Simplify building precess of gradient operator

paddle/framework/backward.cc

@@ -42,9 +42,9 @@ static std::shared_ptr<OperatorBase> NOP() {
 //
 //  no_grad_names the gradient variable names without gradient calculating.
 //
-//  uniq_id is a unique index used inside recursively calling BackwardRecursive.
-//  use `uid = uniq_id++;` to get the unique index, and pass `uniq_id` through
-//  recursive calling.
+//  uniq_id is a unique index used inside recursively calling
+//  BackwardRecursive. use `uid = uniq_id++;` to get the unique index, and
+//  pass `uniq_id` through recursive calling.
 //
 //  returns The backward operator. For simple situation, it is a simple
 //  operator. For complex situation, it is a NetOp.
@@ -64,8 +64,8 @@ std::shared_ptr<OperatorBase> BackwardRecursive(
     return NOP();
   }
 
-  //  All output gradients of forwarding operator do not need to calculate. Then
-  //  all input gradients cannot be computed at all, and we put them into
+  //  All output gradients of forwarding operator do not need to calculate.
+  //  Then all input gradients cannot be computed at all, and we put them into
   //  `no_grad_names` set. Return an NOP.
   if (AllInSet(forwardOp.outputs_, OperatorBase::GRAD_VAR_SUFFIX(),
                no_grad_names)) {
@@ -83,8 +83,8 @@ std::shared_ptr<OperatorBase> BackwardRecursive(
     // Because forwardOp is a net op, it can static_cast.
     auto& forwardNet = static_cast<const NetOp&>(forwardOp);
 
-    // Map from output gradient variable name to operator's indices in backward
-    // net. That operator generates that variable.
+    // Map from output gradient variable name to operator's indices in
+    // backward net. That operator generates that variable.
     std::unordered_map<std::string, std::vector<size_t>> dup_output_ops;
 
     size_t local_op_id = 0;

paddle/framework/backward_test.cc

@@ -161,8 +161,8 @@ TEST(Backward, simple_op_grad) {
   auto fwd = f::OpRegistry::CreateOp("rowwise_add", {"X", "b"}, {"Out"}, {});
   ASSERT_NE(fwd, nullptr);
   auto gop = f::OpRegistry::CreateGradOp(*fwd);
-  ASSERT_EQ(1UL, gop->inputs_.size());
-  ASSERT_EQ("Out" + f::OperatorBase::GRAD_VAR_SUFFIX(), gop->inputs_[0]);
+  ASSERT_EQ(4UL, gop->inputs_.size());
+  ASSERT_EQ(f::OperatorBase::EMPTY_VAR_NAME(), gop->inputs_[0]);
   ASSERT_EQ("rowwise_add_grad", gop->type_);
   ASSERT_EQ("X" + f::OperatorBase::GRAD_VAR_SUFFIX(), gop->outputs_[0]);
   ASSERT_EQ("b" + f::OperatorBase::GRAD_VAR_SUFFIX(), gop->outputs_[1]);
@@ -358,7 +358,7 @@ TEST(Backward, linear_net_intermediate_variable_has_no_grad) {
             3UL       /* external input number */
                 + 1UL /* external output number*/
                 + 1UL /* number of gradient of external output*/
-                - 1UL /*ignoreGradient varable number*/
+                //- 1UL /*ignoreGradient varable number*/
                 + 2U /* internal variable number*/);
   EXPECT_EQ(grad_fc.outputs_.size(), 2UL       /* input number of mul*/
                                          + 2UL /* input number of rowwise_add */

paddle/framework/grad_op_builder.cc

@@ -13,102 +13,92 @@ See the License for the specific language governing permissions and
 limitations under the License. */
 
 #include "paddle/framework/grad_op_builder.h"
+#include "paddle/framework/op_proto.pb.h"
 #include "paddle/framework/op_registry.h"
 
 namespace paddle {
 namespace framework {
 
-OperatorBase* GradOpBuilder::Build() {
-  BuildOpInOutArgList();
-  std::string grad_op_type = OpRegistry::grad_ops().at(op_.type_);
-  OperatorBase* grad_op = OpRegistry::op_creators().at(grad_op_type)();
-  grad_op->type_ = grad_op_type;
-  CompleteGradOp(grad_op);
-  return grad_op;
-}
+class OpRegistry;
+
+using VarIndexMap = std::unordered_map<std::string, int>;
 
-OpInOutArg* GradOpBuilder::BuildArg(const VarProto& var,
-                                    const VarIndexMap& var_map,
-                                    const std::vector<int>& format,
-                                    InOutType type) {
-  int idx = var_map.at(var.name());
-  int begin_idx = format.empty() ? idx : format.at(idx);
-  int end_idx = format.empty() ? idx + 1 : format.at(idx + 1);
-  return new OpInOutArg(var.name(), type, !var.ignore_gradient(), begin_idx,
-                        end_idx);
+enum OpArgType { IN, OUT };
+
+static std::vector<int>* GetOpFormat(OperatorBase* op, const OpArgType& type) {
+  std::string key = type == IN ? "input_format" : "output_name";
+  return op->attrs_.count(key)
+             ? &boost::get<std::vector<int>>(op->attrs_.at(key))
+             : nullptr;
 }
 
