(annotations, v);
     name.accept(v);
-    function?.accept(v);
+    function.accept(v);
   }
 
   @override
   void transformChildren(Transformer v) {
     v.transformList(annotations, this);
+    // ignore: unnecessary_null_comparison
     if (function != null) {
-      function = v.transform(function!);
-      function?.parent = this;
+      function = v.transform(function);
+      function.parent = this;
     }
   }
 
   @override
   void transformOrRemoveChildren(RemovingTransformer v) {
     v.transformExpressionList(annotations, this);
+    // ignore: unnecessary_null_comparison
     if (function != null) {
-      function = v.transformOrRemove(function!, dummyFunctionNode);
-      function?.parent = this;
+      function = v.transform(function);
+      function.parent = this;
     }
   }
 
   @override
   DartType get getterType {
     return isGetter
-        ? function!.returnType
-        : function!.computeFunctionType(enclosingLibrary.nonNullable);
+        ? function.returnType
+        : function.computeFunctionType(enclosingLibrary.nonNullable);
   }
 
   @override
   DartType get setterType {
     return isSetter
-        ? function!.positionalParameters[0].type
+        ? function.positionalParameters[0].type
         : const NeverType.nonNullable();
   }
 
@@ -6025,9 +6031,9 @@ class SuperMethodInvocation extends InvocationExpression {
         .getTypeArgumentsAsInstanceOf(context.thisType!, superclass);
     DartType returnType = Substitution.fromPairs(
             superclass.typeParameters, receiverTypeArguments!)
-        .substituteType(interfaceTarget.function!.returnType);
+        .substituteType(interfaceTarget.function.returnType);
     return Substitution.fromPairs(
-            interfaceTarget.function!.typeParameters, arguments.types)
+            interfaceTarget.function.typeParameters, arguments.types)
         .substituteType(returnType);
   }
 
@@ -6114,8 +6120,8 @@ class StaticInvocation extends InvocationExpression {
   @override
   DartType getStaticTypeInternal(StaticTypeContext context) {
     return Substitution.fromPairs(
-            target.function!.typeParameters, arguments.types)
-        .substituteType(target.function!.returnType);
+            target.function.typeParameters, arguments.types)
+        .substituteType(target.function.returnType);
   }
 
   @override
@@ -8077,8 +8083,7 @@ class AwaitExpression extends Expression {
 
 /// Common super-interface for [FunctionExpression] and [FunctionDeclaration].
 abstract class LocalFunction implements TreeNode {
-  // TODO(johnniwinther): Make this non-nullable.
-  FunctionNode? get function;
+  FunctionNode get function;
 }
 
 /// Expression of form `(x,y) => ...` or `(x,y) { ... }`
@@ -10118,11 +10123,13 @@ class FunctionDeclaration extends Statement implements LocalFunction {
   VariableDeclaration variable; // Is final and has no initializer.
 
   @override
-  FunctionNode? function;
+  FunctionNode function;
 
-  FunctionDeclaration(this.variable, this.function) {
+  FunctionDeclaration(this.variable, this.function)
+      // ignore: unnecessary_null_comparison
+      : assert(function != null) {
     variable.parent = this;
-    function?.parent = this;
+    function.parent = this;
   }
 
   @override
@@ -10135,7 +10142,7 @@ class FunctionDeclaration extends Statement implements LocalFunction {
   @override
   void visitChildren(Visitor v) {
     variable.accept(v);
-    function?.accept(v);
+    function.accept(v);
   }
 
   @override
@@ -10145,9 +10152,10 @@ class FunctionDeclaration extends Statement implements LocalFunction {
       variable = v.transform(variable);
       variable.parent = this;
     }
+    // ignore: unnecessary_null_comparison
     if (function != null) {
-      function = v.transform(function!);
-      function?.parent = this;
+      function = v.transform(function);
+      function.parent = this;
     }
   }
 
@@ -10158,9 +10166,10 @@ class FunctionDeclaration extends Statement implements LocalFunction {
       variable = v.transform(variable);
       variable.parent = this;
     }
+    // ignore: unnecessary_null_comparison
     if (function != null) {
-      function = v.transformOrRemove(function!, dummyFunctionNode);
-      function?.parent = this;
+      function = v.transform(function);
+      function.parent = this;
     }
   }
 
@@ -10171,9 +10180,10 @@ class FunctionDeclaration extends Statement implements LocalFunction {
 
