[PY][FFI] Introduce PyNativeObject, enable runtime.String to subclass str (apache#5426)

To make runtime.String to work as naturally as possible in the python side,
we make it sub-class the python's str object. Note that however, we cannot
sub-class Object at the same time due to python's type layout constraint.

We introduce a PyNativeObject class to handle this kind of object sub-classing
and updated the FFI to handle PyNativeObject classes.

[Relay][Frontend][TFLite] Add parser support for shape and range

Signed-off-by: Dhruva Ray <dhruvaray@gmail.com>

Author: tqchen

CMakeLists.txt

@@ -108,7 +108,7 @@ if(MSVC)
   endif()
 else(MSVC)
   if ("${CMAKE_BUILD_TYPE}" STREQUAL "Debug")
-    message("Build in Debug mode")
+    message(STATUS "Build in Debug mode")
     set(CMAKE_C_FLAGS "-O0 -g -Wall -fPIC ${CMAKE_C_FLAGS}")
     set(CMAKE_CXX_FLAGS "-O0 -g -Wall -fPIC ${CMAKE_CXX_FLAGS}")
     set(CMAKE_CUDA_FLAGS "-O0 -g -Xcompiler=-Wall -Xcompiler=-fPIC ${CMAKE_CUDA_FLAGS}")

python/tvm/_ffi/_ctypes/object.py

@@ -50,6 +50,10 @@ def _return_object(x):
     tindex = ctypes.c_uint()
     check_call(_LIB.TVMObjectGetTypeIndex(handle, ctypes.byref(tindex)))
     cls = OBJECT_TYPE.get(tindex.value, _CLASS_OBJECT)
+    if issubclass(cls, PyNativeObject):
+        obj = _CLASS_OBJECT.__new__(_CLASS_OBJECT)
+        obj.handle = handle
+        return cls.__from_tvm_object__(cls, obj)
     # Avoid calling __init__ of cls, instead directly call __new__
     # This allows child class to implement their own __init__
     obj = cls.__new__(cls)
@@ -64,6 +68,33 @@ def _return_object(x):
     _return_object, TypeCode.OBJECT_RVALUE_REF_ARG)
 
 
+class PyNativeObject:
+    """Base class of all TVM objects that also subclass python's builtin types."""
+    __slots__ = []
+
+    def __init_tvm_object_by_constructor__(self, fconstructor, *args):
+        """Initialize the internal tvm_object by calling constructor function.
+
+        Parameters
+        ----------
+        fconstructor : Function
+            Constructor function.
+
+        args: list of objects
+            The arguments to the constructor
+
+        Note
+        ----
+        We have a special calling convention to call constructor functions.
+        So the return object is directly set into the object
+        """
+        # pylint: disable=assigning-non-slot
+        obj = _CLASS_OBJECT.__new__(_CLASS_OBJECT)
+        obj.__init_handle_by_constructor__(fconstructor, *args)
+        self.__tvm_object__ = obj
+
+
+
 class ObjectBase(object):
     """Base object for all object types"""
     __slots__ = ["handle"]

python/tvm/_ffi/_ctypes/packed_func.py

@@ -29,7 +29,7 @@
 from .types import TVMValue, TypeCode
 from .types import TVMPackedCFunc, TVMCFuncFinalizer
 from .types import RETURN_SWITCH, C_TO_PY_ARG_SWITCH, _wrap_arg_func, _ctx_to_int64
-from .object import ObjectBase, _set_class_object
+from .object import ObjectBase, PyNativeObject, _set_class_object
 from . import object as _object
 
 PackedFuncHandle = ctypes.c_void_p
@@ -123,6 +123,9 @@ def _make_tvm_args(args, temp_args):
             values[i].v_handle = ctypes.cast(arg.handle, ctypes.c_void_p)
             type_codes[i] = (TypeCode.NDARRAY_HANDLE
                              if not arg.is_view else TypeCode.DLTENSOR_HANDLE)
+        elif isinstance(arg, PyNativeObject):
+            values[i].v_handle = arg.__tvm_object__.handle
+            type_codes[i] = TypeCode.OBJECT_HANDLE
         elif isinstance(arg, _nd._TVM_COMPATS):
             values[i].v_handle = ctypes.c_void_p(arg._tvm_handle)
             type_codes[i] = arg.__class__._tvm_tcode

python/tvm/_ffi/_cython/object.pxi

@@ -39,18 +39,49 @@ cdef inline object make_ret_object(void* chandle):
     object_type = OBJECT_TYPE
     handle = ctypes_handle(chandle)
     CALL(TVMObjectGetTypeIndex(chandle, &tindex))
+
     if tindex < len(OBJECT_TYPE):
         cls = OBJECT_TYPE[tindex]
         if cls is not None:
+            if issubclass(cls, PyNativeObject):
+                obj = _CLASS_OBJECT.__new__(_CLASS_OBJECT)
+                (<ObjectBase>obj).chandle = chandle
+                return cls.__from_tvm_object__(cls, obj)
             obj = cls.__new__(cls)
         else:
             obj = _CLASS_OBJECT.__new__(_CLASS_OBJECT)
     else:
         obj = _CLASS_OBJECT.__new__(_CLASS_OBJECT)
+
     (<ObjectBase>obj).chandle = chandle
     return obj
 
