MegEngine/imperative/python/megengine/traced_module/traced_module.py

# MegEngine is Licensed under the Apache License, Version 2.0 (the "License")
#
# Copyright (c) 2014-2021 Megvii Inc. All rights reserved.
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT ARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
import builtins
import collections
import copy
import ctypes
import fnmatch
import functools
import inspect
import keyword
import re
import weakref
from inspect import getcallargs, getmembers, isclass, ismethod
from itertools import chain
from types import FunctionType
from typing import (
    Any,
    Callable,
    Dict,
    Iterable,
    List,
    Optional,
    Sequence,
    Tuple,
    Type,
    Union,
)

from megengine import tensor

from .. import functional as F
from .. import get_logger
from .. import module as M
from ..core._imperative_rt.core2 import Tensor as RawTensor
from ..core._imperative_rt.core2 import (
    is_tracing_module,
    set_module_tracing,
    unset_module_tracing,
)
from ..core._trace_option import set_symbolic_shape
from ..core.tensor.array_method import ArrayMethodMixin
from ..module import Module
from ..module.qat import QATModule
from ..quantization.fake_quant import LSQ, TQT, FakeQuantize, _FakeQuantize
from ..quantization.observer import (
    ExponentialMovingAverageObserver,
    HistogramObserver,
    MinMaxObserver,
    Observer,
    PassiveObserver,
    SyncExponentialMovingAverageObserver,
    SyncMinMaxObserver,
)
from ..tensor import Tensor
from .expr import Apply, CallFunction, CallMethod, Constant, Expr, GetAttr, Input
from .fake_quant import FakeQuantize as TM_FakeQuant
from .module_tracer import (
    PatchedFn,
    Patcher,
    active_module_tracer,
    get_tensor_wrapable_method,
    module_tracer,
    set_active_module_tracer,
)
from .node import ModuleNode, Node, NodeMixin, TensorNode
from .pytree import ArgsIndex, tree_flatten
from .utils import replace_container_with_module_container

logger = get_logger(__name__)


def _is_builtin_name(name: str) -> bool:
    return (
        name in builtins.__dict__
        or name in keyword.kwlist
        or name in {"inf", "nan", "NoneType"}
    )


def _is_leaf(node):
    assert isinstance(node, RawTensor), "doesn't support {} in return values".format(
        type(node)
    )
    return isinstance(node, RawTensor)


_enable_node_to_tensor = False


def _convert_node_flag():
    return _enable_node_to_tensor


def _set_convert_node_flag(flag: bool = False):
    global _enable_node_to_tensor
    pre_flag = _enable_node_to_tensor
    _enable_node_to_tensor = flag
    return pre_flag


def _node_to_tensor(*args, **kwargs):
    tensors = []
    nodes, tree_def = tree_flatten((args, kwargs))
    for n in nodes:
        if isinstance(n, TensorNode):
            if n.top_graph is not None:
                active_module_tracer().current_scope()._add_input(n)
            value = n.value
            if value is None:
                flag = _set_convert_node_flag(False)
                unset_module_tracing()
                value = F.zeros(shape=n._shape, dtype=n._dtype)
                set_module_tracing()
                _set_convert_node_flag(flag)
            orig_n = NodeMixin.get(value, None)
            if orig_n is None or "setitem" not in orig_n._name:
                NodeMixin.wrap_safe(value, n)
            tensors.append(value)
        else:
            tensors.append(n)
    tensors = tree_def.unflatten(tensors)
    return tensors


def _tensor_to_node(tensors):
    if tensors is None:
        return None
    nodes = []
    tensors, out_def = tree_flatten(tensors)
    for t in tensors:
        if isinstance(t, Tensor):
            n = NodeMixin.get(t, None)
            if isinstance(n, TensorNode):
                n.value = t
                nodes.append(n)
            else:
                nodes.append(t)
        else:
            nodes.append(t)
    nodes = out_def.unflatten(nodes)
    return nodes


def _wrap_method_to_tensor_node():
    def _any_method(name):
        def _any(*args, **kwargs):
            args, kwargs = _node_to_tensor(*args, **kwargs)
            attr = getattr(args[0], name)
            outs = attr
            if callable(attr):
                outs = attr(*(args[1:]), **kwargs)
            if name == "__setitem__":
                _node_to_tensor(outs)
                return None
            outs = _tensor_to_node(outs)
            return outs

        return _any

    tensor_method_patch = []
    for method in get_tensor_wrapable_method():
        patch = PatchedFn(TensorNode, method)
        if type(getattr(Tensor, method)) == property:
            patch.set_func(property(_any_method(method)))
        else:
            patch.set_func(_any_method(method))
        tensor_method_patch.append(patch)
    return tensor_method_patch


def _convert_node_and_tensor(orig_func):
    @functools.wraps(orig_func)
    def _convert(*args, **kwargs):
        if _convert_node_flag() and is_tracing_module():
            args, kwargs = _node_to_tensor(*args, **kwargs)
            rst = orig_func(*args, **kwargs, method_func=_convert)
            rst = _tensor_to_node(rst)
            return rst
        else:
            rst = orig_func(*args, **kwargs)
        return rst

    return _convert


def _wrap_mnode_getattr(orig_getattr):
    @functools.wraps(orig_getattr)
    def wraped_fn(self, name):
        obj = self.owner
        if self.top_graph is not None:
            active_module_tracer().current_scope()._add_input(self)
        attr = getattr(obj, name)
        node = attr
        full_name = None
        if id(attr) in active_module_tracer().id2name:
            full_name = active_module_tracer().id2name[id(attr)]

        if not isinstance(attr, TracedModuleBuilder):
            if isinstance(attr, Module):
                attr = TracedModuleBuilder(attr)
                setattr(obj, name, attr)
                active_module_tracer().id2name[id(attr)] = full_name

            if isinstance(attr, (NodeMixin, RawTensor)):
                if full_name:
                    scope_name = active_module_tracer().current_scope()._module_name
                    if scope_name:
                        full_name = full_name[len(scope_name) + 1 :]
                    else:
                        full_name = name
                else:
                    full_name = name
                NodeMixin.wrap(
                    attr,
                    lambda: GetAttr.make(
                        self,
                        name,
                        type=NodeMixin.get_wrapped_type(attr),
                        orig_name=full_name,
                    ),
                )
        if isinstance(attr, (NodeMixin, RawTensor)):
            node = NodeMixin.get(attr)
        if isinstance(node, ModuleNode):
            node._owner = weakref.ref(attr)
        return node

    return wraped_fn


def _wrap_mnode_call(orig_call):
    @functools.wraps(orig_call)
    def wraped_fn(self, *args, **kwargs):
        obj = self.owner
        if self.top_graph is not None:
            active_module_tracer().current_scope()._add_input(self)
        rst = obj(*args, **kwargs)
        return rst

    return wraped_fn


def _init_id2name(mod: Module, prefix: str = ""):
    id2name = {
        id(m): "%s.%s" % (prefix, key)
        for key, m in chain(
            mod.named_modules(), mod.named_parameters(), mod.named_buffers()
        )
    }
    return id2name


class _InsertExprs:
    def __init__(self, graph, expr: Optional[Expr] = None):
        self.graph = graph
        while graph.top_graph is not None:
            graph = graph.top_graph
        assert graph.inputs[0].owner._is_top
        self.root_graph = graph
        self.global_scope = InternalGraph(
            graph._name, graph._prefix_name, graph._module_name
        )
        self.global_scope._used_names.update(graph._used_names)
        self.expr = expr
        self._tensor_method_patch = None

    def __enter__(self):
        self.use_sym_shape = set_symbolic_shape(True)
        node_id, expr_id = self.root_graph._total_ids
        Node._set_next_id(node_id)
        Expr._set_next_id(expr_id)
        set_module_tracing()
        _set_convert_node_flag(True)
        assert active_module_tracer() is None
        module = self.graph.inputs[0].owner
        _wrap_func = lambda x: _convert_node_and_tensor(_wrapped_function(x))
        set_active_module_tracer(
            module_tracer(_wrap_func, _init_id2name(module, self.graph._module_name))
        )
        active_module_tracer().patcher.__enter__()
        for cls, name, func in [
            [ModuleNode, "__getattr__", _wrap_mnode_getattr],
            [ModuleNode, "__call__", _wrap_mnode_call],
            [TracedModuleBuilder, "__call__", _convert_node_and_tensor],
        ]:
            active_module_tracer().patcher.patch_function(cls, name, func)
        self._tensor_method_patch = _wrap_method_to_tensor_node()
        active_module_tracer().push_scope(self.global_scope)

    def __exit__(self, ty, va, tr):
        if va is not None:
            return False
        set_symbolic_shape(self.use_sym_shape)
        unset_module_tracing()
        active_module_tracer().patcher.__exit__(ty, va, tr)
        _set_convert_node_flag(False)

