diff --git a/imperative/CMakeLists.txt b/imperative/CMakeLists.txt
index 3bbdeffd0befd82baa263a72ec689eb90cfd8f53..cdff2af50d3558160fd6190dc27ae19fab94502d 100644
--- a/imperative/CMakeLists.txt
+++ b/imperative/CMakeLists.txt
@@ -45,30 +45,6 @@ add_custom_command(
 
 add_custom_target(gen_opr_py DEPENDS ${GEN_OPS_FILE})
 
-##################### generate opdef c header and python binding ##############
-
-set(OP_DEF_HEADER_OUT_DIR ${CMAKE_CURRENT_BINARY_DIR}/src/include)
-file(MAKE_DIRECTORY ${OP_DEF_HEADER_OUT_DIR}/megbrain/imperative/opdef)
-set(OP_DEF_HEADER ${OP_DEF_HEADER_OUT_DIR}/megbrain/imperative/opdef/all.h)
-set(OP_DEF_PYTHON_BINDING_OUT_DIR ${MEGENGINE_DIR}/${PACKAGE_NAME}/src)
-file(MAKE_DIRECTORY ${OP_DEF_PYTHON_BINDING_OUT_DIR})
-set(OP_DEF_PYTHON_BINDING ${OP_DEF_PYTHON_BINDING_OUT_DIR}/opdef.inl)
-set(OP_PARAM_DEF ${CMAKE_CURRENT_BINARY_DIR}/opr_param_defs.py)
-set(GEN_OP_DEF_SCRIPT ${CMAKE_CURRENT_SOURCE_DIR}/python/tools/gen_op_defs.py)
-
-add_custom_command(
-    OUTPUT ${OP_DEF_HEADER} ${OP_DEF_PYTHON_BINDING}
-    COMMAND ${PYTHON_EXECUTABLE} ${GEN_OP_DEF_SCRIPT} ${OP_PARAM_DEF} ${OP_DEF_HEADER}
-    COMMAND ${PYTHON_EXECUTABLE} ${GEN_OP_DEF_SCRIPT} -t py ${OP_PARAM_DEF} ${OP_DEF_PYTHON_BINDING}
-    DEPENDS ${GEN_OP_DEF_SCRIPT} ${OP_PARAM_DEF}
-    VERBATIM
-)
-
-add_custom_target(gen_op_def_internal DEPENDS ${OP_DEF_HEADER} ${OP_DEF_PYTHON_BINDING})
-add_library(gen_op_def INTERFACE)
-target_include_directories(gen_op_def INTERFACE ${OP_DEF_HEADER_OUT_DIR} ${OP_DEF_PYTHON_BINDING_OUT_DIR})
-add_dependencies(gen_op_def gen_op_def_internal)
-
 ##################### end of opdef generation #########################
 
 set(VERSION_SCRIPT ${CMAKE_CURRENT_SOURCE_DIR}/src/version.ld)
@@ -77,9 +53,9 @@ add_custom_target(_version_ld SOURCES ${VERSION_SCRIPT})
 add_subdirectory(${PROJECT_SOURCE_DIR}/third_party/pybind11 ${PROJECT_BINARY_DIR}/third_party/pybind11)
 pybind11_add_module(${MODULE_NAME} NO_EXTRAS ${SRCS})
 if (APPLE OR MSVC OR WIN32)
-    target_link_libraries(${MODULE_NAME} PRIVATE gen_op_def megbrain megdnn)
+    target_link_libraries(${MODULE_NAME} PRIVATE megbrain megdnn)
 else()
-    target_link_libraries(${MODULE_NAME} PRIVATE gen_op_def megbrain megdnn -Wl,--version-script=${VERSION_SCRIPT})
+    target_link_libraries(${MODULE_NAME} PRIVATE megbrain megdnn -Wl,--version-script=${VERSION_SCRIPT})
 endif()
 if (MGE_WITH_DISTRIBUTED)
     message("Imperative configured to link megray")
diff --git a/imperative/python/megengine/functional/distributed.py b/imperative/python/megengine/functional/distributed.py
index 92e93f84601a833e864fb34c6d3ddf24c7dc5434..ebb81cf7a2ab8d094a85343d8fa81d27aa6349f2 100644
--- a/imperative/python/megengine/functional/distributed.py
+++ b/imperative/python/megengine/functional/distributed.py
@@ -8,7 +8,7 @@
 # "AS IS" BASIS, WITHOUT ARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 from typing import Optional, Tuple
 