   @override
   void toTextInternal(AstPrinter printer) {
+    // ignore: unnecessary_null_comparison
     if (function != null) {
-      printer.writeFunctionNode(function!, printer.getVariableName(variable));
-      if (function!.body is ReturnStatement) {
+      printer.writeFunctionNode(function, printer.getVariableName(variable));
+      if (function.body is ReturnStatement) {
         printer.write(';');
       }
     }
@@ -12624,7 +12634,7 @@ class TearOffConstant extends Constant {
   }
 
   FunctionType getType(StaticTypeContext context) {
-    return procedure.function!.computeFunctionType(context.nonNullable);
+    return procedure.function.computeFunctionType(context.nonNullable);
   }
 }
 
diff --git a/pkg/kernel/lib/binary/ast_from_binary.dart b/pkg/kernel/lib/binary/ast_from_binary.dart
index 7c1de525dd8..0d99e602bb0 100644
--- a/pkg/kernel/lib/binary/ast_from_binary.dart
+++ b/pkg/kernel/lib/binary/ast_from_binary.dart
@@ -499,7 +499,7 @@ class BinaryBuilder {
     }
   }
 
-  List<Expression> readAnnotationList(TreeNode? parent) {
+  List<Expression> readAnnotationList([TreeNode? parent]) {
     int length = readUInt30();
     if (length == 0) return const <Expression>[];
     return new List<Expression>.generate(
@@ -1493,15 +1493,15 @@ class BinaryBuilder {
     int fileEndOffset = readOffset();
     int flags = readByte();
     Name name = readName();
-    if (node == null) {
-      node = new Constructor(null, reference: reference, name: name);
-    }
-    List<Expression> annotations = readAnnotationList(node);
+    List<Expression> annotations = readAnnotationList();
     assert(() {
       debugPath.add(name.text);
       return true;
     }());
     FunctionNode function = readFunctionNode();
+    if (node == null) {
+      node = new Constructor(function, reference: reference, name: name);
+    }
     pushVariableDeclarations(function.positionalParameters);
     pushVariableDeclarations(function.namedParameters);
     _fillTreeNodeList(node.initializers, (index) => readInitializer(), node);
@@ -1515,6 +1515,7 @@ class BinaryBuilder {
     node.name = name;
     node.fileUri = fileUri;
     node.annotations = annotations;
+    setParents(annotations, node);
     node.function = function..parent = node;
     node.transformerFlags = transformerFlags;
     return node;
@@ -1538,12 +1539,7 @@ class BinaryBuilder {
     ProcedureStubKind stubKind = ProcedureStubKind.values[readByte()];
     int flags = readUInt30();
     Name name = readName();
-    if (node == null) {
-      node = new Procedure(name, kind, null, reference: reference);
-    } else {
-      assert(node.kind == kind);
-    }
-    List<Expression> annotations = readAnnotationList(node);
+    List<Expression> annotations = readAnnotationList();
     assert(() {
       debugPath.add(name.text);
       return true;
@@ -1554,8 +1550,13 @@ class BinaryBuilder {
         (kind == ProcedureKind.Factory && functionNodeSize <= 50) ||
             _disableLazyReading;
     Reference? stubTargetReference = readNullableMemberReference();
-    FunctionNode? function =
-        readFunctionNodeOption(!readFunctionNodeNow, endOffset);
+    FunctionNode function = readFunctionNode(
+        lazyLoadBody: !readFunctionNodeNow, outerEndOffset: endOffset);
+    if (node == null) {
+      node = new Procedure(name, kind, function, reference: reference);
+    } else {
+      assert(node.kind == kind);
+    }
     int transformerFlags = getAndResetTransformerFlags();
     assert(((_) => true)(debugPath.removeLast()));
     node.startFileOffset = startFileOffset;
@@ -1565,15 +1566,15 @@ class BinaryBuilder {
     node.name = name;
     node.fileUri = fileUri;
     node.annotations = annotations;
-    node.function = function;
-    function?.parent = node;
+    setParents(annotations, node);
+    node.function = function..parent = node;
     node.setTransformerFlagsWithoutLazyLoading(transformerFlags);
     node.stubKind = stubKind;
     node.stubTargetReference = stubTargetReference;
 
     assert((node.stubKind == ProcedureStubKind.ConcreteForwardingStub &&
             node.stubTargetReference != null) ||
-        !(node.isForwardingStub && node.function!.body != null));
+        !(node.isForwardingStub && node.function.body != null));
     assert(!(node.isMemberSignature && node.stubTargetReference == null),
         "No member signature origin for member signature $node.");
     return node;
@@ -1686,13 +1687,6 @@ class BinaryBuilder {
     return new AssertInitializer(readStatement() as AssertStatement);
   }
 
