diff --git a/rlp/rlpgen/gen.go b/rlp/rlpgen/gen.go
new file mode 100644
index 0000000000000..b36b269478344
--- /dev/null
+++ b/rlp/rlpgen/gen.go
@@ -0,0 +1,735 @@
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"go/format"
+	"go/types"
+	"sort"
+
+	"github.com/ethereum/go-ethereum/rlp/internal/rlpstruct"
+)
+
+// buildContext keeps the data needed for make*Op.
+type buildContext struct {
+	topType *types.Named // the type we're creating methods for
+
+	encoderIface *types.Interface
+	decoderIface *types.Interface
+	rawValueType *types.Named
+
+	typeToStructCache map[types.Type]*rlpstruct.Type
+}
+
+func newBuildContext(packageRLP *types.Package) *buildContext {
+	enc := packageRLP.Scope().Lookup("Encoder").Type().Underlying()
+	dec := packageRLP.Scope().Lookup("Decoder").Type().Underlying()
+	rawv := packageRLP.Scope().Lookup("RawValue").Type()
+	return &buildContext{
+		typeToStructCache: make(map[types.Type]*rlpstruct.Type),
+		encoderIface:      enc.(*types.Interface),
+		decoderIface:      dec.(*types.Interface),
+		rawValueType:      rawv.(*types.Named),
+	}
+}
+
+func (bctx *buildContext) isEncoder(typ types.Type) bool {
+	return types.Implements(typ, bctx.encoderIface)
+}
+
+func (bctx *buildContext) isDecoder(typ types.Type) bool {
+	return types.Implements(typ, bctx.decoderIface)
+}
+
+// typeToStructType converts typ to rlpstruct.Type.
+func (bctx *buildContext) typeToStructType(typ types.Type) *rlpstruct.Type {
+	if prev := bctx.typeToStructCache[typ]; prev != nil {
+		return prev // short-circuit for recursive types.
+	}
+
+	// Resolve named types to their underlying type, but keep the name.
+	name := types.TypeString(typ, nil)
+	for {
+		utype := typ.Underlying()
+		if utype == typ {
+			break
+		}
+		typ = utype
+	}
+
+	// Create the type and store it in cache.
+	t := &rlpstruct.Type{
+		Name:      name,
+		Kind:      typeReflectKind(typ),
+		IsEncoder: bctx.isEncoder(typ),
+		IsDecoder: bctx.isDecoder(typ),
+	}
+	bctx.typeToStructCache[typ] = t
+
+	// Assign element type.
+	switch typ.(type) {
+	case *types.Array, *types.Slice, *types.Pointer:
+		etype := typ.(interface{ Elem() types.Type }).Elem()
+		t.Elem = bctx.typeToStructType(etype)
+	}
+	return t
+}
+
+// genContext is passed to the gen* methods of op when generating
+// the output code. It tracks packages to be imported by the output
+// file and assigns unique names of temporary variables.
+type genContext struct {
+	inPackage   *types.Package
+	imports     map[string]struct{}
+	tempCounter int
+}
+
+func newGenContext(inPackage *types.Package) *genContext {
+	return &genContext{
+		inPackage: inPackage,
+		imports:   make(map[string]struct{}),
+	}
+}
+
+func (ctx *genContext) temp() string {
+	v := fmt.Sprintf("_tmp%d", ctx.tempCounter)
+	ctx.tempCounter++
+	return v
+}
+
+func (ctx *genContext) resetTemp() {
+	ctx.tempCounter = 0
+}
+
+func (ctx *genContext) addImport(path string) {
+	if path == ctx.inPackage.Path() {
+		return // avoid importing the package that we're generating in.
+	}
+	// TODO: renaming?
+	ctx.imports[path] = struct{}{}
+}
+
+// importsList returns all packages that need to be imported.
+func (ctx *genContext) importsList() []string {
+	imp := make([]string, 0, len(ctx.imports))
+	for k := range ctx.imports {
+		imp = append(imp, k)
+	}
+	sort.Strings(imp)
+	return imp
+}
+
+// qualify is the types.Qualifier used for printing types.
+func (ctx *genContext) qualify(pkg *types.Package) string {
+	if pkg.Path() == ctx.inPackage.Path() {
+		return ""
+	}
+	ctx.addImport(pkg.Path())
+	// TODO: renaming?
+	return pkg.Name()
+}
+
+type op interface {
+	// genWrite creates the encoder. The generated code should write v,
+	// which is any Go expression, to the rlp.EncoderBuffer 'w'.
+	genWrite(ctx *genContext, v string) string
+
+	// genDecode creates the decoder. The generated code should read
+	// a value from the rlp.Stream 'dec' and store it to dst.
+	genDecode(ctx *genContext) (string, string)
+}
+
+// basicOp handles basic types bool, uint*, string.
+type basicOp struct {
+	typ           types.Type
+	writeMethod   string     // calle write the value
+	writeArgType  types.Type // parameter type of writeMethod
+	decMethod     string
+	decResultType types.Type // return type of decMethod
+	decUseBitSize bool       // if true, result bit size is appended to decMethod
+}
+
+func (*buildContext) makeBasicOp(typ *types.Basic) (op, error) {
+	op := basicOp{typ: typ}
+	kind := typ.Kind()
+	switch {
+	case kind == types.Bool:
+		op.writeMethod = "WriteBool"
+		op.writeArgType = types.Typ[types.Bool]
+		op.decMethod = "Bool"
+		op.decResultType = types.Typ[types.Bool]
+	case kind >= types.Uint8 && kind <= types.Uint64:
+		op.writeMethod = "WriteUint64"
+		op.writeArgType = types.Typ[types.Uint64]
+		op.decMethod = "Uint"
+		op.decResultType = typ
+		op.decUseBitSize = true
+	case kind == types.String:
+		op.writeMethod = "WriteString"
+		op.writeArgType = types.Typ[types.String]
+		op.decMethod = "String"
+		op.decResultType = types.Typ[types.String]
+	default:
+		return nil, fmt.Errorf("unhandled basic type: %v", typ)
+	}
+	return op, nil
+}
+
+func (*buildContext) makeByteSliceOp(typ *types.Slice) op {
+	if !isByte(typ.Elem()) {
+		panic("non-byte slice type in makeByteSliceOp")
+	}
+	bslice := types.NewSlice(types.Typ[types.Uint8])
+	return basicOp{
+		typ:           typ,
+		writeMethod:   "WriteBytes",
+		writeArgType:  bslice,
+		decMethod:     "Bytes",
+		decResultType: bslice,
+	}
+}
+
+func (bctx *buildContext) makeRawValueOp() op {
+	bslice := types.NewSlice(types.Typ[types.Uint8])
+	return basicOp{
+		typ:           bctx.rawValueType,
+		writeMethod:   "Write",
+		writeArgType:  bslice,
+		decMethod:     "Raw",
+		decResultType: bslice,
+	}
+}
+
+func (op basicOp) writeNeedsConversion() bool {
+	return !types.AssignableTo(op.typ, op.writeArgType)
+}
+
+func (op basicOp) decodeNeedsConversion() bool {
+	return !types.AssignableTo(op.decResultType, op.typ)
+}
+
+func (op basicOp) genWrite(ctx *genContext, v string) string {
+	if op.writeNeedsConversion() {
+		v = fmt.Sprintf("%s(%s)", op.writeArgType, v)
+	}
+	return fmt.Sprintf("w.%s(%s)\n", op.writeMethod, v)
+}
+
+func (op basicOp) genDecode(ctx *genContext) (string, string) {
+	var (
+		resultV = ctx.temp()
+		result  = resultV
+		method  = op.decMethod
+	)
+	if op.decUseBitSize {
+		// Note: For now, this only works for platform-independent integer
+		// sizes. makeBasicOp forbids the platform-dependent types.
+		var sizes types.StdSizes
+		method = fmt.Sprintf("%s%d", op.decMethod, sizes.Sizeof(op.typ)*8)
+	}
+
+	// Call the decoder method.