        while self._tensor_method_patch:
            pf = self._tensor_method_patch.pop()
            pf.set_func(pf.origin_fn)

        module = self.graph.inputs[0].owner

        for mod, parent in module.modules(with_parent=True):
            name = mod._name
            if isinstance(mod, TracedModuleBuilder):
                mod = mod.build()
                if hasattr(mod, "graph"):
                    for node in mod.graph.nodes():
                        node.value = None
                setattr(parent, name, mod)
        set_active_module_tracer(None)

        for node in self.global_scope.nodes():
            node.value = None

        extra_inp_nodes = set(self.global_scope.inputs)
        max_inp_expr_idx = -1
        for node in extra_inp_nodes:
            assert (
                node.top_graph == self.graph
            ), "The input node ({}) is not in the graph ({})".format(node, self.graph)
            if isinstance(node, TensorNode) and node.expr in self.graph._exprs:
                max_inp_expr_idx = max(
                    max_inp_expr_idx, self.graph._exprs.index(node.expr)
                )
        max_inp_expr_idx += 1

        insert_index = -1
        if self.expr is not None:
            insert_index = self.graph._exprs.index(self.expr)
        insert_index += 1

        if insert_index < max_inp_expr_idx:
            insert_index = max_inp_expr_idx

        anchor_index = insert_index - 1
        if anchor_index >= 0:
            logger.info(
                "The new expr will be inserted after ( {} )".format(
                    self.graph._exprs[anchor_index]
                )
            )

        for expr in self.global_scope._exprs:
            self.graph._exprs.insert(insert_index, expr)
            insert_index += 1

        self.graph._used_names.update(self.global_scope._used_names)
        self.root_graph._total_ids = (Node._get_next_id(), Expr._get_next_id())
        self.root_graph.inputs[0].owner._update_ref()
        return True


class InternalGraph:
    r"""``InternalGraph`` is the main data structure used in the TracedModule.
    It is used to represent the execution procedure of Module's forward method.

    For example, the following code

    .. code-block::

        import megengine.random as rand
        import megengine.functional as F
        import megengine.module as M

        import megengine.traced_module as tm

        class MyModule(M.Module):
            def __init__(self):
                super().__init__()
                self.param = rand.normal(size=(3, 4))
                self.linear = M.Linear(4, 5)

            def forward(self, x):
                return F.relu(self.linear(x + self.param))

        net = MyModule()

        inp = F.zeros(shape = (3, 4))
        traced_module = tm.trace_module(net, inp)
    
    Will produce the following ``InternalGraph``::

        print(traced_module.graph)

    .. code-block:: text

        MyModule.Graph (self, x) {
                %2:     linear = getattr(self, "linear") -> (Linear)
                %3:     param = getattr(self, "param") -> (Tensor)
                %4:     add_out = x.__add__(param, )
                %5:     linear_out = linear(add_out, )
                %6:     relu_out = nn.relu(linear_out, )
                return relu_out
        }
    """

    _exprs = None  # type: List[Expr]
    _inputs = None  # type: List[Node]
    _outputs = None  # type: List[Node]
    _top_graph = None  # type: InternalGraph
    _total_ids = None  # type: List[int]

    def __init__(self, name: str = None, prefix_name: str = "", module_name: str = ""):
        self._exprs = []
        self._inputs = []
        self._outputs = []
        self._watch_point = []
        self._end_point = []
        self._used_names = {}
        self._rst = collections.defaultdict(list)
        self._name = name
        self._prefix_name = prefix_name
        self._module_name = module_name

    def _insert(self, expr):
        self._exprs.append(expr)

    def _create_unique_name(self, name: str) -> str:
        assert isinstance(name, str), "The name must be a str"
        name = re.sub("[^0-9a-zA-Z_]+", "_", name)
        if name[0].isdigit():
            name = "_{}".format(name)

        while name in self._used_names or _is_builtin_name(name):
            match = re.match(r"(.*)_(\d+)$", name)
            if match is None:
                name = name + "_1"
            else:
                base, num = match.group(1, 2)
                name = "{}_{}".format(base, int(num) + 1)

        self._used_names.setdefault(name)
        return name

    @property
    def inputs(self) -> List[Node]:
        r"""Get the list of input Nodes of this graph.

        Returns:
            A list of ``Node``.
        """
        return self._inputs

    @property
    def outputs(self) -> List[Node]:
        r"""Get the list of output Nodes of this graph.

        Returns:
            A list of Node.
        """
        return self._outputs

    @property
    def top_graph(self):
        r"""Get the parent graph of this graph.

        Returns:
            An ``InternalGraph``.
        """
        if self._top_graph:
            return self._top_graph()
        return None

    def exprs(self, recursive=True):
        r"""Get the Exprs that constitute this graph.

        Args:
            recursive: whether to get the Exprs in the subgraph.
                Default: True
        Returns:
            A ``ExprFilter`` containing all Exprs of this graph.
        """
        return ExprFilter(_expr_iter(self, recursive))

    def nodes(self, recursive=True):
        r"""Get the Nodes that constitute this graph.

        Args:
            recursive: whether to get the Nodes in the subgraph.
                Default: True
        Returns:
            A ``NodeFilter`` containing all Nodes of this graph.
        """
        return NodeFilter(_node_iter(self, recursive))

    def get_function_by_type(self, func: Callable = None, recursive=True):
        r"""Filter Exprs by the type of ``CallFunction``.

        Args:
            func: a built-in function, such as ``F.relu``.
            recursive: whether to get the Exprs in the subgraph.
                Default: True
        Returns:
            A :class:`~.TracedModule.ExprFilterCallFunction`.
        """
        return self.exprs(recursive).call_function(func)

    def get_method_by_type(self, method: str = None, recursive=True):
        r"""Filter Exprs by the type of ``CallMethod``.

        Args:
            method: a method string, such as "__add__".
            recursive: whether to get the Exprs in the subgraph.
                Default: True
        Returns:
            A :class:`~.TracedModule.ExprFilterCallMethod`.
        """
        return self.exprs(recursive).call_method(method)

    def get_expr_by_id(self, expr_id: List[int] = None, recursive=True):
        r"""Filter Exprs by their ``id``.

        Args:
            expr_id: a list of :class:`int`.
            recursive: whether to get the Exprs in the subgraph.
                Default: True
        Returns:
            A :class:`~.TracedModule.ExprFilterExprId`.
        """
        return self.exprs(recursive).expr_id(expr_id)

    def get_module_by_type(self, module_cls: Module, recursive=True):
        r"""Filter Nodes by the ``module_type`` of ``ModuleNode``.

        Args:
            module_cls: a subclass of :class:`~.Module`.
            recursive: whether to get the Nodes in the subgraph.
                Default: True
        Returns:
            A :class:`~.TracedModule.NodeFilterType`.
        """
        assert issubclass(module_cls, Module)
        return self.nodes(recursive).type(module_cls)

    def get_node_by_id(self, node_id: List[int] = None, recursive=True):
        r"""Filter Nodes by their ``id``.

        The ``id`` of the ``Node`` can be obtained by the following code

        .. code-block::

            # node : Node
            print("{:i}".format(node))
            print(node.__format__("i"))
            # graph : InternalGraph
            print("{:i}".format(graph))
            print(graph.__format__("i"))

        Args:
            node_id: a list of :class:`int`.
            recursive: whether to get the Nodes in the subgraph.
                Default: True
        Returns:
            A :class:`~.TracedModule.NodeFilterNodeId`.
        """
        return self.nodes(recursive).node_id(node_id)

    def get_node_by_name(
        self, name: str = None, ignorecase: bool = True, recursive=True
    ):
        r"""Filter Nodes by their full name.

