Merge pull request #6741 from JiayiFeng/dev_new_backward

[WIP] new backward

doc/design/optimizer.md

@@ -79,7 +79,7 @@ class Optimizer(object):
     def minimize(self, loss, parameter_list):
         """Add operations to minimize `loss` by updating `parameter_list`.
 
-        This method combines interface `append_backward_ops()` and
+        This method combines interface `append_backward()` and
         `create_optimization_pass()` into one.
         """
         params_grads = self.create_backward_pass(loss, parameter_list)

paddle/framework/op_desc.cc

@@ -88,6 +88,14 @@ OpDesc::OpDesc(const std::string &type, const VariableNameMap &inputs,
   need_update_ = true;
 }
 
+void OpDesc::CopyFrom(const OpDesc &op_desc) {
+  desc_.set_type(op_desc.Type());
+  inputs_ = op_desc.inputs_;
+  outputs_ = op_desc.outputs_;
+  attrs_ = op_desc.attrs_;
+  need_update_ = true;
+}
+
 OpDesc::OpDesc(const proto::OpDesc &desc, ProgramDesc *prog)
     : desc_(desc), need_update_(false) {
   // restore inputs_

paddle/framework/op_desc.h

@@ -35,6 +35,8 @@ class OpDesc {
 
   OpDesc(const proto::OpDesc &desc, ProgramDesc *prog);
 
+  void CopyFrom(const OpDesc &op_desc);
+
   proto::OpDesc *Proto();
 
   std::string Type() const { return desc_.type(); }

paddle/framework/var_desc.cc

@@ -74,7 +74,7 @@ const proto::TensorDesc &VarDesc::tensor_desc() const {
     case proto::VarDesc::LOD_TENSOR_ARRAY:
       return desc_.tensor_array().tensor();
     default:
-      PADDLE_THROW("Unexpected branch.");
+      PADDLE_THROW("The type of var '", this->Name(), "' is unsupported.");
   }
 }
 

paddle/pybind/protobuf.cc

@@ -171,12 +171,23 @@ void BindBlockDesc(py::module &m) {
              std::string name = byte_name;
              return self.HasVar(name);
            })
+      .def("has_var_recursive",
+           [](BlockDesc &self, py::bytes byte_name) {
+             std::string name = byte_name;
+             return self.HasVarRecursive(name);
+           })
       .def("find_var",
            [](BlockDesc &self, py::bytes byte_name) {
              std::string name = byte_name;
              return self.FindVar(name);
            },
            py::return_value_policy::reference)
+      .def("find_var_recursive",
+           [](BlockDesc &self, py::bytes byte_name) {
+             std::string name = byte_name;
+             return self.FindVarRecursive(name);
+           },
+           py::return_value_policy::reference)
       .def("all_vars", &BlockDesc::AllVars, py::return_value_policy::reference)
       .def("op_size", &BlockDesc::OpSize)
       .def("op", &BlockDesc::Op, py::return_value_policy::reference)
@@ -204,7 +215,7 @@ void BindVarDsec(py::module &m) {
       .def("set_shape", &VarDesc::SetShape)
       .def("set_dtype", &VarDesc::SetDataType)
       .def("shape", &VarDesc::Shape, py::return_value_policy::reference)
-      .def("dtype", &VarDesc::GetDataType)
+      .def("dtype", &VarDesc::GetDataType, py::return_value_policy::reference)
       .def("lod_level", &VarDesc::GetLodLevel)
       .def("set_lod_level", &VarDesc::SetLoDLevel)
       .def("type", &VarDesc::GetType)
@@ -236,14 +247,22 @@ void BindOpDesc(py::module &m) {
       .value("BLOCK", proto::AttrType::BLOCK);
 
