Ejemplo n.º 1
0
    def unroll_constant(self, const):
        # const = self.context.constants[self.expr.id]

        ann_expr = None
        expr = Expr.parse_value_expr(const.value, Context(vars=None, global_ctx=self, origcode=const.source_code))
        annotation_type = parse_type(const.annotation.args[0], None, custom_units=self._custom_units, custom_structs=self._structs)

        fail = False

        if self.is_instances([expr.typ, annotation_type], ByteArrayType):
            if expr.typ.maxlen < annotation_type.maxlen:
                return const
            fail = True

        elif expr.typ != annotation_type:
            fail = True
            # special case for literals, which can be uint256 types as well.
            if self.is_instances([expr.typ, annotation_type], BaseType) and \
               [annotation_type.typ, expr.typ.typ] == ['uint256', 'int128'] and \
               SizeLimits.in_bounds('uint256', expr.value):
                fail = False

            elif self.is_instances([expr.typ, annotation_type], BaseType) and \
               [annotation_type.typ, expr.typ.typ] == ['int128', 'int128'] and \
               SizeLimits.in_bounds('int128', expr.value):
                fail = False

        if fail:
            raise TypeMismatchException('Invalid value for constant type, expected %r' % annotation_type, const.value)

        ann_expr = copy.deepcopy(expr)
        ann_expr.typ = annotation_type
        ann_expr.typ.is_literal = expr.typ.is_literal  # Annotation type doesn't have literal set.

        return ann_expr
Ejemplo n.º 2
0
def generate_inline_function(code, variables, memory_allocator):
    ast_code = parse_to_ast(code)
    new_context = Context(
        vars=variables, global_ctx=GlobalContext(), memory_allocator=memory_allocator, origcode=code
    )
    generated_lll = parse_body(ast_code.body, new_context)
    return new_context, generated_lll
Ejemplo n.º 3
0
def parse_function(code,
                   sigs,
                   origcode,
                   global_ctx,
                   is_contract_payable,
                   _vars=None):
    """
    Parses a function and produces LLL code for the function, includes:
        - Signature method if statement
        - Argument handling
        - Clamping and copying of arguments
        - Function body
    """
    if _vars is None:
        _vars = {}
    sig = FunctionSignature.from_definition(
        code,
        sigs=sigs,
        custom_structs=global_ctx._structs,
    )

    # Validate return statements.
    sig.validate_return_statement_balance()

    # Create a local (per function) context.
    memory_allocator = MemoryAllocator()
    context = Context(
        vars=_vars,
        global_ctx=global_ctx,
        sigs=sigs,
        memory_allocator=memory_allocator,
        return_type=sig.output_type,
        constancy=Constancy.Constant
        if sig.mutability in ("view", "pure") else Constancy.Mutable,
        is_payable=sig.mutability == "payable",
        origcode=origcode,
        is_internal=sig.internal,
        method_id=sig.method_id,
        sig=sig,
    )

    if sig.internal:
        o = parse_internal_function(
            code=code,
            sig=sig,
            context=context,
        )
    else:
        o = parse_external_function(code=code,
                                    sig=sig,
                                    context=context,
                                    is_contract_payable=is_contract_payable)

    o.context = context
    o.total_gas = o.gas + calc_mem_gas(
        o.context.memory_allocator.get_next_memory_position())
    o.func_name = sig.name
    return o
Ejemplo n.º 4
0
    def unroll_constant(self, const, global_ctx):
        # const = self._constants[self.expr.id]

        ann_expr = None
        expr = Expr.parse_value_expr(
            const.value,
            Context(vars=None,
                    global_ctx=global_ctx,
                    origcode=const.source_code),
        )
        annotation_type = global_ctx.parse_type(const.annotation.args[0], None)
        fail = False

        if is_instances([expr.typ, annotation_type], ByteArrayType):
            if expr.typ.maxlen < annotation_type.maxlen:
                return const
            fail = True

        elif expr.typ != annotation_type:
            fail = True
            # special case for literals, which can be uint256 types as well.
            is_special_case_uint256_literal = (is_instances(
                [expr.typ, annotation_type], BaseType)) and ([
                    annotation_type.typ, expr.typ.typ
                ] == ['uint256', 'int128']) and SizeLimits.in_bounds(
                    'uint256', expr.value)