        The full name of the ``Node`` can be obtained by the following code

        .. code-block::

            # node : Node
            print("{:p}".format(node))
            print(node.__format__("p"))
            # graph : InternalGraph
            print("{:p}".format(graph))
            print(graph.__format__("p"))
        
        Args:
            name: a string in glob syntax that can contain ``?`` and
             ``*`` to match a single or arbitrary characters.
            ignorecase: whether to ignroe case.
                Default: True
            recursive: whether to get the Nodes in the subgraph.
                Default: True
        Returns:
            A :class:`~.TracedModule.NodeFilterName`.
        """
        return self.nodes(recursive).name(name, ignorecase)

    def _add_input(self, i):
        self._inputs.append(i)

    def _add_output(self, o):
        self._outputs.append(o)

    def _replace_inputs_outputs(self, repl_dict, prefix_name="", module_name=""):
        for node, repl_node in repl_dict.items():
            assert node in self._inputs or node in self._outputs
            for i in node.users:
                if i not in repl_node.users:
                    repl_node.users.append(i)

        for idx, i in enumerate(self._inputs):
            if i in repl_dict:
                self._inputs[idx] = repl_dict[i]

        for idx, o in enumerate(self._outputs):
            if o in repl_dict:
                repl_dict[o]._orig_name = "{}{}".format(module_name, o._orig_name)
                self._outputs[idx] = repl_dict[o]

        for expr in self._exprs:

            for idx, i in enumerate(expr.inputs):
                assert isinstance(
                    i._name, str
                ), "The node ({}) name must be a str".format(i)
                if i in repl_dict:
                    expr.inputs[idx] = repl_dict[i]
                elif isinstance(i, TensorNode) and prefix_name not in i._name:
                    if i.top_graph != active_module_tracer().current_scope():
                        i._name = (
                            active_module_tracer()
                            .current_scope()
                            ._create_unique_name(prefix_name + i._name.lstrip("_"))
                        )
                        i._orig_name = "{}{}".format(module_name, i._orig_name)

            for idx, o in enumerate(expr.outputs):
                assert isinstance(
                    o._name, str
                ), "The node ({}) name must be a str".format(i)
                if o in repl_dict:
                    expr.outputs[idx] = repl_dict[o]
                    expr.outputs[idx].expr = expr
                elif isinstance(o, TensorNode) and prefix_name not in i._name:
                    if o.top_graph != active_module_tracer().current_scope():
                        o._name = (
                            active_module_tracer()
                            .current_scope()
                            ._create_unique_name(prefix_name + o._name.lstrip("_"))
                        )
                        o._orig_name = "{}{}".format(module_name, o._orig_name)

    def get_dep_exprs(self, nodes: Sequence[Node]) -> List[Expr]:
        r"""Get the dependent Exprs of the ``nodes``.
        
        Args:
            nodes: a list of :class:`Node`.
        Returns:
            A list of dependent :class:`Expr`.
        """
        if not isinstance(nodes, Sequence):
            nodes = (nodes,)
        ret = list()
        queue = list(nodes)
        visited_queue = list()
        while queue:
            node = queue.pop()
            visited_queue.append(node)

            expr = node.expr

            if expr not in ret:
                ret.append(expr)

            for i in expr.inputs:
                if i not in queue and i not in visited_queue:
                    queue.append(i)
        return ret

    def reset_inputs(self, *args, **kwargs):
        forma_mnode = self.inputs[0]
        actual_mnodes = forma_mnode.actual_node
        call_nodes = []
        for n in actual_mnodes:
            for c_expr in n.users:
                if isinstance(c_expr, CallMethod) and c_expr.method == "__call__":
                    call_nodes.append((c_expr, n))

        moudle = forma_mnode.owner
        assert moudle._is_top, "reset_inputs only support the top-level graph"

        inputs, tree_def = tree_flatten(((moudle, *args), kwargs))

        def create_node(val: Tensor):
            node = Input(type=TensorNode).outputs[0]
            node.shape = val.shape
            node.dtype = val.dtype
            return node

        formal_node_inputs = [
            forma_mnode,
        ]

        org_argdef = list(moudle.argdef_graph_map.keys())[0]
        if call_nodes:
            org_argdef = call_nodes[0][0].arg_def

        for v in inputs[1:]:
            assert isinstance(v, RawTensor)
            formal_node_inputs.append(create_node(v))

        actual_nodes = []
        for e, n in call_nodes:
            e.arg_def = tree_def
            actual_node_inputs = [
                n,
            ]
            for v in inputs[1:]:
                actual_node_inputs.append(create_node(v))

            for org_n in e.inputs:
                org_n.users.pop(e)

            e.inputs[:] = actual_node_inputs
            e.const_val = []
            actual_nodes.append(actual_node_inputs[1:])

        self._inputs[:] = formal_node_inputs
        moudle.argdef_graph_map[tree_def] = moudle.argdef_graph_map.pop(org_argdef)
        moudle.argdef_outdef_map[tree_def] = moudle.argdef_outdef_map.pop(org_argdef)
        return formal_node_inputs[1:]

    def add_input_node(
        self, shape: Tuple[int], dtype: str = "float32", name: str = "args"
    ):
        r"""Add an input node to the graph.

        The new Node will be the last of the positional arguments.

        Args:
            shape: the shape of the new input Node.
            dtype: the dtype of the new input Node.
                Default: float32
            name: the name of the new input Node. When the name is used in the graph, 
             a suffix will be added to it.
        """
        forma_mnode = self.inputs[0]
        actual_mnodes = forma_mnode.actual_node

        moudle = forma_mnode.owner
        assert moudle._is_top, "add_input_node only support the top-level graph"

        call_nodes = []
        for n in actual_mnodes:
            for c_expr in n.users:
                if isinstance(c_expr, CallMethod) and c_expr.method == "__call__":
                    call_nodes.append(c_expr)

        def create_node(name=None, is_input: bool = True):
            if is_input:
                node = Input(type=TensorNode, name=name).outputs[0]
            else:
                node = TensorNode(expr=None, name=None)
            node.shape = shape
            node.dtype = dtype
            return node

        org_argdef = list(moudle.argdef_graph_map.keys())[0]

        if call_nodes:
            org_argdef = call_nodes[0].arg_def

        args, kwargs = org_argdef.unflatten(self._inputs)
        formal_inp_node = create_node(self._create_unique_name(name), True)
        inputs, tree_def = tree_flatten(
            ((*args, formal_inp_node), kwargs),
            is_const_leaf=lambda x: not isinstance(x, (TensorNode, ModuleNode)),
        )
        self._inputs[:] = inputs[:]

        actual_inp_nodes = []
        for e in call_nodes:
            args, kwargs = e.unflatten_args(e.inputs)
            args = args + (create_node(False),)
            inputs, tree_def = tree_flatten(
                (args, kwargs),
                is_const_leaf=lambda x: not isinstance(x, (TensorNode, ModuleNode)),
            )
            e.inputs[:] = inputs[:]
            e.arg_def = tree_def
            actual_inp_nodes.append(args[-1])

        moudle.argdef_graph_map[tree_def] = moudle.argdef_graph_map.pop(org_argdef)
        moudle.argdef_outdef_map[tree_def] = moudle.argdef_outdef_map.pop(org_argdef)
        return formal_inp_node

    def reset_outputs(self, outputs):
        r"""Reset the output Nodes of the graph.
        
        .. note::

            This method only supports resetting the output of graphs
            that do not have a parent graph.
            
        Args:
            outputs: an object which inner element is Node. Support tuple, list
             dict, etc.
        
        For example, the following code

        .. code-block::

            import megengine.functional as F
            import megengine.module as M
            import megengine.traced_module as tm

            class MyModule(M.Module):
                def forward(self, x):
                    x = x + 1
                    return x

            net = MyModule()

            inp = F.zeros(shape = (1, ))
            traced_module = tm.trace_module(net, inp)
            graph = traced_module.graph
            inp_node = graph.inputs[1]
            out_node = graph.outputs[0]
            graph.reset_outputs((out_node, {"input": inp_node}))
            out = traced_module(inp)
        
        Will produce the following ``InternalGraph`` and ``out``::

            print(graph)
            print(out)

        .. code-block:: text

            MyModule.Graph (self, x) {
                    %2:     add_out = x.__add__(1, )
                    return add_out, x
            }
            (Tensor([1.], device=xpux:0), {'input': Tensor([0.], device=xpux:0)})
        """
        outputs, out_def = tree_flatten(
            outputs, is_leaf=lambda x: isinstance(x, TensorNode),
        )
        forma_mnode = self.inputs[0]

        moudle = forma_mnode.owner
        assert moudle._is_top, "reset_outputs only support the top graph"

        actual_mnodes = forma_mnode.actual_node
        call_nodes = []
        for n in actual_mnodes:
            for c_expr in n.users:
                if isinstance(c_expr, CallMethod) and c_expr.method == "__call__":
                    call_nodes.append((c_expr))

        def create_node(val: TensorNode, expr: Expr):
            node = TensorNode(expr)
            node.shape = val.shape
            node.dtype = val.dtype
            return node

        tree_def = list(moudle.argdef_graph_map.keys())[0]
        if call_nodes:
            tree_def = call_nodes[0].arg_def

        actual_nodes = []
        for e in call_nodes:
            actual_node_outputs = []
            for v in outputs:
                actual_node_outputs.append(create_node(v, e))
            e.outputs[:] = actual_node_outputs
            e.out_def = out_def
            actual_nodes.append(actual_node_outputs)

        self._outputs[:] = outputs
        moudle.argdef_outdef_map[tree_def] = out_def
        return actual_nodes

    def add_output_node(self, node: TensorNode):
        r"""Add an output node to the Graph.
        
        The Graph output will become a ``tuple`` after calling ``add_output_node``.
        The first element of the ``tuple`` is the original output, and the second 
        is the ``node``.

