From c8fc33798a1a28354b90d78feac181000b96451b Mon Sep 17 00:00:00 2001
From: Zhou Wei <1183042833@qq.com>
Date: Mon, 31 Oct 2022 11:01:16 +0800
Subject: [PATCH] [Zero-Dim] support input 0D Tensor for reduce_sum/reduce_mean
 (#47219)

---
 paddle/phi/infermeta/unary.cc                 |  9 ++-
 paddle/phi/kernels/funcs/broadcast_function.h |  8 +-
 paddle/phi/kernels/funcs/reduce_function.h    |  8 ++
 .../kernels/gpu/reduce_mean_grad_kernel.cu    | 31 +++++---
 .../phi/kernels/gpu/reduce_sum_grad_kernel.cu | 36 ++++-----
 paddle/phi/kernels/reduce_mean_kernel.cc      |  3 +
 python/paddle/fluid/layers/nn.py              |  3 -
 .../fluid/tests/unittests/test_mean_op.py     | 15 ++++
 .../fluid/tests/unittests/test_reduce_op.py   | 15 ++++
 .../tests/unittests/test_zero_dim_shape.py    | 51 ++++++++++++
 python/paddle/tensor/math.py                  | 78 ++++++-------------
 python/paddle/tensor/stat.py                  | 19 +----
 12 files changed, 160 insertions(+), 116 deletions(-)

diff --git a/paddle/phi/infermeta/unary.cc b/paddle/phi/infermeta/unary.cc
index 3c66523aef..150da6d59b 100644
--- a/paddle/phi/infermeta/unary.cc
+++ b/paddle/phi/infermeta/unary.cc
@@ -2685,7 +2685,7 @@ DDim ReduceInferDim(const MetaTensor& x,
 
   bool full_dim = true;
   std::set<int64_t> dims_set(formated_axis.begin(), formated_axis.end());
-  for (int64_t i = 0; i < x.dims().size(); ++i) {
+  for (int64_t i = 0; i < x_rank; ++i) {
     if (dims_set.find(i) == dims_set.end()) {
       full_dim = false;
       break;
@@ -2695,7 +2695,7 @@ DDim ReduceInferDim(const MetaTensor& x,
 
   std::vector<int64_t> out_dim_vector;
   if (keep_dim) {
-    for (int64_t i = 0; i < x.dims().size(); ++i) {
+    for (int64_t i = 0; i < x_rank; ++i) {
       if (reduce_all || dims_set.find(i) != dims_set.end()) {
         out_dim_vector.push_back(1);
       } else {
@@ -2703,7 +2703,7 @@ DDim ReduceInferDim(const MetaTensor& x,
       }
     }
   } else {
-    for (int64_t i = 0; i < x.dims().size(); ++i) {
+    for (int64_t i = 0; i < x_rank; ++i) {
       if (reduce_all || dims_set.find(i) != dims_set.end()) {
         continue;
       } else {
@@ -2711,7 +2711,7 @@ DDim ReduceInferDim(const MetaTensor& x,
       }
     }
 
-    if (out_dim_vector.size() == 0) {
+    if (x_rank > 0 && out_dim_vector.size() == 0) {
       out_dim_vector.push_back(1);
     }
   }
@@ -3013,6 +3013,7 @@ void SetValueInferMeta(const MetaTensor& x, MetaTensor* out) {
       phi::errors::InvalidArgument(
           "The rank of input should be less than 7, but received %d.",
           in_dims.size()));
+  out->set_dims(in_dims);
 }
 
