fix GetTensorFromVar

test=release/1.1

paddle/fluid/framework/operator.cc

@@ -358,11 +358,11 @@ static bool VarIsTensor(const Variable* var) {
   return var->IsType<LoDTensor>() || var->IsType<SelectedRows>();
 }
 
-const Tensor* GetTensorFromVar(Variable* var) {
+const Tensor* GetTensorFromVar(const Variable* var) {
   if (var->IsType<LoDTensor>()) {
-    return var->GetMutable<LoDTensor>();
+    return static_cast<const Tensor*>(&(var->Get<LoDTensor>()));
   } else if (var->IsType<SelectedRows>()) {
-    return var->GetMutable<SelectedRows>()->mutable_value();
+    return &(var->Get<SelectedRows>().value());
   } else {
     PADDLE_THROW("Variable type_id %s, expect LoDTensor/SelectedRows.",
                  var->Type().name());
@@ -415,8 +415,7 @@ bool ExecutionContext::HasOutput(const std::string& name) const {
 template <>
 const Tensor* ExecutionContext::Input<Tensor>(const std::string& name) const {
   auto* var = InputVar(name);
-  return var == nullptr ? nullptr
-                        : GetTensorFromVar(const_cast<Variable*>(var));
+  return var == nullptr ? nullptr : GetTensorFromVar(var);
 }
 
 template <>

paddle/fluid/framework/operator.h

@@ -63,7 +63,7 @@ inline std::string GradVarName(const std::string& var_name) {
 }
 
 proto::VarType::Type GetDataTypeOfVar(const Variable* var);
-const Tensor* GetTensorFromVar(Variable* var);
+const Tensor* GetTensorFromVar(const Variable* var);
 
 class OperatorBase;
 class ExecutionContext;

paddle/fluid/operators/sum_op.cc

@@ -83,8 +83,7 @@ class SumOp : public framework::OperatorWithKernel {
       int dtype = -1;
       for (auto& x_var : x_vars) {
         // FIXME(zcd): The input x_var may be SelectedRows or LoDTensor.
-        auto tensor = framework::GetTensorFromVar(
-            const_cast<framework::Variable*>(x_var));
+        auto tensor = framework::GetTensorFromVar(x_var);
         if (tensor->numel() == 0) {
           continue;
         }