+	var b bytes.Buffer
+	fmt.Fprintf(&b, "%s, err := dec.%s()\n", resultV, method)
+	fmt.Fprintf(&b, "if err != nil { return err }\n")
+	if op.decodeNeedsConversion() {
+		conv := ctx.temp()
+		fmt.Fprintf(&b, "%s := %s(%s)\n", conv, types.TypeString(op.typ, ctx.qualify), resultV)
+		result = conv
+	}
+	return result, b.String()
+}
+
+// byteArrayOp handles [...]byte.
+type byteArrayOp struct {
+	typ  types.Type
+	name types.Type // name != typ for named byte array types (e.g. common.Address)
+}
+
+func (bctx *buildContext) makeByteArrayOp(name *types.Named, typ *types.Array) byteArrayOp {
+	nt := types.Type(name)
+	if name == nil {
+		nt = typ
+	}
+	return byteArrayOp{typ, nt}
+}
+
+func (op byteArrayOp) genWrite(ctx *genContext, v string) string {
+	return fmt.Sprintf("w.WriteBytes(%s[:])\n", v)
+}
+
+func (op byteArrayOp) genDecode(ctx *genContext) (string, string) {
+	var resultV = ctx.temp()
+
+	var b bytes.Buffer
+	fmt.Fprintf(&b, "var %s %s\n", resultV, types.TypeString(op.name, ctx.qualify))
+	fmt.Fprintf(&b, "if err := dec.ReadBytes(%s[:]); err != nil { return err }\n", resultV)
+	return resultV, b.String()
+}
+
+// bigIntNoPtrOp handles non-pointer big.Int.
+// This exists because big.Int has it's own decoder operation on rlp.Stream,
+// but the decode method returns *big.Int, so it needs to be dereferenced.
+type bigIntOp struct {
+	pointer bool
+}
+
+func (op bigIntOp) genWrite(ctx *genContext, v string) string {
+	var b bytes.Buffer
+
+	fmt.Fprintf(&b, "if %s.Sign() == -1 {\n", v)
+	fmt.Fprintf(&b, "  return rlp.ErrNegativeBigInt\n")
+	fmt.Fprintf(&b, "}\n")
+	dst := v
+	if !op.pointer {
+		dst = "&" + v
+	}
+	fmt.Fprintf(&b, "w.WriteBigInt(%s)\n", dst)
+
+	// Wrap with nil check.
+	if op.pointer {
+		code := b.String()
+		b.Reset()
+		fmt.Fprintf(&b, "if %s == nil {\n", v)
+		fmt.Fprintf(&b, "  w.Write(rlp.EmptyString)")
+		fmt.Fprintf(&b, "} else {\n")
+		fmt.Fprint(&b, code)
+		fmt.Fprintf(&b, "}\n")
+	}
+
+	return b.String()
+}
+
+func (op bigIntOp) genDecode(ctx *genContext) (string, string) {
+	var resultV = ctx.temp()
+
+	var b bytes.Buffer
+	fmt.Fprintf(&b, "%s, err := dec.BigInt()\n", resultV)
+	fmt.Fprintf(&b, "if err != nil { return err }\n")
+
+	result := resultV
+	if !op.pointer {
+		result = "(*" + resultV + ")"
+	}
+	return result, b.String()
+}
+
+// encoderDecoderOp handles rlp.Encoder and rlp.Decoder.
+// In order to be used with this, the type must implement both interfaces.
+// This restriction may be lifted in the future by creating separate ops for
+// encoding and decoding.
+type encoderDecoderOp struct {
+	typ types.Type
+}
+
+func (op encoderDecoderOp) genWrite(ctx *genContext, v string) string {
+	return fmt.Sprintf("if err := %s.EncodeRLP(w); err != nil { return err }\n", v)
+}
+
+func (op encoderDecoderOp) genDecode(ctx *genContext) (string, string) {
+	// DecodeRLP must have pointer receiver, and this is verified in makeOp.
+	etyp := op.typ.(*types.Pointer).Elem()
+	var resultV = ctx.temp()
+
+	var b bytes.Buffer
+	fmt.Fprintf(&b, "%s := new(%s)\n", resultV, types.TypeString(etyp, ctx.qualify))
+	fmt.Fprintf(&b, "if err := %s.DecodeRLP(dec); err != nil { return err }\n", resultV)
+	return resultV, b.String()
+}
+
+// ptrOp handles pointer types.
+type ptrOp struct {
+	elemTyp  types.Type
+	elem     op
+	nilOK    bool
+	nilValue rlpstruct.NilKind
+}
+
+func (bctx *buildContext) makePtrOp(elemTyp types.Type, tags rlpstruct.Tags) (op, error) {
+	elemOp, err := bctx.makeOp(nil, elemTyp, rlpstruct.Tags{})
+	if err != nil {
+		return nil, err
+	}
+	op := ptrOp{elemTyp: elemTyp, elem: elemOp}
+
+	// Determine nil value.
+	if tags.NilOK {
+		op.nilOK = true
+		op.nilValue = tags.NilKind
+	} else {
+		styp := bctx.typeToStructType(elemTyp)
+		op.nilValue = styp.DefaultNilValue()
+	}
+	return op, nil
+}
+
+func (op ptrOp) genWrite(ctx *genContext, v string) string {
+	// Note: in writer functions, accesses to v are read-only, i.e. v is any Go
+	// expression. To make all accesses work through the pointer, we substitute
+	// v with (*v). This is required for most accesses including `v`, `call(v)`,
+	// and `v[index]` on slices.
+	//
+	// For `v.field` and `v[:]` on arrays, the dereference operation is not required.
+	var vv string
+	_, isStruct := op.elem.(structOp)
+	_, isByteArray := op.elem.(byteArrayOp)
+	if isStruct || isByteArray {
+		vv = v
+	} else {
+		vv = fmt.Sprintf("(*%s)", v)
+	}
+
+	var b bytes.Buffer
+	fmt.Fprintf(&b, "if %s == nil {\n", v)
+	fmt.Fprintf(&b, "  w.Write([]byte{0x%X})\n", op.nilValue)
+	fmt.Fprintf(&b, "} else {\n")
+	fmt.Fprintf(&b, "  %s", op.elem.genWrite(ctx, vv))
+	fmt.Fprintf(&b, "}\n")
+	return b.String()
+}
+
+func (op ptrOp) genDecode(ctx *genContext) (string, string) {
+	result, code := op.elem.genDecode(ctx)
+	if !op.nilOK {
+		// If nil pointers are not allowed, we can just decode the element.
+		return "&" + result, code
+	}
+
+	// nil is allowed, so check the kind and size first.
+	// If size is zero and kind matches the nilKind of the type,
+	// the value decodes as a nil pointer.
+	var (
+		resultV  = ctx.temp()
+		kindV    = ctx.temp()
+		sizeV    = ctx.temp()
+		wantKind string
+	)
+	if op.nilValue == rlpstruct.NilKindList {
+		wantKind = "rlp.List"
+	} else {
+		wantKind = "rlp.String"
+	}
+	var b bytes.Buffer
+	fmt.Fprintf(&b, "var %s %s\n", resultV, types.TypeString(types.NewPointer(op.elemTyp), ctx.qualify))
+	fmt.Fprintf(&b, "if %s, %s, err := dec.Kind(); err != nil {\n", kindV, sizeV)
+	fmt.Fprintf(&b, "  return err\n")
+	fmt.Fprintf(&b, "} else if %s != 0 || %s != %s {\n", sizeV, kindV, wantKind)
+	fmt.Fprint(&b, code)
+	fmt.Fprintf(&b, "  %s = &%s\n", resultV, result)
+	fmt.Fprintf(&b, "}\n")
+	return resultV, b.String()
+}
+
+// structOp handles struct types.
