[DygraphToStatic]Add cast transform for dygraph_to_static. (#25325)

* add cast transform and its UT for dygraph_to_static.

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

@@ -21,9 +21,10 @@ from __future__ import print_function
 import gast
 
 from paddle.fluid.dygraph.dygraph_to_static.assert_transformer import AssertTransformer
-from paddle.fluid.dygraph.dygraph_to_static.call_transformer import CallTransformer
 from paddle.fluid.dygraph.dygraph_to_static.basic_api_transformer import BasicApiTransformer
 from paddle.fluid.dygraph.dygraph_to_static.break_continue_transformer import BreakContinueTransformer
+from paddle.fluid.dygraph.dygraph_to_static.call_transformer import CallTransformer
+from paddle.fluid.dygraph.dygraph_to_static.cast_transformer import CastTransformer
 from paddle.fluid.dygraph.dygraph_to_static.ifelse_transformer import IfElseTransformer
 from paddle.fluid.dygraph.dygraph_to_static.list_transformer import ListTransformer
 from paddle.fluid.dygraph.dygraph_to_static.logical_transformer import LogicalTransformer
@@ -93,6 +94,9 @@ class DygraphToStaticAst(gast.NodeTransformer):
         # Transform call recursively
         CallTransformer(node_wrapper).transform()
 
+        # Transform python type casting statement
+        CastTransformer(node_wrapper).transform()
+
     def visit_FunctionDef(self, node):
         if self.decorate_func_name is None:
             self.decorate_func_name = node.name

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

@@ -0,0 +1,47 @@
+#   Copyright (c) 2020 PaddlePaddle Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import print_function
+import gast
+
+from paddle.fluid.dygraph.dygraph_to_static.static_analysis import AstNodeWrapper
+from paddle.fluid.dygraph.dygraph_to_static.utils import ast_to_source_code
+
+
+class CastTransformer(gast.NodeTransformer):
+    """
+    This class transforms type casting into Static Graph Ast.
+    """
+
+    def __init__(self, wrapper_root):
+        assert isinstance(
+            wrapper_root, AstNodeWrapper
+        ), "Input non-AstNodeWrapper node for the initialization of CastTransformer."
+        self._root = wrapper_root.node
+        self._castable_type = {'bool', 'int', 'float'}
+
+    def transform(self):
+        self.visit(self._root)
+
+    def visit_Call(self, node):
+        self.generic_visit(node)
+        func_str = ast_to_source_code(node.func).strip()
+        if func_str in self._castable_type and len(node.args) > 0:
+            args_str = ast_to_source_code(node.args[0]).strip()
+            new_func_str = "fluid.dygraph.dygraph_to_static.convert_operators.convert_var_dtype({}, '{}')".format(
+                args_str, func_str)
+            new_node = gast.parse(new_func_str).body[0].value
+            return new_node
+
+        return node

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

@@ -238,3 +238,24 @@ def cast_bool_if_necessary(var):
     if convert_dtype(var.dtype) not in ['bool']:
         var = cast(var, dtype="bool")
     return var
+
+
+def convert_var_dtype(var, dtype):
+    if isinstance(var, Variable):
+        src_dtype = convert_dtype(var.dtype)
+        assert src_dtype in [
+            'bool', 'float16', 'float32', 'float64', 'int32', 'int64', 'uint8'
+        ], "The dtype of var {} is {}, which is not supported in the cast op.".format(
+            var.name, src_dtype)
+        assert dtype in [
+            'bool', 'int', 'float'
+        ], "The casted target dtype is {}, which is not supported in type casting.".format(
+            dtype)
+        cast_map = {
+            'bool': 'bool',
+            'int': 'int32',
+            'float': 'float32',
+        }
+        return cast(var, dtype=cast_map[dtype])
+    else:
+        return eval('{}(var)'.format(dtype))