-void GradOpBuilder::BuildOpInOutArgList() {
-  const OpProto& op_proto = OpRegistry::protos().at(op_.type_);
-  const auto& var_map = *(OpRegistry::VarIndexMaps().at(op_.type_));
-  const std::vector<int>& in_format =
-      op_.attrs_.count("input_format")
-          ? op_.GetAttr<std::vector<int>>("input_format")
-          : std::vector<int>();
-  const std::vector<int>& out_format =
-      op_.attrs_.count("output_format")
-          ? op_.GetAttr<std::vector<int>>("output_format")
-          : std::vector<int>();
-  for (const auto& var : op_proto.inputs()) {
-    arg_list_.emplace_back(
-        std::shared_ptr<OpInOutArg>(BuildArg(var, var_map, in_format, IN)));
-  }
-  for (const auto& var : op_proto.outputs()) {
-    arg_list_.emplace_back(
-        std::shared_ptr<OpInOutArg>(BuildArg(var, var_map, out_format, OUT)));
-  }
+static const std::vector<int>* GetOpFormat(const OperatorBase* op,
+                                           const OpArgType& type) {
+  std::string key = type == IN ? "input_format" : "output_name";
+  return op->attrs_.count(key)
+             ? &boost::get<std::vector<int>>(op->attrs_.at(key))
+             : nullptr;
 }
 
-void GradOpBuilder::AddArgIntoGradOp(const OpInOutArg* arg,
-                                     std::vector<std::string>& in_out,
-                                     std::vector<int>& format,
-                                     VarIndexMap* varmap, int& idx,
-                                     bool is_grad) const {
-  std::string var_name = arg->proto_name_;
-  if (is_grad) {
-    var_name += OperatorBase::GRAD_VAR_SUFFIX();
-  }
-  (*varmap)[var_name] = idx++;
-  size_t pre_sz = in_out.size();
-  auto base_it = arg->type_ == IN ? op_.inputs_.begin() : op_.outputs_.begin();
-  std::copy(base_it + arg->begin_idx_, base_it + arg->end_idx_,
-            std::back_inserter(in_out));
-  if (is_grad) {
-    for (size_t i = pre_sz; i < in_out.size(); ++i) {
-      in_out[i] += OperatorBase::GRAD_VAR_SUFFIX();
+static void TransOpArg(const OperatorBase* src_op, OperatorBase* dst_op,
+                       const OpArgType& src_type, const OpArgType& dst_type,
+                       int& idx, bool is_grad) {
+  const std::vector<std::string>& src_inout =
+      src_type == IN ? src_op->inputs_ : src_op->outputs_;
+  const VarIndexMap& src_varmap = *src_op->in_out_idxs_;
+  const std::vector<int>* src_format = GetOpFormat(src_op, src_type);
+
+  std::vector<std::string>& dst_inout =
+      dst_type == IN ? dst_op->inputs_ : dst_op->outputs_;
+  VarIndexMap& dst_varmap = *dst_op->in_out_idxs_;
+  std::vector<int>* dst_format = GetOpFormat(dst_op, dst_type);
+  const OpProto& proto = OpRegistry::protos().at(src_op->type_);
+  const auto& src_arg_list = src_type == IN ? proto.inputs() : proto.outputs();
+
+  for (const auto& arg : src_arg_list) {
+    std::string src_name = arg.name();
+    std::string dst_name =
+        is_grad ? src_name + OperatorBase::GRAD_VAR_SUFFIX() : src_name;
+    dst_varmap[dst_name] = idx++;
+    int src_arg_idx = src_varmap.at(src_name);
+    int src_begin =
+        src_format == nullptr ? src_arg_idx : src_format->at(src_arg_idx);
+    int src_end = src_format == nullptr ? src_arg_idx + 1
+                                        : src_format->at(src_arg_idx + 1);
+    for (int i = src_begin; i < src_end; ++i) {
+      std::string s = is_grad ? src_inout[i] + OperatorBase::GRAD_VAR_SUFFIX()
+                              : arg.ignore_gradient()
+                                    ? OperatorBase::EMPTY_VAR_NAME()
+                                    : src_inout[i];
+      dst_inout.emplace_back(s);
+    }
+    if (dst_format != nullptr) {
+      dst_format->push_back(dst_inout.size());
     }
   }
-  format.push_back(in_out.size());
 }
 