            is_special_case_int256_literal = (is_instances(
                [expr.typ, annotation_type], BaseType)) and ([
                    annotation_type.typ, expr.typ.typ
                ] == ['int128', 'int128']) and SizeLimits.in_bounds(
                    'int128', expr.value)

            if is_special_case_uint256_literal or is_special_case_int256_literal:
                fail = False

        if fail:
            raise TypeMismatchException(
                'Invalid value for constant type, expected %r got %r instead' %
                (
                    annotation_type,
                    expr.typ,
                ),
                const.value,
            )

        ann_expr = copy.deepcopy(expr)
        ann_expr.typ = annotation_type
        ann_expr.typ.is_literal = expr.typ.is_literal  # Annotation type doesn't have literal set.

        return ann_expr
Ejemplo n.º 5
0
    def unroll_constant(self, const, global_ctx):
        ann_expr = None
        expr = Expr.parse_value_expr(
            const.value,
            Context(
                vars=None,
                global_ctx=global_ctx,
                origcode=const.full_source_code,
                memory_allocator=MemoryAllocator(),
            ),
        )
        annotation_type = global_ctx.parse_type(const.annotation.args[0], None)
        fail = False

        if is_instances([expr.typ, annotation_type], ByteArrayType):
            if expr.typ.maxlen < annotation_type.maxlen:
                return const
            fail = True

        elif expr.typ != annotation_type:
            fail = True
            # special case for literals, which can be uint256 types as well.
            is_special_case_uint256_literal = (
                (is_instances([expr.typ, annotation_type], BaseType)) and
                ([annotation_type.typ, expr.typ.typ] == ["uint256", "int128"])
                and SizeLimits.in_bounds("uint256", expr.value))

            is_special_case_int256_literal = (
                (is_instances([expr.typ, annotation_type], BaseType)) and
                ([annotation_type.typ, expr.typ.typ] == ["int128", "int128"])
                and SizeLimits.in_bounds("int128", expr.value))

            if is_special_case_uint256_literal or is_special_case_int256_literal:
                fail = False

        if fail:
            raise TypeMismatch(
                f"Invalid value for constant type, expected {annotation_type} got "
                f"{expr.typ} instead",
                const.value,
            )

        ann_expr = copy.deepcopy(expr)
        ann_expr.typ = annotation_type
        ann_expr.typ.is_literal = expr.typ.is_literal  # Annotation type doesn't have literal set.

        return ann_expr
Ejemplo n.º 6
0
def parse_func(code, sigs, origcode, global_ctx, _vars=None):
    if _vars is None:
        _vars = {}
    sig = FunctionSignature.from_definition(
        code,
        sigs=sigs,
        custom_units=global_ctx._custom_units,
        custom_structs=global_ctx._structs,
        constants=global_ctx._constants)
    # Get base args for function.
    total_default_args = len(code.args.defaults)
    base_args = sig.args[:
                         -total_default_args] if total_default_args > 0 else sig.args
    default_args = code.args.args[-total_default_args:]
    default_values = dict(
        zip([arg.arg for arg in default_args], code.args.defaults))
    # __init__ function may not have defaults.
    if sig.name == '__init__' and total_default_args > 0:
        raise FunctionDeclarationException(
            "__init__ function may not have default parameters.")
    # Check for duplicate variables with globals
    for arg in sig.args:
        if arg.name in global_ctx._globals:
            raise FunctionDeclarationException(
                "Variable name duplicated between function arguments and globals: "
                + arg.name)

    nonreentrant_pre = [['pass']]
    nonreentrant_post = [['pass']]
    if sig.nonreentrant_key:
        nkey = global_ctx.get_nonrentrant_counter(sig.nonreentrant_key)
        nonreentrant_pre = [[
            'seq', ['assert', ['iszero', ['sload', nkey]]],
            ['sstore', nkey, 1]
        ]]
        nonreentrant_post = [['sstore', nkey, 0]]

    # Create a local (per function) context.
    context = Context(
        vars=_vars,
        global_ctx=global_ctx,
        sigs=sigs,
        return_type=sig.output_type,
        constancy=Constancy.Constant if sig.const else Constancy.Mutable,
        is_payable=sig.payable,
        origcode=origcode,
        is_private=sig.private,
        method_id=sig.method_id)