-  FunctionNode? readFunctionNodeOption(bool lazyLoadBody, int outerEndOffset) {
-    return readAndCheckOptionTag()
-        ? readFunctionNode(
-            lazyLoadBody: lazyLoadBody, outerEndOffset: outerEndOffset)
-        : null;
-  }
-
   FunctionNode readFunctionNode(
       {bool lazyLoadBody: false, int outerEndOffset: -1}) {
     int tag = readByte();
diff --git a/pkg/kernel/lib/binary/ast_to_binary.dart b/pkg/kernel/lib/binary/ast_to_binary.dart
index 5652534677d..e7271c54630 100644
--- a/pkg/kernel/lib/binary/ast_to_binary.dart
+++ b/pkg/kernel/lib/binary/ast_to_binary.dart
@@ -488,15 +488,6 @@ class BinaryPrinter implements Visitor<void>, BinarySink {
     }
   }
 
-  void writeOptionalFunctionNode(FunctionNode? node) {
-    if (node == null) {
-      writeByte(Tag.Nothing);
-    } else {
-      writeByte(Tag.Something);
-      writeFunctionNode(node);
-    }
-  }
-
   void writeLinkTable(Component component) {
     _binaryOffsetForLinkTable = getBufferOffset();
     writeList(_canonicalNameList, writeCanonicalNameEntry);
@@ -1209,12 +1200,12 @@ class BinaryPrinter implements Visitor<void>, BinarySink {
     writeName(node.name);
 
     writeAnnotationList(node.annotations);
-    assert(node.function!.typeParameters.isEmpty);
-    writeFunctionNode(node.function!);
+    assert(node.function.typeParameters.isEmpty);
+    writeFunctionNode(node.function);
     // Parameters are in scope in the initializers.
     _variableIndexer ??= new VariableIndexer();
-    _variableIndexer!.restoreScope(node.function!.positionalParameters.length +
-        node.function!.namedParameters.length);
+    _variableIndexer!.restoreScope(node.function.positionalParameters.length +
+        node.function.namedParameters.length);
     writeNodeList(node.initializers);
 
     leaveScope(memberScope: true);
@@ -1273,13 +1264,13 @@ class BinaryPrinter implements Visitor<void>, BinarySink {
     writeName(node.name);
     writeAnnotationList(node.annotations);
     writeNullAllowedReference(node.stubTargetReference);
-    writeOptionalFunctionNode(node.function);
+    writeFunctionNode(node.function);
     leaveScope(memberScope: true);
 
     _currentlyInNonimplementation = currentlyInNonimplementationSaved;
     assert(
         (node.concreteForwardingStubTarget != null) ||
-            !(node.isForwardingStub && node.function!.body != null),
+            !(node.isForwardingStub && node.function.body != null),
         "Invalid forwarding stub $node.");
   }
 
@@ -2251,7 +2242,7 @@ class BinaryPrinter implements Visitor<void>, BinarySink {
     writeByte(Tag.FunctionDeclaration);
     writeOffset(node.fileOffset);
     writeVariableDeclaration(node.variable);
-    writeFunctionNode(node.function!);
+    writeFunctionNode(node.function);
   }
 
   @override
diff --git a/pkg/kernel/lib/binary/tag.dart b/pkg/kernel/lib/binary/tag.dart
index fca44c61929..523a5a225c2 100644
--- a/pkg/kernel/lib/binary/tag.dart
+++ b/pkg/kernel/lib/binary/tag.dart
@@ -174,7 +174,7 @@ class Tag {
   /// Internal version of kernel binary format.
   /// Bump it when making incompatible changes in kernel binaries.
   /// Keep in sync with runtime/vm/kernel_binary.h, pkg/kernel/binary.md.
-  static const int BinaryFormatVersion = 60;
+  static const int BinaryFormatVersion = 61;
 }
 