   py::class_<OpDesc> op_desc(m, "OpDesc", "");
-  op_desc.def("type", &OpDesc::Type)
+  op_desc
+      .def("__init__", [](OpDesc &self) { new (&self) OpDesc(); },
+           py::return_value_policy::reference)
+      .def("copy_from", &OpDesc::CopyFrom)
+      .def("type", &OpDesc::Type)
       .def("set_type", &OpDesc::SetType)
       .def("input", &OpDesc::Input)
       .def("input_names", &OpDesc::InputNames)
-      .def("set_input", &OpDesc::SetInput)
       .def("output", &OpDesc::Output)
       .def("output_names", &OpDesc::OutputNames)
+      .def("set_input", &OpDesc::SetInput)
       .def("set_output", &OpDesc::SetOutput)
+      .def("input_arg_names", &OpDesc::InputArgumentNames)
+      .def("output_arg_names", &OpDesc::OutputArgumentNames)
+      .def("rename_input", &OpDesc::RenameInput)
+      .def("rename_output", &OpDesc::RenameOutput)
       .def("has_attr", &OpDesc::HasAttr)
       .def("attr_type", &OpDesc::GetAttrType)
       .def("attr_names", &OpDesc::AttrNames)

paddle/pybind/pybind.cc

@@ -269,23 +269,22 @@ All parameter, weight, gradient are variables in Paddle.
     }
     return ret_values;
   });
-  m.def("get_grad_op_descs",
-        [](const OpDesc &op_desc,
-           const std::unordered_set<std::string> &no_grad_set,
-           std::unordered_map<std::string, std::string> &grad_to_var,
-           const std::vector<BlockDesc *> &grad_sub_block) {
-          std::vector<std::unique_ptr<OpDesc>> grad_op_descs =
-              framework::OpInfoMap::Instance()
-                  .Get(op_desc.Type())
-                  .GradOpMaker()(op_desc, no_grad_set, &grad_to_var,
-                                 grad_sub_block);
-          std::vector<OpDesc *> grad_op_desc_ptrs(grad_op_descs.size());
-          std::transform(
-              grad_op_descs.begin(), grad_op_descs.end(),
-              grad_op_desc_ptrs.begin(),
-              [](std::unique_ptr<OpDesc> &p) { return p.release(); });
-          return grad_op_desc_ptrs;
-        });
+  m.def(
+      "get_grad_op_desc", [](const OpDesc &op_desc,
+                             const std::unordered_set<std::string> &no_grad_set,
+                             const std::vector<BlockDesc *> &grad_sub_block) {
+        std::unordered_map<std::string, std::string> grad_to_var;
+        std::vector<std::unique_ptr<OpDesc>> grad_op_descs =
+            framework::OpInfoMap::Instance()
+                .Get(op_desc.Type())
+                .GradOpMaker()(op_desc, no_grad_set, &grad_to_var,
+                               grad_sub_block);
+        std::vector<OpDesc *> grad_op_desc_ptrs(grad_op_descs.size());
+        std::transform(grad_op_descs.begin(), grad_op_descs.end(),
+                       grad_op_desc_ptrs.begin(),
+                       [](std::unique_ptr<OpDesc> &p) { return p.release(); });
+        return std::make_pair(grad_op_desc_ptrs, grad_to_var);
+      });
   m.def("prune", [](const ProgramDesc &origin,
                     const std::vector<std::array<size_t, 2>> &targets) {
     ProgramDesc prog_with_targets(origin);
@@ -301,6 +300,8 @@ All parameter, weight, gradient are variables in Paddle.
     InferenceOptimize(*(origin.Proto()), &pruned_desc);
     return new ProgramDesc(pruned_desc);
   });
+  m.def("empty_var_name", []() { return framework::kEmptyVarName; });
+  m.def("grad_var_suffix", []() { return framework::kGradVarSuffix; });
   m.def_submodule(
        "var_names",
        "The module will return special predefined variable name in Paddle")

python/paddle/v2/fluid/backward.py

 from paddle.v2.fluid import framework as framework
+from . import core
+import collections
 
-__all__ = ['append_backward_ops']
+__all__ = ['append_backward']
 
