Merge pull request #3831 from reyoung/feature/fix_empty_input_and_output

Make operator Input/Output can return nullptr

paddle/framework/backward_test.cc

@@ -127,8 +127,8 @@ class FillZeroOpMaker : public OpProtoAndCheckerMaker {
  public:
   FillZeroOpMaker(OpProto *proto, OpAttrChecker *op_checker)
       : OpProtoAndCheckerMaker(proto, op_checker) {
-    AddInput("x", "x");
-    AddOutput("out", "out");
+    AddInput("Src", "x");
+    AddOutput("Dst", "out");
     AddComment("");
   }
 };
@@ -138,7 +138,7 @@ class AddOpMaker : public OpProtoAndCheckerMaker {
   AddOpMaker(OpProto *proto, OpAttrChecker *op_checker)
       : OpProtoAndCheckerMaker(proto, op_checker) {
     AddInput("X", "x").AsDuplicable();
-    AddOutput("Y", "y");
+    AddOutput("Out", "out");
     AddComment("");
   }
 };

paddle/framework/op_info.h

@@ -80,9 +80,19 @@ class OpInfoMap {
   }
 
   const OpInfo& Get(const std::string& type) const {
+    auto op_info_ptr = GetNullable(type);
+    PADDLE_ENFORCE_NOT_NULL(op_info_ptr, "Operator %s has not been registered",
+                            type);
+    return *op_info_ptr;
+  }
+
+  const OpInfo* GetNullable(const std::string& type) const {
     auto it = map_.find(type);
-    PADDLE_ENFORCE(it != map_.end(), "Operator %s are not found", type);
-    return it->second;
+    if (it == map_.end()) {
+      return nullptr;
+    } else {
+      return &it->second;
+    }
   }
 
   template <typename Callback>

paddle/framework/operator.cc

@@ -33,12 +33,12 @@ ExecutionContext::GetEigenDevice<platform::GPUPlace, Eigen::GpuDevice>() const {
 }
 #endif
 
-const std::string& OperatorBase::Input(const std::string& name) const {
+std::string OperatorBase::Input(const std::string& name) const {
   auto& ins = Inputs(name);
-  PADDLE_ENFORCE_EQ(ins.size(), 1UL,
+  PADDLE_ENFORCE_LE(ins.size(), 1UL,
                     "Op %s input %s should contain only one variable", type_,
                     name);
-  return ins[0];
+  return ins.empty() ? kEmptyVarName : ins[0];
 }
 
 const std::vector<std::string>& OperatorBase::Inputs(
@@ -49,12 +49,12 @@ const std::vector<std::string>& OperatorBase::Inputs(
   return it->second;
 }
 
-const std::string& OperatorBase::Output(const std::string& name) const {
+std::string OperatorBase::Output(const std::string& name) const {
   auto& outs = Outputs(name);
-  PADDLE_ENFORCE_EQ(outs.size(), 1UL,
+  PADDLE_ENFORCE_LE(outs.size(), 1UL,
                     "Op %s output %s should contain only one variable", type_,
                     name);
-  return outs[0];
+  return outs.empty() ? kEmptyVarName : outs[0];
 }
 
 const std::vector<std::string>& OperatorBase::Outputs(
@@ -119,16 +119,8 @@ OperatorBase::OperatorBase(const std::string& type,
                            const VariableNameMap& outputs,
                            const AttributeMap& attrs)
     : type_(type), inputs_(inputs), outputs_(outputs), attrs_(attrs) {
-  static std::atomic<size_t> gUniqId(0UL);
-  for (auto& output : outputs_) {
-    for (auto& output_name : output.second) {
-      if (output_name == kTempVarName) {
-        output_name += type_;
-        output_name += "@";
-        output_name += std::to_string(gUniqId.fetch_add(1));
-      }
-    }
-  }
+  GenerateTemporaryNames();
+  CheckAllInputOutputSet();
 }
 
 std::vector<std::string> OperatorBase::OutputVars(bool has_intermediate) const {
@@ -156,6 +148,35 @@ std::vector<std::string> OperatorBase::OutputVars(bool has_intermediate) const {
   return ret_val;
 }
 
+void OperatorBase::CheckAllInputOutputSet() const {
+  auto& info_map = OpInfoMap::Instance();
+  auto* op_info = info_map.GetNullable(Type());
+  if (op_info == nullptr || op_info->proto_ == nullptr) return;
+
+  for (auto& in : op_info->Proto().inputs()) {
+    PADDLE_ENFORCE(inputs_.find(in.name()) != inputs_.end(),
+                   "Type %s's input %s is not set", Type(), in.name());
+  }
+
+  for (auto& out : op_info->Proto().outputs()) {
+    PADDLE_ENFORCE(outputs_.find(out.name()) != outputs_.end(),
+                   "Type %s's output %s is not set", Type(), out.name());
+  }
+}
+
+void OperatorBase::GenerateTemporaryNames() {
+  static std::atomic<size_t> gUniqId(0UL);
+  for (auto& output : outputs_) {
+    for (auto& output_name : output.second) {
+      if (output_name == kTempVarName) {
+        output_name += type_;
+        output_name += "@";
+        output_name += std::to_string(gUniqId.fetch_add(1));
+      }
+    }
+  }
+}
+
 void OpProtoAndCheckerMaker::Validate() {
   validated_ = true;
   CheckNoDuplicatedInOutAttrs();

