[numpy] Infra for supporting numpy ops in imperative mode and Gluon A…

…PIs (#14758)

* Infra of new ndarray and symbol types for numpy operators

* Rename

* Fix import problem

* Refactor

* Remove redundant code

* Add docstring

* More on numpy ndarray and symbol

* Override unimplemented methdos for ndarray and _NumpySymbol

* Fix built-in methods of ndarray and _NumpySymbol

* Fix test and sanity check

* Fix pylint

* Address cr comments

* Add unit tests for ndarray and _NumpySymbol

* Add _true_divide

* Fix gpu build

* Add future import division

* More correct way of checking if an output is from a np compat op

* Fix gpu build

* Fix output ndarray/symbol types with at least one new ndarray/symbol

* Modify true_divide doc

* Fix flaky copying zero-size arrays via gpus

* Fix zero size in gluon hybridize and zeros/ones symbol not creating new symbol type

* Fix doc

include/mxnet/c_api.h

@@ -2893,6 +2893,35 @@ MXNET_DLL int MXEnginePushSync(EngineSyncFunc sync_func, void* func_param,
                                EngineVarHandle mutable_vars_handle, int num_mutable_vars,
                                EngineFnPropertyHandle prop_handle DEFAULT(NULL),
                                int priority DEFAULT(0), const char* opr_name DEFAULT(NULL));
+/*!
+  * \brief Determines if an op is a Numpy op by its name prefix.
+  * Every Numpy op starts with a prefix string "_numpy_".
+  * \param creator Operator handle
+  * \param is_np_op Indicator of whether creator is a numpy op handle
+  */
+MXNET_DLL int MXIsNumpyCompatOp(AtomicSymbolCreator creator,
+                                int* is_np_op);
+/*!
+ * \brief Create an NDArray from source sharing the same data chunk.
+ * \param src source NDArray
+ * \param out new NDArray sharing the same data chunck with src
+ */
+MXNET_DLL int MXShallowCopyNDArray(NDArrayHandle src, NDArrayHandle* out);
+/*!
+ * \brief Create an Symbol from source sharing the same graph structure.
+ * \param src source Symbol
+ * \param out new Symbol sharing the same graph structure with src
+ */
+MXNET_DLL int MXShallowCopySymbol(SymbolHandle src, SymbolHandle * out);
+/*!
+ * \brief Checks if an output of CachedOp is from a numpy op.
+ * \param handle CachedOp shared ptr
+ * \param output_idx index of the output of the CachedOp
+ * \param is_from_np_op indicator of whether the output is from a numpy op
+ */
+MXNET_DLL int MXIsCachedOpOutputFromNumpyCompatOp(CachedOpHandle handle,
+                                                  int output_idx,
+                                                  int* is_from_np_op);
 
 /*!
   * \brief Push an asynchronous operation to the engine.

include/mxnet/op_attr_types.h

@@ -319,6 +319,15 @@ using FNeedRequantize = std::function<bool (const NodeAttrs& attrs)>;
 using FAvoidQuantizeInput = std::function<bool (const NodeAttrs& attrs,
                                                 size_t index)>;
 
+/*!
+ * \brief Indicates whether this operator is NumPy compatible.
+ * It is for distinguishing the operator from classic MXNet operators
+ * which do not support zero-dim and zero-size tensors.
+ * In Python, it is used to determine whether to output numpy ndarrays
+ * or symbols that are NumPy compatible.
+ */
+using TIsNumpyCompatible = bool;
+
 }  // namespace mxnet
 
 #endif  // MXNET_OP_ATTR_TYPES_H_

python/mxnet/__init__.py

@@ -26,10 +26,10 @@
 from .base import MXNetError
 from .util import is_np_shape, set_np_shape, np_shape, use_np_shape
 from . import base
-from . import numpy
 from . import contrib
 from . import ndarray
 from . import ndarray as nd
+from . import numpy
 from . import name
 # use mx.sym as short for symbol
 from . import symbol as sym

python/mxnet/_ctypes/ndarray.py

@@ -26,7 +26,7 @@
 from ..base import _LIB
 from ..base import c_str_array, c_handle_array
 from ..base import NDArrayHandle, CachedOpHandle
-from ..base import check_call
+from ..base import check_call, _is_np_compat_op
 
 
 class NDArrayBase(object):
@@ -55,13 +55,21 @@ def __reduce__(self):
 
 
 _ndarray_cls = None
+_np_ndarray_cls = None
+
 
 def _set_ndarray_class(cls):
     """Set the symbolic class to be cls"""
     global _ndarray_cls
     _ndarray_cls = cls
 