 
-def append_backward_ops(loss, parameter_list=None, no_grad_set=None):
+def _rename_arg_(op_desc_list, old_name, new_name, begin_idx=None,
+                 end_idx=None):
+    if begin_idx is None:
+        begin_idx = 0
+    if end_idx is None:
+        end_idx = len(op_desc_list)
+    for i in range(begin_idx, end_idx):
+        op_desc = op_desc_list[i]
+        if isinstance(op_desc, tuple):
+            op_desc = op_desc[0]
+        op_desc.rename_input(old_name, new_name)
+        op_desc.rename_output(old_name, new_name)
+
+
+def _create_op_desc_(op_type, inputs, outputs, attrs):
+    op_desc = core.OpDesc()
+    op_desc.set_type(op_type)
+    for para, args in inputs.iteritems():
+        op_desc.set_input(para, args)
+    for para, args in outputs.iteritems():
+        op_desc.set_output(para, args)
+    for name, val in attrs.iteritems():
+        if isinstance(val, framework.Block):
+            op_desc.set_block_attr(name, val.desc)
+        else:
+            op_desc.set_attr(name, val)
+    return op_desc
+
+
+def _infer_var_data_type_(var_name, block):
+    grad_var = block.desc.find_var(var_name.encode("ascii"))
+    fwd_name = _strip_grad_suffix_(var_name.encode("ascii"))
+    if block.desc.has_var_recursive(fwd_name):
+        fwd_var = block.desc.find_var_recursive(fwd_name.encode("ascii"))
+        grad_var.set_dtype(fwd_var.dtype())
+    else:
+        grad_var.set_dtype(core.DataType.FP32)
+
+
+def _all_in_set_(cands, s):
+    for c in cands:
+        if not c in s:
+            return False
+    return True
+
+
+def _strip_grad_suffix_(name):
+    pos = name.find(core.grad_var_suffix())
+    return name[:pos] if pos != -1 else name
+
+
+def _append_grad_suffix_(name):
+    return name + core.grad_var_suffix()
+
+
+def _addup_repetitive_outputs_(op_descs):
+    # In backward part, an variable my be the output of more than one ops.
+    # In this case, the variable should be the accumulation of all the outputs.
+    # We adopt adding `sum_op`s to implement the accumulate.
+    pending_sum_ops = []
+    var_rename_count = collections.defaultdict(int)
+    renamed_vars = collections.defaultdict(list)
+    for idx, op_desc in enumerate(op_descs):
+        for var_name in op_desc.input_arg_names():
+            if len(renamed_vars[var_name]) > 1:
+                pending_sum_ops.append(
+                    (_create_op_desc_("sum", {"X": renamed_vars[var_name]},
+                                      {"Out": [var_name]}, {}), idx))
+                renamed_vars[var_name] = [var_name]
+        for var_name in op_desc.output_arg_names():
+            if var_name == core.empty_var_name(
+            ) or var_name in op_desc.input_arg_names():
+                # empty variable or inplace op
+                continue
+            if len(renamed_vars[var_name]) == 0:
+                # it's the first time we get the variable
+                renamed_vars[var_name] = [var_name]
+            else:
+                if len(renamed_vars[var_name]) == 1:
+                    new_name = var_name + "@RENAME@" + \
+                        str(var_rename_count[var_name])
+                    var_rename_count[var_name] += 1
+                    # rename original var_name
+                    renamed_vars[var_name][0] = new_name
+                    _rename_arg_(op_descs, var_name, new_name, 0, idx)
+                    _rename_arg_(pending_sum_ops, var_name, new_name)
+
+                new_name = var_name + "@RENAME@" + \
+                    str(var_rename_count[var_name])
+                var_rename_count[var_name] += 1
+                op_desc.rename_output(var_name, new_name)
+                renamed_vars[var_name].append(new_name)
+    for var_name, inputs in renamed_vars.iteritems():
+        if len(inputs) > 1:
+            pending_sum_ops.append((_create_op_desc_(
+                "sum", {"X": inputs}, {"Out": [var_name]}, {}), len(op_descs)))
+    # sum_op descs are sorted according to their insert position