 void ShapeInferMeta(const MetaTensor& input, MetaTensor* out) {
diff --git a/paddle/phi/kernels/funcs/broadcast_function.h b/paddle/phi/kernels/funcs/broadcast_function.h
index 59c3df0fce..22ed5b29d7 100644
--- a/paddle/phi/kernels/funcs/broadcast_function.h
+++ b/paddle/phi/kernels/funcs/broadcast_function.h
@@ -44,7 +44,7 @@ struct DimensionsTransform {
       int64_t in_idx = 0;
       if (in_dim.size() < dim_size) {
         DimVector tmp_dim(dim_size, 1);
-        do {
+        for (; in_idx < in_dim.size();) {
           if (in_dim[in_idx] == out_dims[axis] || in_dim[in_idx] == 1) {
             tmp_dim[axis] = in_dim[in_idx];
             in_idx++;
@@ -59,11 +59,11 @@ struct DimensionsTransform {
                 out_dims[axis],
                 in_dim[in_idx]));
           }
-        } while (in_idx < in_dim.size());
+        }
         in_dim.resize(dim_size);
         std::copy(tmp_dim.begin(), tmp_dim.end(), in_dim.begin());
       } else {
-        do {
+        for (; in_idx < dim_size;) {
           if (in_dim[in_idx] == out_dims[in_idx] || in_dim[in_idx] == 1) {
             in_idx++;
           } else {
@@ -76,7 +76,7 @@ struct DimensionsTransform {
                 out_dims[in_idx],
                 in_dim[in_idx]));
           }
-        } while (in_idx < dim_size);
+        }
       }
       std::reverse(in_dim.begin(), in_dim.end());
     }
diff --git a/paddle/phi/kernels/funcs/reduce_function.h b/paddle/phi/kernels/funcs/reduce_function.h
index 92fe3885b4..9138fd85e6 100644
--- a/paddle/phi/kernels/funcs/reduce_function.h
+++ b/paddle/phi/kernels/funcs/reduce_function.h
@@ -1063,6 +1063,14 @@ void ReduceKernel(const KPDevice& dev_ctx,
   dev_ctx.Alloc<Ty>(y);
 
   auto x_dim = phi::vectorize<int>(x.dims());
+
+  if (x_dim.size() == 0) {
+    std::vector<const DenseTensor*> inputs = {&x};
+    std::vector<DenseTensor*> outputs = {y};
+    funcs::ElementwiseKernel<Ty>(dev_ctx, inputs, &outputs, transform);
+    return;
+  }
+
   auto config = ReduceConfig<Ty>(origin_reduce_dims, x_dim);
   config.Run(dev_ctx);
   int numel = x.numel();
diff --git a/paddle/phi/kernels/gpu/reduce_mean_grad_kernel.cu b/paddle/phi/kernels/gpu/reduce_mean_grad_kernel.cu
index 7da2502a5e..40c317e126 100644
--- a/paddle/phi/kernels/gpu/reduce_mean_grad_kernel.cu
+++ b/paddle/phi/kernels/gpu/reduce_mean_grad_kernel.cu
@@ -16,8 +16,8 @@
 
 #include "paddle/phi/backends/gpu/gpu_context.h"
 #include "paddle/phi/core/kernel_registry.h"
+#include "paddle/phi/kernels/funcs/broadcast_function.h"
 #include "paddle/phi/kernels/funcs/reduce_function.h"
-#include "paddle/phi/kernels/gpu/reduce_grad.h"
 
 namespace phi {
 
@@ -29,23 +29,34 @@ void ReduceMeanGradKernel(const Context& dev_ctx,
                           bool keep_dim,
                           bool reduce_all,
                           DenseTensor* x_grad) {
+  // get reduce_dim and reduce_num for reduce_mean_grad
   int dim_size = x.dims().size();
+  if (dims.size() == 0) {
+    reduce_all = true;
+  }
   std::vector<int> reduce_dims =
       funcs::details::GetReduceDim(dims.GetData(), dim_size, reduce_all);
+
+  auto update_dims = vectorize(x.dims());
   int reduce_num = 1;
   for (auto i : reduce_dims) {
     reduce_num *= (x.dims())[i];
+    update_dims[i] = 1;
   }
+
+  // make new tensor
+  DenseTensor new_out_grad(out_grad.dtype());
+  new_out_grad.ShareDataWith(out_grad);
+  new_out_grad.Resize(phi::make_ddim(update_dims));
+
+  // call BroadcastKernel
+  dev_ctx.Alloc(x_grad, x.dtype());
+  std::vector<const DenseTensor*> inputs = {&new_out_grad};
+  std::vector<DenseTensor*> outputs = {x_grad};
+
   using MPType = typename kps::details::MPTypeTrait<T>::Type;
-  ReduceGradKernel<T, T, Context, kps::DivideFunctor<T, MPType>>(
-      dev_ctx,
-      x,
-      out_grad,
-      dims.GetData(),
-      keep_dim,
-      reduce_all,
-      x_grad,
-      kps::DivideFunctor<T, MPType>(reduce_num));
+  funcs::BroadcastKernel<phi::ElementwiseType::kUnary, T, T>(
+      dev_ctx, inputs, &outputs, 0, kps::DivideFunctor<T, MPType>(reduce_num));
 }
 
