move hook function to primtivePy class

mindspore/_extends/builtin_operations.py

@@ -13,7 +13,6 @@
 # limitations under the License.
 # ============================================================================
 """builtin_operations"""
-import functools
 import numpy as np
 from mindspore.common.tensor import Tensor
 from mindspore.common.dtype import dtype_to_nptype, get_py_obj_dtype
@@ -124,17 +123,8 @@ def list_len(x):
     """Implement `list_len`."""
     return len(x)
 
-
-# only used in PyNative mode
-def partial(*args):
-    """Implement `partial`."""
-    func = args[0].__call__
-    partial_func = functools.partial(func, *args[1:])
-    return partial_func
-
-
-# only used in PyNative mode
-def depend(value, expr):
+def Depend(value, expr):
+    """Implement `Depend`."""
     return value
 
 # only used in PyNative mode

mindspore/ccsrc/ir/primitive.h

@@ -49,6 +49,8 @@ class PrimitivePy : public Primitive {
   void AddPyAttr(const py::str &name, const py::object &obj);
 
   py::dict GetAttrDict();
+  void set_hook(const py::function &hook) { hook_ = hook; }
+  py::function hook() const { return hook_; }
 
   const bool parse_info_ = true;
   const py::object &GetPyObj() const { return python_obj_; }
@@ -56,6 +58,7 @@ class PrimitivePy : public Primitive {
 
  private:
   py::object python_obj_;
+  py::function hook_;
   std::vector<Signature> signatures_;
 };
 

mindspore/ccsrc/ir/primitive_base.h

@@ -89,9 +89,6 @@ class Primitive : public Named {
     return iter == attrs_.cend() ? nullptr : iter->second;
   }
 
-  void set_hook(const py::function &hook) { hook_ = hook; }
-  py::function hook() const { return hook_; }
-
   const std::unordered_map<std::string, ValuePtr> &attrs() const { return attrs_; }
   std::unordered_map<std::string, ValuePtr> &evaluate_added_attrs() { return evaluate_added_attrs_; }
 
@@ -124,7 +121,6 @@ class Primitive : public Named {
 
  private:
   std::string instance_name_;
-  py::function hook_;
   bool is_base_;
   bool has_signature_;
   PrimType prim_type_;

mindspore/ccsrc/operator/ops.cc

@@ -220,7 +220,7 @@ const PrimitivePtr kPrimBpropCut = std::make_shared<Primitive>("bprop_cut");
 
 // Other miscellaneous
 const PrimitivePtr kPrimIdentity = std::make_shared<Primitive>("identity");
-const PrimitivePtr kPrimPartial = std::make_shared<Primitive>("partial");
+const PrimitivePtr kPrimPartial = std::make_shared<Primitive>("Partial");
 const PrimitivePtr kPrimJ = std::make_shared<Primitive>("J");
 const PrimitivePtr kPrimEnvSetItem = std::make_shared<Primitive>("env_setitem");
 const PrimitivePtr kPrimEnvGetItem = std::make_shared<Primitive>("env_getitem");
@@ -237,7 +237,7 @@ const PrimitivePtr kPrimCheckBprop = std::make_shared<Primitive>("CheckBprop");
 const PrimitivePtr kPrimPrint = std::make_shared<Primitive>("Print");
 
 const PrimitivePtr kPrimMakeRef = std::make_shared<Primitive>("make_ref");
-const PrimitivePtr kPrimDepend = std::make_shared<Primitive>("depend");
+const PrimitivePtr kPrimDepend = std::make_shared<Primitive>("Depend");
 const PrimitivePtr kPrimStateSetItem = std::make_shared<Primitive>("state_setitem");
 
 const PrimitivePtr kPrimBroadcastGradientArgs = std::make_shared<Primitive>("BroadcastGradientArgs");

mindspore/ccsrc/optimizer/ad/kprim.cc

@@ -238,8 +238,12 @@ FuncGraphPtr KPrim::BpropCut(const ValueNodePtr &value_node, const pipeline::Res
   auto func_graph = std::make_shared<FuncGraph>();
   std::vector<AnfNodePtr> outputs;
 