+type structOp struct {
+	named          *types.Named
+	typ            *types.Struct
+	fields         []*structField
+	optionalFields []*structField
+}
+
+type structField struct {
+	name string
+	typ  types.Type
+	elem op
+}
+
+func (bctx *buildContext) makeStructOp(named *types.Named, typ *types.Struct) (op, error) {
+	// Convert fields to []rlpstruct.Field.
+	var allStructFields []rlpstruct.Field
+	for i := 0; i < typ.NumFields(); i++ {
+		f := typ.Field(i)
+		allStructFields = append(allStructFields, rlpstruct.Field{
+			Name:     f.Name(),
+			Exported: f.Exported(),
+			Index:    i,
+			Tag:      typ.Tag(i),
+			Type:     *bctx.typeToStructType(f.Type()),
+		})
+	}
+
+	// Filter/validate fields.
+	fields, tags, err := rlpstruct.ProcessFields(allStructFields)
+	if err != nil {
+		return nil, err
+	}
+
+	// Create field ops.
+	var op = structOp{named: named, typ: typ}
+	for i, field := range fields {
+		// Advanced struct tags are not supported yet.
+		tag := tags[i]
+		if err := checkUnsupportedTags(field.Name, tag); err != nil {
+			return nil, err
+		}
+		typ := typ.Field(field.Index).Type()
+		elem, err := bctx.makeOp(nil, typ, tags[i])
+		if err != nil {
+			return nil, fmt.Errorf("field %s: %v", field.Name, err)
+		}
+		f := &structField{name: field.Name, typ: typ, elem: elem}
+		if tag.Optional {
+			op.optionalFields = append(op.optionalFields, f)
+		} else {
+			op.fields = append(op.fields, f)
+		}
+	}
+	return op, nil
+}
+
+func checkUnsupportedTags(field string, tag rlpstruct.Tags) error {
+	if tag.Tail {
+		return fmt.Errorf(`field %s has unsupported struct tag "tail"`, field)
+	}
+	return nil
+}
+
+func (op structOp) genWrite(ctx *genContext, v string) string {
+	var b bytes.Buffer
+	var listMarker = ctx.temp()
+	fmt.Fprintf(&b, "%s := w.List()\n", listMarker)
+	for _, field := range op.fields {
+		selector := v + "." + field.name
+		fmt.Fprint(&b, field.elem.genWrite(ctx, selector))
+	}
+	op.writeOptionalFields(&b, ctx, v)
+	fmt.Fprintf(&b, "w.ListEnd(%s)\n", listMarker)
+	return b.String()
+}
+
+func (op structOp) writeOptionalFields(b *bytes.Buffer, ctx *genContext, v string) {
+	if len(op.optionalFields) == 0 {
+		return
+	}
+	// First check zero-ness of all optional fields.
+	var zeroV = make([]string, len(op.optionalFields))
+	for i, field := range op.optionalFields {
+		selector := v + "." + field.name
+		zeroV[i] = ctx.temp()
+		fmt.Fprintf(b, "%s := %s\n", zeroV[i], nonZeroCheck(selector, field.typ, ctx.qualify))
+	}
+	// Now write the fields.
+	for i, field := range op.optionalFields {
+		selector := v + "." + field.name
+		cond := ""
+		for j := i; j < len(op.optionalFields); j++ {
+			if j > i {
+				cond += " || "
+			}
+			cond += zeroV[j]
+		}
+		fmt.Fprintf(b, "if %s {\n", cond)
+		fmt.Fprint(b, field.elem.genWrite(ctx, selector))
+		fmt.Fprintf(b, "}\n")
+	}
+}
+
+func (op structOp) genDecode(ctx *genContext) (string, string) {
+	// Get the string representation of the type.
+	// Here, named types are handled separately because the output
+	// would contain a copy of the struct definition otherwise.
+	var typeName string
+	if op.named != nil {
+		typeName = types.TypeString(op.named, ctx.qualify)
+	} else {
+		typeName = types.TypeString(op.typ, ctx.qualify)
+	}
+
+	// Create struct object.
+	var resultV = ctx.temp()
+	var b bytes.Buffer
+	fmt.Fprintf(&b, "var %s %s\n", resultV, typeName)
+
+	// Decode fields.
+	fmt.Fprintf(&b, "{\n")
+	fmt.Fprintf(&b, "if _, err := dec.List(); err != nil { return err }\n")
+	for _, field := range op.fields {
+		result, code := field.elem.genDecode(ctx)
+		fmt.Fprintf(&b, "// %s:\n", field.name)
+		fmt.Fprint(&b, code)
+		fmt.Fprintf(&b, "%s.%s = %s\n", resultV, field.name, result)
+	}
+	op.decodeOptionalFields(&b, ctx, resultV)
+	fmt.Fprintf(&b, "if err := dec.ListEnd(); err != nil { return err }\n")
+	fmt.Fprintf(&b, "}\n")
+	return resultV, b.String()
+}
+
+func (op structOp) decodeOptionalFields(b *bytes.Buffer, ctx *genContext, resultV string) {
+	var suffix bytes.Buffer
+	for _, field := range op.optionalFields {
+		result, code := field.elem.genDecode(ctx)
+		fmt.Fprintf(b, "// %s:\n", field.name)
+		fmt.Fprintf(b, "if dec.MoreDataInList() {\n")
+		fmt.Fprint(b, code)
+		fmt.Fprintf(b, "%s.%s = %s\n", resultV, field.name, result)
+		fmt.Fprintf(&suffix, "}\n")
+	}
+	suffix.WriteTo(b)
+}
+
+// sliceOp handles slice types.
+type sliceOp struct {
+	typ    *types.Slice
+	elemOp op
+}
+
+func (bctx *buildContext) makeSliceOp(typ *types.Slice) (op, error) {
+	elemOp, err := bctx.makeOp(nil, typ.Elem(), rlpstruct.Tags{})
+	if err != nil {
+		return nil, err
+	}
+	return sliceOp{typ: typ, elemOp: elemOp}, nil
+}
+
+func (op sliceOp) genWrite(ctx *genContext, v string) string {
+	var (
+		listMarker = ctx.temp() // holds return value of w.List()
+		iterElemV  = ctx.temp() // iteration variable
+		elemCode   = op.elemOp.genWrite(ctx, iterElemV)
+	)
+
+	var b bytes.Buffer
+	fmt.Fprintf(&b, "%s := w.List()\n", listMarker)
+	fmt.Fprintf(&b, "for _, %s := range %s {\n", iterElemV, v)
+	fmt.Fprint(&b, elemCode)
+	fmt.Fprintf(&b, "}\n")
+	fmt.Fprintf(&b, "w.ListEnd(%s)\n", listMarker)
+	return b.String()
+}
+
+func (op sliceOp) genDecode(ctx *genContext) (string, string) {
+	var sliceV = ctx.temp() // holds the output slice
+	elemResult, elemCode := op.elemOp.genDecode(ctx)
+
+	var b bytes.Buffer
+	fmt.Fprintf(&b, "var %s %s\n", sliceV, types.TypeString(op.typ, ctx.qualify))
+	fmt.Fprintf(&b, "if _, err := dec.List(); err != nil { return err }\n")
+	fmt.Fprintf(&b, "for dec.MoreDataInList() {\n")
+	fmt.Fprintf(&b, "  %s", elemCode)
+	fmt.Fprintf(&b, "  %s = append(%s, %s)\n", sliceV, sliceV, elemResult)
+	fmt.Fprintf(&b, "}\n")
+	fmt.Fprintf(&b, "if err := dec.ListEnd(); err != nil { return err }\n")
+	return sliceV, b.String()
+}
+
+func (bctx *buildContext) makeOp(name *types.Named, typ types.Type, tags rlpstruct.Tags) (op, error) {
+	switch typ := typ.(type) {
+	case *types.Named:
+		if isBigInt(typ) {
+			return bigIntOp{}, nil
+		}
+		if typ == bctx.rawValueType {
+			return bctx.makeRawValueOp(), nil
+		}
+		if bctx.isDecoder(typ) {
+			return nil, fmt.Errorf("type %v implements rlp.Decoder with non-pointer receiver", typ)
+		}
+		// TODO: same check for encoder?