 abstract class ConstantTag {
diff --git a/pkg/kernel/lib/clone.dart b/pkg/kernel/lib/clone.dart
index 3f09922adc9..6c76c2f73ab 100644
--- a/pkg/kernel/lib/clone.dart
+++ b/pkg/kernel/lib/clone.dart
@@ -485,8 +485,8 @@ class CloneVisitorNotMembers implements TreeVisitor<TreeNode> {
     // Create the declaration before cloning the body to support recursive
     // [LocalFunctionInvocation] nodes.
     FunctionDeclaration declaration =
-        new FunctionDeclaration(newVariable, null);
-    FunctionNode functionNode = clone(node.function!);
+        new FunctionDeclaration(newVariable, dummyFunctionNode);
+    FunctionNode functionNode = clone(node.function);
     declaration.function = functionNode..parent = declaration;
     return declaration;
   }
@@ -757,7 +757,7 @@ class CloneVisitorWithMembers extends CloneVisitorNotMembers {
     _activeFileUri = node.fileUri ?? _activeFileUri;
 
     Constructor result = new Constructor(
-      super.clone(node.function!),
+      super.clone(node.function),
       name: node.name,
       isConst: node.isConst,
       isExternal: node.isExternal,
@@ -781,7 +781,7 @@ class CloneVisitorWithMembers extends CloneVisitorNotMembers {
     final Uri? activeFileUriSaved = _activeFileUri;
     _activeFileUri = node.fileUri ?? _activeFileUri;
     Procedure result = new Procedure(
-        node.name, node.kind, super.clone(node.function!),
+        node.name, node.kind, super.clone(node.function),
         reference: reference,
         transformerFlags: node.transformerFlags,
         fileUri: _activeFileUri,
diff --git a/pkg/kernel/lib/text/ast_to_text.dart b/pkg/kernel/lib/text/ast_to_text.dart
index 3565196e3e4..27edbc162a4 100644
--- a/pkg/kernel/lib/text/ast_to_text.dart
+++ b/pkg/kernel/lib/text/ast_to_text.dart
@@ -1206,13 +1206,13 @@ class Printer extends Visitor<void> with VisitorVoidMixin {
       case ProcedureStubKind.ConcreteForwardingStub:
       case ProcedureStubKind.NoSuchMethodForwarder:
       case ProcedureStubKind.ConcreteMixinStub:
-        writeFunction(node.function!, name: getMemberName(node));
+        writeFunction(node.function, name: getMemberName(node));
         break;
       case ProcedureStubKind.MemberSignature:
       case ProcedureStubKind.AbstractMixinStub:
-        writeFunction(node.function!,
+        writeFunction(node.function,
             name: getMemberName(node), terminateLine: false);
-        if (node.function!.body is ReturnStatement) {
+        if (node.function.body is ReturnStatement) {
           writeSymbol(';');
         }
         writeSymbol(' -> ');
@@ -1241,7 +1241,7 @@ class Printer extends Visitor<void> with VisitorVoidMixin {
     if (features.isNotEmpty) {
       writeWord("/*${features.join(',')}*/");
     }
-    writeFunction(node.function!,
+    writeFunction(node.function,
         name: node.name, initializers: node.initializers);
   }
 
@@ -2289,8 +2289,9 @@ class Printer extends Visitor<void> with VisitorVoidMixin {
     writeAnnotationList(node.variable.annotations);
     writeIndentation();
     writeWord('function');
+    // ignore: unnecessary_null_comparison
     if (node.function != null) {
-      writeFunction(node.function!, name: getVariableName(node.variable));
+      writeFunction(node.function, name: getVariableName(node.variable));
     } else {
       writeWord(getVariableName(node.variable));
       endLine('...;');
diff --git a/pkg/kernel/lib/text/text_serializer.dart b/pkg/kernel/lib/text/text_serializer.dart
index 0899fe860c4..f544010b041 100644
--- a/pkg/kernel/lib/text/text_serializer.dart
+++ b/pkg/kernel/lib/text/text_serializer.dart
@@ -1750,7 +1750,7 @@ TextSerializer<ContinueSwitchStatement> continueSwitchStatementSerializer =
 
 TextSerializer<FunctionDeclaration> functionDeclarationSerializer =
     Wrapped<Tuple2<VariableDeclaration, FunctionNode>, FunctionDeclaration>(
-        (w) => Tuple2(w.variable, w.function!),
+        (w) => Tuple2(w.variable, w.function),
         (u) => FunctionDeclaration(u.first, u.second),
         Rebind(variableDeclarationSerializer, functionNodeSerializer));
 