-  auto bprop_cut = std::make_shared<Primitive>("bprop_cut");
-  bprop_cut->set_hook(prim->hook());
+  auto bprop_cut = std::make_shared<PrimitivePy>("bprop_cut", py::object());
+  if (!prim->is_base()) {
+    PrimitivePyPtr prim_py = dyn_cast<PrimitivePy>(prim);
+    bprop_cut->set_hook(prim_py->hook());
+  }
+
   auto cell_id = GetValue<std::string>(prim->GetAttr("cell_id"));
   if (cell_id != "") {
     (void)bprop_cut->AddAttr("cell_hook", MakeValue(true));

mindspore/ccsrc/parallel/ops_info/ops_utils.h

@@ -72,7 +72,7 @@ constexpr char OP[] = "op";
 constexpr char IDENTITY_INFO[] = "identity_info";
 constexpr char DIVISOR[] = "divisor";
 constexpr char NONE[] = "None";
-constexpr char DEPEND[] = "depend";
+constexpr char DEPEND[] = "Depend";
 constexpr char BATCH_PARALLEL[] = "BatchParallel";
 
 constexpr char ACTIVATION_TYPE[] = "activation_type";

mindspore/ccsrc/pipeline/parse/data_converter.cc

@@ -217,7 +217,7 @@ FuncGraphPtr ConvertToBpropCut(py::object obj) {
   FuncGraphPtr bprop_graph = std::make_shared<FuncGraph>();
   std::vector<AnfNodePtr> outputs;
 
-  auto fake_bprop = std::make_shared<Primitive>("bprop_cut");
+  auto fake_bprop = std::make_shared<PrimitivePy>("bprop_cut", py::object());
   fake_bprop->set_hook(bprop_func);
   (void)fake_bprop->AddAttr("bprop", MakeValue(true));
   outputs.push_back(NewValueNode(fake_bprop));

mindspore/ccsrc/pynative/base.h

@@ -59,7 +59,7 @@ struct OpExecInfo {
 using OpExecInfoPtr = std::shared_ptr<OpExecInfo>;
 OpExecInfoPtr GenerateOpExecInfo(const py::args &args);
 
-const std::set<std::string> ignore_infer_prim = {"partial", "make_ref"};
+const std::set<std::string> ignore_infer_prim = {"make_ref"};
 }  // namespace pynative
 }  // namespace mindspore
 

mindspore/ccsrc/pynative/pynative_execute.cc

@@ -53,7 +53,7 @@
 
 const char SINGLE_OP_GRAPH[] = "single_op_graph";
 // primitive unable to infer value for constant input in PyNative mode
-const std::set<std::string> vm_operators = {"partial", "depend", "make_ref", "HookBackward"};
+const std::set<std::string> vm_operators = {"make_ref", "HookBackward"};
 
 namespace mindspore {
 namespace pynative {

mindspore/ccsrc/transform/convert.cc

@@ -959,8 +959,8 @@ void DfGraphConvertor::TraceOutput(const AnfNodePtr node) {
     for (unsigned int i = 1; i < c->inputs().size(); i++) {
       TraceOutput(c->input(i));
     }
-  } else if (name == "depend") {
-    if (c->inputs().size() < 3) {  // "depend" primitive have 3 inputs
+  } else if (name == "Depend") {
+    if (c->inputs().size() < 3) {  // "Depend" primitive have 3 inputs
       MS_LOG(EXCEPTION) << "length of inputs is " << c->inputs().size() << ", which is less than 3";
     }
     TraceOutput(c->input(1));
@@ -1183,7 +1183,7 @@ void DfGraphConvertor::SetOpInput(const OpAdapterPtr &adpt, const CNodePtr &node
   auto &inputs = node->inputs();
   for (size_t i = 1; i < inputs.size(); i++) {
     auto pred = inputs[i];
-    while (pred->isa<CNode>() && GetCNodeFuncName(pred->cast<CNodePtr>()) == "depend") {
+    while (pred->isa<CNode>() && GetCNodeFuncName(pred->cast<CNodePtr>()) == "Depend") {
       pred = pred->cast<CNodePtr>()->input(1);
     }
     // skip the None input
@@ -1362,7 +1362,7 @@ AnfNodePtr DfGraphConvertor::TraceTupleGetItem(const CNodePtr &node, unsigned in
 