        For example, the following code

        .. code-block::

            import megengine.functional as F
            import megengine.module as M
            import megengine.traced_module as tm

            class MyModule(M.Module):
                def forward(self, x):
                    x = x + 1
                    return x

            net = MyModule()

            inp = F.zeros(shape = (1, ))
            traced_module = tm.trace_module(net, inp)
            graph = traced_module.graph
            inp_node = graph.inputs[1]
            out_node = graph.outputs[0]
            graph.add_output_node(inp_node)
            graph.add_output_node(out_node)
            out = traced_module(inp)
        
        Will produce the following ``InternalGraph`` and ``out``::

            print(graph)
            print(out)

        .. code-block:: text

            MyModule.Graph (self, x) {
                    %2:     add_out = x.__add__(1, )
                    return add_out, x, add_out
            }
            ((Tensor([1.], device=xpux:0), Tensor([0.], device=xpux:0)), Tensor([1.], device=xpux:0))
        """
        forma_mnode = self.inputs[0]

        moudle = forma_mnode.owner
        assert moudle._is_top, "add_output_node only support the top graph"

        actual_mnodes = forma_mnode.actual_node
        call_nodes = []

        for n in actual_mnodes:
            for c_expr in n.users:
                if isinstance(c_expr, CallMethod) and c_expr.method == "__call__":
                    call_nodes.append((c_expr))

        def create_node(val: TensorNode, expr: Expr):
            node = TensorNode(expr)
            node.shape = val.shape
            node.dtype = val.dtype
            return node

        tree_def = list(moudle.argdef_graph_map.keys())[0]
        if call_nodes:
            tree_def = call_nodes[0].arg_def

        org_out_def = moudle.argdef_outdef_map[tree_def]
        org_outs = org_out_def.unflatten(self._outputs)
        outputs, out_def = tree_flatten(
            (org_outs, node), is_leaf=lambda x: isinstance(x, TensorNode),
        )
        self._outputs[:] = outputs

        actual_out_nodes = []
        for e in call_nodes:
            actual_node = create_node(node, e)
            org_outs = org_out_def.unflatten(e.outputs)
            outputs, out_def = tree_flatten(
                (org_outs, actual_node), is_leaf=lambda x: isinstance(x, TensorNode),
            )
            e.outputs[:] = outputs
            e.out_def = out_def
            actual_out_nodes.append(actual_node)

        moudle.argdef_outdef_map[tree_def] = out_def

        return actual_out_nodes

    def insert_exprs(self, expr: Optional[Expr] = None):
        r"""Initialize the trace mode and insertion position.

        When used within a 'with' statement, this will temporary set the trace mode and
        then restore normal mode when the with statement exits::

            with graph.insert_exprs(e): # set the trace mode
                ... # trace function or module
            ... # inert exprs into graph and resotre normal mode

        Args:
            expr: the ``expr`` after which to insert. If None, the insertion position will be 
                automatically set based on the input node.

        Returns:
            A resource manager that will initialize trace mode on ``__enter__`` and 
            restore normal mode on ``__exit__``.
        """
        if expr is not None:
            assert expr.top_graph == self, "Expr to insert after is not in graph."
        return _InsertExprs(self, expr)

    def replace_node(self, repl_dict: Dict[Node, Node]):
        r"""Replace the Nodes in the graph.
        
        Args:
            repl_dict: the map {old_Node: new_Node} that specifies how to replace the Nodes.
        """
        while repl_dict:
            node, repl_node = repl_dict.popitem()
            assert type(node) == type(
                repl_node
            ), "The type of {}({}) and {}({}) are not the same".format(
                node, type(node).__name__, repl_node, type(repl_node).__name__
            )
            # check graph inputs and outputs
            for i, n in enumerate(self.outputs):
                if n is node:
                    self.outputs[i] = repl_node
            # update users of node and repl_node
            # update inputs of expr in node.users
            graph = repl_node.top_graph
            assert graph is not None
            assert graph is self
            index = -1
            if not isinstance(repl_node.expr, Input):
                index = graph._exprs.index(repl_node.expr)
            dep_exprs = self.get_dep_exprs(repl_node)
            i = 0
            while i < len(node.users):
                n = node.users[i]
                if n in graph._exprs and index >= graph._exprs.index(n):
                    i += 1
                    continue
                if n in dep_exprs:
                    logger.info("Find a loop: ignore this replacement once")
                    logger.info("node: %s" % node.__repr__())
                    logger.info("expr: %s" % n.__repr__())
                    i += 1
                    continue
                repl_node.users.append(n)
                node.users.pop(i)
                idx = n.inputs.index(node)
                n.inputs[idx] = repl_node

    def compile(self):
        r"""Delete unused expr."""
        dep_exprs = self.get_dep_exprs(self.outputs)
        i = 0
        while i < len(self._exprs):
            expr = self._exprs[i]
            if expr in dep_exprs or expr._disable_remove:
                i += 1
                continue
            for n in expr.inputs:
                n.users.remove(expr)
            self._exprs.remove(expr)

    def _reset_ids(self):
        for total_expr_id, expr in enumerate(self.exprs()):
            expr._id = total_expr_id
        for total_node_id, node in enumerate(self.nodes()):
            node._id = total_node_id
        self._total_ids = (total_node_id + 1, total_expr_id + 1)

    def interpret(self, *inputs):
        node2value = {}
        end_nodes_set = set(self._end_point)
        endnode2value = {}

        def get_all_endnode_val(n, v):
            if n in end_nodes_set:
                endnode2value[n] = v
                end_nodes_set.remove(n)
                return not end_nodes_set
            return False

        ref_count = lambda n: len(n.users) + (1 if n in self._outputs else 0)

        for n, v in zip(self._inputs, inputs):
            if ref_count(n) > 0:
                node2value[n] = [v, ref_count(n)]
            if n in self._watch_point:
                self._rst[n].append(v)
            if n in self._end_point and get_all_endnode_val(n, v):
                return list(endnode2value[i] for i in self._end_point)

        for expr in self._exprs:
            values = expr.interpret(*list(node2value[i][0] for i in expr.inputs))
            for n in expr.inputs:
                node2value[n][1] -= 1
                if node2value[n][1] == 0:
                    node2value.pop(n)
            if values is not None:
                for n, v in zip(expr.outputs, values):
                    if ref_count(n) > 0:
                        node2value[n] = [v, ref_count(n)]
                    if n in self._watch_point:
                        self._rst[n] = v
                    if self._end_point and get_all_endnode_val(n, v):
                        return list(endnode2value[i] for i in self._end_point)

        return list(node2value[i][0] for i in self._outputs)

    def eval(self, *inputs: Tuple[Tensor]):
        r"""Call this method to execute the graph.

        Args:
            inputs: the tensors corresponding to the ``graph.inputs[1:]``.
        """
        assert len(inputs) == len(self._inputs) - 1
        inp = [self._inputs[0].owner] + list(inputs)
        return self.interpret(*inp)

    def __repr__(self):
        return self.__format__()

    def __format__(self, format_spec: str = "") -> str:
        saved_format_spec = Node._set_format_spec(format_spec)
        name = ""
        if self._name:
            name = "%s.Graph" % self._name
        res = "{} ({}) {{\n\t{}\n\treturn {}\n}}".format(
            name,
            ", ".join(str(i) for i in self._inputs),
            "\n\t".join("{}".format(str(i)) for i in self._exprs),
            ", ".join(str(i) for i in self._outputs),
        )
        Node._set_format_spec(saved_format_spec)
        return res

    def __getstate__(self):
        state = self.__dict__.copy()
        if "_top_graph" in state:
            state.pop("_top_graph")
        return state


def _get_meth_name(obj, func):
    tp = obj if isinstance(obj, type) else type(obj)
    for cls in tp.mro():
        for k, v in cls.__dict__.items():
            if v == func:
                return k
    return None


def _wrapped_function(orig_func):
    @functools.wraps(orig_func)
    def wrapped_fn(*args, **kwargs):
        method_func = wrapped_fn
        if "method_func" in kwargs:
            method_func = kwargs.pop("method_func")
        if is_tracing_module():
            unset_module_tracing()
            inputs, tree_def = tree_flatten((args, kwargs))
            for i in inputs:
                if not NodeMixin.get(i, None):
                    if isinstance(i, (RawTensor, NodeMixin)):
                        NodeMixin.wrap_safe(i, Constant.make(i))
            meth_name, arg_type = None, None
            if args:
                meth_name = _get_meth_name(args[0], method_func)
                arg_type = args[0] if isinstance(args[0], type) else type(args[0])
            if meth_name and arg_type and issubclass(arg_type, RawTensor):
                self = inputs[0]
                if meth_name == "__new__":
                    if all([not isinstance(i, RawTensor) for i in inputs]):
                        # only trace Tensor.__new__() when there are tensors in args
                        set_module_tracing()
                        return orig_func(*args, **kwargs)
                    if isinstance(args[1], RawTensor):
                        node = NodeMixin.get(inputs[1])
                        inputs[1] = copy.copy(inputs[1])
                        # copy inputs[1] to avoid tensor and Tensor(tensor) share same m_tensor, which will cause they have same _NodeMixin__node in tracing.
                        NodeMixin.wrap_safe(inputs[1], node)
                        args, kwargs = tree_def.unflatten(inputs)
                    call_node = CallMethod.make(self, meth_name)
                else:
                    call_node = CallMethod.make(NodeMixin.get(self), meth_name)
                call_node.add_inputs(inputs[1:])
            else:
                call_node = CallFunction.make(orig_func)
                call_node.add_inputs(inputs)

            call_node.arg_def = tree_def
            rst = orig_func(*args, **kwargs)
            if meth_name == "__setitem__":
                rst = self
            if rst is not None:
                outputs, out_def = tree_flatten(rst, is_leaf=_is_leaf)
                call_node.out_def = out_def
            else:
                outputs = None
            call_node.add_outputs(outputs)
            set_module_tracing()
            return rst
        return orig_func(*args, **kwargs)

    return wrapped_fn


class TracedModuleBuilder(NodeMixin):

