[Cherry-pick]Add code examples for paddle.save/load (#32900) (#32929)

* doc of paddle.save/load

* polish doc of paddle.save/load

python/paddle/framework/io.py

@@ -496,7 +496,7 @@ def save(obj, path, protocol=2, **configs):
     Save an object to the specified path.
     
     .. note::
-        Now supports saving ``state_dict`` of Layer/Optimizer, Layer, Tensor and nested structure containing Tensor.
+        Now supports saving ``state_dict`` of Layer/Optimizer, Layer, Tensor and nested structure containing Tensor, Program.
 
     .. note::
         Different from ``paddle.jit.save``, since the save result of ``paddle.save`` is a single file, 
@@ -544,7 +544,18 @@ def save(obj, path, protocol=2, **configs):
             # save weight of emb
             paddle.save(emb.weight, "emb.weight.pdtensor")
 
-            # example 2: static graph
+            # example 2: Save multiple state_dict at the same time
+            from paddle import nn
+            from paddle.optimizer import Adam
+
+            layer = paddle.nn.Linear(3, 4)
+            adam = Adam(learning_rate=0.001, parameters=layer.parameters())
+            obj = {'model': layer.state_dict(), 'opt': adam.state_dict(), 'epoch': 100}
+            path = 'example/model.pdparams'
+            paddle.save(obj, path)
+
+
+            # example 3: static graph
             import paddle
             import paddle.static as static
 
@@ -570,6 +581,18 @@ def save(obj, path, protocol=2, **configs):
             # save/load state_dict
             path_state_dict = 'temp/model.pdparams'
             paddle.save(prog.state_dict("param"), path_tensor)
+
+            # example 4: save program
+            import paddle
+
+            paddle.enable_static()
+
+            data = paddle.static.data(
+                name='x_static_save', shape=(None, 224), dtype='float32')
+            y_static = z = paddle.static.nn.fc(data, 10)
+            main_program = paddle.static.default_main_program()
+            path = "example/main_program.pdmodel"
+            paddle.save(main_program, path)
     '''
     # 1. input check
     filename = os.path.basename(path)
@@ -667,7 +690,7 @@ def load(path, **configs):
     Load an object can be used in paddle from specified path.
 
     .. note::
-        Now supports loading ``state_dict`` of Layer/Optimizer, Layer, Tensor and nested structure containing Tensor.
+        Now supports loading ``state_dict`` of Layer/Optimizer, Layer, Tensor and nested structure containing Tensor, Program.
 
     .. note::
         In order to use the model parameters saved by paddle more efficiently, 
@@ -714,8 +737,6 @@ def load(path, **configs):
     Examples:
         .. code-block:: python
 
-            import paddle
-
             # example 1: dynamic graph
             import paddle
             emb = paddle.nn.Embedding(10, 10)
@@ -744,7 +765,19 @@ def load(path, **configs):
             load_weight = paddle.load("emb.weight.pdtensor")
 
 
-            # example 2: static graph
+            # example 2: Load multiple state_dict at the same time
+            from paddle import nn
+            from paddle.optimizer import Adam
+
+            layer = paddle.nn.Linear(3, 4)
+            adam = Adam(learning_rate=0.001, parameters=layer.parameters())
+            obj = {'model': layer.state_dict(), 'opt': adam.state_dict(), 'epoch': 100}
+            path = 'example/model.pdparams'
+            paddle.save(obj, path)
+            obj_load = paddle.load(path)
+
+
+            # example 3: static graph
             import paddle
             import paddle.static as static
 
@@ -773,6 +806,22 @@ def load(path, **configs):
             paddle.save(prog.state_dict("param"), path_tensor)
             load_state_dict = paddle.load(path_tensor)
 
+
+            # example 4: load program
+            import paddle
+
+            paddle.enable_static()
+
+            data = paddle.static.data(
+                name='x_static_save', shape=(None, 224), dtype='float32')
+            y_static = z = paddle.static.nn.fc(data, 10)
+            main_program = paddle.static.default_main_program()
+            path = "example/main_program.pdmodel"
+            paddle.save(main_program, path)
+            load_main = paddle.load(path)
+            print(load_main)
+
+
     '''
 
     if os.path.isfile(path):