+		return bctx.makeOp(typ, typ.Underlying(), tags)
+	case *types.Pointer:
+		if isBigInt(typ.Elem()) {
+			return bigIntOp{pointer: true}, nil
+		}
+		// Encoder/Decoder interfaces.
+		if bctx.isEncoder(typ) {
+			if bctx.isDecoder(typ) {
+				return encoderDecoderOp{typ}, nil
+			}
+			return nil, fmt.Errorf("type %v implements rlp.Encoder but not rlp.Decoder", typ)
+		}
+		if bctx.isDecoder(typ) {
+			return nil, fmt.Errorf("type %v implements rlp.Decoder but not rlp.Encoder", typ)
+		}
+		// Default pointer handling.
+		return bctx.makePtrOp(typ.Elem(), tags)
+	case *types.Basic:
+		return bctx.makeBasicOp(typ)
+	case *types.Struct:
+		return bctx.makeStructOp(name, typ)
+	case *types.Slice:
+		etyp := typ.Elem()
+		if isByte(etyp) && !bctx.isEncoder(etyp) {
+			return bctx.makeByteSliceOp(typ), nil
+		}
+		return bctx.makeSliceOp(typ)
+	case *types.Array:
+		etyp := typ.Elem()
+		if isByte(etyp) && !bctx.isEncoder(etyp) {
+			return bctx.makeByteArrayOp(name, typ), nil
+		}
+		return nil, fmt.Errorf("unhandled array type: %v", typ)
+	default:
+		return nil, fmt.Errorf("unhandled type: %v", typ)
+	}
+}
+
+// generateDecoder generates the DecodeRLP method on 'typ'.
+func generateDecoder(ctx *genContext, typ string, op op) []byte {
+	ctx.resetTemp()
+	ctx.addImport(pathOfPackageRLP)
+
+	result, code := op.genDecode(ctx)
+	var b bytes.Buffer
+	fmt.Fprintf(&b, "func (obj *%s) DecodeRLP(dec *rlp.Stream) error {\n", typ)
+	fmt.Fprint(&b, code)
+	fmt.Fprintf(&b, "  *obj = %s\n", result)
+	fmt.Fprintf(&b, "  return nil\n")
+	fmt.Fprintf(&b, "}\n")
+	return b.Bytes()
+}
+
+// generateEncoder generates the EncodeRLP method on 'typ'.
+func generateEncoder(ctx *genContext, typ string, op op) []byte {
+	ctx.resetTemp()
+	ctx.addImport("io")
+	ctx.addImport(pathOfPackageRLP)
+
+	var b bytes.Buffer
+	fmt.Fprintf(&b, "func (obj *%s) EncodeRLP(_w io.Writer) error {\n", typ)
+	fmt.Fprintf(&b, "  w := rlp.NewEncoderBuffer(_w)\n")
+	fmt.Fprint(&b, op.genWrite(ctx, "obj"))
+	fmt.Fprintf(&b, "  return w.Flush()\n")
+	fmt.Fprintf(&b, "}\n")
+	return b.Bytes()
+}
+
+func (bctx *buildContext) generate(typ *types.Named, encoder, decoder bool) ([]byte, error) {
+	bctx.topType = typ
+
+	pkg := typ.Obj().Pkg()
+	op, err := bctx.makeOp(nil, typ, rlpstruct.Tags{})
+	if err != nil {
+		return nil, err
+	}
+
+	var (
+		ctx       = newGenContext(pkg)
+		encSource []byte
+		decSource []byte
+	)
+	if encoder {
+		encSource = generateEncoder(ctx, typ.Obj().Name(), op)
+	}
+	if decoder {
+		decSource = generateDecoder(ctx, typ.Obj().Name(), op)
+	}
+
+	var b bytes.Buffer
+	fmt.Fprintf(&b, "package %s\n\n", pkg.Name())
+	for _, imp := range ctx.importsList() {
+		fmt.Fprintf(&b, "import %q\n", imp)
+	}
+	if encoder {
+		fmt.Fprintln(&b)
+		b.Write(encSource)
+	}
+	if decoder {
+		fmt.Fprintln(&b)
+		b.Write(decSource)
+	}
+
+	source := b.Bytes()
+	// fmt.Println(string(source))
+	return format.Source(source)
+}
diff --git a/rlp/rlpgen/gen_test.go b/rlp/rlpgen/gen_test.go
new file mode 100644
index 0000000000000..9940db188da99
--- /dev/null
+++ b/rlp/rlpgen/gen_test.go
@@ -0,0 +1,92 @@
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"go/ast"
+	"go/importer"
+	"go/parser"
+	"go/token"
+	"go/types"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+// Package RLP is loaded only once and reused for all tests.
+var (
+	testFset       = token.NewFileSet()
+	testImporter   = importer.ForCompiler(testFset, "source", nil).(types.ImporterFrom)
+	testPackageRLP *types.Package
+)
+
+func init() {
+	cwd, err := os.Getwd()
+	if err != nil {
+		panic(err)
+	}
+	testPackageRLP, err = testImporter.ImportFrom(pathOfPackageRLP, cwd, 0)
+	if err != nil {
+		panic(fmt.Errorf("can't load package RLP: %v", err))
+	}
+}
+
+var tests = []string{"uints", "nil", "rawvalue", "optional", "bigint"}
+
+func TestOutput(t *testing.T) {
+	for _, test := range tests {
+		test := test
+		t.Run(test, func(t *testing.T) {
+			inputFile := filepath.Join("testdata", test+".in.txt")
+			outputFile := filepath.Join("testdata", test+".out.txt")
+			bctx, typ, err := loadTestSource(inputFile, "Test")
+			if err != nil {
+				t.Fatal("error loading test source:", err)
+			}
+			output, err := bctx.generate(typ, true, true)
+			if err != nil {
+				t.Fatal("error in generate:", err)
+			}
+
+			// Set this environment variable to regenerate the test outputs.
+			if os.Getenv("WRITE_TEST_FILES") != "" {
+				ioutil.WriteFile(outputFile, output, 0644)
+			}
+
+			// Check if output matches.
+			wantOutput, err := ioutil.ReadFile(outputFile)
+			if err != nil {
+				t.Fatal("error loading expected test output:", err)
+			}
+			if !bytes.Equal(output, wantOutput) {
+				t.Fatal("output mismatch:\n", string(output))
+			}
+		})
+	}
+}
+
+func loadTestSource(file string, typeName string) (*buildContext, *types.Named, error) {
+	// Load the test input.
+	content, err := ioutil.ReadFile(file)
+	if err != nil {
+		return nil, nil, err
+	}
+	f, err := parser.ParseFile(testFset, file, content, 0)
+	if err != nil {
+		return nil, nil, err
+	}
+	conf := types.Config{Importer: testImporter}
+	pkg, err := conf.Check("test", testFset, []*ast.File{f}, nil)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	// Find the test struct.
+	bctx := newBuildContext(testPackageRLP)
+	typ, err := lookupStructType(pkg.Scope(), typeName)
+	if err != nil {
+		return nil, nil, fmt.Errorf("can't find type %s: %v", typeName, err)
+	}
+	return bctx, typ, nil
+}
diff --git a/rlp/rlpgen/main.go b/rlp/rlpgen/main.go
new file mode 100644
index 0000000000000..5b240bfd85fb6
--- /dev/null
+++ b/rlp/rlpgen/main.go
@@ -0,0 +1,148 @@
+// Copyright 2021 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package main
+
+import (
+	"bytes"
+	"errors"
+	"flag"
+	"fmt"
+	"go/types"
+	"io/ioutil"
+	"os"
+
+	"golang.org/x/tools/go/packages"
+)
+
+const pathOfPackageRLP = "github.com/ethereum/go-ethereum/rlp"
+
+func main() {
+	var (
+		pkgdir     = flag.String("dir", ".", "input package")
+		output     = flag.String("out", "-", "output file (default is stdout)")
+		genEncoder = flag.Bool("encoder", true, "generate EncodeRLP?")
