support view strategy in eager_fluid state (#40830)

* support view strategy in eager_fluid state

* little change

* little change

* optimize unittest

* fix

paddle/fluid/eager/auto_code_generator/eager_generator.cc

@@ -1707,10 +1707,31 @@ static std::pair<std::string, std::string> GenerateForwardFunctionContents(
       }
     }
   }
-  generated_function_body += "\n";
 
   VLOG(6) << "Generated Outs Map";
 
+  // [Generation] Apply View Strategy (Tensor)
+  if (inplace_map.empty() && view_op_map.count(op_type)) {
+    const char* HANDLE_VIEW_BETWEEN_INPUT_AND_OUTPUT =
+        "  if (ins.count(\"%s\") && outs.count(\"%s\")) {\n"
+        "    egr::EagerUtils::HandleViewBetweenInputAndOutput(ins[\"%s\"][0], "
+        "outs[\"%s\"][0]);\n"
+        "  };\n";
+
+    std::string view_strategy_str = "";
+    std::string viwe_input_name = view_op_map[op_type].first;
+    std::string viwe_output_name = view_op_map[op_type].second;
+    view_strategy_str += paddle::string::Sprintf(
+        HANDLE_VIEW_BETWEEN_INPUT_AND_OUTPUT, viwe_input_name, viwe_output_name,
+        viwe_input_name, viwe_output_name);
+
+    generated_function_body += view_strategy_str;
+    generated_function_body += "\n";
+
+    VLOG(6) << "Generated View Strategy";
+  }
+  generated_function_body += "\n";
+
   // [Generation] Get Attrs
   dygraph_function_args_str +=
       ", const paddle::framework::AttributeMap& attr_map";

paddle/fluid/eager/utils.cc

@@ -244,6 +244,33 @@ std::vector<std::shared_ptr<EagerVariable>> EagerUtils::CreateVars(
   return res;
 }
 
+void EagerUtils::HandleViewBetweenInputAndOutput(
+    const std::shared_ptr<EagerVariable>& input_var,
+    const std::shared_ptr<EagerVariable>& view_output_var) {
+  PADDLE_ENFORCE_EQ(
+      input_var->Var().IsInitialized(), true,
+      paddle::platform::errors::InvalidArgument(
+          "Tensor %s has not been initialized!", input_var->name()));
+
+  if (phi::DenseTensor::classof(input_var->GetTensorBase().get())) {
+    auto input_dense_tensor =
+        std::dynamic_pointer_cast<phi::DenseTensor>(input_var->GetTensorBase());
+    PADDLE_ENFORCE_EQ(
+        input_dense_tensor->IsInitialized(), true,
+        paddle::platform::errors::InvalidArgument(
+            "DenseTensor %s has not been initialized!", input_var->name()));
+
+    auto* view_output_tensor =
+        view_output_var->MutableVar()->GetMutable<phi::DenseTensor>();
+    view_output_tensor->ShareBufferWith(*input_dense_tensor);
+    view_output_tensor->ShareInplaceVersionCounterWith(*input_dense_tensor);
+
+    VLOG(3) << "Perform View between Output Var(" << view_output_var->name()
+            << ") and Input Var(" << input_var->name()
+            << "), share allocation and inplace version.";
+  }
+}
+
 void EagerUtils::ModifyInplaceInput(
     const std::shared_ptr<EagerVariable>& inplace_variable,
     paddle::experimental::Tensor* inplace_tensor) {

paddle/fluid/eager/utils.h

@@ -168,6 +168,11 @@ class EagerUtils {
     }
   }
 
+  // View Strategy
+  static void HandleViewBetweenInputAndOutput(
+      const std::shared_ptr<EagerVariable>& input_var,
+      const std::shared_ptr<EagerVariable>& view_output_var);
+
   // TensorWrapper Utils
   static paddle::experimental::Tensor RecoverTensorWrapper(
       TensorWrapper* tw, const std::shared_ptr<GradNodeBase>& grad_node);

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

@@ -29,13 +29,8 @@
 # View APIs include: `squeeze`, `unsqueeze`, `reshape`, `flatten`, `detach`
 class TestDygraphViewReuseAllocation(unittest.TestCase):
     def setUp(self):
-        self.set_flag_to_test_eager_mode()
         self.init_shape()
 
