fix ExecutionContext::HasInput and ExecutionContext::HasOutput depend on the...

fix ExecutionContext::HasInput and ExecutionContext::HasOutput depend on the scope structure, test=develop (#20721)

paddle/fluid/framework/operator.cc

@@ -417,34 +417,12 @@ Tensor* GetMutableLoDTensorOrSelectedRowsValueFromVar(Variable* var) {
 }
 
 bool ExecutionContext::HasInput(const std::string& name) const {
-  if (!op_.HasInputs(name)) {
-    return false;
-  }
-  auto& ins = Inputs(name);
-  size_t length = ins.size();
-  if (length == 0) {
-    return false;
-  }
-  PADDLE_ENFORCE_EQ(length, 1UL,
-                    "Input %s should not have more than one inputs", name);
-  auto arg = ins[0];
-  auto* var = arg == kEmptyVarName ? nullptr : scope_.FindVar(arg);
+  auto* var = InputVar(name);
   return var != nullptr;
 }
 
 bool ExecutionContext::HasOutput(const std::string& name) const {
-  if (!op_.HasOutputs(name)) {
-    return false;
-  }
-  auto& outs = Outputs(name);
-  size_t length = outs.size();
-  if (length == 0) {
-    return false;
-  }
-  PADDLE_ENFORCE_EQ(length, 1UL,
-                    "Output %s should not have more than one inputs", name);
-  auto arg = outs[0];
-  auto* var = arg == kEmptyVarName ? nullptr : scope_.FindVar(arg);
+  auto* var = OutputVar(name);
   return var != nullptr;
 }