-void GradOpBuilder::CompleteGradOp(OperatorBase* grad_op) const {
-  grad_op->attrs_ = op_.attrs_;
+OperatorBase* BuildGradOp(const OperatorBase* op) {
+  std::string grad_op_type = OpRegistry::grad_ops().at(op->type_);
+  OperatorBase* grad_op = OpRegistry::op_creators().at(grad_op_type)();
+  grad_op->type_ = grad_op_type;
+  grad_op->attrs_ = op->attrs_;
   grad_op->attrs_.erase("input_format");
   grad_op->attrs_.erase("output_format");
-  VarIndexMap* grad_varmap = new VarIndexMap();
+  if (GetOpFormat(op, OUT) != nullptr) {
+    grad_op->attrs_["output_format"] = std::vector<int>({0});
+  }
+  if (GetOpFormat(op, IN) != nullptr || GetOpFormat(op, OUT) != nullptr) {
+    grad_op->attrs_["input_format"] = std::vector<int>({0});
+  }
+  grad_op->in_out_idxs_.reset(new VarIndexMap());
   int in_idx = 0;
   int out_idx = 0;
-  std::vector<int> in_format({0});
-  std::vector<int> out_format({0});
-  for (const auto& arg : arg_list_) {
-    // op_'s inputs_ and outputs_
-    if (arg->needed_in_grad_) {
-      AddArgIntoGradOp(arg.get(), grad_op->inputs_, in_format, grad_varmap,
-                       in_idx, false);
-    }
-    if (arg->type_ == IN) {
-      // gradients of op_'s inputs_
-      AddArgIntoGradOp(arg.get(), grad_op->outputs_, out_format, grad_varmap,
-                       out_idx, true);
-    } else {
-      // gradients of op_'s outputs_
-      AddArgIntoGradOp(arg.get(), grad_op->inputs_, in_format, grad_varmap,
-                       in_idx, true);
-    }
-  }
-  grad_op->attrs_["input_format"] = in_format;
-  grad_op->attrs_["output_format"] = out_format;
-  grad_op->in_out_idxs_.reset(grad_varmap);
+  TransOpArg(op, grad_op, IN, IN, in_idx, false);   // I
+  TransOpArg(op, grad_op, OUT, IN, in_idx, false);  // G
+  TransOpArg(op, grad_op, OUT, IN, in_idx, true);   // OG
+  TransOpArg(op, grad_op, IN, OUT, out_idx, true);  // IG
+  return grad_op;
 }
 
 }  // namespace framework

paddle/framework/grad_op_builder.h

@@ -1,48 +1,11 @@
 #pragma once
 
-#include "paddle/framework/op_proto.pb.h"
 #include "paddle/framework/operator.h"
 
 namespace paddle {
 namespace framework {
-class OpRegistry;
 
-enum InOutType { IN, OUT };
-
-struct OpInOutArg {
-  OpInOutArg(const std::string& proto_name, const InOutType& type,
-             bool needed_in_grad, size_t begin_idx, size_t end_idx)
-      : proto_name_(proto_name),
-        type_(type),
-        needed_in_grad_(needed_in_grad),
-        begin_idx_(begin_idx),
-        end_idx_(end_idx) {}
-
-  std::string proto_name_;
-  InOutType type_;
-  bool needed_in_grad_;
-  size_t begin_idx_;
-  size_t end_idx_;
-};
-
-class GradOpBuilder {
-  using VarIndexMap = std::unordered_map<std::string, int>;
-
- public:
-  GradOpBuilder(const OperatorBase& op) : op_(op) {}
-  OperatorBase* Build();
-
- private:
-  OpInOutArg* BuildArg(const VarProto& var, const VarIndexMap& var_map,
-                       const std::vector<int>& format, InOutType type);
-  void BuildOpInOutArgList();
-  void AddArgIntoGradOp(const OpInOutArg* arg, std::vector<std::string>& in_out,
-                        std::vector<int>& format, VarIndexMap* varmap, int& idx,
-                        bool is_grad) const;
-  void CompleteGradOp(OperatorBase* grad_op) const;
-  const OperatorBase& op_;
-  std::vector<std::shared_ptr<OpInOutArg>> arg_list_;
-};
+OperatorBase* BuildGradOp(const OperatorBase* op);
 
 }  // namespace framework
 }  // namespace paddle

paddle/framework/op_registry.h

@@ -306,8 +306,7 @@ class OpRegistry {
   static std::shared_ptr<OperatorBase> CreateGradOp(const OperatorBase& op) {
     PADDLE_ENFORCE(!op.IsNetOp(),
                    "Use framework::Backward to get backward ops");
-    GradOpBuilder builder(op);
-    std::shared_ptr<OperatorBase> grad_op(builder.Build());
+    std::shared_ptr<OperatorBase> grad_op(BuildGradOp(&op));
     grad_op->Init();
     return grad_op;
   }