+    for p in reversed(pending_sum_ops):
+        op_descs.insert(p[1], p[0])
+
+    return op_descs
+
+
+def _remove_no_grad_branch_(op_descs, no_grad_set):
+    # Remove ops whose outputs are all in no_grad_dict
+    op_descs = filter(
+        lambda op_desc: not _all_in_set_(op_desc.output_arg_names(), no_grad_set),
+        op_descs)
+    # Insert fill_zeros_like_op
+    to_insert = []
+    for idx, op_desc in enumerate(op_descs):
+        for arg in op_desc.input_arg_names():
+            if core.grad_var_suffix() in arg and arg in no_grad_set:
+                to_insert.append((_create_op_desc_("fill_zeros_like", {
+                    "X": [_strip_grad_suffix_(arg)]
+                }, {"Y": [arg]}, {}), idx))
+
+    map(lambda p: op_descs.insert(p[1], p[0]), reversed(to_insert))
+
+    return op_descs
+
+
+def _append_backward_ops_(target,
+                          block,
+                          target_block,
+                          no_grad_dict,
+                          grad_to_var,
+                          callback=None):
+    grad_op_descs = []
+    program = block.program
+    for op in reversed(block.ops):
+        grad_sub_block_list = []
+        # If the op has its own sub-block, deal with the sub-block first
+        if op.has_attr("sub_block"):
+            sub_block = program.block(op.block_attr("sub_block"))
+            grad_sub_block = program.create_block(parent_idx=sub_block.idx)
+            _append_backward_ops_(target, sub_block, grad_sub_block,
+                                  no_grad_dict, grad_to_var, callback)
+            grad_sub_block_list.append(grad_sub_block.desc)
+
+        grad_op_desc, op_grad_to_var = core.get_grad_op_desc(
+            op.desc, no_grad_dict[block.idx], grad_sub_block_list)
+        grad_op_descs.extend(grad_op_desc)
+        grad_to_var.update(op_grad_to_var)
+
+    grad_op_descs = _addup_repetitive_outputs_(grad_op_descs)
+
+    grad_op_descs = _remove_no_grad_branch_(grad_op_descs,
+                                            no_grad_dict[block.idx])
+
+    if target_block.idx == 0:
+        grad_op_descs.insert(
+            0,
+            _create_op_desc_("fill_constant", {}, {
+                "Out": [_append_grad_suffix_(target.name)]
+            }, {"shape": [1],
+                "value": 1.0,
+                "dtype": target.dtype}))
+    # append op_desc in grad_op_descs to target_block
+    for op_desc in grad_op_descs:
+        new_op_desc = target_block.desc.append_op()
+        new_op_desc.copy_from(op_desc)
+
+
+def _append_backward_vars_(block, start_op_idx, grad_to_var, grad_info_map):
+    for op_idx in range(start_op_idx, block.desc.op_size()):
+        op_desc = block.desc.op(op_idx)
+        if op_desc.has_attr("sub_block"):
+            sub_block = block.program.block(op_desc.block_attr("sub_block"))
+            _append_backward_vars_(sub_block, 0, grad_to_var, grad_info_map)
+        new_vars = set()
+        # create new gradient variables
+        for grad_var_name in op_desc.output_arg_names():
+            grad_var_name = grad_var_name.encode("ascii")
+            if block.desc.has_var_recursive(
+                    grad_var_name) or grad_var_name == core.empty_var_name():
+                continue
+            block.desc.var(grad_var_name)
+            new_vars.add(grad_var_name)
+            if not grad_to_var.has_key(grad_var_name):
+                continue
+            grad_info_map[grad_to_var[grad_var_name]] = (grad_var_name, block)
+        # infer_shape and infer_type
+        op_desc.infer_var_type(block.desc)
+        op_desc.infer_shape(block.desc)
+        for arg in op_desc.output_arg_names():
+            if arg in new_vars:
+                _infer_var_data_type_(arg, block)
+
+
+def append_backward(loss, parameter_list=None, no_grad_set=None):
     """
     Create and add gradient Operators in BlockDesc to compute
     gradients of `loss` for parameters in parameter_list
 