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

@@ -0,0 +1,173 @@
+# Copyright (c) 2020 PaddlePaddle Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import print_function
+
+import unittest
+import numpy as np
+import paddle.fluid as fluid
+from paddle.fluid.dygraph import declarative
+
+SEED = 2020
+np.random.seed(SEED)
+
+
+@declarative
+def test_bool_cast(x):
+    x = fluid.dygraph.to_variable(x)
+    x = bool(x)
+    return x
+
+
+@declarative
+def test_int_cast(x):
+    x = fluid.dygraph.to_variable(x)
+    x = int(x)
+    return x
+
+
+@declarative
+def test_float_cast(x):
+    x = fluid.dygraph.to_variable(x)
+    x = float(x)
+    return x
+
+
+@declarative
+def test_not_var_cast(x):
+    x = int(x)
+    return x
+
+
+@declarative
+def test_mix_cast(x):
+    x = fluid.dygraph.to_variable(x)
+    x = int(x)
+    x = float(x)
+    x = bool(x)
+    x = float(x)
+    return x
+
+
+class TestCastBase(unittest.TestCase):
+    def setUp(self):
+        self.place = fluid.CUDAPlace(0) if fluid.is_compiled_with_cuda(
+        ) else fluid.CPUPlace()
+        self.prepare()
+        self.set_func()
+
+    def prepare(self):
+        self.input_shape = (16, 32)
+        self.input_dtype = 'float32'
+        self.input = np.random.binomial(
+            4, 0.3, size=np.product(self.input_shape)).reshape(
+                self.input_shape).astype(self.input_dtype)
+        self.cast_dtype = 'bool'
+
+    def set_func(self):
+        self.func = test_bool_cast
+
+    def do_test(self):
+        with fluid.dygraph.guard():
+            res = self.func(self.input)
+            return res
+
+    def test_cast_result(self):
+        res = self.do_test().numpy()
+        self.assertTrue(
+            res.dtype == self.cast_dtype,
+            msg='The target dtype is {}, but the casted dtype is {}.'.format(
+                self.cast_dtype, res.dtype))
+        ref_val = self.input.astype(self.cast_dtype)
+        self.assertTrue(
+            np.allclose(res, ref_val),
+            msg='The casted value is {}.\nThe correct value is {}.'.format(
+                res, ref_val))
+
+
+class TestIntCast(TestCastBase):
+    def prepare(self):
+        self.input_shape = (1, )
+        self.input_dtype = 'float32'
+        self.input = np.random.normal(
+            loc=6, scale=10, size=np.product(self.input_shape)).reshape(
+                self.input_shape).astype(self.input_dtype)
+        self.cast_dtype = 'int32'
+
+    def set_func(self):
+        self.func = test_int_cast
+
+
+class TestFloatCast(TestCastBase):
+    def prepare(self):
+        self.input_shape = (8, 16)
+        self.input_dtype = 'bool'
+        self.input = np.random.binomial(
+            2, 0.5, size=np.product(self.input_shape)).reshape(
+                self.input_shape).astype(self.input_dtype)
+        self.cast_dtype = 'float32'
+
+    def set_func(self):
+        self.func = test_float_cast
+
+
+class TestMixCast(TestCastBase):
+    def prepare(self):
+        self.input_shape = (8, 32)
+        self.input_dtype = 'float32'
+        self.input = np.random.normal(
+            loc=6, scale=10, size=np.product(self.input_shape)).reshape(
+                self.input_shape).astype(self.input_dtype)
+        self.cast_int = 'int'
+        self.cast_float = 'float32'
+        self.cast_bool = 'bool'
+        self.cast_dtype = 'float32'
+
+    def set_func(self):
+        self.func = test_mix_cast
+
+    def test_cast_result(self):
+        res = self.do_test().numpy()
+        self.assertTrue(
+            res.dtype == self.cast_dtype,
+            msg='The target dtype is {}, but the casted dtype is {}.'.format(
+                self.cast_dtype, res.dtype))
+        ref_val = self.input.astype(self.cast_int).astype(
+            self.cast_float).astype(self.cast_bool).astype(self.cast_dtype)
+        self.assertTrue(
+            np.allclose(res, ref_val),
+            msg='The casted value is {}.\nThe correct value is {}.'.format(
+                res, ref_val))
+
+
+class TestNotVarCast(TestCastBase):
+    def prepare(self):
+        self.input = 3.14
+        self.cast_dtype = 'int'
+
+    def set_func(self):
+        self.func = test_not_var_cast
+
+    def test_cast_result(self):
+        res = self.do_test()
+        self.assertTrue(type(res) == int, msg='The casted dtype is not int.')
+        ref_val = int(self.input)
+        self.assertTrue(
+            res == ref_val,
+            msg='The casted value is {}.\nThe correct value is {}.'.format(
+                res, ref_val))
+
+
+if __name__ == '__main__':
+    unittest.main()