 AnfNodePtr DfGraphConvertor::TraceDepend(const CNodePtr &node) {
   auto cnode = node->cast<CNodePtr>();
-  if (cnode->inputs().size() < 3) {  // "depend" primitive have 3 inputs
+  if (cnode->inputs().size() < 3) {  // "Depend" primitive have 3 inputs
     MS_LOG(EXCEPTION) << "length of inputs of depend is less than 3";
   }
   return cnode->inputs()[1];
@@ -1483,7 +1483,7 @@ AnfNodePtr DfGraphConvertor::GetRealOpNode(AnfNodePtr node) {
   // depend apply inputs: depend,output,depended_node
   if (IsPrimitiveCNode(node, prim::kPrimDepend)) {
     auto depend_inputs = node->cast<CNodePtr>()->inputs();
-    if (depend_inputs.size() != 3) {  // "depend" primitive have 3 inputs
+    if (depend_inputs.size() != 3) {  // "Depend" primitive have 3 inputs
       MS_LOG(ERROR) << "depend input items not correct";
       error_ = FAILED;
       return node;
@@ -1700,7 +1700,7 @@ void DfGraphConvertor::ConvertControlDependNode(const CNodePtr node) {
 
 bool DfGraphConvertor::CheckCNode(const std::string &name, const CNodePtr node) {
   // ignore apply node of return
-  if (name == "return" || name == "depend") {
+  if (name == "return" || name == "Depend") {
     return false;
   }
 

mindspore/ccsrc/vm/vm.cc

@@ -585,8 +585,8 @@ void FinalVM::InstPushPrim(const VectorRef &args) {
     return;
   }
 
-  VectorRef tuple;
   auto prim = utils::cast<PrimitivePtr>(args[0]);
+  VectorRef tuple;
   for (size_t i = 1; i < args.size(); ++i) {
     auto index = utils::cast<int>(args[i]);
     tuple.push_back(Ref(index));
@@ -618,6 +618,7 @@ void FinalVM::SyncData(const py::object &arg) {
 
 BaseRef FinalVM::RunHook(const PrimitivePtr &prim, const VectorRef &args) {
   MS_LOG(DEBUG) << "input for operation:";
+  auto prim_py = dyn_cast<PrimitivePy>(prim);
   std::size_t args_size = args.size();
   auto py_args = py::tuple(args_size);
   size_t i = 0;
@@ -631,7 +632,7 @@ BaseRef FinalVM::RunHook(const PrimitivePtr &prim, const VectorRef &args) {
   bool is_bprop = prim->HasAttr("bprop");
   if (is_bprop) {
     SyncData(py_args);
-    py::function fn_bprop = prim->hook();
+    py::function fn_bprop = prim_py->hook();
     obj = fn_bprop(*py_args);
     return obj;
   }
@@ -647,7 +648,7 @@ BaseRef FinalVM::RunHook(const PrimitivePtr &prim, const VectorRef &args) {
       hook_args[0] = cell_id;
       hook_args[1] = py::make_tuple(_hook_grad[cell_id]);
       hook_args[2] = py::make_tuple(py_args[2]);
-      py::function fn_hook = prim->hook();
+      py::function fn_hook = prim_py->hook();
       obj = fn_hook(*hook_args);
       if (py::isinstance<py::none>(obj)) {
         obj = py_args[2];
@@ -659,7 +660,7 @@ BaseRef FinalVM::RunHook(const PrimitivePtr &prim, const VectorRef &args) {
     }
   } else {
     // Hook operator for execute variable hook function
-    py::function fn_hook = prim->hook();
+    py::function fn_hook = prim_py->hook();
     obj = fn_hook(py::make_tuple(py_args[2]));
     if (py::isinstance<py::none>(obj)) {
       obj = py_args[2];

mindspore/common/tensor.py

@@ -78,6 +78,8 @@ class Tensor(Tensor_):
     def __eq__(self, other):
         if not isinstance(other, Tensor):
             return False
+        #  The GE backend don't support single `Equal` operator execution.
+        #  bool type is not supported for `Equal` operator in backend.
         if context.get_context("enable_ge") or self.dtype() == mstype.bool_ or other.dtype() == mstype.bool_:
             return Tensor(np.array(self.asnumpy() == other.asnumpy()))
         return tensor_operator_registry.get('__eq__')(self, other)

mindspore/ops/_grad/grad_implementations.py

@@ -195,7 +195,7 @@ def bprop_array_reduce(fn, x, shp, out, dout):
     return F.distribute(dout, F.shape(x)), C.zeros_like(shp)
 
