Refine mechanism of calling outer function in dy2static (#23688)

* Refine mechanism of calling outer function test=develop

* fix typo test=develop

python/paddle/fluid/dygraph/dygraph_to_static/utils.py

@@ -308,42 +308,6 @@ def create_funcDef_node(nodes, name, input_args, return_name_ids):
     return func_def_node
 
 
-class ImportVisitor(gast.NodeVisitor):
-    """
-    Visitor to parse all `import` statement.
-    """
-
-    def __init__(self, file_name):
-        self.root = self.file_to_ast(file_name)
-        self.import_statements = []
-
-    def transform(self):
-        if self.root is not None:
-            self.visit(self.root)
-        self.after_visit()
-        return self.import_statements
-
-    def visit_Import(self, node):
-        self.import_statements.append(ast_to_source_code(node))
-        return node
-
-    def visit_ImportFrom(self, node):
-        self.import_statements.append(ast_to_source_code(node))
-        return node
-
-    def after_visit(self):
-        essential_statements = ["import paddle.fluid as fluid\n"]
-        new_stmts = set(essential_statements) - set(self.import_statements)
-        self.import_statements.extend(list(new_stmts))
-
-    def file_to_ast(self, file_name):
-        root = None
-        if file_name is not None:
-            with open(file_name) as f:
-                root = gast.parse(f.read())
-        return root
-
-
 def index_in_list(array_list, item):
     try:
         return array_list.index(item)
@@ -392,6 +356,8 @@ class RenameTransformer(gast.NodeTransformer):
 def ast_to_func(ast_root, dyfunc, delete_on_exit=True):
     """
     Transform modified AST of decorated function into python callable object.
+    TODO: If only decorate one of inner function instead of decorating the main
+    function, the other inner functions are invisible for the decorated function.
     """
     source = ast_to_source_code(ast_root)
     if six.PY2:
@@ -400,16 +366,8 @@ def ast_to_func(ast_root, dyfunc, delete_on_exit=True):
     else:
         f = tempfile.NamedTemporaryFile(
             mode='w', suffix='.py', delete=False, encoding='utf-8')
-    # `sys.modules` is used to cache all modules and packages that avoids
-    # to import same modules twice by the import mechanism in python.
-    # We insert the import statements defined in source file into the tmpfile
-    # to make it easier to import external functions correctly.
-    source_file = inspect.getfile(dyfunc)
-    import_statements = ImportVisitor(source_file).transform()
-    import_str = "".join(import_statements)
     with f:
         module_name = os.path.basename(f.name[:-3])
-        f.write(import_str)
         f.write(source)
 
     if delete_on_exit:
@@ -420,8 +378,25 @@ def ast_to_func(ast_root, dyfunc, delete_on_exit=True):
         raise ValueError(
             'Function: %s doesn\'t exist in the Module transformed from AST.' %
             func_name)
+    callable_func = getattr(module, func_name)
+    # After transform dygraph function into callable_func saved in tmp file,
+    # it lost the global variables from imported statements or defined in source file.
+    # Recovers the necessary variables by `__globals__`.
+    recover_globals_attribute(dyfunc, callable_func)
+
+    return callable_func, f.name
+
+
+def recover_globals_attribute(src_obj, dst_obj):
+    attr_name = '__globals__'
+
+    src_globals = getattr(src_obj, attr_name, {})
+    dst_globals = getattr(dst_obj, attr_name, {})
 
-    return getattr(module, func_name), f.name
+    for k, v in src_globals.items():
+        # ignore builtin attribute.
+        if not (k.startswith('__') and k.endswith('__')):
+            dst_globals[k] = v
 
 
 def ast_to_source_code(ast_node):

python/paddle/fluid/tests/unittests/dygraph_to_static/test_dict.py

@@ -99,14 +99,16 @@ class MainNetWithDict(fluid.dygraph.Layer):
         out = input
         for i in range(max_len):
             out = self.sub_net(out, cache)
-            cache = self.update_cache(cache)
+            cache = update_cache(cache)
         return out
 
-    def update_cache(self, cache):
-        for k, val in six.iteritems(cache):
-            cache[k] = fluid.layers.softmax(val)
 
-        return cache
+# Test to call function defined outside of class.
+def update_cache(cache):
+    for k, val in six.iteritems(cache):
+        cache[k] = fluid.layers.softmax(val)
+
+    return cache
 
 
 class TestNetWithDict(unittest.TestCase):

python/paddle/fluid/tests/unittests/dygraph_to_static/test_ifelse.py

@@ -209,12 +209,18 @@ class TestDygraphIfElseNet(unittest.TestCase):
         self.assertTrue((self._run_dygraph() == self._run_static()).all())
 
 
+# Test to call function ahead caller.
+def relu(x):
+    return fluid.layers.relu(x)
+
+
 def call_external_func(x, label=None):
-    if fluid.layers.mean(x).numpy()[0] > 5:
+    if fluid.layers.mean(x) < 0:
         x_v = x - 1
     else:
         x_v = add_fn(x)
 
+    x_v = relu(x_v)
     if label is not None:
         loss = loss_fn(x_v, label)
         return loss
@@ -230,17 +236,23 @@ class TestAst2FuncWithExternalFunc(TestDygraphIfElse):
 class NetWithExternalFunc(fluid.dygraph.Layer):
     @dygraph_to_static_func
     def forward(self, x, label=None):
-        if fluid.layers.mean(x).numpy()[0] > 5:
+        if fluid.layers.mean(x) < 0:
             x_v = x - 1
         else:
             x_v = add_fn(x)
 
+        x_v = softmax(x_v)
         if label is not None:
             loss = loss_fn(x_v, label)
             return loss
         return x_v
 
 
+# Test to call function behind caller.
+def softmax(x):
+    return fluid.layers.softmax(x)
+
+
 class TestNetWithExternalFunc(TestDygraphIfElseNet):
     def setUp(self):
         self.x = np.random.random([10, 16]).astype('float32')