-from ..core._imperative_rt.ops import CollectiveCommDefModeEnum
+from ..core._imperative_rt.ops import CollectiveCommMode
 from ..core.autodiff.builtin_op_utils import builtin_op_get_backward_fn
 from ..core.autodiff.grad import (
     Tracer,
@@ -135,7 +135,7 @@ def reduce_sum(
     :param group: communication group
     :param device: execute placement
     """
-    mode = CollectiveCommDefModeEnum.REDUCE_SUM
+    mode = CollectiveCommMode.REDUCE_SUM
     return collective_comm(inp, mode, group, device)
 
 
@@ -148,7 +148,7 @@ def broadcast(
     :param group: communication group
     :param device: execute placement
     """
-    mode = CollectiveCommDefModeEnum.BROADCAST
+    mode = CollectiveCommMode.BROADCAST
     return collective_comm(inp, mode, group, device)
 
 
@@ -161,7 +161,7 @@ def all_gather(
     :param group: communication group
     :param device: execute placement
     """
-    mode = CollectiveCommDefModeEnum.ALL_GATHER
+    mode = CollectiveCommMode.ALL_GATHER
     return collective_comm(inp, mode, group, device)
 
 
@@ -174,7 +174,7 @@ def reduce_scatter_sum(
     :param group: communication group
     :param device: execute placement
     """
-    mode = CollectiveCommDefModeEnum.REDUCE_SCATTER_SUM
+    mode = CollectiveCommMode.REDUCE_SCATTER_SUM
     return collective_comm(inp, mode, group, device)
 
 
@@ -187,7 +187,7 @@ def all_reduce_sum(
     :param group: communication group
     :param device: execute placement
     """
-    mode = CollectiveCommDefModeEnum.ALL_REDUCE_SUM
+    mode = CollectiveCommMode.ALL_REDUCE_SUM
     return collective_comm(inp, mode, group, device)
 
 
@@ -200,7 +200,7 @@ def all_reduce_max(
     :param group: communication group
     :param device: execute placement
     """
-    mode = CollectiveCommDefModeEnum.ALL_REDUCE_MAX
+    mode = CollectiveCommMode.ALL_REDUCE_MAX
     return collective_comm(inp, mode, group, device)
 
 
@@ -213,7 +213,7 @@ def all_reduce_min(
     :param group: communication group
     :param device: execute placement
     """
-    mode = CollectiveCommDefModeEnum.ALL_REDUCE_MIN
+    mode = CollectiveCommMode.ALL_REDUCE_MIN
     return collective_comm(inp, mode, group, device)
 
 
@@ -226,7 +226,7 @@ def gather(
     :param group: communication group
     :param device: execute placement
     """
-    mode = CollectiveCommDefModeEnum.GATHER
+    mode = CollectiveCommMode.GATHER
     return collective_comm(inp, mode, group, device)
 
 
@@ -239,7 +239,7 @@ def scatter(
     :param group: communication group
     :param device: execute placement
     """
-    mode = CollectiveCommDefModeEnum.SCATTER
+    mode = CollectiveCommMode.SCATTER
     return collective_comm(inp, mode, group, device)
 
 
@@ -252,7 +252,7 @@ def all_to_all(
     :param group: communication group
     :param device: execute placement
     """
-    mode = CollectiveCommDefModeEnum.ALL_TO_ALL
+    mode = CollectiveCommMode.ALL_TO_ALL
     return collective_comm(inp, mode, group, device)
 
 
diff --git a/imperative/python/src/ops.cpp b/imperative/python/src/ops.cpp
index b7f1e01e799355006e6948b05bb1503a400adec7..abedeeea0ac49f113d0b622a9a82b218ef090b73 100644
--- a/imperative/python/src/ops.cpp
+++ b/imperative/python/src/ops.cpp
@@ -23,7 +23,7 @@
 namespace py = pybind11;
 
 void init_ops(py::module m) {
-    #include "opdef.inl"
+    using namespace mgb::imperative;
 
     py::class_<OprAttr, std::shared_ptr<OprAttr>, OpDef>(m, "OprAttr")
         .def(py::init<>())
@@ -43,6 +43,21 @@ void init_ops(py::module m) {
     py::class_<GetVarShape, std::shared_ptr<GetVarShape>, OpDef>(m, "GetVarShape")
         .def(py::init());
 