    _mod = None  # type: Module
    _body = None  # type: InternalGraph
    _is_builtin = None  # type: bool
    _argdef_graph_map = None  # type: Dict[Treedef, "InternalGraph"]
    _argdef_outdef_map = None  # type: Dict[Treedef, Treedef]
    nodes = None

    __builder_attributes__ = [
        "_mod",
        "_body",
        "_NodeMixin__node",
        "_is_builtin",
        "build",
        "_record_wrapped_nodes",
        "_argdef_graph_map",
        "_argdef_outdef_map",
        "nodes",
        "__class__",
        "__dict__",
    ]

    def __init__(self, mod, is_top_module=False):
        super(TracedModuleBuilder, self).__init__()
        assert isinstance(mod, Module)
        self._mod = mod
        self._body = None
        self._is_top = is_top_module
        self._is_builtin = (
            True
            if isinstance(mod, (Observer, _FakeQuantize))
            else module_tracer.is_builtin(mod)
        )
        if isinstance(self._mod, QATModule):
            unset_module_tracing()
            self._check_qat_module(self._mod)
            set_module_tracing()
        self._argdef_graph_map = {}
        self._argdef_outdef_map = {}

        self.nodes = set()
        # The builder will be passed to self._mod.forward as 'self' argument. If the 'forward' uses super().xxx to call method of its base classes, the trace procedure will throw exceprion, because the builder doesn't inherit from self._mod.__bases__.
        # modify self.__class__ and let the builder inherit from TracedModuleBuilder and mod.__class__.
        self.__class__ = type(
            "TracedModuleBuilder",
            (TracedModuleBuilder, mod.__class__),
            dict(TracedModuleBuilder.__dict__),
        )

    def _check_qat_module(self, qat_module):
        def isbuiltin(m):
            return m is None or module_tracer.is_builtin(m)

        if qat_module.with_act:
            act_observer = qat_module.act_observer
            act_fakequant = qat_module.act_fake_quant
            if not isbuiltin(act_observer) or not isbuiltin(act_fakequant):
                qparams = (
                    act_observer.get_qparams()
                    if hasattr(act_observer, "get_qparams")
                    else act_fakequant.get_qparams()
                )
                dtype = (
                    act_observer.dtype
                    if hasattr(act_observer, "dtype")
                    else act_fakequant.dtype
                )
                qat_module.act_observer = None
                qat_module.act_fake_quant = TM_FakeQuant(dtype)
                qat_module.act_fake_quant.set_qparams(qparams)

        if qat_module.with_weight:
            weight_observer = qat_module.weight_observer
            weight_fakequant = qat_module.weight_fake_quant
            if not isbuiltin(weight_observer) or not isbuiltin(weight_fakequant):
                qparams = (
                    weight_observer.get_qparams()
                    if hasattr(weight_observer, "get_qparams")
                    else weight_fakequant.get_qparams()
                )
                dtype = (
                    weight_observer.dtype
                    if hasattr(weight_observer, "dtype")
                    else weight_fakequant.dtype
                )
                qat_module.weight_observer = None
                qat_module.weight_fake_quant = TM_FakeQuant(dtype)
                qat_module.weight_fake_quant.set_qparams(qparams)

    def build(self):
        if self._is_builtin or isinstance(self._mod, TracedModule):
            if module_tracer.is_builtin(self._mod) or isinstance(
                self._mod, TracedModule
            ):
                mod_type = type(self._mod)
            else:
                assert isinstance(self._mod, (Observer, _FakeQuantize))
                mod_type = (
                    Observer if isinstance(self._mod, Observer) else _FakeQuantize
                )
            for node in self.nodes:
                node.module_type = mod_type

            return self._mod
        else:
            is_qat = isinstance(self._mod, QATModule)
            traced_module = TracedModule(
                self._is_top, self._argdef_graph_map, self._argdef_outdef_map, is_qat
            )
            for _, g in self._argdef_graph_map.items():
                g.compile()
                if self._is_top:
                    g._total_ids = (Node._get_next_id(), Expr._get_next_id())

            for k, v in self.__dict__.items():
                if k not in TracedModuleBuilder.__builder_attributes__:
                    if isinstance(v, TracedModuleBuilder):
                        v = v.build()
                        setattr(traced_module, k, v)
                    elif isinstance(v, RawTensor):
                        setattr(traced_module, k, v)

            if isinstance(self._mod, QATModule):
                unset_module_tracing()
                traced_module.with_act = self._mod.with_act
                traced_module.with_weight = self._mod.with_weight
                if not hasattr(traced_module, "act_fake_quant"):
                    traced_module.act_fakequant = None
                if not hasattr(traced_module, "act_observer"):
                    traced_module.act_observer = None
                if not hasattr(traced_module, "weight_fake_quant"):
                    traced_module.weight_fakequant = None
                if not hasattr(traced_module, "weight_observer"):
                    traced_module.weight_observer = None
                set_module_tracing()

            return traced_module

    def _record_wrapped_nodes(self, node):
        self.nodes.add(node)

    def __call__(self, *args, **kwargs):
        assert isinstance(self._mod, Module)
        # prepare args and kwargs for inner graph
        if "method_func" in kwargs:
            kwargs.pop("method_func")

        def mark_constant(x):
            node = NodeMixin.get(x, None)
            if node is None:  # capture as constant
                NodeMixin.wrap(x, lambda: Constant.make(x))

        inputs, tree_def = tree_flatten(((self, *args), kwargs))
        for i in inputs:
            mark_constant(i)
        callnode = CallMethod.make(NodeMixin.get(self))

        callnode.add_inputs(inputs[1:])

        callnode.arg_def = tree_def

        if (
            self._is_builtin
            or tree_def in self._argdef_graph_map
            or isinstance(self._mod, TracedModule)
        ):
            unset_module_tracing()
            rst = self._mod(*args, **kwargs)
            outputs, out_def = tree_flatten(rst, is_leaf=_is_leaf)
            set_module_tracing()
            if self._is_builtin:
                self._body = None
            elif tree_def in self._argdef_graph_map:
                self._body = self._argdef_graph_map[tree_def]
            else:
                self._mod._is_top = False
                self._body = self._mod.graph
        else:
            self_node = None
            orig_self = NodeMixin.get(self)
            top_graph = active_module_tracer().current_scope()
            graph_prefix_name = top_graph._name
            if top_graph._prefix_name:
                graph_prefix_name = "{}_{}".format(
                    top_graph._prefix_name, graph_prefix_name.lstrip("_")
                )
            module_name = orig_self._orig_name
            if top_graph._module_name:
                module_name = "{}.{}".format(top_graph._module_name, module_name)
            self._body = InternalGraph(
                orig_self._name, prefix_name=graph_prefix_name, module_name=module_name
            )
            active_module_tracer().push_scope(self._body)
            # rebind self to new input node

            if self_node:
                NodeMixin.wrap_safe(self, self_node)
                active_module_tracer().current_scope()._add_input(self_node)
            else:
                NodeMixin.wrap_safe(
                    self,
                    self_node
                    if self_node
                    else Input.make("self", NodeMixin.get_wrapped_type(self), ""),
                )
            origin_inp_node = [NodeMixin.get(i, None) for i in inputs[1:]]
            # prepare args and kwargs for inner graph
            index_args, index_kwargs = tree_def.unflatten(
                [
                    ArgsIndex(0),
                    *list(ArgsIndex(i + 1) for i in range(len(origin_inp_node))),
                ]
            )
            key2idx = getcallargs(type(self._mod).forward, *index_args, **index_kwargs)
            idx2key = {}
            for k, v in key2idx.items():
                if isinstance(v, ArgsIndex):
                    idx2key[v.index] = k
                else:
                    flatten_argidx, _ = tree_flatten(v)
                    for _i, v in enumerate(flatten_argidx):
                        if isinstance(v, ArgsIndex):
                            idx2key[v.index] = k + "_%d" % _i

            def wrap(x, name):
                if isinstance(x, (RawTensor, NodeMixin)):
                    NodeMixin.wrap(
                        x,
                        lambda: Input.make(
                            type=NodeMixin.get_wrapped_type(x), name=name
                        ),
                    )
                return x

            args = [self]
            for i, v in enumerate(inputs[1:]):
                args.append(wrap(v, idx2key[i + 1]))

            args, kwargs = tree_def.unflatten(args)
            active_module_tracer().patcher.auto_patch(
                getattr(getattr(self._mod, "forward", self._mod), "__globals__", {})
            )
            rst = type(self._mod).forward(*args, **kwargs)
            if _convert_node_flag():
                rst = _node_to_tensor(rst)[0][0]
            outputs, out_def = tree_flatten(rst, is_leaf=_is_leaf)
            for i in (
                outputs if isinstance(outputs, collections.abc.Sequence) else (outputs,)
            ):
                active_module_tracer().current_scope()._add_output(NodeMixin.get(i))
            NodeMixin.wrap_safe(self, orig_self)
            for arg, node in zip(inputs[1:], origin_inp_node):
                if node:
                    NodeMixin.wrap_safe(arg, node)
            active_module_tracer().pop_scope()