    # Copy calldata to memory for fixed-size arguments
    max_copy_size = sum([
        32 if isinstance(arg.typ, ByteArrayLike) else
        get_size_of_type(arg.typ) * 32 for arg in sig.args
    ])
    base_copy_size = sum([
        32 if isinstance(arg.typ, ByteArrayLike) else
        get_size_of_type(arg.typ) * 32 for arg in base_args
    ])
    context.next_mem += max_copy_size

    clampers = []

    # Create callback_ptr, this stores a destination in the bytecode for a private
    # function to jump to after a function has executed.
    _post_callback_ptr = "{}_{}_post_callback_ptr".format(
        sig.name, sig.method_id)
    if sig.private:
        context.callback_ptr = context.new_placeholder(typ=BaseType('uint256'))
        clampers.append(
            LLLnode.from_list(
                ['mstore', context.callback_ptr, 'pass'],
                annotation='pop callback pointer',
            ))
        if total_default_args > 0:
            clampers.append(['label', _post_callback_ptr])

    # private functions without return types need to jump back to
    # the calling function, as there is no return statement to handle the
    # jump.
    stop_func = [['stop']]
    if sig.output_type is None and sig.private:
        stop_func = [['jump', ['mload', context.callback_ptr]]]

    if not len(base_args):
        copier = 'pass'
    elif sig.name == '__init__':
        copier = [
            'codecopy', MemoryPositions.RESERVED_MEMORY, '~codelen',
            base_copy_size
        ]
    else:
        copier = get_arg_copier(sig=sig,
                                total_size=base_copy_size,
                                memory_dest=MemoryPositions.RESERVED_MEMORY)
    clampers.append(copier)

    # Add asserts for payable and internal
    # private never gets payable check.
    if not sig.payable and not sig.private:
        clampers.append(['assert', ['iszero', 'callvalue']])

    # Fill variable positions
    for i, arg in enumerate(sig.args):
        if i < len(base_args) and not sig.private:
            clampers.append(
                make_clamper(
                    arg.pos,
                    context.next_mem,
                    arg.typ,
                    sig.name == '__init__',
                ))
        if isinstance(arg.typ, ByteArrayLike):
            context.vars[arg.name] = VariableRecord(arg.name, context.next_mem,
                                                    arg.typ, False)
            context.next_mem += 32 * get_size_of_type(arg.typ)
        else:
            context.vars[arg.name] = VariableRecord(
                arg.name,
                MemoryPositions.RESERVED_MEMORY + arg.pos,
                arg.typ,
                False,
            )

    # Private function copiers. No clamping for private functions.
    dyn_variable_names = [
        a.name for a in base_args if isinstance(a.typ, ByteArrayLike)
    ]
    if sig.private and dyn_variable_names:
        i_placeholder = context.new_placeholder(typ=BaseType('uint256'))
        unpackers = []
        for idx, var_name in enumerate(dyn_variable_names):
            var = context.vars[var_name]
            ident = "_load_args_%d_dynarg%d" % (sig.method_id, idx)
            o = make_unpacker(ident=ident,
                              i_placeholder=i_placeholder,
                              begin_pos=var.pos)
            unpackers.append(o)

        if not unpackers:
            unpackers = ['pass']

        clampers.append(
            LLLnode.from_list(
                # [0] to complete full overarching 'seq' statement, see private_label.
                ['seq_unchecked'] + unpackers + [0],
                typ=None,
                annotation='dynamic unpacker',
                pos=getpos(code),
            ))

    # Create "clampers" (input well-formedness checkers)
    # Return function body
    if sig.name == '__init__':
        o = LLLnode.from_list(
            ['seq'] + clampers + [parse_body(code.body, context)],
            pos=getpos(code),
        )
    elif is_default_func(sig):
        if len(sig.args) > 0:
            raise FunctionDeclarationException(
                'Default function may not receive any arguments.', code)
        if sig.private:
            raise FunctionDeclarationException(
                'Default function may only be public.',
                code,
            )
        o = LLLnode.from_list(
            ['seq'] + clampers + [parse_body(code.body, context)],
            pos=getpos(code),
        )
    else:

        if total_default_args > 0:  # Function with default parameters.
            function_routine = "{}_{}".format(sig.name, sig.method_id)
            default_sigs = generate_default_arg_sigs(code, sigs, global_ctx)
            sig_chain = ['seq']

            for default_sig in default_sigs:
                sig_compare, private_label = get_sig_statements(
                    default_sig, getpos(code))