 
-@bprops.register("depend")
+@bprops.register("Depend")
 def bprop_depend(x, y, out, dout):
     """Backpropagator for primitive `depend`."""
     return dout, C.zeros_like(y)
@@ -236,7 +236,6 @@ def bprop_control_depend(x, y, out, dout):
     """Backpropagator for primitive `Control_depend`."""
     return C.zeros_like(x), C.zeros_like(y)
 
-
 @bprops.register("switch")
 def bprop_switch(cond, tb, fb, out, dout):
     """Backpropagator for primitive `switch`."""

mindspore/ops/composite/base.py

@@ -22,7 +22,7 @@ from mindspore import context
 from ..._c_expression import EnvInstance_, GradOperation_, HyperMap_, MultitypeFuncGraph_, Tail_, TensorSlice_, \
                              TupleAdd_, TupleSlice_, UnpackCall_, ZipOperation_, ListAppend_, TupleGetItemTensor_
 from ...common import dtype as mstype
-from ...common.api import ms_function, _pynative_exec
+from ...common.api import ms_function, _pynative_exec, _wrap_func
 from .. import functional as F
 from ...common.parameter import Parameter
 
@@ -117,6 +117,7 @@ class GradOperation(GradOperation_):
                     def after_grad(*args):
                         return grad_(fn, weights)(*args)
                 else:
+                    @_wrap_func
                     def after_grad(*args):
                         if fn.is_run and not fn.requires_grad:
                             raise ValueError("obj must set_grad.")

mindspore/ops/functional.py

@@ -77,6 +77,9 @@ gather_nd = P.GatherNd()
 scatter_update = P.ScatterUpdate()
 scatter_nd_update = P.ScatterNdUpdate()
 pack = P.Pack()
+partial = P.Partial()
+# depend: mount a node to another node
+depend = P.Depend()
 
 
 tuple_setitem = Primitive('tuple_setitem')
@@ -131,12 +134,9 @@ mixed_precision_cast = Primitive("mixed_precision_cast")
 broadcast_gradient_args = Primitive('BroadcastGradientArgs')
 dot = Primitive('dot')
 array_reduce = Primitive('array_reduce')
-partial = Primitive('partial')
 zeros_like = P.ZerosLike()
 identity = Primitive('identity')
 distribute = Primitive('distribute')
-# depend: mount a node to another node
-depend = Primitive('depend')
 embed = Primitive('embed')
 ref_to_embed = _grad_ops.RefToEmbed()
 env_setitem = Primitive('env_setitem')

mindspore/ops/operations/__init__.py

@@ -74,7 +74,7 @@ from .nn_ops import (LSTM, SGD, Adam, ApplyMomentum, BatchNorm,
                      ApplyProximalAdagrad, SparseApplyProximalAdagrad,
                      ApplyRMSProp, ApplyCenteredRMSProp, BasicLSTMCell)
 from .other_ops import (Assign, IOU, BoundingBoxDecode, BoundingBoxEncode,
-                        CheckValid, MakeRefKey, CheckBprop, ConfusionMatrix)
+                        CheckValid, MakeRefKey, Partial, Depend, CheckBprop, ConfusionMatrix)
 from . import _quant_ops
 from ._quant_ops import *
 from .thor_ops import *
@@ -213,6 +213,8 @@ __all__ = [
     'NMSWithMask',
     'IOU',
     'MakeRefKey',
+    'Partial',
+    'Depend',
     'AvgPool',
     # Back Primitive
     'Equal',

mindspore/ops/operations/other_ops.py

@@ -14,6 +14,7 @@
 # ============================================================================
 
 """Other operators."""
+import functools
 from ..._c_expression import signature_rw as sig_rw
 from ..._c_expression import signature_kind as sig_kind
 from ..._c_expression import signature_dtype as sig_dtype
@@ -304,6 +305,46 @@ class MakeRefKey(Primitive):
         pass
 
