ignore no_need_buffer tensor_wrapper in inplace checking (#41350)

* support inplace no_need_buffer

* fix

* use padle.add

paddle/fluid/eager/tensor_wrapper.h

@@ -51,6 +51,7 @@ class TensorWrapper {
      * to avoid recursive depends on GradNodeBase
      * **/
     full_reserved_ = full_reserved;
+    no_need_buffer_ = no_need_buffer;
     if (full_reserved_) {
       VLOG(6) << "Fully reserved tensor: " << tensor.name();
       intermidiate_tensor_ = tensor;
@@ -58,7 +59,6 @@ class TensorWrapper {
     }
 
     // shallow copy tensor_impl here
-    no_need_buffer_ = no_need_buffer;
     if (no_need_buffer) {
       if (phi::DenseTensor::classof(tensor.impl().get())) {
         // Only Copy Meta

python/paddle/fluid/tests/unittests/test_inplace.py

@@ -103,7 +103,9 @@ class TestInplace(unittest.TestCase):
 
             var_b[1:2] = 3  # var_b is modified inplace before using it
 
-            var_c = var_b + var_b  # Here, the grad op of sum doesn't use the value of var_b
+            var_c = paddle.add(
+                var_b,
+                var_b)  # Here, the grad op of sum doesn't use the value of var_b
             loss = var_c.sum()
 
             var_b[1:2] = 3  # var_b is modified inplace after using it
@@ -111,9 +113,8 @@ class TestInplace(unittest.TestCase):
             loss.backward()
 
     def test_backward_success_2(self):
-        # TODO: need to process no_need_buffer in eager mode
-        # with _test_eager_guard():
-        #     self.func_test_backward_success_2()
+        with _test_eager_guard():
+            self.func_test_backward_success_2()
         self.func_test_backward_success_2()