                # Populate unset default variables
                populate_arg_count = len(sig.args) - len(default_sig.args)
                set_defaults = []
                if populate_arg_count > 0:
                    current_sig_arg_names = {x.name for x in default_sig.args}
                    missing_arg_names = [
                        arg.arg for arg in default_args
                        if arg.arg not in current_sig_arg_names
                    ]
                    for arg_name in missing_arg_names:
                        value = Expr(default_values[arg_name],
                                     context).lll_node
                        var = context.vars[arg_name]
                        left = LLLnode.from_list(var.pos,
                                                 typ=var.typ,
                                                 location='memory',
                                                 pos=getpos(code),
                                                 mutable=var.mutable)
                        set_defaults.append(
                            make_setter(left,
                                        value,
                                        'memory',
                                        pos=getpos(code)))

                current_sig_arg_names = {x.name for x in default_sig.args}
                base_arg_names = {arg.name for arg in base_args}
                if sig.private:
                    # Load all variables in default section, if private,
                    # because the stack is a linear pipe.
                    copier_arg_count = len(default_sig.args)
                    copier_arg_names = current_sig_arg_names
                else:
                    copier_arg_count = len(default_sig.args) - len(base_args)
                    copier_arg_names = current_sig_arg_names - base_arg_names
                # Order copier_arg_names, this is very important.
                copier_arg_names = [
                    x.name for x in default_sig.args
                    if x.name in copier_arg_names
                ]

                # Variables to be populated from calldata/stack.
                default_copiers = []
                if copier_arg_count > 0:
                    # Get map of variables in calldata, with thier offsets
                    offset = 4
                    calldata_offset_map = {}
                    for arg in default_sig.args:
                        calldata_offset_map[arg.name] = offset
                        offset += (32 if isinstance(arg.typ, ByteArrayLike)
                                   else get_size_of_type(arg.typ) * 32)
                    # Copy set default parameters from calldata
                    dynamics = []
                    for arg_name in copier_arg_names:
                        var = context.vars[arg_name]
                        calldata_offset = calldata_offset_map[arg_name]
                        if sig.private:
                            _offset = calldata_offset
                            if isinstance(var.typ, ByteArrayLike):
                                _size = 32
                                dynamics.append(var.pos)
                            else:
                                _size = var.size * 32
                            default_copiers.append(
                                get_arg_copier(
                                    sig=sig,
                                    memory_dest=var.pos,
                                    total_size=_size,
                                    offset=_offset,
                                ))
                        else:
                            # Add clampers.
                            default_copiers.append(
                                make_clamper(
                                    calldata_offset - 4,
                                    var.pos,
                                    var.typ,
                                ))
                            # Add copying code.
                            if isinstance(var.typ, ByteArrayLike):
                                _offset = [
                                    'add', 4,
                                    ['calldataload', calldata_offset]
                                ]
                            else:
                                _offset = calldata_offset
                            default_copiers.append(
                                get_arg_copier(
                                    sig=sig,
                                    memory_dest=var.pos,
                                    total_size=var.size * 32,
                                    offset=_offset,
                                ))

                    # Unpack byte array if necessary.
                    if dynamics:
                        i_placeholder = context.new_placeholder(
                            typ=BaseType('uint256'))
                        for idx, var_pos in enumerate(dynamics):
                            ident = 'unpack_default_sig_dyn_%d_arg%d' % (
                                default_sig.method_id, idx)
                            default_copiers.append(
                                make_unpacker(
                                    ident=ident,
                                    i_placeholder=i_placeholder,
                                    begin_pos=var_pos,
                                ))
                    default_copiers.append(0)  # for over arching seq, POP

                sig_chain.append([
                    'if', sig_compare,
                    [
                        'seq', private_label, ['pass'] if not sig.private else
                        LLLnode.from_list([
                            'mstore',
                            context.callback_ptr,
                            'pass',
                        ],
                                          annotation='pop callback pointer',
                                          pos=getpos(code)),
                        ['seq'] + set_defaults if set_defaults else ['pass'],
                        ['seq_unchecked'] +
                        default_copiers if default_copiers else ['pass'],
                        [
                            'goto', _post_callback_ptr
                            if sig.private else function_routine
                        ]
                    ]
                ])