@@ -1983,7 +1983,7 @@ TextSerializer<Field> immutableFieldSerializer =
 
 TextSerializer<Procedure> methodSerializer =
     Wrapped<Tuple3<Name, int, FunctionNode>, Procedure>(
-        (w) => Tuple3(w.name, w.flags, w.function!),
+        (w) => Tuple3(w.name, w.flags, w.function),
         (u) =>
             Procedure(u.first, ProcedureKind.Method, u.third)..flags = u.second,
         Tuple3Serializer(
@@ -1991,7 +1991,7 @@ TextSerializer<Procedure> methodSerializer =
 
 TextSerializer<Procedure> getterSerializer =
     Wrapped<Tuple3<Name, int, FunctionNode>, Procedure>(
-        (w) => Tuple3(w.name, w.flags, w.function!),
+        (w) => Tuple3(w.name, w.flags, w.function),
         (u) =>
             Procedure(u.first, ProcedureKind.Getter, u.third)..flags = u.second,
         Tuple3Serializer(
@@ -1999,7 +1999,7 @@ TextSerializer<Procedure> getterSerializer =
 
 TextSerializer<Procedure> setterSerializer =
     Wrapped<Tuple3<Name, int, FunctionNode>, Procedure>(
-        (w) => Tuple3(w.name, w.flags, w.function!),
+        (w) => Tuple3(w.name, w.flags, w.function),
         (u) =>
             Procedure(u.first, ProcedureKind.Setter, u.third)..flags = u.second,
         Tuple3Serializer(
@@ -2007,7 +2007,7 @@ TextSerializer<Procedure> setterSerializer =
 
 TextSerializer<Procedure> operatorSerializer =
     Wrapped<Tuple3<Name, int, FunctionNode>, Procedure>(
-        (w) => Tuple3(w.name, w.flags, w.function!),
+        (w) => Tuple3(w.name, w.flags, w.function),
         (u) => Procedure(u.first, ProcedureKind.Operator, u.third)
           ..flags = u.second,
         Tuple3Serializer(
@@ -2015,7 +2015,7 @@ TextSerializer<Procedure> operatorSerializer =
 
 TextSerializer<Procedure> factorySerializer =
     Wrapped<Tuple3<Name, int, FunctionNode>, Procedure>(
-        (w) => Tuple3(w.name, w.flags, w.function!),
+        (w) => Tuple3(w.name, w.flags, w.function),
         (u) => Procedure(u.first, ProcedureKind.Factory, u.third)
           ..flags = u.second,
         Tuple3Serializer(
@@ -2024,7 +2024,7 @@ TextSerializer<Procedure> factorySerializer =
 TextSerializer<Constructor> constructorSerializer = Wrapped<
         Tuple3<Name, int, Tuple2<FunctionNode, List<Initializer>?>>,
         Constructor>(
-    (w) => Tuple3(w.name, w.flags, Tuple2(w.function!, w.initializers)),
+    (w) => Tuple3(w.name, w.flags, Tuple2(w.function, w.initializers)),
     (u) =>
         Constructor(u.third.first, name: u.first, initializers: u.third.second)
           ..flags = u.second,
diff --git a/pkg/kernel/lib/transformations/continuation.dart b/pkg/kernel/lib/transformations/continuation.dart
index c477db5eb8a..2404a997679 100644
--- a/pkg/kernel/lib/transformations/continuation.dart
+++ b/pkg/kernel/lib/transformations/continuation.dart
@@ -189,7 +189,7 @@ class RecursiveContinuationRewriter extends RemovingTransformer {
     assert(const [
       Nullability.nonNullable,
       Nullability.legacy
-    ].contains(coreTypes.iterableGetIterator.function!.returnType.nullability));
+    ].contains(coreTypes.iterableGetIterator.function.returnType.nullability));
 
     final DartType elementType = stmt.getElementType(staticTypeContext);
     final iteratorType = InterfaceType(
@@ -1144,7 +1144,7 @@ abstract class AsyncRewriterBase extends ContinuationRewriterBase {
 