     :param loss: an variable generated by cost function.
     :type loss: Variable
-    :param no_grad_set: variable that should not create gradient
-    :type no_grad_set: set
+    :param no_grad_dict: variable that should not create gradient
+    :type no_grad_dict: set
     :param parameter_list: parameters that need to compute gradient and 
     update to optimize the lost.
     :type: list
@@ -20,35 +212,53 @@ def append_backward_ops(loss, parameter_list=None, no_grad_set=None):
     """
     assert isinstance(loss, framework.Variable)
 
+    program = loss.block.program
+    no_grad_dict = dict()
     if no_grad_set is None:
-        program = loss.block.program
         assert isinstance(program, framework.Program)
-        no_grad_set = list()
         for block in program.blocks:
             assert isinstance(block, framework.Block)
+            block_no_grad_set = set()
             for var in block.vars.itervalues():
                 assert isinstance(var, framework.Variable)
                 if var.stop_gradient:
-                    no_grad_set.append(var.name)
-        no_grad_set = set(no_grad_set)
+                    block_no_grad_set.add(_append_grad_suffix_(var.name))
+            no_grad_dict[block.idx] = block_no_grad_set
+    elif isinstance(no_grad_set, set):
+        no_grad_dict = {0: no_grad_set}
+    else:
+        raise ValueError("'no_grad_set' should be a set or None.")
+
+    grad_info_map = dict()
+    root_block = program.block(0)
+
+    fwd_op_num = root_block.desc.op_size()
+    current_block_idx = program.current_block_idx
+    grad_to_var = dict()
+
+    _append_backward_ops_(loss, root_block, root_block, no_grad_dict,
+                          grad_to_var)
+    _append_backward_vars_(root_block, fwd_op_num, grad_to_var, grad_info_map)
+
+    program.current_block_idx = current_block_idx
+    program.sync_with_cpp()
 
-    param_grad_map = loss.block.program.append_backward(loss, no_grad_set)
     if parameter_list is not None:
         parameters = parameter_list
     else:
-        params = loss.block.program.global_block().all_parameters()
+        params = program.global_block().all_parameters()
         parameters = [param.name for param in params]
     params_and_grads = []
     for param in parameters:
-        if param not in param_grad_map:
+        if param not in grad_info_map:
             raise ValueError("param %s is not in map" % param)
-        grad_info = param_grad_map[param]
-        grad_block = loss.block.program.block(grad_info[1])
+        grad_info = grad_info_map[param]
+        grad_block = grad_info[1]
         if not grad_block.has_var(grad_info[0]):
             raise ValueError("grad block[{0}] did not have grad var {1}".format(
                 grad_info[1], grad_info[0]))
         # Get the param var from the global block
-        param_var = loss.block.program.global_block().var(param)
+        param_var = program.global_block().var(param)
         grad_var = grad_block.var(grad_info[0])
         if loss.block.has_var(grad_info[0]):
             params_and_grads.append((param_var, grad_var))

python/paddle/v2/fluid/framework.py

@@ -846,9 +846,11 @@ class Program(object):
         self.sync_with_cpp()
         return param_to_grad_info
 
-    def create_block(self):
+    def create_block(self, parent_idx=None):
         new_block_idx = len(self.blocks)
-        self.desc.append_block(self.current_block().desc)
+        parent = self.current_block() if parent_idx is None else self.block(
+            parent_idx)
+        self.desc.append_block(parent.desc)
         self.current_block_idx = new_block_idx
         self.blocks.append(Block(self, self.current_block_idx))
         return self.current_block()

python/paddle/v2/fluid/optimizer.py

 from collections import defaultdict
 
 import framework
-from backward import append_backward_ops
+from backward import append_backward
 from framework import unique_name, program_guard
 from initializer import Constant
 from layer_helper import LayerHelper
@@ -194,10 +194,10 @@ class Optimizer(object):
                  no_grad_set=None):
         """Add operations to minimize `loss` by updating `parameter_list`.
 
-        This method combines interface `append_backward_ops()` and
+        This method combines interface `append_backward()` and
         `create_optimization_pass()` into one.
         """
-        params_grads = append_backward_ops(loss, parameter_list, no_grad_set)
+        params_grads = append_backward(loss, parameter_list, no_grad_set)
 
         params_grads = append_gradient_clip_ops(params_grads)
 

python/paddle/v2/fluid/tests/op_test.py

@@ -4,7 +4,7 @@ import random
 import itertools
 import paddle.v2.fluid.core as core
 import collections
-from paddle.v2.fluid.backward import append_backward_ops
+from paddle.v2.fluid.backward import append_backward
 from paddle.v2.fluid.op import Operator
 from paddle.v2.fluid.executor import Executor
 from paddle.v2.fluid.framework import Program, OpProtoHolder
@@ -491,7 +491,7 @@ class OpTest(unittest.TestCase):
             op_loss.desc.infer_var_type(block.desc)
             op_loss.desc.infer_shape(block.desc)
 