 
+def _set_np_ndarray_class(cls):
+    """Set the symbolic class to be cls"""
+    global _np_ndarray_cls
+    _np_ndarray_cls = cls
+
+
 def _imperative_invoke(handle, ndargs, keys, vals, out):
     """ctypes implementation of imperative invoke wrapper"""
     if out is not None:
@@ -93,18 +101,19 @@ def _imperative_invoke(handle, ndargs, keys, vals, out):
 
     if original_output is not None:
         return original_output
+    create_ndarray_fn = _np_ndarray_cls if _is_np_compat_op(handle) else _ndarray_cls
     if num_output.value == 1:
-        return _ndarray_cls(ctypes.cast(output_vars[0], NDArrayHandle),
-                            stype=out_stypes[0])
+        return create_ndarray_fn(ctypes.cast(output_vars[0], NDArrayHandle),
+                                 stype=out_stypes[0])
     else:
-        return [_ndarray_cls(ctypes.cast(output_vars[i], NDArrayHandle),
-                             stype=out_stypes[i])
-                for i in range(num_output.value)]
+        return [create_ndarray_fn(ctypes.cast(output_vars[i], NDArrayHandle),
+                                  stype=out_stypes[i]) for i in range(num_output.value)]
 
 
 class CachedOp(object):
     """Cached operator handle."""
     __slots__ = ["handle"]
+
     def __init__(self, sym, flags=()):
         self.handle = CachedOpHandle()
 
@@ -118,6 +127,13 @@ def __init__(self, sym, flags=()):
     def __del__(self):
         check_call(_LIB.MXFreeCachedOp(self.handle))
 
+    def _is_from_np_compat_op(self, idx):
+        """Check if the CachedOp's idx-th output is directly from a numpy op."""
+        is_from_np_op = ctypes.c_int(0)
+        check_call(_LIB.MXIsCachedOpOutputFromNumpyCompatOp(self.handle, ctypes.c_int(idx),
+                                                            ctypes.byref(is_from_np_op)))
+        return is_from_np_op.value != 0
+
     def __call__(self, *args, **kwargs):
         """ctypes implementation of imperative invoke wrapper"""
         out = kwargs.pop('out', None)
@@ -152,9 +168,11 @@ def __call__(self, *args, **kwargs):
         if original_output is not None:
             return original_output
         if num_output.value == 1:
-            return _ndarray_cls(ctypes.cast(output_vars[0], NDArrayHandle),
-                                stype=out_stypes[0])
+            create_ndarray_fn = _np_ndarray_cls if self._is_from_np_compat_op(0) else _ndarray_cls
+            return create_ndarray_fn(ctypes.cast(output_vars[0], NDArrayHandle),
+                                     stype=out_stypes[0])
         else:
-            return [_ndarray_cls(ctypes.cast(output_vars[i], NDArrayHandle),
-                                 stype=out_stypes[i])
+            return [_np_ndarray_cls(ctypes.cast(output_vars[i], NDArrayHandle), stype=out_stypes[i])
+                    if self._is_from_np_compat_op(i) else
+                    _ndarray_cls(ctypes.cast(output_vars[i], NDArrayHandle), stype=out_stypes[i])
                     for i in range(num_output.value)]

python/mxnet/_ctypes/symbol.py

@@ -22,11 +22,12 @@
 
 import ctypes
 from ..base import _LIB
-from ..base import c_str_array, c_handle_array, c_str, mx_uint
+from ..base import c_str_array, c_handle_array, c_str, mx_uint, _is_np_compat_op
 from ..base import SymbolHandle
 from ..base import check_call
 
 _symbol_cls = None
+_np_symbol_cls = None
 
 class SymbolBase(object):
     """Symbol is symbolic graph."""
@@ -115,6 +116,12 @@ def _set_symbol_class(cls):
     _symbol_cls = cls
 
 
+def _set_np_symbol_class(cls):
+    """Set the symbolic class to be cls"""
+    global _np_symbol_cls
+    _np_symbol_cls = cls
+
+
 def _symbol_creator(handle, args, kwargs, keys, vals, name):
     sym_handle = SymbolHandle()
     check_call(_LIB.MXSymbolCreateAtomicSymbol(
@@ -128,7 +135,10 @@ def _symbol_creator(handle, args, kwargs, keys, vals, name):
         raise TypeError(
             'Operators with variable length input can only accept input'
             'Symbols either as positional or keyword arguments, not both')
-    s = _symbol_cls(sym_handle)
+    if _is_np_compat_op(handle):
+        s = _np_symbol_cls(sym_handle)
+    else:
+        s = _symbol_cls(sym_handle)
     if args:
         s._compose(*args, name=name)
     elif kwargs:

python/mxnet/base.py

@@ -561,7 +561,7 @@ def _as_list(obj):
         return [obj]
 