            # With private functions all variable loading occurs in the default
            # function sub routine.
            if sig.private:
                _clampers = [['label', _post_callback_ptr]]
            else:
                _clampers = clampers

            # Function with default parameters.
            o = LLLnode.from_list(
                [
                    'seq',
                    sig_chain,
                    [
                        'if',
                        0,  # can only be jumped into
                        [
                            'seq', ['label', function_routine]
                            if not sig.private else ['pass'],
                            ['seq'] + nonreentrant_pre + _clampers +
                            [parse_body(c, context) for c in code.body] +
                            nonreentrant_post + stop_func
                        ],
                    ],
                ],
                typ=None,
                pos=getpos(code))

        else:
            # Function without default parameters.
            sig_compare, private_label = get_sig_statements(sig, getpos(code))
            o = LLLnode.from_list([
                'if', sig_compare,
                ['seq'] + [private_label] + nonreentrant_pre + clampers +
                [parse_body(c, context)
                 for c in code.body] + nonreentrant_post + stop_func
            ],
                                  typ=None,
                                  pos=getpos(code))

    # Check for at leasts one return statement if necessary.
    if context.return_type and context.function_return_count == 0:
        raise FunctionDeclarationException(
            "Missing return statement in function '%s' " % sig.name, code)

    o.context = context
    o.total_gas = o.gas + calc_mem_gas(o.context.next_mem)
    o.func_name = sig.name
    return o
Ejemplo n.º 7
0
def parse_func(code, _globals, sigs, origcode, _custom_units, _vars=None):
    if _vars is None:
        _vars = {}
    sig = FunctionSignature.from_definition(code, sigs=sigs, custom_units=_custom_units)
    # Check for duplicate variables with globals
    for arg in sig.args:
        if arg.name in _globals:
            raise FunctionDeclarationException("Variable name duplicated between function arguments and globals: " + arg.name)
    # Create a context
    context = Context(vars=_vars, globals=_globals, sigs=sigs,
                      return_type=sig.output_type, is_constant=sig.const, is_payable=sig.payable, origcode=origcode, custom_units=_custom_units)
    # Copy calldata to memory for fixed-size arguments
    copy_size = sum([32 if isinstance(arg.typ, ByteArrayType) else get_size_of_type(arg.typ) * 32 for arg in sig.args])
    context.next_mem += copy_size
    if not len(sig.args):
        copier = 'pass'
    elif sig.name == '__init__':
        copier = ['codecopy', MemoryPositions.RESERVED_MEMORY, '~codelen', copy_size]
    else:
        copier = ['calldatacopy', MemoryPositions.RESERVED_MEMORY, 4, copy_size]
    clampers = [copier]
    # Add asserts for payable and internal
    if not sig.payable:
        clampers.append(['assert', ['iszero', 'callvalue']])
    if sig.private:
        clampers.append(['assert', ['eq', 'caller', 'address']])
    # Fill in variable positions
    for arg in sig.args:
        clampers.append(make_clamper(arg.pos, context.next_mem, arg.typ, sig.name == '__init__'))
        if isinstance(arg.typ, ByteArrayType):
            context.vars[arg.name] = VariableRecord(arg.name, context.next_mem, arg.typ, False)
            context.next_mem += 32 * get_size_of_type(arg.typ)
        else:
            context.vars[arg.name] = VariableRecord(arg.name, MemoryPositions.RESERVED_MEMORY + arg.pos, arg.typ, False)
    # Create "clampers" (input well-formedness checkers)
    # Return function body
    if sig.name == '__init__':
        o = LLLnode.from_list(['seq'] + clampers + [parse_body(code.body, context)], pos=getpos(code))
    elif is_default_func(sig):
        if len(sig.args) > 0:
            raise FunctionDeclarationException('Default function may not receive any arguments.', code)
        if sig.private:
            raise FunctionDeclarationException('Default function may only be public.', code)
        o = LLLnode.from_list(['seq'] + clampers + [parse_body(code.body, context)], pos=getpos(code))
    else:
        method_id_node = LLLnode.from_list(sig.method_id, pos=getpos(code), annotation='%s' % sig.name)
        o = LLLnode.from_list(['if',
                                  ['eq', ['mload', 0], method_id_node],
                                  ['seq'] + clampers + [parse_body(c, context) for c in code.body] + ['stop']
                               ], typ=None, pos=getpos(code))