-        param_grad_list = append_backward_ops(
+        param_grad_list = append_backward(
             loss=loss, parameter_list=input_to_check, no_grad_set=no_grad_set)
 
         feed_dict = {

python/paddle/v2/fluid/tests/test_array_read_write_op.py

@@ -2,7 +2,7 @@ import unittest
 import paddle.v2.fluid.core as core
 import paddle.v2.fluid.layers as layers
 from paddle.v2.fluid.executor import Executor
-from paddle.v2.fluid.backward import append_backward_ops
+from paddle.v2.fluid.backward import append_backward
 from paddle.v2.fluid.framework import default_main_program
 import numpy
 
@@ -64,7 +64,7 @@ class TestArrayReadWrite(unittest.TestCase):
         total_sum = layers.sums(input=[a_sum, x_sum])
         total_sum_scaled = layers.scale(x=total_sum, scale=1 / 6.0)
 
-        append_backward_ops(total_sum_scaled)
+        append_backward(total_sum_scaled)
 
         g_vars = map(default_main_program().global_block().var,
                      [each_x.name + "@GRAD" for each_x in x])

python/paddle/v2/fluid/tests/test_conditional_block.py

@@ -3,7 +3,7 @@ import paddle.v2.fluid.layers as layers
 import paddle.v2.fluid.core as core
 from paddle.v2.fluid.framework import default_startup_program, default_main_program
 from paddle.v2.fluid.executor import Executor
-from paddle.v2.fluid.backward import append_backward_ops
+from paddle.v2.fluid.backward import append_backward
 import numpy
 
 
@@ -26,7 +26,7 @@ class ConditionalBlock(unittest.TestCase):
         outs = exe.run(feed={'X': x}, fetch_list=[out])[0]
         print outs
         loss = layers.mean(x=out)
-        append_backward_ops(loss=loss)
+        append_backward(loss=loss)
         outs = exe.run(
             feed={'X': x},
             fetch_list=[

python/paddle/v2/fluid/tests/test_lod_tensor_array_ops.py

@@ -4,7 +4,7 @@ import numpy
 import paddle.v2.fluid.layers as layers
 from paddle.v2.fluid.framework import Program, program_guard
 from paddle.v2.fluid.executor import Executor
-from paddle.v2.fluid.backward import append_backward_ops
+from paddle.v2.fluid.backward import append_backward
 
 
 class TestCPULoDTensorArrayOps(unittest.TestCase):
@@ -170,7 +170,7 @@ class TestCPULoDTensorArrayOpGrad(unittest.TestCase):
 
             mean = layers.mean(x=result)
 
-            append_backward_ops(mean)
+            append_backward(mean)
 
         tensor = core.LoDTensor()
         tensor.set(numpy.arange(10).reshape(10, 1).astype('float32'), place)

python/paddle/v2/fluid/tests/test_optimizer.py

@@ -2,7 +2,7 @@ import unittest
 
 import paddle.v2.fluid.framework as framework
 import paddle.v2.fluid.optimizer as optimizer
-from paddle.v2.fluid.backward import append_backward_ops
+from paddle.v2.fluid.backward import append_backward
 
