add X to grad

test=develop

paddle/fluid/operators/cvm_op.cc

@@ -131,6 +131,7 @@ class CVMGradOpDescMaker : public framework::SingleGradOpDescMaker {
   std::unique_ptr<framework::OpDesc> Apply() const override {
     std::unique_ptr<framework::OpDesc> op(new framework::OpDesc());
     op->SetType("cvm_grad");
+    op->SetInput("X", Input("X"));
     op->SetInput("CVM", Input("CVM"));
     op->SetInput(framework::GradVarName("Y"), OutputGrad("Y"));
     op->SetOutput(framework::GradVarName("X"), InputGrad("X"));