+#define V(m) .value(#m, CollectiveComm::Mode::m)
+    py::enum_<CollectiveComm::Mode>(m, "CollectiveCommMode")
+        V(REDUCE_SUM)
+        V(BROADCAST)
+        V(ALL_GATHER)
+        V(REDUCE_SCATTER_SUM)
+        V(ALL_REDUCE_SUM)
+        V(ALL_REDUCE_MAX)
+        V(ALL_REDUCE_MIN)
+        V(ALL_REDUCE_PROD)
+        V(GATHER)
+        V(SCATTER)
+        V(ALL_TO_ALL);
+#undef V
+
     py::class_<CollectiveComm, std::shared_ptr<CollectiveComm>, OpDef>(m, "CollectiveComm")
         .def(py::init<>())
         .def_readwrite("key", &CollectiveComm::key)
diff --git a/imperative/python/tools/gen_op_defs.py b/imperative/python/tools/gen_op_defs.py
deleted file mode 100755
index e892a0f5d34c66a2e7853d3a0190d479d2389307..0000000000000000000000000000000000000000
--- a/imperative/python/tools/gen_op_defs.py
+++ /dev/null
@@ -1,504 +0,0 @@
-# -*- coding: utf-8 -*-
-# MegEngine is Licensed under the Apache License, Version 2.0 (the "License")
-#
-# Copyright (c) 2014-2020 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 argparse
-import collections
-import textwrap
-import os
-import hashlib
-import struct
-
-class member_defs:
-    """contain classes to define members of an opr param"""
-
-    Dtype = collections.namedtuple('Dtype', ['cname', 'pycvt', 'pyfmt',
-                                             'cppjson', 'cname_attr'])
-    Dtype.__new__.__defaults__ = ('', )
-    uint32 = Dtype('uint32_t', 'int', 'I', 'NumberInt')
-    uint64 = Dtype('uint64_t', 'int', 'Q', 'NumberInt',
-                   'alignas(sizeof(uint64_t)) ')
-    int32 = Dtype('int32_t', 'int', 'i', 'NumberInt')
-    float32 = Dtype('float', 'float', 'f', 'Number')
-    float64 = Dtype('double', 'float', 'd', 'Number')
-    dtype = Dtype('DTypeEnum', '_as_dtype_num', 'I', 'Number')
-    bool = Dtype('bool', 'bool', '?', 'Bool')
-
-    class Base:
-        pass
-
-
-    class Doc:
-        """wrap an identifier to associate document
-
-        note: if the doc starts with a linebreak, it would not be reforamtted.
-        """
-        __slots__ = ['id', 'doc']
-
-        def __init__(self, id_, doc):
-            assert isinstance(id_, str) and isinstance(doc, str), (id_, doc)
-            self.id = id_
-            self.doc = doc
-
-        @property
-        def no_reformat(self):
-            """whether reformat is disallowed for this doc string"""
-            return self.doc.startswith('\n')
-
-        @property
-        def raw_lines(self):
-            """the doc lines when ``no_format`` is true"""
-            ret = self.doc.split('\n')
-            assert not ret[0]
-            return ret[1:]
-
-        @classmethod
-        def make(cls, v):
-            """make doc object from str or doc"""
-            if isinstance(v, cls):
-                return v
-            assert isinstance(v, str)
-            return cls(v, '')
-
-        def __str__(self):
-            return self.id
-
-        def __eq__(self, rhs):
-            if isinstance(rhs, str):
-                return self.id == rhs
-            return (isinstance(rhs, Doc) and
-                    (self.id, self.doc) == (rhs.id, rhs.doc))
-
-
-    class Enum(Base):
-        """define an enum; the result would contain both an enum class def and its
-        corresponding data field
-
-        :param default: index of default member value
-
-        :attr name_field: name of the data field of this enum in the param
-            struct
-        :attr member_alias: list of (member, alias) pairs
-        """
-        __slots__ = ['name', 'name_field', 'members', 'default',
-                     'member_alias']
-
-        all_enums = {}
-        """(param_name, name) => enum"""
-
-        def __init__(self, param_name, name, name_field, members, default,
-                     member_alias):
-            name = member_defs.Doc.make(name)
-            assert name.id[0].isupper()
-            members = tuple(map(member_defs.Doc.make, members))
-            if isinstance(default, str):
-                if default not in name_field:
-                    raise ValueError(
-                        "Default value '{}' does not exist.".format(default))
-                default = name_field.index(default)
-            assert isinstance(default, int)
-            self.name = name
-            self.name_field = self.get_name_field(name.id, name_field)
-            self.members = members
-            self.default = default
-
-            self.all_enums[(param_name, name.id)] = self
-
-            assert isinstance(member_alias, list)
-            self.member_alias = member_alias
-
-        @classmethod
-        def get_name_field(cls, name, name_field):
-            if name_field is None:
-                name_field = name[0].lower() + name[1:]
-            assert isinstance(name_field, str)