+		genDecoder = flag.Bool("decoder", false, "generate DecodeRLP?")
+		typename   = flag.String("type", "", "type to generate methods for")
+	)
+	flag.Parse()
+
+	cfg := Config{
+		Dir:             *pkgdir,
+		Type:            *typename,
+		GenerateEncoder: *genEncoder,
+		GenerateDecoder: *genDecoder,
+	}
+	code, err := cfg.process()
+	if err != nil {
+		fatal(err)
+	}
+	if *output == "-" {
+		os.Stdout.Write(code)
+	} else if err := ioutil.WriteFile(*output, code, 0644); err != nil {
+		fatal(err)
+	}
+}
+
+func fatal(args ...interface{}) {
+	fmt.Fprintln(os.Stderr, args...)
+	os.Exit(1)
+}
+
+type Config struct {
+	Dir  string // input package directory
+	Type string
+
+	GenerateEncoder bool
+	GenerateDecoder bool
+}
+
+// process generates the Go code.
+func (cfg *Config) process() (code []byte, err error) {
+	// Load packages.
+	pcfg := &packages.Config{
+		Mode:       packages.NeedName | packages.NeedTypes | packages.NeedImports | packages.NeedDeps,
+		Dir:        cfg.Dir,
+		BuildFlags: []string{"-tags", "norlpgen"},
+	}
+	ps, err := packages.Load(pcfg, pathOfPackageRLP, ".")
+	if err != nil {
+		return nil, err
+	}
+	if len(ps) == 0 {
+		return nil, fmt.Errorf("no Go package found in %s", cfg.Dir)
+	}
+	packages.PrintErrors(ps)
+
+	// Find the packages that were loaded.
+	var (
+		pkg        *types.Package
+		packageRLP *types.Package
+	)
+	for _, p := range ps {
+		if len(p.Errors) > 0 {
+			return nil, fmt.Errorf("package %s has errors", p.PkgPath)
+		}
+		if p.PkgPath == pathOfPackageRLP {
+			packageRLP = p.Types
+		} else {
+			pkg = p.Types
+		}
+	}
+	bctx := newBuildContext(packageRLP)
+
+	// Find the type and generate.
+	typ, err := lookupStructType(pkg.Scope(), cfg.Type)
+	if err != nil {
+		return nil, fmt.Errorf("can't find %s in %s: %v", typ, pkg, err)
+	}
+	code, err = bctx.generate(typ, cfg.GenerateEncoder, cfg.GenerateDecoder)
+	if err != nil {
+		return nil, err
+	}
+
+	// Add build comments.
+	// This is done here to avoid processing these lines with gofmt.
+	var header bytes.Buffer
+	fmt.Fprint(&header, "// Code generated by rlpgen. DO NOT EDIT.\n\n")
+	fmt.Fprint(&header, "//go:build !norlpgen\n")
+	fmt.Fprint(&header, "// +build !norlpgen\n\n")
+	return append(header.Bytes(), code...), nil
+}
+
+func lookupStructType(scope *types.Scope, name string) (*types.Named, error) {
+	typ, err := lookupType(scope, name)
+	if err != nil {
+		return nil, err
+	}
+	_, ok := typ.Underlying().(*types.Struct)
+	if !ok {
+		return nil, errors.New("not a struct type")
+	}
+	return typ, nil
+}
+
+func lookupType(scope *types.Scope, name string) (*types.Named, error) {
+	obj := scope.Lookup(name)
+	if obj == nil {
+		return nil, errors.New("no such identifier")
+	}
+	typ, ok := obj.(*types.TypeName)
+	if !ok {
+		return nil, errors.New("not a type")
+	}
+	return typ.Type().(*types.Named), nil
+}
diff --git a/rlp/rlpgen/testdata/bigint.in.txt b/rlp/rlpgen/testdata/bigint.in.txt
new file mode 100644
index 0000000000000..d23d84a28763f
--- /dev/null
+++ b/rlp/rlpgen/testdata/bigint.in.txt
@@ -0,0 +1,10 @@
+// -*- mode: go -*-
+
+package test
+
+import "math/big"
+
+type Test struct {
+	Int      *big.Int
+	IntNoPtr big.Int
+}
diff --git a/rlp/rlpgen/testdata/bigint.out.txt b/rlp/rlpgen/testdata/bigint.out.txt
new file mode 100644
index 0000000000000..f54d1faa15f73
--- /dev/null
+++ b/rlp/rlpgen/testdata/bigint.out.txt
@@ -0,0 +1,49 @@
+package test
+
+import "github.com/ethereum/go-ethereum/rlp"
+import "io"
+
+func (obj *Test) EncodeRLP(_w io.Writer) error {
+	w := rlp.NewEncoderBuffer(_w)
+	_tmp0 := w.List()
+	if obj.Int == nil {
+		w.Write(rlp.EmptyString)
+	} else {
+		if obj.Int.Sign() == -1 {
+			return rlp.ErrNegativeBigInt
+		}
+		w.WriteBigInt(obj.Int)
+	}
+	if obj.IntNoPtr.Sign() == -1 {
+		return rlp.ErrNegativeBigInt
+	}
+	w.WriteBigInt(&obj.IntNoPtr)
+	w.ListEnd(_tmp0)
+	return w.Flush()
+}
+
+func (obj *Test) DecodeRLP(dec *rlp.Stream) error {
+	var _tmp0 Test
+	{
+		if _, err := dec.List(); err != nil {
+			return err
+		}
+		// Int:
+		_tmp1, err := dec.BigInt()
+		if err != nil {
+			return err
+		}
+		_tmp0.Int = _tmp1
+		// IntNoPtr:
+		_tmp2, err := dec.BigInt()
+		if err != nil {
+			return err
+		}
+		_tmp0.IntNoPtr = (*_tmp2)
+		if err := dec.ListEnd(); err != nil {
+			return err
+		}
+	}
+	*obj = _tmp0
+	return nil
+}
diff --git a/rlp/rlpgen/testdata/nil.in.txt b/rlp/rlpgen/testdata/nil.in.txt
new file mode 100644
index 0000000000000..a28ff344874d9
--- /dev/null
+++ b/rlp/rlpgen/testdata/nil.in.txt
@@ -0,0 +1,30 @@
+// -*- mode: go -*-
+
+package test
+
+type Aux struct{
+    A uint32
+}
+
+type Test struct{
+    Uint8 *byte `rlp:"nil"`
+    Uint8List *byte `rlp:"nilList"`
+
+    Uint32 *uint32 `rlp:"nil"`
+    Uint32List *uint32 `rlp:"nilList"`
+
+    Uint64 *uint64 `rlp:"nil"`
+    Uint64List *uint64 `rlp:"nilList"`
+
+    String *string `rlp:"nil"`
+    StringList *string `rlp:"nilList"`
+
+    ByteArray *[3]byte `rlp:"nil"`
+    ByteArrayList *[3]byte `rlp:"nilList"`
+
+    ByteSlice *[]byte `rlp:"nil"`
+    ByteSliceList *[]byte `rlp:"nilList"`
+
+    Struct *Aux `rlp:"nil"`
+    StructString *Aux `rlp:"nilString"`
+}
diff --git a/rlp/rlpgen/testdata/nil.out.txt b/rlp/rlpgen/testdata/nil.out.txt
new file mode 100644
index 0000000000000..e0d5dcebad3bd
--- /dev/null
+++ b/rlp/rlpgen/testdata/nil.out.txt
@@ -0,0 +1,289 @@
+package test
+
+import "github.com/ethereum/go-ethereum/rlp"
+import "io"
+
+func (obj *Test) EncodeRLP(_w io.Writer) error {
+	w := rlp.NewEncoderBuffer(_w)
+	_tmp0 := w.List()
+	if obj.Uint8 == nil {