 }  // namespace phi
diff --git a/paddle/phi/kernels/gpu/reduce_sum_grad_kernel.cu b/paddle/phi/kernels/gpu/reduce_sum_grad_kernel.cu
index 2230b4b852..74209afe37 100644
--- a/paddle/phi/kernels/gpu/reduce_sum_grad_kernel.cu
+++ b/paddle/phi/kernels/gpu/reduce_sum_grad_kernel.cu
@@ -29,42 +29,32 @@ void ReduceSumGradKernel(const Context& dev_ctx,
                          bool keep_dim,
                          bool reduce_all,
                          DenseTensor* x_grad) {
-  using MPType = typename kps::details::MPTypeTrait<T>::Type;
-  auto out_dtype = x.dtype();
-  auto* in_x = &x;
-  auto* d_out = &out_grad;
-  auto* d_x = x_grad;
-
-  // get reduce_dim and reduce_num for reduce_mean_grad
-  int dim_size = in_x->dims().size();
+  // get reduce_dim for reduce_mean_grad
+  int dim_size = x.dims().size();
   if (dims.size() == 0) {
     reduce_all = true;
   }
   std::vector<int> reduce_dims =
       funcs::details::GetReduceDim(dims.GetData(), dim_size, reduce_all);
 
-  auto update_dims = vectorize(d_x->dims());
-  int reduce_num = 1;
+  auto update_dims = vectorize(x.dims());
   for (auto i : reduce_dims) {
-    reduce_num *= (in_x->dims())[i];
     update_dims[i] = 1;
   }
+
   // make new tensor
-  DenseTensor new_d_out(d_out->dtype());
-  new_d_out.ShareDataWith(*d_out);
-  new_d_out.Resize(phi::make_ddim(update_dims));
+  DenseTensor new_out_grad(out_grad.dtype());
+  new_out_grad.ShareDataWith(out_grad);
+  new_out_grad.Resize(phi::make_ddim(update_dims));
 
-  dev_ctx.Alloc(d_x, x.dtype());
-  auto pt_out_dtype = x.dtype();
-  auto pt_d_out = new_d_out;
-  auto pt_d_x = *d_x;
-  std::vector<const DenseTensor*> inputs = {&pt_d_out};
-  std::vector<DenseTensor*> outputs = {&pt_d_x};
+  // call ReduceGrad
+  dev_ctx.Alloc(x_grad, x.dtype());
+  using MPType = typename kps::details::MPTypeTrait<T>::Type;
   phi::ReduceGrad<T, kps::IdentityFunctor<T, MPType>>(
       dev_ctx,
-      &pt_d_out,
-      &pt_d_x,
-      pt_out_dtype,
+      &new_out_grad,
+      x_grad,
+      x.dtype(),
       kps::IdentityFunctor<T, MPType>());
 }
 
diff --git a/paddle/phi/kernels/reduce_mean_kernel.cc b/paddle/phi/kernels/reduce_mean_kernel.cc
index 375172fdb3..aa615a6bb1 100644
--- a/paddle/phi/kernels/reduce_mean_kernel.cc
+++ b/paddle/phi/kernels/reduce_mean_kernel.cc
@@ -26,6 +26,9 @@ void MeanKernel(const Context& dev_ctx,
                 bool keep_dim,
                 DenseTensor* out) {
   bool reduce_all = false;
+  if (dims.size() == 0) {
+    reduce_all = true;
+  }
   MeanRawKernel<T>(dev_ctx, x, dims, keep_dim, reduce_all, out);
 }
 
diff --git a/python/paddle/fluid/layers/nn.py b/python/paddle/fluid/layers/nn.py
index 9f7cbb1141..4a5dbe4a10 100755
--- a/python/paddle/fluid/layers/nn.py
+++ b/python/paddle/fluid/layers/nn.py
@@ -5096,9 +5096,6 @@ def reduce_sum(input, dim=None, keep_dim=False, name=None):
             fluid.layers.reduce_sum(y, dim=[0, 1]) # [16, 20]
 
     """
-    if dim is not None and not isinstance(dim, list):
-        dim = [dim]
-
     reduce_all, dim = _get_reduce_dim(dim, input)
 
     if in_dygraph_mode():
diff --git a/python/paddle/fluid/tests/unittests/test_mean_op.py b/python/paddle/fluid/tests/unittests/test_mean_op.py
index ed9313b054..68e88c9ba2 100644
--- a/python/paddle/fluid/tests/unittests/test_mean_op.py
+++ b/python/paddle/fluid/tests/unittests/test_mean_op.py
@@ -58,6 +58,21 @@ class TestMeanOp(OpTest):
         self.check_grad(['X'], 'Out', check_eager=True)
 