-            return name_field
-
-    class Field(Base):
-        """define a normal data field"""
-        __slots__ = ['name', 'dtype', 'default']
-
-        def __init__(self, name, dtype, default):
-            assert isinstance(dtype, member_defs.Dtype)
-            self.name = member_defs.Doc.make(name)
-            self.dtype = dtype
-            self.default = default
-
-    class Const(Base):
-        """define a const data field"""
-        __slots__ = ['name', 'dtype', 'default']
-
-        def __init__(self, name, dtype, default):
-            assert isinstance(dtype, member_defs.Dtype)
-            self.name = member_defs.Doc.make(name)
-            self.dtype = dtype
-            self.default = default
-
-    class EnumAlias(Base):
-        """alias of enum type from another param"""
-        __slots__ = ['name', 'name_field', 'src_class', 'src_name', 'default']
-
-        def __init__(self, name, name_field, src_class, src_name, default):
-            self.name = name
-            self.name_field = member_defs.Enum.get_name_field(name, name_field)
-            self.src_class = src_class
-            if src_name is None:
-                src_name = name
-            self.src_name = src_name
-            self.default = default
-
-        @property
-        def src_enum(self):
-            """source Enum class"""
-            return member_defs.Enum.all_enums[(self.src_class, self.src_name)]
-
-        def get_default(self):
-            """get default index; fallback to src index if default is not
-            set"""
-            if self.default is None:
-                return self.src_enum.default
-            return self.default
-
-
-class ParamDef:
-    """"""
-    __all_tags = set()
-    all_param_defs = []
-
-    __slots__ = ['name', 'members', 'tag', 'is_legacy']
-
-    def __init__(self, name, doc='', *, version=0, is_legacy=False):
-        self.members = []
-        self.all_param_defs.append(self)
-        h = hashlib.sha256(name.encode('utf-8'))
-        if version:
-            h.update(struct.pack('<I', version))
-        if is_legacy:
-            name += 'V{}'.format(version)
-        self.name = member_defs.Doc(name, doc)
-        self.tag = int(h.hexdigest()[:8], 16)
-        self.is_legacy = is_legacy
-        if self.tag < 1024:
-            self.tag += 1024
-        assert self.tag not in self.__all_tags, (
-            'tag hash confliction: name={} tag={}'.format(name, self.tag))
-        self.__all_tags.add(self.tag)
-
-    def add_fields(self, dtype, *names_defaults):
-        assert isinstance(dtype, str)
-        dtype = getattr(member_defs, dtype)
-        assert len(names_defaults) % 2 == 0
-        for i, j in zip(names_defaults[::2], names_defaults[1::2]):
-            self.members.append(member_defs.Field(i, dtype, j))
-        return self
-
-    def add_enum(self, name, *members, default=0, name_field=None,
-                 member_alias=[]):
-        self.members.append(member_defs.Enum(
-            self.name.id, name, name_field, members, default, member_alias))
-        return self
-
-    def add_enum_alias(self, name, src_class, src_name=None, name_field=None,
-                       default=None):
-        self.members.append(member_defs.EnumAlias(
-            name, name_field, src_class, src_name, default))
-        return self
-
-    def add_const(self, dtype, *names_defaults):
-        assert isinstance(dtype, str)
-        dtype = getattr(member_defs, dtype)
-        assert len(names_defaults) % 2 == 0
-        for i, j in zip(names_defaults[::2], names_defaults[1::2]):
-            self.members.append(member_defs.Const(i, dtype, j))
-        return self
-
-
-class WriterBase:
-    """base class for output file writer"""
-
-    _fout = None
-    _input_hash = None
-    _cur_class = None
-
-    def __call__(self, fout):
-        self._fout = fout
-
-    def set_input_hash(self, h):
-        self._input_hash = h
-        return self
-
-    def _get_header(self):
-        return 'generated by {} for {}'.format(
-            os.path.basename(__file__),
-            self._input_hash
-        )
-
-    def _process(self, defs):
-        dispatch = {
-            member_defs.Enum: self._on_member_enum,
-            member_defs.EnumAlias: self._on_member_enum_alias,
-            member_defs.Field: self._on_member_field,
-            member_defs.Const: self._on_const_field
-        }
-        for i in defs:
-            assert isinstance(i, ParamDef)
-            if i.is_legacy:
-                continue
-            self._cur_class = i.name
-            self._on_param_begin(i)
-            for j in i.members:
-                dispatch[type(j)](j)
-            self._on_param_end(i)
-
-    def _on_param_begin(self, p):
