add inplace to assign op, test=develop (#19927)

paddle/fluid/framework/no_need_buffer_vars_inference.h

@@ -46,12 +46,13 @@ class NoNeedBufferVarsInference {
 };
 
 #define DECLARE_NO_NEED_BUFFER_VARS_INFERENCE(class_type, ...)  \
-  class class_type : public ::paddle::framework::NoNeedBufferVarsInference { \
+  class class_type final                                        \
+      : public ::paddle::framework::NoNeedBufferVarsInference { \
    public:                                                      \
     using ::paddle::framework::NoNeedBufferVarsInference::      \
         NoNeedBufferVarsInference;                              \
                                                                 \
-    std::unordered_set<std::string> operator()() const override {            \
+    std::unordered_set<std::string> operator()() const final {  \
       return {__VA_ARGS__};                                     \
     }                                                           \
   }

paddle/fluid/operators/assign_op.cc

@@ -144,12 +144,14 @@ class AssignGradMaker : public framework::SingleGradOpDescMaker {
   }
 };
 
+DECLARE_INPLACE_OP_INFERER(AssignOpInplaceInferer, {"X", "Out"});
+
 }  // namespace operators
 }  // namespace paddle
 
 namespace ops = paddle::operators;
 REGISTER_OPERATOR(assign, ops::AssignOp, ops::AssignGradMaker,
-                  ops::AssignOpProtoMaker);
+                  ops::AssignOpProtoMaker, ops::AssignOpInplaceInferer);
 REGISTER_OP_CPU_KERNEL_FUNCTOR(assign, float, ops::AssignKernel, double,
                                ops::AssignKernel, int, ops::AssignKernel,
                                int64_t, ops::AssignKernel);