 
+class TestMeanOp_ZeroDim(OpTest):
+    def setUp(self):
+        self.op_type = "mean"
+        self.python_api = paddle.mean
+        self.dtype = np.float64
+        self.inputs = {'X': np.random.random([]).astype(self.dtype)}
+        self.outputs = {'Out': np.mean(self.inputs["X"])}
+
+    def test_check_output(self):
+        self.check_output(check_eager=True)
+
+    def test_checkout_grad(self):
+        self.check_grad(['X'], 'Out', check_eager=True)
+
+
 class TestMeanOpError(unittest.TestCase):
     def test_errors(self):
         with program_guard(Program(), Program()):
diff --git a/python/paddle/fluid/tests/unittests/test_reduce_op.py b/python/paddle/fluid/tests/unittests/test_reduce_op.py
index 8fa448a692..bf0a968bdb 100644
--- a/python/paddle/fluid/tests/unittests/test_reduce_op.py
+++ b/python/paddle/fluid/tests/unittests/test_reduce_op.py
@@ -37,6 +37,21 @@ class TestSumOp(OpTest):
         self.check_grad(['X'], 'Out', check_eager=True)
 
 
+class TestSumOp_ZeroDim(OpTest):
+    def setUp(self):
+        self.python_api = paddle.sum
+        self.op_type = "reduce_sum"
+        self.inputs = {'X': np.random.random([]).astype("float64")}
+        self.outputs = {'Out': self.inputs['X'].sum(axis=None)}
+        self.attrs = {'dim': [], 'reduce_all': True}
+
+    def test_check_output(self):
+        self.check_output(check_eager=True)
+
+    def test_check_grad(self):
+        self.check_grad(['X'], 'Out', check_eager=True)
+
+
 class TestSumOp_fp16(OpTest):
     def setUp(self):
         self.python_api = paddle.sum
diff --git a/python/paddle/fluid/tests/unittests/test_zero_dim_shape.py b/python/paddle/fluid/tests/unittests/test_zero_dim_shape.py
index df4fa96d4a..0cab423aa7 100644
--- a/python/paddle/fluid/tests/unittests/test_zero_dim_shape.py
+++ b/python/paddle/fluid/tests/unittests/test_zero_dim_shape.py
@@ -17,6 +17,7 @@ import paddle.fluid as fluid
 import numpy as np
 import unittest
 
+
 unary_api_list = [
     paddle.nn.functional.elu,
     paddle.nn.functional.gelu,
@@ -159,5 +160,55 @@ class TestUnaryAPI(unittest.TestCase):
         paddle.disable_static()
 
 
+reduce_api_list = [
+    paddle.sum,
+    paddle.mean,
+    paddle.nansum,
+    paddle.nanmean,
+]
+
+
+class TestReduceAPI(unittest.TestCase):
+    def test_dygraph(self):
+        paddle.disable_static()
+        fluid.set_flags({"FLAGS_retain_grad_for_all_tensor": True})
+        for api in reduce_api_list:
+            x = paddle.rand([])
+            x.stop_gradient = False
+            out = api(x, None)
+            out.backward()
+
+            self.assertEqual(x.shape, [])
+            self.assertEqual(x.grad.shape, [])
+            self.assertEqual(out.shape, [])
+            self.assertEqual(out.grad.shape, [])
+
+        paddle.enable_static()
+
+    def test_static(self):
+        paddle.enable_static()
+        for api in reduce_api_list:
+            main_prog = fluid.Program()
+            with fluid.program_guard(main_prog, fluid.Program()):
+                x = paddle.rand([])
+
+                x.stop_gradient = False
+                out = api(x, None)
+                fluid.backward.append_backward(out)
+
+                # Test compile shape, grad is always [1]
+                self.assertEqual(x.shape, ())
+                self.assertEqual(out.shape, ())
+
+                exe = fluid.Executor()
+                result = exe.run(main_prog, fetch_list=[x, out])
+
+                # Test runtime shape
+                self.assertEqual(result[0].shape, ())
+                self.assertEqual(result[1].shape, ())
+
+        paddle.disable_static()
+
+
 if __name__ == "__main__":
     unittest.main()
diff --git a/python/paddle/tensor/math.py b/python/paddle/tensor/math.py
index 91388a6f99..34bc3b006b 100644
--- a/python/paddle/tensor/math.py
+++ b/python/paddle/tensor/math.py
@@ -1265,22 +1265,7 @@ def sum(x, axis=None, dtype=None, keepdim=False, name=None):
             out8 = paddle.sum(x, axis=0)  # [1, 1, 1, 1]
             out9 = paddle.sum(x, axis=1)  # [4, 0]
     """
-    if isinstance(axis, Variable):
-        reduce_all_flag = True if axis.shape[0] == len(x.shape) else False
-    else:
-        if axis is not None and not isinstance(axis, (list, tuple)):
-            axis = [axis]
-
-        if not axis:
-            axis = []
-
-        if len(axis) == 0:
-            reduce_all_flag = True
-        else:
-            if len(axis) == len(x.shape):
-                reduce_all_flag = True
-            else:
-                reduce_all_flag = False
+    reduce_all, axis = _get_reduce_axis_with_tensor(axis, x)
 