-        """:type p: :class:`.ParamDef`"""
-
-    def _on_param_end(self, p):
-        """:type p: :class:`.ParamDef`"""
-
-    def _on_member_enum(self, e):
-        """:type p: :class:`.Enum`"""
-
-    def _on_member_enum_alias(self, e):
-        """:type p: :class:`.EnumAlias`"""
-
-    def _on_member_field(self, f):
-        """:type p: :class:`.Field`"""
-
-    def _on_const_field(self, f):
-        """:type p: :class:`.Const`"""
-
-
-class IndentWriterBase(WriterBase):
-    _cur_indent = ''
-
-    def _indent(self):
-        self._cur_indent += ' ' * 4
-
-    def _unindent(self):
-        self._cur_indent = self._cur_indent[:-4]
-
-    def _write(self, content, *fmt, indent=0):
-        if indent < 0:
-            self._unindent()
-
-        self._fout.write(self._cur_indent)
-        if fmt:
-            content = content % fmt
-        self._fout.write(content)
-        self._fout.write('\n')
-
-        if indent > 0:
-            self._indent()
-
-
-class PyWriter(IndentWriterBase):
-
-    _static_members = None
-    _non_static_members = None
-    _enums = None
-    _enum_map = None
-
-    def __call__(self, fout, defs):
-        super().__call__(fout)
-        self._enum_map = {}
-        self._write('// %s', self._get_header())
-        self._write('#include "megbrain/imperative/opdef/all.h"')
-        self._write('')
-        self._write('using namespace mgb::imperative;')
-        self._write('')
-        self._process(defs)
-
-    def _on_param_begin(self, p):
-        self._enums = []
-        self._non_static_members = []
-        self._static_members = []
-
-    def _reg_enum_single(self, cur_def, e):
-        alias = None
-        if isinstance(e, member_defs.Enum):
-            src = e
-        else:
-            assert isinstance(e, member_defs.EnumAlias)
-            src = e.src_enum
-            alias = e
-
-        src_py_name = self._enum_map.get(src, None)
-        if src_py_name is not None:
-            py_name = '{}{}Enum'.format(cur_def, src.name if alias is None else alias.name)
-            self._write('m.attr("{}") = m.attr("{}");\n'.format(py_name, src_py_name))
-            return
-
-        if alias is None:
-            enum_name = str(src.name)
-        else:
-            enum_name = str(alias.name)
-        c_name = 'opdef::{}::{}'.format(cur_def, enum_name)
-        py_name = '{}{}Enum'.format(cur_def, enum_name)
-        self._write('py::enum_<{}>(m, "{}")'.format(c_name, py_name), indent=1)
-        for i in src.members:
-            self._write('.value("{0}", {1}::{0})'.format(i, c_name))
-        self._write(';\n', indent=-1)
-        self._enum_map[src] = py_name
-
-    def _on_param_end(self, p):
-        cur_def = '{}Def'.format(p.name)
-        for e in self._enums:
-            self._reg_enum_single(cur_def, e)
-        self._write('py::class_<opdef::{0}>(m, "{0}")'.format(cur_def), indent=1)
-        # TODO: use ctor with given default value
-        self._write('.def(py::init<>())')
-        for i in self._static_members:
-            assert isinstance(i, member_defs.Const)
-            self._write('.def_property_readonly_static("{0}", []() {{ return opdef::{1}::{0}; }})'.format(i.name, cur_def))
-        for i in self._non_static_members:
-            fname = None
-            if isinstance(i, member_defs.Field):
-                fname = i.name
-            else:
-                assert isinstance(i, (member_defs.Enum, member_defs.EnumAlias))
-                fname = i.name_field
-            self._write('.def_readwrite("{0}", &opdef::{1}::{0})'.format(fname, cur_def))
-        self._write(';\n', indent=-1)
-
-
-    def _on_member_enum(self, e,):
-        self._enums.append(e)
-        self._non_static_members.append(e)
-
-    def _on_member_enum_alias(self, e):
-        self._enums.append(e)
-        self._non_static_members.append(e)
-
-    def _on_member_field(self, f):
-        self._non_static_members.append(f)
-
-    def _on_const_field(self, f):
-        self._static_members.append(f)
-
-
-class CPPWriter(IndentWriterBase):
-    _param_namespace = 'opdef'
-
-    _ctor_args = None
-    """list of (text in func param, var name); func param name must be var name
-    appended by an underscore"""
-    _non_static_members = None
-
-    def __call__(self, fout, defs):
-        super().__call__(fout)
-        self._write('// %s', self._get_header())
-        self._write('#pragma once')
-        self._write('#include "megdnn.h"')
-        # which defined in megbrain/tools/param_defs/mgb_opr_param_defs.py
-        self._write('#include "megbrain/opr/param_defs.h"')
-        self._write('#include <stdint.h>')
-        self._write('namespace mgb {')
-        self._write('namespace imperative {')
-        self._write('namespace %s {', self._param_namespace)