   TreeNode visitFunctionDeclaration(
       FunctionDeclaration stmt, TreeNode? removalSentinel) {
-    stmt.function = transform(stmt.function!)..parent = stmt;
+    stmt.function = transform(stmt.function)..parent = stmt;
     statements.add(stmt);
     return removalSentinel ?? EmptyStatement();
   }
diff --git a/pkg/kernel/lib/transformations/mixin_full_resolution.dart b/pkg/kernel/lib/transformations/mixin_full_resolution.dart
index b1a72a8310c..c9b5c39f876 100644
--- a/pkg/kernel/lib/transformations/mixin_full_resolution.dart
+++ b/pkg/kernel/lib/transformations/mixin_full_resolution.dart
@@ -138,7 +138,7 @@ class MixinFullResolution {
         if (setter != null) {
           setters.remove(field.name);
           VariableDeclaration parameter =
-              setter.function!.positionalParameters.first;
+              setter.function.positionalParameters.first;
           clone.isCovariant = parameter.isCovariant;
           clone.isGenericCovariantImpl = parameter.isGenericCovariantImpl;
         }
@@ -180,8 +180,8 @@ class MixinFullResolution {
         var originalProcedure = class_.procedures[i];
         if (originalProcedure.name == procedure.name &&
             originalProcedure.kind == procedure.kind) {
-          FunctionNode src = originalProcedure.function!;
-          FunctionNode dst = procedure.function!;
+          FunctionNode src = originalProcedure.function;
+          FunctionNode dst = procedure.function;
 
           if (src.positionalParameters.length !=
                   dst.positionalParameters.length ||
@@ -200,8 +200,8 @@ class MixinFullResolution {
       Procedure clone = cloner.cloneProcedure(procedure, reference);
       if (originalIndex != null) {
         Procedure originalProcedure = class_.procedures[originalIndex];
-        FunctionNode src = originalProcedure.function!;
-        FunctionNode dst = clone.function!;
+        FunctionNode src = originalProcedure.function;
+        FunctionNode dst = clone.function;
         assert(src.typeParameters.length == dst.typeParameters.length);
         for (int j = 0; j < src.typeParameters.length; ++j) {
           dst.typeParameters[j].flags = src.typeParameters[j].flags;
diff --git a/pkg/kernel/lib/transformations/track_widget_constructor_locations.dart b/pkg/kernel/lib/transformations/track_widget_constructor_locations.dart
index 7e81c8d62c1..6538a7b4df3 100644
--- a/pkg/kernel/lib/transformations/track_widget_constructor_locations.dart
+++ b/pkg/kernel/lib/transformations/track_widget_constructor_locations.dart
@@ -208,7 +208,7 @@ class _WidgetCallSiteTransformer extends Transformer {
       return node;
     }
 
-    _addLocationArgument(node, target.function!, constructedClass,
+    _addLocationArgument(node, target.function, constructedClass,
         isConst: node.isConst);
     return node;
   }
@@ -234,7 +234,7 @@ class _WidgetCallSiteTransformer extends Transformer {
       return node;
     }
 
-    _addLocationArgument(node, constructor.function!, constructedClass,
+    _addLocationArgument(node, constructor.function, constructedClass,
         isConst: node.isConst);
     return node;
   }
@@ -252,7 +252,7 @@ class _WidgetCallSiteTransformer extends Transformer {
         // constant expression.
         !isConst) {
       final VariableDeclaration? creationLocationParameter = _getNamedParameter(
-        _currentFactory!.function!,
+        _currentFactory!.function,
         _creationLocationParameterName,
       );
       if (creationLocationParameter != null) {
@@ -401,7 +401,7 @@ class WidgetCreatorTracker {
         return;
       }
       assert(!_hasNamedParameter(
-        constructor.function!,
+        constructor.function,
         _creationLocationParameterName,
       ));
       final VariableDeclaration variable = new VariableDeclaration(
@@ -409,7 +409,7 @@ class WidgetCreatorTracker {
           type: new InterfaceType(
               _locationClass, clazz.enclosingLibrary.nullable),
           initializer: new NullLiteral());
-      if (!_maybeAddNamedParameter(constructor.function!, variable)) {
+      if (!_maybeAddNamedParameter(constructor.function, variable)) {
         return;
       }
 