-    # some op don't suport eager_final_state in temporary
-    def set_flag_to_test_eager_mode(self):
-        self.flag_test_eager_mode = False
-
     def init_shape(self):
         self.input_shape = [2, 3, 1]
         self.output_shape = [2, 3]
@@ -46,10 +41,7 @@ def view_api_processing(self, var):
     def func_test_view_api(self):
         var = paddle.rand(self.input_shape)
         view_var = self.view_api_processing(var)
-        # setitem don't support inplace in temporary.
-        # replace setitem with inplace exp_ in temporary.
-        # view_var[0] = 2.
-        view_var.exp_()
+        view_var[0] = 2.
         self.assertEqual(var.shape, self.input_shape)
         self.assertEqual(view_var.shape, self.output_shape)
 
@@ -58,9 +50,8 @@ def func_test_view_api(self):
         self.assertTrue(np.array_equal(var_numpy, view_var_numpy))
 
     def test_view_api(self):
-        if self.flag_test_eager_mode:
-            with _test_eager_guard():
-                self.func_test_view_api()
+        with _test_eager_guard():
+            self.func_test_view_api()
         self.func_test_view_api()
 
     def func_test_forward_version(self):
@@ -69,23 +60,20 @@ def func_test_forward_version(self):
         view_var = self.view_api_processing(var)
         self.assertEqual(view_var.inplace_version, 0)
 
-        # var[0] = 2.
-        var.exp_()
+        var[0] = 2.
         self.assertEqual(var.inplace_version, 1)
         self.assertEqual(view_var.inplace_version, 1)
 
         view_var_2 = self.view_api_processing(var)
         self.assertEqual(view_var_2.inplace_version, 1)
 
-        # var[0] = 3.
-        var.exp_()
+        var[0] = 3.
         self.assertEqual(view_var.inplace_version, 2)
         self.assertEqual(view_var_2.inplace_version, 2)
 
     def test_forward_version(self):
-        if self.flag_test_eager_mode:
-            with _test_eager_guard():
-                self.func_test_forward_version()
+        with _test_eager_guard():
+            self.func_test_forward_version()
         self.func_test_forward_version()
 
     def func_test_backward_error(self):
@@ -100,8 +88,7 @@ def func_test_backward_error(self):
             # Here, the gradient computation will use the value of var_b
             var_c = var_b**2
             view_var_b = self.view_api_processing(var_b)
-            # view_var_b[0] = 2.  # var_b is modified inplace
-            view_var_b.exp_()
+            view_var_b[0] = 2.  # var_b is modified inplace
 
             loss = paddle.nn.functional.relu(var_c)
             if in_dygraph_mode():
@@ -118,16 +105,12 @@ def func_test_backward_error(self):
                     loss.backward()
 
     def test_backward_error(self):
-        if self.flag_test_eager_mode:
-            with _test_eager_guard():
-                self.func_test_backward_error()
+        with _test_eager_guard():
+            self.func_test_backward_error()
         self.func_test_backward_error()
 
 
 class TestUnsqueezeDygraphViewReuseAllocation(TestDygraphViewReuseAllocation):
-    def set_flag_to_test_eager_mode(self):
-        self.flag_test_eager_mode = False
-
     def init_shape(self):
         self.input_shape = [2, 3]
         self.output_shape = [2, 3, 1]
@@ -137,9 +120,6 @@ def view_api_processing(self, var):
 
 
 class TestReshapeDygraphViewReuseAllocation(TestDygraphViewReuseAllocation):
-    def set_flag_to_test_eager_mode(self):
-        self.flag_test_eager_mode = True
-
     def init_shape(self):
         self.input_shape = [3, 4]
         self.output_shape = [2, 2, 3]
@@ -149,9 +129,6 @@ def view_api_processing(self, var):
 
 
 class TestFlattenDygraphViewReuseAllocation(TestDygraphViewReuseAllocation):
-    def set_flag_to_test_eager_mode(self):
-        self.flag_test_eager_mode = False
-
     def init_shape(self):
         self.input_shape = [3, 4]
         self.output_shape = [12]