-        self._write('namespace {')
-        self._write('#include "megdnn/dtype.h"')
-        self._write('using DTypeEnum = megdnn::DTypeEnum;')
-        self._write('} // anonymous namespace')
-        self._process(defs)
-        self._write('} // namespace %s', self._param_namespace)
-        self._write('} // namespace imperative')
-        self._write('} // namespace mgb')
-        self._write('// vim: syntax=cpp.doxygen')
-
-    def _on_param_begin(self, p):
-        self._write('struct %sDef {', p.name, indent=1)
-        self._ctor_args = []
-        self._non_static_members = []
-
-    def _add_ctor_args(self, typename, default, varname):
-        self._ctor_args.append((
-            '{} {}_={}'.format(typename, varname, default),
-            varname))
-
-    def _on_param_end(self, p):
-        '''
-        MegDNN param structures are not packed and we need to initialize the structure
-        paddings to zero or it would break MegBrain hash system. We do memset(0) in default
-        ctor and use a trick, wrapping non-static members in a anonymous union which would
-        copy the object representation in its default copy/move ctor, for copy/move ctor.
-        > The implicitly-defined copy/move constructor for a non-union class X performs
-        > a memberwise copy/move of its bases and members. [class.copy.ctor 14]
-        > The implicitly-defined copy/move constructor for a union X copies the object
-        > representation (6.9) of X. [class.copy.ctor 15]
-        '''
-        if self._non_static_members:
-            self._write('union { struct {')
-            for i in self._non_static_members:
-                if isinstance(i, member_defs.Field):
-                    self._write('%s%s %s;', i.dtype.cname_attr, i.dtype.cname, i.name)
-                else:
-                    assert isinstance(i, (member_defs.Enum, member_defs.EnumAlias))
-                    self._write('%s %s;', i.name, i.name_field)
-            self._write('}; };')
-        param_list = []
-        if self._ctor_args:
-            pdefs, varnames = zip(*self._ctor_args)
-            self._write('%sDef(%s) {', p.name, ', '.join(pdefs), indent=1)
-            self._write('memset(this, 0, sizeof(*this));')
-            for var in varnames:
-                self._write('this->%s = %s_;', var, var)
-                param_list.append(str(var))
-            self._write('}', indent=-1)
-        self._write('megdnn::param::%s param() {', self._cur_class, indent=1)
-        self._write('return {%s};', ','.join(param_list))
-        self._write('}', indent=-1)
-        self._write('};\n', indent=-1)
-
-
-    def __on_member_enum(self, e, default_value):
-        self._write('using %s = megdnn::param::%s::%s;', e.name, self._cur_class, e.name)
-        self._non_static_members.append(e)
-        self._add_ctor_args(e.name, default_value, e.name_field)
-
-    def _on_member_enum(self, e,):
-        self.__on_member_enum(e, '{}::{}'.format(e.name, e.members[e.default]))
-
-    def _on_member_enum_alias(self, e):
-        self.__on_member_enum(e, '{}::{}'.format(e.name, e.src_enum.members[e.get_default()]))
-
-    def _on_member_field(self, f):
-        self._non_static_members.append(f)
-        self._add_ctor_args(f.dtype.cname, f.default, f.name)
-
-    def _on_const_field(self, f):
-        if 'int' in f.dtype.cname:
-            self._write('static constexpr %s%s %s = %s;', f.dtype.cname_attr, f.dtype.cname, f.name, f.default)
-        else:
-            self._write('static const %s%s %s = %s;', f.dtype.cname_attr, f.dtype.cname, f.name, f.default)
-
-def main():
-    parser = argparse.ArgumentParser(
-        'generate opr param defs from description file')
-    parser.add_argument('-t', '--type', choices=['c++', 'py'], default='c++',
-                        help='output type')
-    parser.add_argument('input')
-    parser.add_argument('output')
-    args = parser.parse_args()
-
-    with open(args.input) as fin:
-        inputs = fin.read()
-        exec(inputs, {'pdef': ParamDef, 'Doc': member_defs.Doc})
-        input_hash = hashlib.sha256()
-        input_hash.update(inputs.encode(encoding='UTF-8'))
-        input_hash = input_hash.hexdigest()
-
-    if args.type == 'py':
-        writer = PyWriter()
-    else:
-        writer = CPPWriter()
-
-    with open(args.output, 'w') as fout:
-        writer.set_input_hash(input_hash)(fout, ParamDef.all_param_defs)
-
-if __name__ == '__main__':
-    main()
diff --git a/imperative/src/include/megbrain/imperative.h b/imperative/src/include/megbrain/imperative.h
index 4d2ec50e670b2a69f0b7e5145c1bc497a9d89722..ca62217d446813731486b17bfeea9ddf89f7a667 100644
--- a/imperative/src/include/megbrain/imperative.h
+++ b/imperative/src/include/megbrain/imperative.h
@@ -13,6 +13,5 @@
 