     dtype_flag = False
     if dtype is not None:
@@ -1290,11 +1275,6 @@ def sum(x, axis=None, dtype=None, keepdim=False, name=None):
     if in_dygraph_mode():
         return _C_ops.sum(x, axis, dtype, keepdim)
 
-    if not isinstance(axis, Variable):
-        axis = axis if axis != None and axis != [] and axis != () else [0]
-        if utils._contain_var(axis):
-            axis = utils._convert_to_tensor_list(axis)
-
     if _in_legacy_dygraph():
         if dtype_flag:
             return _legacy_C_ops.reduce_sum(
@@ -1304,7 +1284,7 @@ def sum(x, axis=None, dtype=None, keepdim=False, name=None):
                 'keep_dim',
                 keepdim,
                 'reduce_all',
-                reduce_all_flag,
+                reduce_all,
                 'in_dtype',
                 x.dtype,
                 'out_dtype',
@@ -1318,10 +1298,10 @@ def sum(x, axis=None, dtype=None, keepdim=False, name=None):
                 'keep_dim',
                 keepdim,
                 'reduce_all',
-                reduce_all_flag,
+                reduce_all,
             )
 
-    attrs = {'dim': axis, 'keep_dim': keepdim, 'reduce_all': reduce_all_flag}
+    attrs = {'dim': axis, 'keep_dim': keepdim, 'reduce_all': reduce_all}
 
     if dtype_flag:
         attrs.update({'in_dtype': x.dtype, 'out_dtype': dtype})
@@ -2304,13 +2284,13 @@ def inverse(x, name=None):
     return out
 
 
-def _get_reduce_axis(axis):
+def _get_reduce_axis(axis, x):
     """
     Internal function for max, min, amax and amin.
     It computes the attribute reduce_all value based on axis.
     """
     if axis is not None and not isinstance(axis, list):
-        if isinstance(axis, tuple):
+        if isinstance(axis, (tuple, range)):
             axis = list(axis)
         elif isinstance(axis, int):
             axis = [axis]
@@ -2320,37 +2300,25 @@ def _get_reduce_axis(axis):
                     type(axis)
                 )
             )
-    reduce_all = True if axis == None or axis == [] else False
-    if axis == None:
+    if axis is None:
         axis = []
+    if axis == [] or len(axis) == len(x.shape):
+        reduce_all = True
+    else:
+        reduce_all = False
     return reduce_all, axis
 
 
-def _get_reduce_axis_with_tensor(axis):
+def _get_reduce_axis_with_tensor(axis, x):
     if isinstance(axis, Variable):
-        return False, axis
-    return _get_reduce_axis(axis)
-
-
-def _get_reduce_all_value(axis):
-    """
-    Internal function for max, min, amax and amin.
-    It computes the attribute reduce_all value based on axis.
-    """
-    if axis is not None and not isinstance(axis, list):
-        if isinstance(axis, tuple):
-            axis = list(axis)
-        elif isinstance(axis, int):
-            axis = [axis]
+        if axis.shape[0] == len(x.shape):
+            reduce_all = True
         else:
-            raise TypeError(
-                "The type of axis must be int, list or tuple, but received {}".format(
-                    type(axis)
-                )
-            )
-
-    reduce_all = True if axis == None or axis == [] else False
-    axis = axis if axis != None and axis != [] else [0]
+            reduce_all = False
+    else:
+        reduce_all, axis = _get_reduce_axis(axis, x)
+        if utils._contain_var(axis):
+            axis = utils._convert_to_tensor_list(axis)
     return reduce_all, axis
 