 
+class PyNativeObject:
+    """Base class of all TVM objects that also subclass python's builtin types."""
+    __slots__ = []
+
+    def __init_tvm_object_by_constructor__(self, fconstructor, *args):
+        """Initialize the internal tvm_object by calling constructor function.
+
+        Parameters
+        ----------
+        fconstructor : Function
+            Constructor function.
+
+        args: list of objects
+            The arguments to the constructor
+
+        Note
+        ----
+        We have a special calling convention to call constructor functions.
+        So the return object is directly set into the object
+        """
+        obj = _CLASS_OBJECT.__new__(_CLASS_OBJECT)
+        obj.__init_handle_by_constructor__(fconstructor, *args)
+        self.__tvm_object__ = obj
+
+
 cdef class ObjectBase:
     cdef void* chandle
 

python/tvm/_ffi/_cython/packed_func.pxi

@@ -109,6 +109,9 @@ cdef inline int make_arg(object arg,
         value[0].v_handle = (<NDArrayBase>arg).chandle
         tcode[0] = (kTVMNDArrayHandle if
                     not (<NDArrayBase>arg).c_is_view else kTVMDLTensorHandle)
+    elif isinstance(arg, PyNativeObject):
+        value[0].v_handle = (<ObjectBase>(arg.__tvm_object__)).chandle
+        tcode[0] = kTVMObjectHandle
     elif isinstance(arg, _TVM_COMPATS):
         ptr = arg._tvm_handle
         value[0].v_handle = (<void*>ptr)

python/tvm/relay/frontend/tflite.py

@@ -32,6 +32,7 @@
 from .common import ExprTable
 from .common import infer_shape as _infer_shape
 
+
 __all__ = ['from_tflite']
 
 class TensorWrapper(object):
@@ -105,6 +106,7 @@ def __init__(self, model, subgraph, exp_tab):
             'PAD': self.convert_pad,
             'POW': self.convert_pow,
             'PRELU': self.convert_prelu,
+            'RANGE': self.convert_range,
             'REDUCE_ANY': self._convert_reduce_any,
             'REDUCE_MAX': self._convert_reduce_max,
             'REDUCE_MIN': self._convert_reduce_min,
@@ -115,6 +117,7 @@ def __init__(self, model, subgraph, exp_tab):
             'RESIZE_NEAREST_NEIGHBOR': self.convert_resize_nearest_neighbor,
             'ROUND': self.convert_round,
             'RSQRT': self.convert_rsqrt,
+            'SHAPE': self.convert_shape,
             'SIN': self.convert_sin,
             'SLICE': self.convert_slice,
             'SOFTMAX': self.convert_softmax,
@@ -552,6 +555,63 @@ def convert_tanh(self, op):
 
         return out
 
+    def convert_range(self, op):
+        """Convert TFLite Range"""
+        try:
+            from tflite.Operator import Operator
+            from tflite.TensorType import TensorType
+        except ImportError:
+            raise ImportError("The tflite package must be installed")
+
+        if self.is_quantized(op):
+            raise tvm.error.OpNotImplemented(
+                'TFlite quantized RANGE operator is not supported yet.')
+
+        assert isinstance(op, Operator)
+        input_tensors = self.get_input_tensors(op)
+        assert len(input_tensors) == 3, "input tensors length should be 3"
+
+        start, limit, delta = input_tensors[0], input_tensors[1], input_tensors[2]
+        expressions = []
+
+        for t in [start, limit, delta]:
+            if self.has_expr(t.tensor_idx):
+                expressions.append(self.get_expr(t.tensor_idx))
+            else:
+                tensor_type = self.get_tensor_type_str(t.tensor.Type())
+                tensor_value = self.get_tensor_value(t)
+                expressions.append(self.exp_tab.new_const(tensor_value, dtype=tensor_type))
+
+        #out type inference
+        if delta.tensor.Type() == TensorType.FLOAT32:
+            out_type = self.get_tensor_type_str(delta.tensor.Type())
+        else:
+            out_type = self.get_tensor_type_str(start.tensor.Type())
+
+        #put type here form op
+        out = _op.arange(expressions[0], expressions[1], expressions[2], out_type)
+
+        return out
+
+    def convert_shape(self, op):
+        """Convert TFLite Shape"""
+        try:
+            from tflite.Operator import Operator
+        except ImportError:
+            raise ImportError("The tflite package must be installed")
+
+        if self.is_quantized(op):
+            raise tvm.error.OpNotImplemented(
+                'TFlite quantized SHAPE operator is not supported yet.')
+
+        assert isinstance(op, Operator)
+        input_tensors = self.get_input_tensors(op)
+        assert len(input_tensors) == 1, "input tensors length should be 1"
+
+        out = _op.shape_of(self.get_expr(input_tensors[0].tensor_idx))
+
+        return out
+
     def convert_relu(self, op):
         """Convert TFLite ReLU"""
         input_tensors = self.get_input_tensors(op)

python/tvm/runtime/container.py

@@ -16,9 +16,10 @@
 # under the License.
 """Runtime container structures."""
 import tvm._ffi
-from tvm._ffi.base import string_types
-from tvm.runtime import Object, ObjectTypes
-from tvm.runtime import _ffi_api
+from .object import Object, PyNativeObject
+from .object_generic import ObjectTypes
+from . import _ffi_api
+
 
 def getitem_helper(obj, elem_getter, length, idx):
     """Helper function to implement a pythonic getitem function.
@@ -112,64 +113,26 @@ def tuple_object(fields=None):
 
 
 @tvm._ffi.register_object("runtime.String")
-class String(Object):
-    """The string object.
+class String(str, PyNativeObject):
+    """TVM runtime.String object, represented as a python str.
 