paddle/framework/operator.h

@@ -95,12 +95,12 @@ class OperatorBase {
   const VariableNameMap& Inputs() const { return inputs_; }
   const VariableNameMap& Outputs() const { return outputs_; }
   //! Get a input with argument's name described in `op_proto`
-  const std::string& Input(const std::string& name) const;
+  std::string Input(const std::string& name) const;
   //! Get a input which has multiple variables.
   const std::vector<std::string>& Inputs(const std::string& name) const;
 
   //! Get a output with argument's name described in `op_proto`
-  const std::string& Output(const std::string& name) const;
+  std::string Output(const std::string& name) const;
   //! Get an output which has multiple variables.
   //! TODO add a vector_view to prevent memory copy.
   const std::vector<std::string>& Outputs(const std::string& name) const;
@@ -127,6 +127,10 @@ class OperatorBase {
   // IG (Inputs Gradients)
   VariableNameMap outputs_;
   AttributeMap attrs_;
+
+ private:
+  void GenerateTemporaryNames();
+  void CheckAllInputOutputSet() const;
 };
 
 // Macro for define a clone method.
@@ -238,11 +242,13 @@ class InferShapeContext {
   }
 
   const Variable* InputVar(const std::string& name) const {
-    return scope_.FindVar(op_.Input(name));
+    auto ipt = op_.Input(name);
+    return ipt == kEmptyVarName ? nullptr : scope_.FindVar(ipt);
   }
 
   Variable* OutputVar(const std::string& name) const {
-    return scope_.FindVar(op_.Output(name));
+    auto opt = op_.Output(name);
+    return opt == kEmptyVarName ? nullptr : scope_.FindVar(opt);
   }
 
   const std::vector<const Variable*> MultiInputVar(
@@ -250,9 +256,11 @@ class InferShapeContext {
     auto names = op_.Inputs(name);
     std::vector<const Variable*> res;
     res.reserve(names.size());
-    std::transform(
-        names.begin(), names.end(), std::back_inserter(res),
-        [this](const std::string& name) { return scope_.FindVar(name); });
+    std::transform(names.begin(), names.end(), std::back_inserter(res),
+                   [this](const std::string& name) {
+                     return name == kEmptyVarName ? nullptr
+                                                  : scope_.FindVar(name);
+                   });
     return res;
   }
 
@@ -260,24 +268,24 @@ class InferShapeContext {
     auto names = op_.Outputs(name);
     std::vector<const Variable*> res;
     res.reserve(names.size());
-    std::transform(
-        names.begin(), names.end(), std::back_inserter(res),
-        [this](const std::string& name) { return scope_.FindVar(name); });
+    std::transform(names.begin(), names.end(), std::back_inserter(res),
+                   [this](const std::string& name) {
+                     return name == kEmptyVarName ? nullptr
+                                                  : scope_.FindVar(name);
+                   });
     return res;
   }
 
   template <typename T>
   const T* Input(const std::string& name) const {
     auto* var = InputVar(name);
-    PADDLE_ENFORCE_NOT_NULL(var, "Input(%s) should not be nullptr", name);
-    return &var->Get<T>();
+    return var == nullptr ? nullptr : &var->Get<T>();
   }
 
   template <typename T>
   T* Output(const std::string& name) const {
     auto var = OutputVar(name);
-    PADDLE_ENFORCE_NOT_NULL(var, "Output(%s) should not be nullptr", name);
-    return var->GetMutable<T>();
+    return var == nullptr ? nullptr : var->GetMutable<T>();
   }
 
   template <typename T>
@@ -288,10 +296,7 @@ class InferShapeContext {
     std::transform(names.begin(), names.end(), std::back_inserter(res),
                    [&](const std::string& sub_name) {
                      auto var = scope_.FindVar(sub_name);
-                     PADDLE_ENFORCE_NOT_NULL(
-                         var, "MultiInput(%s:%s) should not be nullptr", name,
-                         sub_name);
-                     return &var->Get<T>();
+                     return var == nullptr ? nullptr : &var->Get<T>();
                    });
     return res;
   }
@@ -304,10 +309,7 @@ class InferShapeContext {
     std::transform(names.begin(), names.end(), std::back_inserter(res),
                    [&](const std::string& sub_name) {
                      auto var = scope_.FindVar(sub_name);
-                     PADDLE_ENFORCE_NOT_NULL(
-                         var, "MultiOutput(%s:%s) should not be nullptr.", name,
-                         sub_name);
-                     return var->GetMutable<T>();
+                     return var == nullptr ? nullptr : var->GetMutable<T>();
                    });
     return res;
   }