 
 class TestOptimizer(unittest.TestCase):
@@ -102,7 +102,7 @@ class TestMomentumOptimizer(unittest.TestCase):
             dtype="float32", shape=[1], lod_level=0, name="mean.out")
         block.append_op(
             type="mean", inputs={"X": mul_out}, outputs={"Out": mean_out})
-        params_grads = append_backward_ops(mean_out)
+        params_grads = append_backward(mean_out)
         self.assertEqual(len(params_grads), 1)
         self.assertEqual(len(momentum_optimizer.get_accumulators()), 0)
         opts = momentum_optimizer.create_optimization_pass(
@@ -151,7 +151,7 @@ class TestMomentumOptimizer(unittest.TestCase):
         learning_rate = 0.01
         momentum_optimizer = self.MockMomentum(
             learning_rate=learning_rate, momentum=0.2, use_nesterov=True)
-        params_grads = append_backward_ops(mean_out)
+        params_grads = append_backward(mean_out)
         self.assertEqual(len(params_grads), 1)
         self.assertEqual(len(momentum_optimizer.get_accumulators()), 0)
         opts = momentum_optimizer.create_optimization_pass(
@@ -209,7 +209,7 @@ class TestAdagradOptimizer(unittest.TestCase):
         learning_rate = 0.01
         adagrad_optimizer = self.MockAdagrad(
             learning_rate=learning_rate, epsilon=1.0e-6)
-        params_grads = append_backward_ops(mean_out)
+        params_grads = append_backward(mean_out)
         self.assertEqual(len(params_grads), 1)
         self.assertEqual(len(adagrad_optimizer.get_accumulators()), 0)
         opts = adagrad_optimizer.create_optimization_pass(params_grads, mul_out,
@@ -269,7 +269,7 @@ class TestAdamOptimizer(unittest.TestCase):
         learning_rate = 0.01
         adam_optimizer = self.MockAdam(
             learning_rate=learning_rate, beta1=0.9, beta2=0.999)
-        params_grads = append_backward_ops(mean_out)
+        params_grads = append_backward(mean_out)
         self.assertEqual(len(params_grads), 1)
         self.assertEqual(len(adam_optimizer.get_accumulators()), 0)
         opts = adam_optimizer.create_optimization_pass(params_grads, mul_out,
@@ -331,7 +331,7 @@ class TestAdamaxOptimizer(unittest.TestCase):
         learning_rate = 0.01
         adamax_optimizer = self.MockAdamax(
             learning_rate=learning_rate, beta1=0.9, beta2=0.999)
-        params_grads = append_backward_ops(mean_out)
+        params_grads = append_backward(mean_out)
         self.assertEqual(len(params_grads), 1)
         self.assertEqual(len(adamax_optimizer.get_accumulators()), 0)
         opts = adamax_optimizer.create_optimization_pass(params_grads, mul_out,
@@ -390,7 +390,7 @@ class TestDecayedAdagradOptimizer(unittest.TestCase):
         learning_rate = 0.01
         decayed_adagrad_optimizer = self.MockDecayedAdagrad(
             learning_rate=learning_rate, decay=0.95, epsilon=1.0e-6)
-        params_grads = append_backward_ops(mean_out)
+        params_grads = append_backward(mean_out)
         self.assertEqual(len(params_grads), 1)
         self.assertEqual(len(decayed_adagrad_optimizer.get_accumulators()), 0)
         opts = decayed_adagrad_optimizer.create_optimization_pass(

python/paddle/v2/fluid/tests/test_recurrent_op.py

@@ -3,7 +3,7 @@ import unittest
 import paddle.v2.fluid.layers as layers
 from paddle.v2.fluid.framework import Program, grad_var_name
 from paddle.v2.fluid.executor import Executor
-from paddle.v2.fluid.backward import append_backward_ops
+from paddle.v2.fluid.backward import append_backward
 import numpy as np
 import paddle.v2.fluid.core as core
 
@@ -177,7 +177,7 @@ class RecurrentOpTest1(unittest.TestCase):
     def test_backward(self):
         self.check_forward()
 
-        append_backward_ops(self.output)
+        append_backward(self.output)
 
         ana_grad = [np.array(x) for x in self.backward()]
 

python/paddle/v2/fluid/tests/test_regularizer.py

@@ -3,7 +3,7 @@ import unittest
 import paddle.v2.fluid.framework as framework
 import paddle.v2.fluid.optimizer as optimizer
 import paddle.v2.fluid.regularizer as regularizer
-from paddle.v2.fluid.backward import append_backward_ops
+from paddle.v2.fluid.backward import append_backward
 
