instr: support nop

compile.go

@@ -454,6 +454,10 @@ func (c *compiler) Compile(t Token) error {
 		c.Must([]byte{0xc3}) // ret
 		return nil
 
+	case NopInstrToken:
+		c.Must([]byte{0x90}) // nop
+		return nil
+
 	default:
 		return fmt.Errorf("can't compile token of type %#t", t)
 	}

lexer.go

@@ -80,6 +80,9 @@ func (l *lexer) Next() (Token, error) {
 	case "ret":
 		return RetInstrToken{}, nil
 
+	case "nop":
+		return NopInstrToken{}, nil
+
 	default:
 		// If the field ends with `:`, it's a (local) label
 		if strings.HasSuffix(fields[0], `:`) {

token.go

@@ -23,6 +23,8 @@ type SyscallInstrToken struct{}
 
 type RetInstrToken struct{}
 
+type NopInstrToken struct{}
+
 type DataVariableInstrToken struct {
 	VarName   string
 	Sizeclass string // sz, u8, u16, u32, u64