@@ -424,7 +424,7 @@ class WidgetCreatorTracker {
           }
           _maybeAddCreationLocationArgument(
             initializer.arguments,
-            initializer.target.function!,
+            initializer.target.function,
             new VariableGet(variable),
             _locationClass,
           );
@@ -548,7 +548,7 @@ class WidgetCreatorTracker {
     for (Procedure procedure in clazz.procedures) {
       if (procedure.isFactory) {
         _maybeAddNamedParameter(
-          procedure.function!,
+          procedure.function,
           new VariableDeclaration(_creationLocationParameterName,
               type: new InterfaceType(
                   _locationClass, clazz.enclosingLibrary.nullable),
@@ -578,12 +578,12 @@ class WidgetCreatorTracker {
               _locationClass, clazz.enclosingLibrary.nullable),
           initializer: new NullLiteral());
       if (_hasNamedParameter(
-          constructor.function!, _creationLocationParameterName)) {
+          constructor.function, _creationLocationParameterName)) {
         // Constructor was already rewritten.
         // TODO(jacobr): is this case actually hit?
         return;
       }
-      if (!_maybeAddNamedParameter(constructor.function!, variable)) {
+      if (!_maybeAddNamedParameter(constructor.function, variable)) {
         return;
       }
       for (Initializer initializer in constructor.initializers) {
@@ -597,7 +597,7 @@ class WidgetCreatorTracker {
 
           _maybeAddCreationLocationArgument(
             initializer.arguments,
-            initializer.target.function!,
+            initializer.target.function,
             new VariableGet(variable),
             _locationClass,
           );
@@ -605,7 +605,7 @@ class WidgetCreatorTracker {
             _isSubclassOfWidget(initializer.target.enclosingClass)) {
           _maybeAddCreationLocationArgument(
             initializer.arguments,
-            initializer.target.function!,
+            initializer.target.function,
             new VariableGet(variable),
             _locationClass,
           );
diff --git a/pkg/kernel/lib/verifier.dart b/pkg/kernel/lib/verifier.dart
index a263a040bb5..9431e8eb84a 100644
--- a/pkg/kernel/lib/verifier.dart
+++ b/pkg/kernel/lib/verifier.dart
@@ -363,7 +363,7 @@ class VerifyingVisitor extends RecursiveResultVisitor<void> {
           "Only forwarding stubs can have a forwarding stub super target "
           "$node.");
     }
-    node.function!.accept(this);
+    node.function.accept(this);
     classTypeParametersAreInScope = false;
     visitList(node.annotations, this);
     exitParent(oldParent);
@@ -377,7 +377,7 @@ class VerifyingVisitor extends RecursiveResultVisitor<void> {
     // in scope in the initializer list.
     TreeNode? oldParent = enterParent(node);
     int stackHeight = enterLocalScope();
-    visitChildren(node.function!);
+    visitChildren(node.function);
     visitList(node.initializers, this);
     if (!isOutline) {
       checkInitializers(node);
diff --git a/pkg/kernel/test/verify_test.dart b/pkg/kernel/test/verify_test.dart
index 097200d70e8..f8b17180a69 100644
--- a/pkg/kernel/test/verify_test.dart
+++ b/pkg/kernel/test/verify_test.dart
@@ -258,8 +258,8 @@ main() {
     "Incorrect parent pointer on FunctionNode:"
         " expected 'Procedure', but found: 'Null'.",
     (TestHarness test) {
-      var procedure =
-          new Procedure(new Name('bar'), ProcedureKind.Method, null);
+      var procedure = new Procedure(
+          new Name('bar'), ProcedureKind.Method, dummyFunctionNode);
       procedure.function = new FunctionNode(new EmptyStatement());
       test.addNode(procedure);
     },
diff --git a/pkg/vm/lib/transformations/type_flow/analysis.dart b/pkg/vm/lib/transformations/type_flow/analysis.dart
index c8a530da355..b22fa57e76b 100644
--- a/pkg/vm/lib/transformations/type_flow/analysis.dart
+++ b/pkg/vm/lib/transformations/type_flow/analysis.dart
@@ -373,8 +373,8 @@ class _DispatchableInvocation extends _Invocation {
   }
 
   /// Marker for noSuchMethod() invocation in the map of invocation targets.
-  static final Member kNoSuchMethodMarker =
-      new Procedure(new Name('noSuchMethod&&'), ProcedureKind.Method, null);
+  static final Member kNoSuchMethodMarker = new Procedure(
+      new Name('noSuchMethod&&'), ProcedureKind.Method, new FunctionNode(null));
 
   _DispatchableInvocation(Selector selector, Args<Type> args)
       : super(selector, args) {
diff --git a/runtime/vm/compiler/frontend/kernel_fingerprints.cc b/runtime/vm/compiler/frontend/kernel_fingerprints.cc
index ca9ebbf2574..aff6de70333 100644
--- a/runtime/vm/compiler/frontend/kernel_fingerprints.cc
+++ b/runtime/vm/compiler/frontend/kernel_fingerprints.cc
@@ -778,9 +778,7 @@ uint32_t KernelFingerprintHelper::CalculateFunctionFingerprint() {
   procedure_helper.SetJustRead(ProcedureHelper::kName);
 
   procedure_helper.ReadUntilExcluding(ProcedureHelper::kFunction);
-  if (ReadTag() == kSomething) {
-    CalculateFunctionNodeFingerprint();
-  }
+  CalculateFunctionNodeFingerprint();
 