 
 class TestL2DecayRegularizer(unittest.TestCase):
@@ -33,7 +33,7 @@ class TestL2DecayRegularizer(unittest.TestCase):
             dtype="float32", shape=[1], lod_level=0, name="mean.out")
         block.append_op(
             type="mean", inputs={"X": mul_out}, outputs={"Out": mean_out})
-        params_grads = append_backward_ops(mean_out)
+        params_grads = append_backward(mean_out)
         self.assertEqual(len(params_grads), 1)
         count_ops = len(block.ops)
         params_grads = optimizer.append_regularization_ops(params_grads)
@@ -70,7 +70,7 @@ class TestL1DecayRegularizer(unittest.TestCase):
             dtype="float32", shape=[1], lod_level=0, name="mean.out")
         block.append_op(
             type="mean", inputs={"X": mul_out}, outputs={"Out": mean_out})
-        params_grads = append_backward_ops(mean_out)
+        params_grads = append_backward(mean_out)
         self.assertEqual(len(params_grads), 1)
         count_ops = len(block.ops)
         params_grads = optimizer.append_regularization_ops(params_grads)

python/paddle/v2/fluid/tests/test_reorder_lod_tensor.py

@@ -12,7 +12,7 @@ class TestReorderLoDTensor(unittest.TestCase):
         new_dat = fluid.layers.reorder_lod_tensor_by_rank(
             x=dat, rank_table=table)
         loss = fluid.layers.mean(x=new_dat)
-        fluid.backward.append_backward_ops(loss=loss)
+        fluid.backward.append_backward(loss=loss)
 
         cpu = fluid.CPUPlace()
         exe = fluid.Executor(cpu)

python/paddle/v2/fluid/tests/test_rnn_memory_helper_op.py

@@ -2,7 +2,7 @@ import unittest
 
 from paddle.v2.fluid.framework import Program
 from paddle.v2.fluid.executor import Executor
-from paddle.v2.fluid.backward import append_backward_ops
+from paddle.v2.fluid.backward import append_backward
 import numpy as np
 import paddle.v2.fluid.core as core
 

python/paddle/v2/fluid/tests/test_shrink_rnn_memory.py

@@ -2,7 +2,7 @@ import unittest
 import paddle.v2.fluid.core as core
 from paddle.v2.fluid.executor import Executor
 import paddle.v2.fluid.layers as layers
-from paddle.v2.fluid.backward import append_backward_ops
+from paddle.v2.fluid.backward import append_backward
 from paddle.v2.fluid.framework import default_main_program
 import numpy
 
@@ -35,7 +35,7 @@ class TestShrinkRNNMemory(unittest.TestCase):
         self.assertTrue(numpy.allclose(tensor_np[0:1], outs[2]))
 
         mem3_mean = layers.mean(x=mem3)
-        append_backward_ops(loss=mem3_mean)
+        append_backward(loss=mem3_mean)
         x_grad = exe.run(
             feed={'x': tensor},
             fetch_list=[main_program.global_block().var('x@GRAD')])[0]

python/paddle/v2/fluid/tests/test_split_and_merge_lod_tensor_op.py

@@ -4,7 +4,7 @@ import numpy as np
 import paddle.v2.fluid.layers as layers
 from paddle.v2.fluid.framework import Program, program_guard
 from paddle.v2.fluid.executor import Executor
-from paddle.v2.fluid.backward import append_backward_ops
+from paddle.v2.fluid.backward import append_backward
 
 
 class TestCPULoDTensorArrayOps(unittest.TestCase):
@@ -133,7 +133,7 @@ class TestCPUSplitMergeLoDTensorGrad(unittest.TestCase):
                 in_true=out_true, in_false=out_false, mask=y, x=x, level=level)
             mean = layers.mean(x=out)
 
-            append_backward_ops(mean)
+            append_backward(mean)
 
         tensor = core.LoDTensor()
         tensor.set(np.arange(10).reshape(10, 1).astype('float32'), place)

python/paddle/v2/fluid/tests/test_while_op.py

@@ -2,7 +2,7 @@ import unittest
 import paddle.v2.fluid.layers as layers
 from paddle.v2.fluid.executor import Executor
 import paddle.v2.fluid.core as core
-from paddle.v2.fluid.backward import append_backward_ops
+from paddle.v2.fluid.backward import append_backward
 import numpy
 
 
@@ -46,7 +46,7 @@ class TestWhileOp(unittest.TestCase):
         sum_result = layers.array_read(array=mem_array, i=i)
         loss = layers.mean(x=sum_result)
 
-        append_backward_ops(loss)
+        append_backward(loss)
 
         cpu = core.CPUPlace()
         exe = Executor(cpu)