    # Check for at leasts one return statement if necessary.
    if context.return_type and context.function_return_count == 0:
        raise FunctionDeclarationException(
            "Missing return statement in function '%s' " % sig.name, code
        )

    o.context = context
    o.total_gas = o.gas + calc_mem_gas(o.context.next_mem)
    o.func_name = sig.name
    return o
Ejemplo n.º 8
0
def parse_func(code, sigs, origcode, global_ctx, _vars=None):
    if _vars is None:
        _vars = {}
    sig = FunctionSignature.from_definition(
        code, sigs=sigs, custom_units=global_ctx._custom_units)
    # Get base args for function.
    total_default_args = len(code.args.defaults)
    base_args = sig.args[:
                         -total_default_args] if total_default_args > 0 else sig.args
    default_args = code.args.args[-total_default_args:]
    default_values = dict(
        zip([arg.arg for arg in default_args], code.args.defaults))
    # __init__ function may not have defaults.
    if sig.name == '__init__' and total_default_args > 0:
        raise FunctionDeclarationException(
            "__init__ function may not have default parameters.")
    # Check for duplicate variables with globals
    for arg in sig.args:
        if arg.name in global_ctx._globals:
            raise FunctionDeclarationException(
                "Variable name duplicated between function arguments and globals: "
                + arg.name)

    # Create a context
    context = Context(vars=_vars,
                      globals=global_ctx._globals,
                      sigs=sigs,
                      return_type=sig.output_type,
                      is_constant=sig.const,
                      is_payable=sig.payable,
                      origcode=origcode,
                      custom_units=global_ctx._custom_units)
    # Copy calldata to memory for fixed-size arguments
    max_copy_size = sum([
        32 if isinstance(arg.typ, ByteArrayType) else
        get_size_of_type(arg.typ) * 32 for arg in sig.args
    ])
    base_copy_size = sum([
        32 if isinstance(arg.typ, ByteArrayType) else
        get_size_of_type(arg.typ) * 32 for arg in base_args
    ])
    context.next_mem += max_copy_size

    if not len(base_args):
        copier = 'pass'
    elif sig.name == '__init__':
        copier = [
            'codecopy', MemoryPositions.RESERVED_MEMORY, '~codelen',
            base_copy_size
        ]
    else:
        copier = [
            'calldatacopy', MemoryPositions.RESERVED_MEMORY, 4, base_copy_size
        ]
    clampers = [copier]
    # Add asserts for payable and internal
    if not sig.payable:
        clampers.append(['assert', ['iszero', 'callvalue']])
    if sig.private:
        clampers.append(['assert', ['eq', 'caller', 'address']])

    # Fill variable positions
    for i, arg in enumerate(sig.args):
        if i < len(base_args):
            clampers.append(
                make_clamper(arg.pos, context.next_mem, arg.typ,
                             sig.name == '__init__'))
        if isinstance(arg.typ, ByteArrayType):
            context.vars[arg.name] = VariableRecord(arg.name, context.next_mem,
                                                    arg.typ, False)
            context.next_mem += 32 * get_size_of_type(arg.typ)
        else:
            context.vars[arg.name] = VariableRecord(
                arg.name, MemoryPositions.RESERVED_MEMORY + arg.pos, arg.typ,
                False)