 
@@ -2432,7 +2400,7 @@ def max(x, axis=None, keepdim=False, name=None):
             #[7., 8.], [[[0., 0.], [0., 0.]], [[0., 0.], [1., 1.]]]
     """
 
-    reduce_all, axis = _get_reduce_axis_with_tensor(axis)
+    reduce_all, axis = _get_reduce_axis_with_tensor(axis, x)
     if in_dygraph_mode():
         return _C_ops.max(x, axis, keepdim)
     if _in_legacy_dygraph():
@@ -2534,7 +2502,7 @@ def min(x, axis=None, keepdim=False, name=None):
             #[1., 2.], [[[1., 1.], [0., 0.]], [[0., 0.], [0., 0.]]]
     """
 
-    reduce_all, axis = _get_reduce_axis_with_tensor(axis)
+    reduce_all, axis = _get_reduce_axis_with_tensor(axis, x)
     if in_dygraph_mode():
         return _C_ops.min(x, axis, keepdim)
 
@@ -2650,7 +2618,7 @@ def amax(x, axis=None, keepdim=False, name=None):
             #[0.9., 0.9], [[[0., 0.3333], [0.5, 0.3333]], [[0.5, 0.3333], [1., 1.]]]
     """
 
-    reduce_all, axis = _get_reduce_axis(axis)
+    reduce_all, axis = _get_reduce_axis(axis, x)
     if in_dygraph_mode():
         return _C_ops.amax(x, axis, keepdim)
     if _in_legacy_dygraph():
@@ -2764,7 +2732,7 @@ def amin(x, axis=None, keepdim=False, name=None):
             #[0.1., 0.1], [[[0., 0.3333], [0.5, 0.3333]], [[0.5, 0.3333], [1., 1.]]]
     """
 
-    reduce_all, axis = _get_reduce_axis(axis)
+    reduce_all, axis = _get_reduce_axis(axis, x)
     if in_dygraph_mode():
         return _C_ops.amin(x, axis, keepdim)
     elif _in_legacy_dygraph():
diff --git a/python/paddle/tensor/stat.py b/python/paddle/tensor/stat.py
index 371e3fafd0..ad061673ab 100644
--- a/python/paddle/tensor/stat.py
+++ b/python/paddle/tensor/stat.py
@@ -20,9 +20,9 @@ from ..framework import core
 from paddle.fluid.framework import _in_legacy_dygraph, in_dygraph_mode
 from .search import where
 from ..fluid.data_feeder import check_type, check_variable_and_dtype
-from ..fluid.layers import utils
 import paddle
 from paddle import _C_ops, _legacy_C_ops
+from .math import _get_reduce_axis_with_tensor
 
 __all__ = []
 
@@ -80,22 +80,9 @@ def mean(x, axis=None, keepdim=False, name=None):
             # [ 8.5 12.5 16.5]
     """
 
-    if isinstance(axis, Variable):
-        reduce_all = True if axis.shape[0] == len(x.shape) else False
-    else:
-        if isinstance(axis, int):
-            axis = [axis]
-        reduce_all = (
-            True
-            if axis is None or len(axis) == 0 or len(axis) == len(x.shape)
-            else False
-        )
-        if axis is None or len(axis) == 0:
-            axis = [0]
+    reduce_all, axis = _get_reduce_axis_with_tensor(axis, x)
 
     if in_dygraph_mode():
-        if reduce_all:
-            axis = list(range(len(x.shape)))
         return _C_ops.mean(x, axis, keepdim)
     if _in_legacy_dygraph():
         return _legacy_C_ops.reduce_mean(
@@ -122,8 +109,6 @@ def mean(x, axis=None, keepdim=False, name=None):
 
     helper = LayerHelper('mean', **locals())
 
-    if not isinstance(axis, Variable) and utils._contain_var(axis):
-        axis = utils._convert_to_tensor_list(axis)
     attrs = {'dim': axis, 'keep_dim': keepdim, 'reduce_all': reduce_all}
     out = helper.create_variable_for_type_inference(x.dtype)
     helper.append_op(
-- 
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