 
+class Partial(Primitive):
+    """
+    Make a partial function instance, used for pynative mode.
+
+    Inputs:
+        - **args** (Union[FunctionType, Tensor]) - The function and bind arguments.
+
+    Outputs:
+        FunctionType, partial function binded with arguments.
+    """
+
+    @prim_attr_register
+    def __init__(self):
+        pass
+
+    def __call__(self, *args):
+        func = args[0].__call__
+        partial_func = functools.partial(func, *args[1:])
+        return partial_func
+
+class Depend(Primitive):
+    """
+    Depend is used for process side-effect operations.
+
+    Inputs:
+        - **value** (Tensor) - the real value to return for depend operator.
+        - **expr** (Expression) - the expression to execute with no outputs.
+
+    Outputs:
+        Tensor, the value passed by last operator.
+    """
+
+    @prim_attr_register
+    def __init__(self):
+        pass
+
+    def __call__(self, value, expr):
+        return value
+
+
 class CheckBprop(PrimitiveWithInfer):
     """
     Checks whether data type and shape of corresponding element from tuple x and y are the same.

tests/ut/cpp/operator/ops_test.cc

@@ -341,7 +341,7 @@ TEST_F(TestOps, ResolveTest) {
 }
 
 TEST_F(TestOps, PartialTest) {
-  auto prim = std::make_shared<Primitive>("partial");
+  auto prim = std::make_shared<Primitive>("Partial");
   ASSERT_EQ(prim->name(), kPrimPartial->name());
 }
 

tests/ut/cpp/python_input/gtest_input/optimizer/opt_test.py

@@ -636,7 +636,7 @@ def test_tuple_get_set_item(tag):
 def test_partial(tag):
     """ test_partial """
     fns = FnDict()
-    partail = Primitive('partial')
+    partail = P.Partial()
 
     def f(x, y):
         return scalar_add(x, y)
@@ -655,7 +655,7 @@ def test_partial(tag):
 def test_replace_applicator(tag):
     """ test_replace_applicator """
     fns = FnDict()
-    partail = Primitive('partial')
+    partail = P.Partial()
 
     def app1(x, y):
         return scalar_add(x, y)

tests/ut/cpp/python_input/gtest_input/pre_activate/eliminate_redundant_op_test.py

@@ -22,7 +22,7 @@ four2five = Primitive('Four2Five')
 five2four = Primitive('Five2Four')
 transdata = Primitive("TransData")
 cast = Primitive('Cast')
-depend = Primitive('depend')
+depend = P.Depend()
 
 
 class FnDict:

tests/ut/cpp/python_input/gtest_input/pre_activate/fused_batch_norm_fusion_test.py

@@ -16,13 +16,13 @@ import mindspore.common.dtype as mstype
 from mindspore.common.tensor import Tensor
 from mindspore.ops import Primitive
 from mindspore.ops import operations as P
+from mindspore.ops import functional as F
 
 AssignSub = P.AssignSub()
 Mul = P.Mul()
 Sub = P.Sub()
 make_tuple = Primitive('make_tuple')
 tuple_getitem = Primitive('tuple_getitem')
-depend = Primitive('depend')
 BatchNorm = P.BatchNorm()
 Cast = P.Cast()
 BNTrainingReduce = Primitive('BNTrainingReduce')
@@ -54,8 +54,8 @@ def test_fused_batch_norm_fusion(tag):
         mul1 = Mul(sub1, constant1)
         assign_sub0 = AssignSub(var0, mul0)
         assign_sub1 = AssignSub(var1, mul1)
-        depend0 = depend(tuple_getitem(batch_norm, 0), assign_sub0)
-        depend1 = depend(depend0, assign_sub1)
+        depend0 = F.depend(tuple_getitem(batch_norm, 0), assign_sub0)
+        depend1 = F.depend(depend0, assign_sub1)
         outputs = make_tuple(depend1, tuple_getitem(batch_norm, 3), tuple_getitem(batch_norm, 4))
         output = tuple_getitem(outputs, 0)
         return output
@@ -69,8 +69,8 @@ def test_fused_batch_norm_fusion(tag):
         mul1 = Mul(sub1, constant1)
         assign_sub0 = AssignSub(var0, Cast(mul0, mstype.float32))
         assign_sub1 = AssignSub(var1, Cast(mul1, mstype.float32))
-        depend0 = depend(tuple_getitem(batch_norm, 0), assign_sub0)
-        depend1 = depend(depend0, assign_sub1)
+        depend0 = F.depend(tuple_getitem(batch_norm, 0), assign_sub0)
+        depend1 = F.depend(depend0, assign_sub1)
         outputs = make_tuple(depend1, tuple_getitem(batch_norm, 3), tuple_getitem(batch_norm, 4))
         output = tuple_getitem(outputs, 0)
         return output
@@ -84,8 +84,8 @@ def test_fused_batch_norm_fusion(tag):
         mul1 = Mul(Cast(sub1, mstype.float32), constant1)
         assign_sub0 = AssignSub(var0, mul0)
         assign_sub1 = AssignSub(var1, mul1)
-        depend0 = depend(tuple_getitem(batch_norm, 0), assign_sub0)
-        depend1 = depend(depend0, assign_sub1)
+        depend0 = F.depend(tuple_getitem(batch_norm, 0), assign_sub0)
+        depend1 = F.depend(depend0, assign_sub1)
         outputs = make_tuple(depend1, tuple_getitem(batch_norm, 3), tuple_getitem(batch_norm, 4))
         output = tuple_getitem(outputs, 0)
         return output