        # rebind output to outer graph
        callnode.out_def = out_def
        callnode.add_outputs(outputs)
        self._argdef_graph_map[callnode.arg_def] = self._body
        self._argdef_outdef_map[callnode.arg_def] = out_def
        return rst

    def __setattr__(self, name, value):
        object.__setattr__(self, name, value)

    def __repr__(self):
        return repr(self._mod)

    def __getattr__(self, name):
        if name not in self._mod.__dict__:
            attr = getattr(type(self._mod), name).__get__(self, type(self))
        else:
            attr = getattr(self._mod, name)
            full_name = None
            if (
                isinstance(attr, FunctionType)
                and id(attr) in active_module_tracer().patcher.patched_fn_ids
            ):
                return active_module_tracer().patcher.wrap_fn(attr)

            if id(attr) in active_module_tracer().id2name:
                full_name = active_module_tracer().id2name[id(attr)]
            if isinstance(attr, (List, Dict)):
                unset_module_tracing()
                has_module, m_container = replace_container_with_module_container(attr)
                if m_container:
                    attr = m_container
                if has_module and not m_container:
                    raise ValueError(
                        "Can not trace the module that uses the same container to store Module and Non-Module objects "
                    )
                set_module_tracing()
            if isinstance(attr, Module):
                attr = TracedModuleBuilder(attr)

            if isinstance(attr, (Module, RawTensor)):
                setattr(self, name, attr)
                active_module_tracer().id2name[id(attr)] = full_name

            if full_name:
                scope_name = active_module_tracer().current_scope()._module_name
                if scope_name:
                    full_name = full_name[len(scope_name) + 1 :]
                else:
                    full_name = name
            else:
                full_name = name
            NodeMixin.wrap(
                attr,
                lambda: GetAttr.make(
                    NodeMixin.get(self),
                    name,
                    type=NodeMixin.get_wrapped_type(attr),
                    orig_name=full_name,
                ),
            )
        return attr

    def __getattribute__(self, name):
        if name in TracedModuleBuilder.__builder_attributes__:
            return object.__getattribute__(self, name)
        else:
            wrapped = object.__getattribute__(self, name)
            class_members = dict(inspect.getmembers(self.__class__))
            if name in self._mod.__dict__:
                mod_attr = getattr(self._mod, name)
                if name in class_members:
                    if (
                        not isinstance(wrapped, TracedModuleBuilder)
                        and wrapped is not mod_attr
                    ):
                        wrapped = self.__getattr__(name)

                if isinstance(wrapped, TracedModuleBuilder):
                    if not isinstance(mod_attr, (List, Dict)):
                        assert mod_attr is wrapped._mod
                else:
                    assert mod_attr is wrapped

                full_name = None
                if id(mod_attr) in active_module_tracer().id2name:
                    full_name = active_module_tracer().id2name[id(mod_attr)]
                    scope_name = active_module_tracer().current_scope()._module_name
                    if full_name and scope_name:
                        full_name = full_name[len(scope_name) + 1 :]
                    else:
                        full_name = name
                else:
                    full_name = name
                # assert not self._is_builtin
                if isinstance(wrapped, (NodeMixin, RawTensor)):
                    NodeMixin.wrap(
                        wrapped,
                        lambda: GetAttr.make(
                            NodeMixin.get(self),
                            name,
                            type=NodeMixin.get_wrapped_type(wrapped),
                            orig_name=full_name,
                        ),
                    )

            return wrapped


class _expr_iter:
    def __init__(self, graph: InternalGraph, recursive: bool = True):
        self.graph = graph
        self.recursive = recursive

    def __iter__(self):
        for inp_node in self.graph.inputs:
            yield inp_node.expr
        for expr in self.graph._exprs:
            if isinstance(expr, CallMethod) and isinstance(expr.inputs[0], ModuleNode):
                yield expr
                if self.recursive and expr.graph is not None:
                    yield from expr.graph.exprs(self.recursive)
            else:
                yield expr


class _node_iter:
    def __init__(self, graph: InternalGraph, recursive: bool = True) -> None:
        nodes = []
        node_ids = set()
        for expr in graph.exprs(recursive):
            for n in expr.inputs + expr.outputs:
                if id(n) in node_ids:
                    continue
                nodes.append(n)
                node_ids.add(id(n))
        self.nodes = list(sorted(nodes, key=lambda x: x._id))

    def __iter__(self):
        for node in self.nodes:
            yield node


class BaseFilter:
    r"""``BaseFilter`` exposes some methods for converting ``_node_iter/_expr_iter`` to ``list``, ``dict``, etc."""

    def __init__(self, iter: Iterable):
        self._iter = iter

    def __iter__(self):
        return iter(self._iter)

    def as_list(self):
        r"""Consume this iterator and return its content as a list.

        Returns:
            A list of ``Node`` or ``Expr``.
        """
        return list(self)

    def as_dict(self):
        r"""Construct an ordered dict to map from ``id`` to objects in this iterator.

        Returns:
            An :class:`OrderedDict`.
        """
        return collections.OrderedDict((i._id, i) for i in self)

    def as_unique(self):
        """Assert that this iterator yields only one ``Node`` or ``Expr`` and return it.

        Rerurns:
            A ``Node`` or ``Expr``.
        """
        rst = self.as_list()
        assert len(rst) == 1, "{} elements found".format(len(rst))
        (elem,) = self
        return elem

    def as_count(self):
        r"""Consume this iterator and get the number of elements."""
        return sum(1 for _ in self)


class ExprFilter(BaseFilter):
    """Filter on Expr iterator.
    This class is an iterator of :class:`.Expr` objects and multiple 
    filtering conditions and mappers can be chained.
    """

    def call_function(self, func):
        r"""Filter by specific ``CallFunction.func``.
        See :meth:`~.InternalGraph.get_function_by_type` for details.
        """
        return ExprFilterCallFunction(self, func)

    def call_method(self, method):
        r"""Filter by specific ``CallMethod.method``.
        See :meth:`~.InternalGraph.get_function_by_type` for details.
        """
        return ExprFilterCallMethod(self, method)

    def expr_id(self, expr_id: List[int]):
        r"""Filter Exprs by their ``id``.
        See :meth:`~.InternalGraph.get_function_by_type` for details.
        """
        return ExprFilterExprId(self, expr_id)


class NodeFilter(BaseFilter):
    """Filter on Node iterator.
    This class is an iterator of :class:`.Node` objects and multiple 
    filtering conditions and mappers can be chained.
    """

    def type(self, owner_type):
        r"""Filter by specific Module type.
        See :meth:`~.InternalGraph.get_module_by_type` for details.
        """
        return NodeFilterType(self, owner_type)

    def node_id(self, node_id: List[int]):
        r"""Filter Nodes by their ``id``.
        See :meth:`~.InternalGraph.get_node_by_id` for details.
        """
        return NodeFilterNodeId(self, node_id)

    def name(self, name: str, ignorecase: bool = True):
        r"""Filter Nodes by their full name.
        See :meth:`~.InternalGraph.get_node_by_name` for details.
        """
        return NodeFilterName(self, name, ignorecase)


class NodeFilterType(NodeFilter):
    """See :meth:`~.InternalGraph.get_module_by_type`"""

    def __init__(self, expr_iter, owner_type):
        super().__init__(expr_iter)
        self.owner_type = owner_type

    def __iter__(self):
        for node in self._iter:
            if not isinstance(node, ModuleNode):
                continue
            if not hasattr(node, "owner"):
                continue
            if isinstance(node.owner, self.owner_type):
                yield node


class NodeFilterNodeId(NodeFilter):
    """See :meth:`~.InternalGraph.get_node_by_id`"""

    def __init__(self, expr_iter, node_id: List[int]):
        super().__init__(expr_iter)
        if not isinstance(node_id, Sequence):
            node_id = [node_id]
        self.node_id = node_id

    def __iter__(self):
        for node in self._iter:
            if node._id in self.node_id:
                yield node


class NodeFilterName(NodeFilter):
    """See :meth:`~.InternalGraph.get_node_by_name`"""