     Parameters
     ----------
-    string : str
-        The string used to construct a runtime String object
-
-    Returns
-    -------
-    ret : String
-        The created object.
+    content : str
+        The content string used to construct the object.
     """
-    def __init__(self, string):
-        self.__init_handle_by_constructor__(_ffi_api.String, string)
-
-    def __str__(self):
-        return _ffi_api.GetStdString(self)
-
-    def __len__(self):
-        return _ffi_api.GetStringSize(self)
-
-    def __hash__(self):
-        return _ffi_api.StringHash(self)
-
-    def __eq__(self, other):
-        if isinstance(other, string_types):
-            return self.__str__() == other
-
-        if not isinstance(other, String):
-            return False
-
-        return _ffi_api.CompareString(self, other) == 0
-
-    def __ne__(self, other):
-        return not self.__eq__(other)
-
-    def __gt__(self, other):
-        return _ffi_api.CompareString(self, other) > 0
-
-    def __lt__(self, other):
-        return _ffi_api.CompareString(self, other) < 0
-
-    def __getitem__(self, key):
-        return self.__str__()[key]
-
-    def startswith(self, string):
-        """Check if the runtime string starts with a given string
-
-        Parameters
-        ----------
-        string : str
-            The provided string
-
-        Returns
-        -------
-        ret : boolean
-            Return true if the runtime string starts with the given string,
-        otherwise, false.
-        """
-        return self.__str__().startswith(string)
+    __slots__ = ["__tvm_object__"]
+
+    def __new__(cls, content):
+        """Construct from string content."""
+        val = str.__new__(cls, content)
+        val.__init_tvm_object_by_constructor__(_ffi_api.String, content)
+        return val
+
+    # pylint: disable=no-self-argument
+    def __from_tvm_object__(cls, obj):
+        """Construct from a given tvm object."""
+        content = _ffi_api.GetFFIString(obj)
+        val = str.__new__(cls, content)
+        val.__tvm_object__ = obj
+        return val

python/tvm/runtime/object.py

@@ -27,11 +27,11 @@
     if _FFI_MODE == "ctypes":
         raise ImportError()
     from tvm._ffi._cy3.core import _set_class_object, _set_class_object_generic
-    from tvm._ffi._cy3.core import ObjectBase
+    from tvm._ffi._cy3.core import ObjectBase, PyNativeObject
 except (RuntimeError, ImportError):
     # pylint: disable=wrong-import-position,unused-import
     from tvm._ffi._ctypes.packed_func import _set_class_object, _set_class_object_generic
-    from tvm._ffi._ctypes.object import ObjectBase
+    from tvm._ffi._ctypes.object import ObjectBase, PyNativeObject
 
 
 def _new_object(cls):
@@ -41,6 +41,7 @@ def _new_object(cls):
 
 class Object(ObjectBase):
     """Base class for all tvm's runtime objects."""
+    __slots__ = []
     def __repr__(self):
         return _ffi_node_api.AsRepr(self)
 
@@ -78,13 +79,10 @@ def __getstate__(self):
     def __setstate__(self, state):
         # pylint: disable=assigning-non-slot, assignment-from-no-return
         handle = state['handle']
+        self.handle = None
         if handle is not None:
-            json_str = handle
-            other = _ffi_node_api.LoadJSON(json_str)
-            self.handle = other.handle
-            other.handle = None
-        else:
-            self.handle = None
+            self.__init_handle_by_constructor__(
+                _ffi_node_api.LoadJSON, handle)
 
     def _move(self):
         """Create an RValue reference to the object and mark the object as moved.

python/tvm/runtime/object_generic.py

@@ -21,7 +21,7 @@
 from tvm._ffi.runtime_ctypes import ObjectRValueRef
 
 from . import _ffi_node_api, _ffi_api
-from .object import ObjectBase, _set_class_object_generic
+from .object import ObjectBase, PyNativeObject, _set_class_object_generic
 from .ndarray import NDArrayBase
 from .packed_func import PackedFuncBase, convert_to_tvm_func
 from .module import Module
@@ -34,7 +34,7 @@ def asobject(self):
         raise NotImplementedError()
 
 
-ObjectTypes = (ObjectBase, NDArrayBase, Module, ObjectRValueRef)
+ObjectTypes = (ObjectBase, NDArrayBase, Module, ObjectRValueRef, PyNativeObject)
 
 
 def convert_to_object(value):