tests/ut/cpp/python_input/gtest_input/pre_activate/hw_opt_test.py

@@ -16,7 +16,7 @@ from mindspore.ops import Primitive
 from mindspore.ops import operations as P
 
 tuple_getitem = Primitive('tuple_getitem')
-depend = Primitive('depend')
+depend = P.Depend()
 addn = P.AddN()
 add = P.TensorAdd()
 sub = P.Sub()

tests/ut/cpp/python_input/gtest_input/pre_activate/mixed_precision_test.py

@@ -16,7 +16,7 @@ from mindspore.ops import Primitive
 from mindspore.ops import operations as P
 
 tuple_getitem = Primitive('tuple_getitem')
-depend = Primitive('depend')
+depend = P.Depend()
 addn = P.AddN()
 add = P.TensorAdd()
 sub = P.Sub()

tests/ut/cpp/python_input/gtest_input/pre_activate/optimize_dependence_test.py

@@ -15,7 +15,7 @@
 from mindspore.ops import Primitive
 from mindspore.ops import operations as P
 
-depend = Primitive('depend')
+depend = P.Depend()
 TransData = Primitive('TransData')
 add = P.TensorAdd()
 make_tuple = Primitive('make_tuple')

tests/ut/python/ops/test_nn_ops.py

@@ -20,9 +20,9 @@ import mindspore.context as context
 import mindspore.nn as nn
 from mindspore import Tensor, Parameter
 from mindspore.common.initializer import initializer
-from mindspore.ops import Primitive
 from mindspore.ops import composite as C
 from mindspore.ops import operations as P
+from mindspore.ops import functional as F
 from mindspore.ops.operations import _grad_ops as G
 from mindspore.ops import prim_attr_register, PrimitiveWithInfer
 from ..ut_filter import non_graph_engine
@@ -358,7 +358,7 @@ class StateNet(nn.Cell):
         self.assign = P.Assign()
 
     def construct(self, x):
-        x = Primitive('depend')(x, self.assign(self.s1, x + self.s1))
+        x = F.depend(x, self.assign(self.s1, x + self.s1))
         self.s1 = self.sub(self.s1, x)
         self.s2 = self.sub(self.s2, x)
         return x

tests/ut/python/pynative_mode/ops/test_hypermap.py

@@ -132,7 +132,7 @@ def test_hypermap_add3_easy():
 
 
 add3 = C.MultitypeFuncGraph('add')
-partial = Primitive('partial')
+partial = P.Partial()
 
 
 @add3.register("Number", "Number", "Number")

tests/vm_impl/array_ops_vm_impl.py

@@ -284,3 +284,21 @@ def vm_impl_zeros_like(self):
     """Generate vm_impl function for ZerosLike"""
     def vm_impl(x):
         return Tensor(np.zeros_like(x.asnumpy()))
+
+@vm_impl_getters.register(P.Partial)
+def vm_impl_partial(self):
+    """Generate vm_impl function for Partial"""
+    def vm_impl(*args):
+        func = args[0].__call__
+        partial_func = functools.partial(func, *args[1:])
+        return partial_func
+
+    return vm_impl
+
+@vm_impl_getters.register(P.Depend)
+def vm_impl_depend(self):
+    """Generate vm_impl function for Depend"""
+    def vm_impl(value, expr):
+        return value
+
+    return vm_impl