+		w.Write([]byte{0x80})
+	} else {
+		w.WriteUint64(uint64((*obj.Uint8)))
+	}
+	if obj.Uint8List == nil {
+		w.Write([]byte{0xC0})
+	} else {
+		w.WriteUint64(uint64((*obj.Uint8List)))
+	}
+	if obj.Uint32 == nil {
+		w.Write([]byte{0x80})
+	} else {
+		w.WriteUint64(uint64((*obj.Uint32)))
+	}
+	if obj.Uint32List == nil {
+		w.Write([]byte{0xC0})
+	} else {
+		w.WriteUint64(uint64((*obj.Uint32List)))
+	}
+	if obj.Uint64 == nil {
+		w.Write([]byte{0x80})
+	} else {
+		w.WriteUint64((*obj.Uint64))
+	}
+	if obj.Uint64List == nil {
+		w.Write([]byte{0xC0})
+	} else {
+		w.WriteUint64((*obj.Uint64List))
+	}
+	if obj.String == nil {
+		w.Write([]byte{0x80})
+	} else {
+		w.WriteString((*obj.String))
+	}
+	if obj.StringList == nil {
+		w.Write([]byte{0xC0})
+	} else {
+		w.WriteString((*obj.StringList))
+	}
+	if obj.ByteArray == nil {
+		w.Write([]byte{0x80})
+	} else {
+		w.WriteBytes(obj.ByteArray[:])
+	}
+	if obj.ByteArrayList == nil {
+		w.Write([]byte{0xC0})
+	} else {
+		w.WriteBytes(obj.ByteArrayList[:])
+	}
+	if obj.ByteSlice == nil {
+		w.Write([]byte{0x80})
+	} else {
+		w.WriteBytes((*obj.ByteSlice))
+	}
+	if obj.ByteSliceList == nil {
+		w.Write([]byte{0xC0})
+	} else {
+		w.WriteBytes((*obj.ByteSliceList))
+	}
+	if obj.Struct == nil {
+		w.Write([]byte{0xC0})
+	} else {
+		_tmp1 := w.List()
+		w.WriteUint64(uint64(obj.Struct.A))
+		w.ListEnd(_tmp1)
+	}
+	if obj.StructString == nil {
+		w.Write([]byte{0x80})
+	} else {
+		_tmp2 := w.List()
+		w.WriteUint64(uint64(obj.StructString.A))
+		w.ListEnd(_tmp2)
+	}
+	w.ListEnd(_tmp0)
+	return w.Flush()
+}
+
+func (obj *Test) DecodeRLP(dec *rlp.Stream) error {
+	var _tmp0 Test
+	{
+		if _, err := dec.List(); err != nil {
+			return err
+		}
+		// Uint8:
+		var _tmp2 *byte
+		if _tmp3, _tmp4, err := dec.Kind(); err != nil {
+			return err
+		} else if _tmp4 != 0 || _tmp3 != rlp.String {
+			_tmp1, err := dec.Uint8()
+			if err != nil {
+				return err
+			}
+			_tmp2 = &_tmp1
+		}
+		_tmp0.Uint8 = _tmp2
+		// Uint8List:
+		var _tmp6 *byte
+		if _tmp7, _tmp8, err := dec.Kind(); err != nil {
+			return err
+		} else if _tmp8 != 0 || _tmp7 != rlp.List {
+			_tmp5, err := dec.Uint8()
+			if err != nil {
+				return err
+			}
+			_tmp6 = &_tmp5
+		}
+		_tmp0.Uint8List = _tmp6
+		// Uint32:
+		var _tmp10 *uint32
+		if _tmp11, _tmp12, err := dec.Kind(); err != nil {
+			return err
+		} else if _tmp12 != 0 || _tmp11 != rlp.String {
+			_tmp9, err := dec.Uint32()
+			if err != nil {
+				return err
+			}
+			_tmp10 = &_tmp9
+		}
+		_tmp0.Uint32 = _tmp10
+		// Uint32List:
+		var _tmp14 *uint32
+		if _tmp15, _tmp16, err := dec.Kind(); err != nil {
+			return err
+		} else if _tmp16 != 0 || _tmp15 != rlp.List {
+			_tmp13, err := dec.Uint32()
+			if err != nil {
+				return err
+			}
+			_tmp14 = &_tmp13
+		}
+		_tmp0.Uint32List = _tmp14
+		// Uint64:
+		var _tmp18 *uint64
+		if _tmp19, _tmp20, err := dec.Kind(); err != nil {
+			return err
+		} else if _tmp20 != 0 || _tmp19 != rlp.String {
+			_tmp17, err := dec.Uint64()
+			if err != nil {
+				return err
+			}
+			_tmp18 = &_tmp17
+		}
+		_tmp0.Uint64 = _tmp18
+		// Uint64List:
+		var _tmp22 *uint64
+		if _tmp23, _tmp24, err := dec.Kind(); err != nil {
+			return err
+		} else if _tmp24 != 0 || _tmp23 != rlp.List {
+			_tmp21, err := dec.Uint64()
+			if err != nil {
+				return err
+			}
+			_tmp22 = &_tmp21
+		}
+		_tmp0.Uint64List = _tmp22
+		// String:
+		var _tmp26 *string
+		if _tmp27, _tmp28, err := dec.Kind(); err != nil {
+			return err
+		} else if _tmp28 != 0 || _tmp27 != rlp.String {
+			_tmp25, err := dec.String()
+			if err != nil {
+				return err
+			}
+			_tmp26 = &_tmp25
+		}
+		_tmp0.String = _tmp26
+		// StringList:
+		var _tmp30 *string
+		if _tmp31, _tmp32, err := dec.Kind(); err != nil {
+			return err
+		} else if _tmp32 != 0 || _tmp31 != rlp.List {
+			_tmp29, err := dec.String()
+			if err != nil {
+				return err
+			}
+			_tmp30 = &_tmp29
+		}
+		_tmp0.StringList = _tmp30
+		// ByteArray:
+		var _tmp34 *[3]byte
+		if _tmp35, _tmp36, err := dec.Kind(); err != nil {
+			return err
+		} else if _tmp36 != 0 || _tmp35 != rlp.String {
+			var _tmp33 [3]byte
+			if err := dec.ReadBytes(_tmp33[:]); err != nil {
+				return err
+			}
+			_tmp34 = &_tmp33
+		}
+		_tmp0.ByteArray = _tmp34
+		// ByteArrayList:
+		var _tmp38 *[3]byte
+		if _tmp39, _tmp40, err := dec.Kind(); err != nil {
+			return err
+		} else if _tmp40 != 0 || _tmp39 != rlp.List {
+			var _tmp37 [3]byte
+			if err := dec.ReadBytes(_tmp37[:]); err != nil {
+				return err
+			}
+			_tmp38 = &_tmp37
+		}
+		_tmp0.ByteArrayList = _tmp38
+		// ByteSlice:
+		var _tmp42 *[]byte
+		if _tmp43, _tmp44, err := dec.Kind(); err != nil {
+			return err
+		} else if _tmp44 != 0 || _tmp43 != rlp.String {
+			_tmp41, err := dec.Bytes()
+			if err != nil {
+				return err
+			}
+			_tmp42 = &_tmp41
+		}
+		_tmp0.ByteSlice = _tmp42
+		// ByteSliceList:
+		var _tmp46 *[]byte
+		if _tmp47, _tmp48, err := dec.Kind(); err != nil {
+			return err
+		} else if _tmp48 != 0 || _tmp47 != rlp.List {
+			_tmp45, err := dec.Bytes()
+			if err != nil {
+				return err
+			}
+			_tmp46 = &_tmp45
+		}
+		_tmp0.ByteSliceList = _tmp46
+		// Struct:
+		var _tmp51 *Aux
+		if _tmp52, _tmp53, err := dec.Kind(); err != nil {
+			return err
+		} else if _tmp53 != 0 || _tmp52 != rlp.List {
+			var _tmp49 Aux
+			{
+				if _, err := dec.List(); err != nil {
+					return err
+				}
+				// A:
+				_tmp50, err := dec.Uint32()
+				if err != nil {
+					return err
+				}
+				_tmp49.A = _tmp50
+				if err := dec.ListEnd(); err != nil {
+					return err