    _re = None

    def __init__(self, node_iter, pattern, ignorecase):
        super().__init__(node_iter)
        self.pattern = pattern
        self._re = self.make_re(pattern, ignorecase)

    @classmethod
    def make_re(cls, pattern, ignorecase=True):
        assert isinstance(pattern, str), "bad pattern: {!r}".format(pattern)
        assert isinstance(ignorecase, bool)
        flags = 0
        if ignorecase:
            flags |= re.IGNORECASE
        return re.compile(fnmatch.translate(pattern), flags=flags)

    def __iter__(self):
        for i in self._iter:
            graph = i.top_graph
            name = "{}_{}".format(graph._name, i._name.lstrip("_"))
            if graph._prefix_name:
                name = "{}_{}".format(graph._prefix_name, name.lstrip("_"))
            if self.pattern == name or self._re.match(name):
                yield i


class ExprFilterCallFunction(ExprFilter):
    """See :meth:`~.InternalGraph.get_function_by_type`"""

    def __init__(self, expr_iter, func: Callable = None):
        super().__init__(expr_iter)
        self.func = func

    def __iter__(self):
        for expr in self._iter:
            if not isinstance(expr, CallFunction):
                continue
            if self.func is None or expr.func == self.func:
                yield expr


class ExprFilterCallMethod(ExprFilter):
    """See :meth:`~.InternalGraph.get_method_by_type`"""

    def __init__(self, expr_iter, method: str = None):
        super().__init__(expr_iter)
        self.method = method

    def __iter__(self):
        for expr in self._iter:
            if not isinstance(expr, CallMethod):
                continue
            if self.method is None or expr.method == self.method:
                yield expr


class ExprFilterExprId(ExprFilter):
    """See :meth:`~.InternalGraph.get_expr_by_id`"""

    def __init__(self, expr_iter, expr_id: List[int]):
        super().__init__(expr_iter)
        if not isinstance(expr_id, Sequence):
            expr_id = [expr_id]
        self.expr_id = expr_id

    def __iter__(self):
        for expr in self._iter:
            if expr._id in self.expr_id:
                yield expr


class TracedModule(Module):
    r"""``TracedModule`` is the Module created by tracing normal module. 
    
    It owns an argdef to graph(InternalGraph) map. The forward method of ``TracedModule`` 
    will get a graph from ``argdef_graph_map`` according to the argdef of input ``args/kwargs`` 
    and interpret it.
    
    .. note::
        ``TracedModule`` can only be created by :func:`~.trace_module`. See :func:`~.trace_module` 
        for more details.
    """
    # m_node = None  # type: ModuleNode
    argdef_graph_map = None
    argdef_outdef_map = None

    def __init__(self, is_top, argdef_graph_map, argdef_outdef_map, is_qat=False):
        super(TracedModule, self).__init__()
        self.argdef_graph_map = argdef_graph_map
        self.argdef_outdef_map = argdef_outdef_map
        self._is_top = is_top
        self.watch_points = []
        self.watch_node_value = {}
        self.end_points = []
        self.is_qat = is_qat

    def forward(self, *args, **kwargs):
        inputs, treedef = tree_flatten(((self, *args), kwargs))
        assert treedef in self.argdef_graph_map
        inputs = filter(
            lambda i: isinstance(i, (Module, TracedModuleBuilder, RawTensor)), inputs
        )  # allow TracedModuleBuilder for retrace.
        outputs = self.argdef_graph_map[treedef].interpret(*inputs)
        if self.watch_points:
            self.watch_node_value = {}
            for n in self.watch_points:
                self.watch_node_value[n] = n.top_graph._rst.pop(n)

        if self.end_points:
            return outputs

        out_def = self.argdef_outdef_map[treedef]
        outputs = out_def.unflatten(outputs)

        return outputs

    def set_watch_points(self, nodes):
        r"""Initialize the :attr:`~.TracedModule.watch_points`.

        You can call this function to get the ``Tensor/Module`` corresponding to a ``Node`` at runtime.
        
        Args:
            nodes: a list of ``Node``.
        
        For example, the following code

        .. code-block::

            import megengine.module as M
            import megengine as mge
            import megengine.traced_module as tm

            class MyModule(M.Module):
                def forward(self, x):
                    x = x + 1 + 2
                    return x

            net = MyModule()

            inp = mge.Tensor([0])
            traced_module = tm.trace_module(net, inp)
            add_1_node = traced_module.graph.get_node_by_id(2).as_unique()
            traced_module.set_watch_points(add_1_node)

            out = traced_module(inp)
        
        Will get the following ``watch_node_value``::

            print(traced_module.watch_node_value)

        .. code-block:: text

            {add_out: Tensor([1.], device=xpux:0)}
        """
        if not isinstance(nodes, Sequence):
            nodes = [nodes]
        self.watch_points = nodes
        if nodes:
            nodes[0].top_graph._watch_point = []
        for n in nodes:
            n.top_graph._watch_point.append(n)

    def clear_watch_points(self):
        r"""Clear the :attr:`~.TracedModule.watch_points` and :attr:`~.TracedModule.watch_node_value`.
        """
        for n in self.watch_points:
            n.top_graph._watch_point = []
        self.watch_points = []
        self.watch_node_value = {}

    def set_end_points(self, nodes: Sequence[Node]):
        r"""Initialize the :attr:`~.TracedModule.end_points`.

        When all the ``nodes`` are generated, the Module will stop execution and return directly.
        
        Args:
            nodes: a list of ``Node``.

        For example, the following code

        .. code-block::

            import megengine.module as M
            import megengine as mge
            import megengine.traced_module as tm

            class MyModule(M.Module):
                def forward(self, x):
                    x = x + 1 + 2
                    return x

            net = MyModule()

            inp = mge.Tensor([0])
            traced_module = tm.trace_module(net, inp)
            add_1_node = traced_module.graph.get_node_by_id(2).as_unique()
            traced_module.set_end_points(add_1_node)

            out = traced_module(inp)
        
        Will get the following ``out``::

            print(out)

        .. code-block:: text

            [Tensor([1.], device=xpux:0)]
        """
        if not isinstance(nodes, Sequence):
            nodes = [nodes]
        self.end_points = nodes
        graphs = list(self.argdef_graph_map.values())
        for n in nodes:
            assert n.top_graph in graphs
            n.top_graph._end_point.append(n)

    def clear_end_points(self):
        r"""Clear the :attr:`~.TracedModule.end_points`.
        """
        for n in self.end_points:
            n.top_graph._end_point = []
        self.end_points = []

    @property
    def graph(self) -> InternalGraph:
        """Return the ``InternalGraph`` of this ``TracedModule``
        """
        if self._is_top:
            self._update_ref()
        assert len(self.argdef_graph_map) == 1
        return list(self.argdef_graph_map.values())[0]

    def _update_ref(self, actual_node_map: Union[Dict] = None, top_graph=None):
        for inp_def, graph in self.argdef_graph_map.items():
            if top_graph is not None:
                graph._top_graph = weakref.ref(top_graph)
            for n in graph._inputs + graph.outputs:
                n._top_graph = weakref.ref(graph)
            graph._inputs[0]._owner = weakref.ref(self)
            for i, n in enumerate(graph._inputs):
                n.actual_node = []
                if actual_node_map is not None and inp_def in actual_node_map.keys():
                    n.actual_node = list(list(zip(*(actual_node_map[inp_def])))[i])
            node2obj = {}
            next_actual_node_map = collections.defaultdict(
                lambda: collections.defaultdict(list)
            )
            node2obj[graph._inputs[0]] = self
            for expr in graph._exprs:
                for n in expr.inputs + expr.outputs:
                    n._top_graph = weakref.ref(graph)
                expr._top_graph = weakref.ref(graph)
                if isinstance(expr, GetAttr) and isinstance(
                    expr.outputs[0], ModuleNode
                ):
                    obj = getattr(node2obj[expr.inputs[0]], expr.name)
                    expr.outputs[0]._owner = weakref.ref(obj)
                    node2obj[expr.outputs[0]] = obj
                if isinstance(expr, Constant) and isinstance(
                    expr.outputs[0], ModuleNode
                ):
                    obj = expr.value
                    expr.outputs[0]._owner = weakref.ref(obj)
                    node2obj[expr.outputs[0]] = obj
                if (
                    isinstance(expr, CallMethod)
                    and expr.method == "__call__"
                    and isinstance(expr.inputs[0], ModuleNode)
                ):
                    obj = node2obj[expr.inputs[0]]
                    if expr.arg_def is not None:
                        next_actual_node_map[obj][expr.arg_def].append(expr.inputs)

            for obj in node2obj.values():
                if obj is self:
                    continue
                mnode_map = None
                if obj in next_actual_node_map.keys():
                    mnode_map = next_actual_node_map[obj]
                if isinstance(obj, TracedModule):
                    obj._update_ref(mnode_map, graph)

    def flatten(self):
        r"""Get a new TracedModule, which eliminates ``GetAttr`` and has no hierarchy.