 #include "megbrain/imperative/physical_tensor.h"
 #include "megbrain/imperative/op_def.h"
-#include "megbrain/imperative/opdef/all.h"
 
 // vim: syntax=cpp.doxygen foldmethod=marker foldmarker=f{{{,f}}}
diff --git a/imperative/src/include/megbrain/imperative/ops/collective_comm.h b/imperative/src/include/megbrain/imperative/ops/collective_comm.h
index 9ec67af89fd1486ceb7bdaecf28acfaa9cef9270..0bc4ab492e2634f8f4a639abf4c8403956d0c160 100644
--- a/imperative/src/include/megbrain/imperative/ops/collective_comm.h
+++ b/imperative/src/include/megbrain/imperative/ops/collective_comm.h
@@ -21,11 +21,13 @@ class CollectiveComm : public OpDefImplBase<CollectiveComm> {
     MGB_DYN_TYPE_OBJ_FINAL_DECL;
 
 public:
+    using Mode = megdnn::param::CollectiveComm::Mode;
+
     CollectiveComm() = default;
     CollectiveComm(const std::string& key_, size_t nr_devices_,
                       uint32_t rank_, bool is_root_, bool local_grad_,
                       const std::string& addr_, uint32_t port_,
-                      const megdnn::param::CollectiveComm::Mode& mode_,
+                      const Mode& mode_,
                       const DType& dtype_, const std::string& backend_,
                       const std::string& comp_node_)
             : key(key_),
@@ -46,7 +48,7 @@ public:
     bool local_grad;
     std::string addr;
     uint32_t port;
-    megdnn::param::CollectiveComm::Mode mode;
+    Mode mode;
     DType dtype;
     std::string backend;
     std::string comp_node;
diff --git a/imperative/test/CMakeLists.txt b/imperative/test/CMakeLists.txt
index 7e50124a30927a35092010333b9b5a287e5ae55e..5599b6ca46b9b95e6e55cc191a2dd613371fc088 100644
--- a/imperative/test/CMakeLists.txt
+++ b/imperative/test/CMakeLists.txt
@@ -18,7 +18,7 @@ target_include_directories(imperative_test PRIVATE ${MODULE_SRC_INCLUDE} ${PYTHO
 target_compile_definitions(imperative_test PRIVATE MODULE_NAME=C)
 target_compile_options(imperative_test PRIVATE -Wno-unused-parameter)
 
-set(LINK_LIBS megbrain megdnn gtest pybind11::embed gen_op_def)
+set(LINK_LIBS megbrain megdnn gtest pybind11::embed)
 if(MGE_WITH_CUDA)
     list(APPEND LINK_LIBS cudart)
 endif()