+				}
+			}
+			_tmp51 = &_tmp49
+		}
+		_tmp0.Struct = _tmp51
+		// StructString:
+		var _tmp56 *Aux
+		if _tmp57, _tmp58, err := dec.Kind(); err != nil {
+			return err
+		} else if _tmp58 != 0 || _tmp57 != rlp.String {
+			var _tmp54 Aux
+			{
+				if _, err := dec.List(); err != nil {
+					return err
+				}
+				// A:
+				_tmp55, err := dec.Uint32()
+				if err != nil {
+					return err
+				}
+				_tmp54.A = _tmp55
+				if err := dec.ListEnd(); err != nil {
+					return err
+				}
+			}
+			_tmp56 = &_tmp54
+		}
+		_tmp0.StructString = _tmp56
+		if err := dec.ListEnd(); err != nil {
+			return err
+		}
+	}
+	*obj = _tmp0
+	return nil
+}
diff --git a/rlp/rlpgen/testdata/optional.in.txt b/rlp/rlpgen/testdata/optional.in.txt
new file mode 100644
index 0000000000000..f1ac9f7899d16
--- /dev/null
+++ b/rlp/rlpgen/testdata/optional.in.txt
@@ -0,0 +1,17 @@
+// -*- mode: go -*-
+
+package test
+
+type Aux struct {
+	A uint64
+}
+
+type Test struct {
+	Uint64      uint64             `rlp:"optional"`
+	Pointer     *uint64            `rlp:"optional"`
+	String      string             `rlp:"optional"`
+	Slice       []uint64           `rlp:"optional"`
+	Array       [3]byte            `rlp:"optional"`
+	NamedStruct Aux                `rlp:"optional"`
+	AnonStruct  struct{ A string } `rlp:"optional"`
+}
diff --git a/rlp/rlpgen/testdata/optional.out.txt b/rlp/rlpgen/testdata/optional.out.txt
new file mode 100644
index 0000000000000..02df8e457f94f
--- /dev/null
+++ b/rlp/rlpgen/testdata/optional.out.txt
@@ -0,0 +1,153 @@
+package test
+
+import "github.com/ethereum/go-ethereum/rlp"
+import "io"
+
+func (obj *Test) EncodeRLP(_w io.Writer) error {
+	w := rlp.NewEncoderBuffer(_w)
+	_tmp0 := w.List()
+	_tmp1 := obj.Uint64 != 0
+	_tmp2 := obj.Pointer != nil
+	_tmp3 := obj.String != ""
+	_tmp4 := len(obj.Slice) > 0
+	_tmp5 := obj.Array != ([3]byte{})
+	_tmp6 := obj.NamedStruct != (Aux{})
+	_tmp7 := obj.AnonStruct != (struct{ A string }{})
+	if _tmp1 || _tmp2 || _tmp3 || _tmp4 || _tmp5 || _tmp6 || _tmp7 {
+		w.WriteUint64(obj.Uint64)
+	}
+	if _tmp2 || _tmp3 || _tmp4 || _tmp5 || _tmp6 || _tmp7 {
+		if obj.Pointer == nil {
+			w.Write([]byte{0x80})
+		} else {
+			w.WriteUint64((*obj.Pointer))
+		}
+	}
+	if _tmp3 || _tmp4 || _tmp5 || _tmp6 || _tmp7 {
+		w.WriteString(obj.String)
+	}
+	if _tmp4 || _tmp5 || _tmp6 || _tmp7 {
+		_tmp8 := w.List()
+		for _, _tmp9 := range obj.Slice {
+			w.WriteUint64(_tmp9)
+		}
+		w.ListEnd(_tmp8)
+	}
+	if _tmp5 || _tmp6 || _tmp7 {
+		w.WriteBytes(obj.Array[:])
+	}
+	if _tmp6 || _tmp7 {
+		_tmp10 := w.List()
+		w.WriteUint64(obj.NamedStruct.A)
+		w.ListEnd(_tmp10)
+	}
+	if _tmp7 {
+		_tmp11 := w.List()
+		w.WriteString(obj.AnonStruct.A)
+		w.ListEnd(_tmp11)
+	}
+	w.ListEnd(_tmp0)
+	return w.Flush()
+}
+
+func (obj *Test) DecodeRLP(dec *rlp.Stream) error {
+	var _tmp0 Test
+	{
+		if _, err := dec.List(); err != nil {
+			return err
+		}
+		// Uint64:
+		if dec.MoreDataInList() {
+			_tmp1, err := dec.Uint64()
+			if err != nil {
+				return err
+			}
+			_tmp0.Uint64 = _tmp1
+			// Pointer:
+			if dec.MoreDataInList() {
+				_tmp2, err := dec.Uint64()
+				if err != nil {
+					return err
+				}
+				_tmp0.Pointer = &_tmp2
+				// String:
+				if dec.MoreDataInList() {
+					_tmp3, err := dec.String()
+					if err != nil {
+						return err
+					}
+					_tmp0.String = _tmp3
+					// Slice:
+					if dec.MoreDataInList() {
+						var _tmp4 []uint64
+						if _, err := dec.List(); err != nil {
+							return err
+						}
+						for dec.MoreDataInList() {
+							_tmp5, err := dec.Uint64()
+							if err != nil {
+								return err
+							}
+							_tmp4 = append(_tmp4, _tmp5)
+						}
+						if err := dec.ListEnd(); err != nil {
+							return err
+						}
+						_tmp0.Slice = _tmp4
+						// Array:
+						if dec.MoreDataInList() {
+							var _tmp6 [3]byte
+							if err := dec.ReadBytes(_tmp6[:]); err != nil {
+								return err
+							}
+							_tmp0.Array = _tmp6
+							// NamedStruct:
+							if dec.MoreDataInList() {
+								var _tmp7 Aux
+								{
+									if _, err := dec.List(); err != nil {
+										return err
+									}
+									// A:
+									_tmp8, err := dec.Uint64()
+									if err != nil {
+										return err
+									}
+									_tmp7.A = _tmp8
+									if err := dec.ListEnd(); err != nil {
+										return err
+									}
+								}
+								_tmp0.NamedStruct = _tmp7
+								// AnonStruct:
+								if dec.MoreDataInList() {
+									var _tmp9 struct{ A string }
+									{
+										if _, err := dec.List(); err != nil {
+											return err
+										}
+										// A:
+										_tmp10, err := dec.String()
+										if err != nil {
+											return err
+										}
+										_tmp9.A = _tmp10
+										if err := dec.ListEnd(); err != nil {
+											return err
+										}
+									}
+									_tmp0.AnonStruct = _tmp9
+								}
+							}
+						}
+					}
+				}
+			}
+		}
+		if err := dec.ListEnd(); err != nil {
+			return err
+		}
+	}
+	*obj = _tmp0
+	return nil
+}
diff --git a/rlp/rlpgen/testdata/rawvalue.in.txt b/rlp/rlpgen/testdata/rawvalue.in.txt
new file mode 100644
index 0000000000000..3a657bc907bb2
--- /dev/null
+++ b/rlp/rlpgen/testdata/rawvalue.in.txt
@@ -0,0 +1,11 @@
+// -*- mode: go -*-
+
+package test
+
+import "github.com/ethereum/go-ethereum/rlp"
+
+type Test struct {
+	RawValue          rlp.RawValue
+	PointerToRawValue *rlp.RawValue
+	SliceOfRawValue   []rlp.RawValue
+}
diff --git a/rlp/rlpgen/testdata/rawvalue.out.txt b/rlp/rlpgen/testdata/rawvalue.out.txt
new file mode 100644