   BuildHash(procedure_helper.kind_);
   BuildHash(procedure_helper.flags_);
diff --git a/runtime/vm/compiler/frontend/kernel_translation_helper.cc b/runtime/vm/compiler/frontend/kernel_translation_helper.cc
index c83e6cb922a..4ede221a8a1 100644
--- a/runtime/vm/compiler/frontend/kernel_translation_helper.cc
+++ b/runtime/vm/compiler/frontend/kernel_translation_helper.cc
@@ -1116,9 +1116,7 @@ void ProcedureHelper::ReadUntilExcluding(Field field) {
       if (++next_read_ == field) return;
       FALL_THROUGH;
     case kFunction:
-      if (helper_->ReadTag() == kSomething) {
-        helper_->SkipFunctionNode();  // read function node.
-      }
+      helper_->SkipFunctionNode();  // read function node.
       if (++next_read_ == field) return;
       FALL_THROUGH;
     case kEnd:
@@ -2105,10 +2103,6 @@ void KernelReaderHelper::ReadUntilFunctionNode() {
   if (tag == kProcedure) {
     ProcedureHelper procedure_helper(this);
     procedure_helper.ReadUntilExcluding(ProcedureHelper::kFunction);
-    if (ReadTag() == kNothing) {  // read function node tag.
-      // Running a procedure without a function node doesn't make sense.
-      UNREACHABLE();
-    }
     // Now at start of FunctionNode.
   } else if (tag == kConstructor) {
     ConstructorHelper constructor_helper(this);
diff --git a/runtime/vm/compiler/frontend/scope_builder.cc b/runtime/vm/compiler/frontend/scope_builder.cc
index f55386b0400..e2be4a97574 100644
--- a/runtime/vm/compiler/frontend/scope_builder.cc
+++ b/runtime/vm/compiler/frontend/scope_builder.cc
@@ -512,9 +512,7 @@ void ScopeBuilder::VisitConstructor() {
 void ScopeBuilder::VisitProcedure() {
   ProcedureHelper procedure_helper(&helper_);
   procedure_helper.ReadUntilExcluding(ProcedureHelper::kFunction);
-  if (helper_.ReadTag() == kSomething) {
-    VisitFunctionNode();
-  }
+  VisitFunctionNode();
 }
 
 void ScopeBuilder::VisitField() {
diff --git a/runtime/vm/kernel_binary.h b/runtime/vm/kernel_binary.h
index 29eae67a0d4..2a78176085f 100644
--- a/runtime/vm/kernel_binary.h
+++ b/runtime/vm/kernel_binary.h
@@ -20,8 +20,8 @@ namespace kernel {
 static const uint32_t kMagicProgramFile = 0x90ABCDEFu;
 
 // Both version numbers are inclusive.
-static const uint32_t kMinSupportedKernelFormatVersion = 60;
-static const uint32_t kMaxSupportedKernelFormatVersion = 60;
+static const uint32_t kMinSupportedKernelFormatVersion = 61;
+static const uint32_t kMaxSupportedKernelFormatVersion = 61;
 
 // Keep in sync with package:kernel/lib/binary/tag.dart
 #define KERNEL_TAG_LIST(V)                                                     \
diff --git a/runtime/vm/kernel_loader.cc b/runtime/vm/kernel_loader.cc
index e5220d1f381..1ac91319ba0 100644
--- a/runtime/vm/kernel_loader.cc
+++ b/runtime/vm/kernel_loader.cc
@@ -2032,8 +2032,6 @@ void KernelLoader::LoadProcedure(const Library& library,
 
   procedure_helper.ReadUntilExcluding(ProcedureHelper::kFunction);
 
-  Tag function_node_tag = helper_.ReadTag();
-  ASSERT(function_node_tag == kSomething);
   FunctionNodeHelper function_node_helper(&helper_);
   function_node_helper.ReadUntilIncluding(FunctionNodeHelper::kDartAsyncMarker);
   function.set_is_debuggable(function_node_helper.dart_async_marker_ ==