    # Create "clampers" (input well-formedness checkers)
    # Return function body
    if sig.name == '__init__':
        o = LLLnode.from_list(['seq'] + clampers +
                              [parse_body(code.body, context)],
                              pos=getpos(code))
    elif is_default_func(sig):
        if len(sig.args) > 0:
            raise FunctionDeclarationException(
                'Default function may not receive any arguments.', code)
        if sig.private:
            raise FunctionDeclarationException(
                'Default function may only be public.', code)
        o = LLLnode.from_list(['seq'] + clampers +
                              [parse_body(code.body, context)],
                              pos=getpos(code))
    else:
        # Handle default args if present.
        function_routine = "{}_{}".format(sig.name, sig.method_id)
        if total_default_args > 0:
            default_sigs = generate_default_arg_sigs(code, sigs,
                                                     global_ctx._custom_units)
            sig_chain = ['seq']

            for default_sig_idx, default_sig in enumerate(default_sigs):
                method_id_node = LLLnode.from_list(default_sig.method_id,
                                                   pos=getpos(code),
                                                   annotation='%s' %
                                                   default_sig.sig)

                # Populate unset default variables
                populate_arg_count = len(sig.args) - len(default_sig.args)
                set_defaults = []
                if populate_arg_count > 0:
                    current_sig_arg_names = {x.name for x in default_sig.args}
                    missing_arg_names = [
                        arg.arg for arg in default_args
                        if arg.arg not in current_sig_arg_names
                    ]
                    for arg_name in missing_arg_names:
                        value = Expr(default_values[arg_name],
                                     context).lll_node
                        var = context.vars[arg_name]
                        left = LLLnode.from_list(var.pos,
                                                 typ=var.typ,
                                                 location='memory',
                                                 pos=getpos(code),
                                                 mutable=var.mutable)
                        set_defaults.append(
                            make_setter(left,
                                        value,
                                        'memory',
                                        pos=getpos(code)))
                # Variables to be populated from calldata
                copier_arg_count = len(default_sig.args) - len(base_args)
                default_copiers = []
                if copier_arg_count > 0:
                    current_sig_arg_names = {x.name for x in default_sig.args}
                    base_arg_names = {arg.name for arg in base_args}
                    copier_arg_names = current_sig_arg_names - base_arg_names

                    # Get map of variables in calldata, with thier offsets
                    offset = 4
                    calldata_offset_map = {}
                    for arg in default_sig.args:
                        calldata_offset_map[arg.name] = offset
                        offset += 32 if isinstance(
                            arg.typ,
                            ByteArrayType) else get_size_of_type(arg.typ) * 32
                    # Copy set default parameters from calldata
                    for arg_name in copier_arg_names:
                        var = context.vars[arg_name]
                        calldata_offset = calldata_offset_map[arg_name]
                        # Add clampers.
                        default_copiers.append(
                            make_clamper(calldata_offset - 4, var.pos,
                                         var.typ))
                        # Add copying code.
                        if isinstance(var.typ, ByteArrayType):
                            default_copiers.append([
                                'calldatacopy', var.pos,
                                ['add', 4, ['calldataload', calldata_offset]],
                                var.size * 32
                            ])
                        else:
                            default_copiers.append([
                                'calldatacopy', var.pos, calldata_offset,
                                var.size * 32
                            ])

                sig_chain.append([
                    'if', ['eq', ['mload', 0], method_id_node],
                    [
                        'seq',
                        ['seq'] + set_defaults if set_defaults else ['pass'],
                        ['seq'] +
                        default_copiers if default_copiers else ['pass'],
                        ['goto', function_routine]
                    ]
                ])

            o = LLLnode.from_list(
                [
                    'seq',
                    sig_chain,
                    [
                        'if',
                        0,  # can only be jumped into
                        [
                            'seq', ['label', function_routine
                                    ], ['seq'] + clampers +
                            [parse_body(c, context)
                             for c in code.body] + ['stop']
                        ]
                    ]
                ],
                typ=None,
                pos=getpos(code))

        else:
            # Function without default parameters.
            method_id_node = LLLnode.from_list(sig.method_id,
                                               pos=getpos(code),
                                               annotation='%s' % sig.sig)
            o = LLLnode.from_list([
                'if', ['eq', ['mload', 0], method_id_node], ['seq'] +
                clampers + [parse_body(c, context)
                            for c in code.body] + ['stop']
            ],
                                  typ=None,
                                  pos=getpos(code))

    # Check for at leasts one return statement if necessary.
    if context.return_type and context.function_return_count == 0:
        raise FunctionDeclarationException(
            "Missing return statement in function '%s' " % sig.name, code)

    o.context = context
    o.total_gas = o.gas + calc_mem_gas(o.context.next_mem)
    o.func_name = sig.name
    return o