        Retruns:
            A new :class:`TracedModule`.
        """
        new_module = copy.deepcopy(self)
        assert active_module_tracer() is None
        id2name = _init_id2name(new_module, "self")
        set_active_module_tracer(module_tracer(lambda x: x, {}))
        active_module_tracer().push_scope(new_module.graph)

        def _flatten_subgraph(
            parent_graph: InternalGraph,
            graph: InternalGraph,
            module: Module,
            call=None,
            prefix_name="",
            module_name="",
        ):
            if isinstance(prefix_name, str) and prefix_name and prefix_name[-1] != "_":
                prefix_name += "_"
            if isinstance(module_name, str) and module_name:
                module_name += "."
            if graph is None or module.is_qat:
                assert not isinstance(module, TracedModule) or module.is_qat
                const = Constant(module, id2name[id(module)])
                m_node = call.inputs[0]
                if m_node.top_graph != active_module_tracer().current_scope():
                    m_node._name = (
                        active_module_tracer()
                        .current_scope()
                        ._create_unique_name(prefix_name)
                    )
                    m_node._orig_name = id2name[id(module)][5:]
                const.outputs[0] = m_node
                const.outputs[0].expr = const
                return [const, call]
            if call is not None:
                graph = copy.deepcopy(graph)
            exprs = []
            node2obj = {}
            node2obj[graph._inputs[0]] = module
            if call:
                node2obj[call.inputs[0]] = module

            # replace inputs for submodule's exprx
            if call:
                repl_dict = dict(zip(graph._inputs, call.inputs))
                for ind, out in enumerate(graph.outputs):
                    if isinstance(out.expr, Input):
                        assert out in repl_dict
                        call_out = call.outputs[ind]
                        for expr in call.outputs[ind].users:
                            for index, inp in enumerate(expr.inputs):
                                if inp is call_out:
                                    expr.inputs[index] = repl_dict[out]
                                    repl_dict[out].users.append(expr)
                        if parent_graph is not None:
                            for index, parent_out in enumerate(parent_graph._outputs):
                                if parent_out is call_out:
                                    parent_graph._outputs[index] = repl_dict[out]
                        continue
                    repl_dict[out] = call.outputs[ind]

                graph._replace_inputs_outputs(repl_dict, prefix_name, module_name)

            for expr in graph._exprs:
                if isinstance(expr, GetAttr):
                    # replace GetAttr with Constant
                    if isinstance(expr.outputs[0], TensorNode):
                        const = Constant(getattr(node2obj[expr.inputs[0]], expr.name))
                        const.outputs = expr.outputs
                        const.outputs[0].expr = const
                        exprs.append(const)
                    elif isinstance(expr.outputs[0], ModuleNode):
                        node2obj[expr.outputs[0]] = getattr(
                            node2obj[expr.inputs[0]], expr.name
                        )

                elif isinstance(expr, CallMethod):
                    obj_node = expr.inputs[0]
                    if isinstance(obj_node, ModuleNode):
                        pre_expr = expr.inputs[0].expr
                        if isinstance(pre_expr, GetAttr):
                            (obj,) = pre_expr.interpret(node2obj[pre_expr.inputs[0]])
                            expr_graph = (
                                obj.argdef_graph_map[expr.arg_def]
                                if hasattr(obj, "argdef_graph_map")
                                else None
                            )
                            exprs.extend(
                                _flatten_subgraph(
                                    graph,
                                    expr_graph,
                                    obj,
                                    expr,
                                    prefix_name + obj_node._name.lstrip("_"),
                                    module_name + obj_node._orig_name,
                                )
                            )
                        else:
                            # module has been replaced.
                            assert isinstance(pre_expr, Constant)
                            exprs.append(expr)
                    else:
                        exprs.append(expr)
                else:
                    exprs.append(expr)

            if call is not None:
                for i in call.inputs:
                    i.users.remove(call)
            return exprs

        new_module.graph._exprs = _flatten_subgraph(None, new_module.graph, new_module)
        new_module.graph.compile()
        set_active_module_tracer(None)
        new_module.graph._reset_ids()
        return new_module

    def __getstate__(self):
        d = self.__dict__
        for k in Module.__dict__:
            d.pop(k, None)
        return d


def cpp_apply_module_trace(opdef, *args):
    return Apply.apply_module_trace_hook(opdef, *args)


def register_as_builtin(mod_cls: Type[Module]) -> None:
    r"""Registers class ``mod_cls`` (subclass of :class:`~.Module`) as builtin module.

    Args:
        mod_cls: the module class which will be treated as builtin module in tracing.
    """
    module_tracer.register_as_builtin(mod_cls)


def wrap(func: Callable):
    r"""Call this function to register ``func`` as a builtin function.

    This function can be called at module-level scope to register ``func`` as a builtin function.
    A builtin function will be converted to a :class:`CallFunction` Expr in tracing::

        def my_func(x, y):
            return x + y

        import megengine.traced_module as tm
        tm.wrap(my_func)

    This function can also equivalently be used as a decorator::

        @tm.wrap
        def my_func(x, y):
            return x + y
    
    Args:
        func: the function of the global function to insert into the graph when it's called.
    """
    assert callable(func), "func must be a callable"
    assert hasattr(func, "__code__")
    fn_name = func.__code__.co_name
    currentframe = inspect.currentframe()
    assert currentframe is not None
    f = currentframe.f_back
    assert f is not None
    assert (
        f.f_code.co_name == "<module>"
    ), "wrap must be called at the top level of a module"
    Patcher._builtin_functions.append((f.f_globals, fn_name))
    return func


def _register_all_builtin_module():

    for sub_mod in [M, M.qat, M.quantized]:
        for m in getmembers(sub_mod):
            if (
                isclass(m[1])
                and issubclass(m[1], M.Module)
                and m[1] is not M.Sequential
            ):
                module_tracer.register_as_builtin(m[1])

    module_tracer.register_as_builtin(Observer)
    module_tracer.register_as_builtin(MinMaxObserver)
    module_tracer.register_as_builtin(SyncMinMaxObserver)
    module_tracer.register_as_builtin(ExponentialMovingAverageObserver)
    module_tracer.register_as_builtin(SyncExponentialMovingAverageObserver)
    module_tracer.register_as_builtin(HistogramObserver)
    module_tracer.register_as_builtin(PassiveObserver)

    module_tracer.register_as_builtin(LSQ)
    module_tracer.register_as_builtin(TQT)
    module_tracer.register_as_builtin(FakeQuantize)
    module_tracer.register_as_builtin(TM_FakeQuant)


def trace_module(
    mod: Module, *args: Tuple[Any], **kwargs: Dict[str, Any]
) -> TracedModule:
    r"""Traces module ``mod`` and returns corresponding :class:`TracedModule`.

    Args:
        mod: the module will be converted to :class:`TracedModule`.
        args: the positional arguments passed to forward method of ``mod``.
        kwargs: the keyword arguments passed to forward method of ``mod``.
    """
    assert active_module_tracer() is None
    assert isinstance(mod, Module)
    try:
        use_sym_shape = set_symbolic_shape(True)
        set_module_tracing()
        set_active_module_tracer(
            module_tracer(_wrapped_function, _init_id2name(mod, "self"))
        )
        for cls in [Expr, Node]:
            cls._set_next_id(0)
        with active_module_tracer().patcher:
            global_scope = InternalGraph(name="")
            active_module_tracer().push_scope(global_scope)
            builder = TracedModuleBuilder(mod, True)
            name = mod._name if mod._name else mod.__class__.__name__
            NodeMixin.wrap_safe(builder, Input.make(name, ModuleNode, orig_name="self"))
            inputs, _ = tree_flatten((args, kwargs))
            for _, i in enumerate(inputs):
                # assert isinstance(i, Tensor), "not support "
                if isinstance(i, RawTensor):
                    NodeMixin.wrap_safe(
                        i, Input.make("arg_{}".format(_), NodeMixin.get_wrapped_type(i))
                    )
            builder(*args, **kwargs)
            active_module_tracer().pop_scope()
            traced_mod = builder.build()
            traced_mod.graph._reset_ids()
            return traced_mod
    finally:
        set_symbolic_shape(use_sym_shape)
        set_active_module_tracer(None)
        unset_module_tracing()