index 0000000000000..3607c9863676e
--- /dev/null
+++ b/rlp/rlpgen/testdata/rawvalue.out.txt
@@ -0,0 +1,64 @@
+package test
+
+import "github.com/ethereum/go-ethereum/rlp"
+import "io"
+
+func (obj *Test) EncodeRLP(_w io.Writer) error {
+	w := rlp.NewEncoderBuffer(_w)
+	_tmp0 := w.List()
+	w.Write(obj.RawValue)
+	if obj.PointerToRawValue == nil {
+		w.Write([]byte{0x80})
+	} else {
+		w.Write((*obj.PointerToRawValue))
+	}
+	_tmp1 := w.List()
+	for _, _tmp2 := range obj.SliceOfRawValue {
+		w.Write(_tmp2)
+	}
+	w.ListEnd(_tmp1)
+	w.ListEnd(_tmp0)
+	return w.Flush()
+}
+
+func (obj *Test) DecodeRLP(dec *rlp.Stream) error {
+	var _tmp0 Test
+	{
+		if _, err := dec.List(); err != nil {
+			return err
+		}
+		// RawValue:
+		_tmp1, err := dec.Raw()
+		if err != nil {
+			return err
+		}
+		_tmp0.RawValue = _tmp1
+		// PointerToRawValue:
+		_tmp2, err := dec.Raw()
+		if err != nil {
+			return err
+		}
+		_tmp0.PointerToRawValue = &_tmp2
+		// SliceOfRawValue:
+		var _tmp3 []rlp.RawValue
+		if _, err := dec.List(); err != nil {
+			return err
+		}
+		for dec.MoreDataInList() {
+			_tmp4, err := dec.Raw()
+			if err != nil {
+				return err
+			}
+			_tmp3 = append(_tmp3, _tmp4)
+		}
+		if err := dec.ListEnd(); err != nil {
+			return err
+		}
+		_tmp0.SliceOfRawValue = _tmp3
+		if err := dec.ListEnd(); err != nil {
+			return err
+		}
+	}
+	*obj = _tmp0
+	return nil
+}
diff --git a/rlp/rlpgen/testdata/uints.in.txt b/rlp/rlpgen/testdata/uints.in.txt
new file mode 100644
index 0000000000000..8095da997d964
--- /dev/null
+++ b/rlp/rlpgen/testdata/uints.in.txt
@@ -0,0 +1,10 @@
+// -*- mode: go -*-
+
+package test
+
+type Test struct{
+     A uint8
+     B uint16
+     C uint32
+     D uint64
+}
diff --git a/rlp/rlpgen/testdata/uints.out.txt b/rlp/rlpgen/testdata/uints.out.txt
new file mode 100644
index 0000000000000..1a354956a4094
--- /dev/null
+++ b/rlp/rlpgen/testdata/uints.out.txt
@@ -0,0 +1,53 @@
+package test
+
+import "github.com/ethereum/go-ethereum/rlp"
+import "io"
+
+func (obj *Test) EncodeRLP(_w io.Writer) error {
+	w := rlp.NewEncoderBuffer(_w)
+	_tmp0 := w.List()
+	w.WriteUint64(uint64(obj.A))
+	w.WriteUint64(uint64(obj.B))
+	w.WriteUint64(uint64(obj.C))
+	w.WriteUint64(obj.D)
+	w.ListEnd(_tmp0)
+	return w.Flush()
+}
+
+func (obj *Test) DecodeRLP(dec *rlp.Stream) error {
+	var _tmp0 Test
+	{
+		if _, err := dec.List(); err != nil {
+			return err
+		}
+		// A:
+		_tmp1, err := dec.Uint8()
+		if err != nil {
+			return err
+		}
+		_tmp0.A = _tmp1
+		// B:
+		_tmp2, err := dec.Uint16()
+		if err != nil {
+			return err
+		}
+		_tmp0.B = _tmp2
+		// C:
+		_tmp3, err := dec.Uint32()
+		if err != nil {
+			return err
+		}
+		_tmp0.C = _tmp3
+		// D:
+		_tmp4, err := dec.Uint64()
+		if err != nil {
+			return err
+		}
+		_tmp0.D = _tmp4
+		if err := dec.ListEnd(); err != nil {
+			return err
+		}
+	}
+	*obj = _tmp0
+	return nil
+}
diff --git a/rlp/rlpgen/types.go b/rlp/rlpgen/types.go
new file mode 100644
index 0000000000000..5926a801eecb2
--- /dev/null
+++ b/rlp/rlpgen/types.go
@@ -0,0 +1,98 @@
+package main
+
+import (
+	"fmt"
+	"go/types"
+	"reflect"
+)
+
+// typeReflectKind gives the reflect.Kind that represents typ.
+func typeReflectKind(typ types.Type) reflect.Kind {
+	switch typ := typ.(type) {
+	case *types.Basic:
+		k := typ.Kind()
+		if k >= types.Bool && k <= types.Complex128 {
+			// value order matches for Bool..Complex128
+			return reflect.Bool + reflect.Kind(k-types.Bool)
+		}
+		if k == types.String {
+			return reflect.String
+		}
+		if k == types.UnsafePointer {
+			return reflect.UnsafePointer
+		}
+		panic(fmt.Errorf("unhandled BasicKind %v", k))
+	case *types.Array:
+		return reflect.Array
+	case *types.Chan:
+		return reflect.Chan
+	case *types.Interface:
+		return reflect.Interface
+	case *types.Map:
+		return reflect.Map
+	case *types.Pointer:
+		return reflect.Ptr
+	case *types.Signature:
+		return reflect.Func
+	case *types.Slice:
+		return reflect.Slice
+	case *types.Struct:
+		return reflect.Struct
+	default:
+		panic(fmt.Errorf("unhandled type %T", typ))
+	}
+}
+
+// nonZeroCheck returns the expression that checks whether 'v' is a non-zero value of type 'vtyp'.
+func nonZeroCheck(v string, vtyp types.Type, qualify types.Qualifier) string {
+	// Resolve type name.
+	typ := resolveUnderlying(vtyp)
+	switch typ := typ.(type) {
+	case *types.Basic:
+		k := typ.Kind()
+		switch {
+		case k == types.Bool:
+			return v
+		case k >= types.Uint && k <= types.Complex128:
+			return fmt.Sprintf("%s != 0", v)
+		case k == types.String:
+			return fmt.Sprintf(`%s != ""`, v)
+		default:
+			panic(fmt.Errorf("unhandled BasicKind %v", k))
+		}
+	case *types.Array, *types.Struct:
+		return fmt.Sprintf("%s != (%s{})", v, types.TypeString(vtyp, qualify))
+	case *types.Interface, *types.Pointer, *types.Signature:
+		return fmt.Sprintf("%s != nil", v)
+	case *types.Slice, *types.Map:
+		return fmt.Sprintf("len(%s) > 0", v)
+	default:
+		panic(fmt.Errorf("unhandled type %T", typ))
+	}
+}
+
+// isBigInt checks whether 'typ' is "math/big".Int.
+func isBigInt(typ types.Type) bool {
+	named, ok := typ.(*types.Named)
+	if !ok {
+		return false
+	}
+	name := named.Obj()
+	return name.Pkg().Path() == "math/big" && name.Name() == "Int"
+}
+
+// isByte checks whether the underlying type of 'typ' is uint8.
+func isByte(typ types.Type) bool {
+	basic, ok := resolveUnderlying(typ).(*types.Basic)
+	return ok && basic.Kind() == types.Uint8
+}
+
+func resolveUnderlying(typ types.Type) types.Type {
+	for {
+		t := typ.Underlying()
+		if t == typ {
+			return t
+		}
+		typ = t
+	}
+}