 
-_OP_NAME_PREFIX_LIST = ['_contrib_', '_linalg_', '_sparse_', '_image_', '_random_', '_numpy_']
+_OP_NAME_PREFIX_LIST = ['_contrib_', '_linalg_', '_sparse_', '_image_', '_random_']
 
 
 def _get_op_name_prefix(op_name):
@@ -607,15 +607,6 @@ def _init_op_module(root_namespace, module_name, make_op_func):
     # use mx.nd.contrib or mx.sym.contrib from now on
     contrib_module_name_old = "%s.contrib.%s" % (root_namespace, module_name)
     contrib_module_old = sys.modules[contrib_module_name_old]
-    # special handling of registering numpy ops
-    # only expose mxnet.numpy.op_name to users for imperative mode.
-    # Symbolic mode should be used in Gluon.
-    if module_name == 'ndarray':
-        numpy_module_name = "%s.numpy" % root_namespace
-        numpy_module = sys.modules[numpy_module_name]
-    else:
-        numpy_module_name = None
-        numpy_module = None
     submodule_dict = {}
     for op_name_prefix in _OP_NAME_PREFIX_LIST:
         submodule_dict[op_name_prefix] =\
@@ -654,16 +645,6 @@ def _init_op_module(root_namespace, module_name, make_op_func):
             function.__module__ = contrib_module_name_old
             setattr(contrib_module_old, function.__name__, function)
             contrib_module_old.__all__.append(function.__name__)
-        elif op_name_prefix == '_numpy_' and numpy_module_name is not None:
-            # only register numpy ops under mxnet.numpy in imperative mode
-            hdl = OpHandle()
-            check_call(_LIB.NNGetOpHandle(c_str(name), ctypes.byref(hdl)))
-            # TODO(reminisce): Didn't consider third level module here, e.g. mxnet.numpy.random.
-            func_name = name[len(op_name_prefix):]
-            function = make_op_func(hdl, name, func_name)
-            function.__module__ = numpy_module_name
-            setattr(numpy_module, function.__name__, function)
-            numpy_module.__all__.append(function.__name__)
 
 
 def _generate_op_module_signature(root_namespace, module_name, op_code_gen_func):
@@ -753,3 +734,83 @@ def write_all_str(module_file, module_all_list):
 
 ctypes.pythonapi.PyCapsule_New.restype = ctypes.py_object
 ctypes.pythonapi.PyCapsule_GetPointer.restype = ctypes.c_void_p
+
+
+def _sanity_check_params(func_name, unsupported_params, param_dict):
+    for param_name in unsupported_params:
+        if param_name in param_dict:
+            raise NotImplementedError("function {} does not support parameter {}"
+                                      .format(func_name, param_name))
+
+
+_NP_OP_SUBMODULE_LIST = ['_random_', '_linalg_']
+_NP_OP_PREFIX = '_numpy_'
+
+
+def _get_np_op_submodule_name(op_name):
+    assert op_name.startswith(_NP_OP_PREFIX)
+    for name in _NP_OP_SUBMODULE_LIST:
+        if op_name[len(_NP_OP_PREFIX):].startswith(name):
+            return name
+    return ""
+
+
+def _init_np_op_module(root_namespace, module_name, make_op_func):
+    """
+    Register numpy operators in namespaces `mxnet.numpy`, `mxnet.ndarray.numpy`
+    and `mxnet.symbol.numpy`. They are used in imperative mode, Gluon APIs w/o hybridization,
+    and Gluon APIs w/ hybridization, respectively. Essentially, operators with the same name
+    registered in three namespaces, respectively share the same functionality in C++ backend.
+    Different namespaces are needed for dispatching operator calls in Gluon's `HybridBlock` by `F`.
+
+    Parameters
+    ----------
+    root_namespace : str
+        Top level module name, `mxnet` in the current cases.
+    module_name : str
+        Second level module name, `ndarray` or `symbol` in the current case.
+    make_op_func : function
+        Function for creating op functions.
+    """
+    plist = ctypes.POINTER(ctypes.c_char_p)()
+    size = ctypes.c_uint()
+
+    check_call(_LIB.MXListAllOpNames(ctypes.byref(size), ctypes.byref(plist)))
+    op_names = []
+    for i in range(size.value):
+        name = py_str(plist[i])
+        if name.startswith(_NP_OP_PREFIX):
+            op_names.append(name)
+
+    if module_name == 'numpy':
+        # register ops for mxnet.numpy
+        module_pattern = "%s.%s._op"
+        submodule_pattern = "%s.%s.%s"
+    else:
+        # register ops for mxnet.ndarray.numpy or mxnet.symbol.numpy
+        module_pattern = "%s.%s.numpy._op"
+        submodule_pattern = "%s.%s.numpy.%s"
+    module_np_op = sys.modules[module_pattern % (root_namespace, module_name)]
+    submodule_dict = {}
+    # TODO(junwu): uncomment the following lines when adding numpy ops in submodules, e.g. np.random
+    # for submodule_name in _NP_OP_SUBMODULE_LIST:
+    #     submodule_dict[submodule_name] = \
+    #         sys.modules[submodule_pattern % (root_namespace, module_name, submodule_name[1:-1])]
+    for name in op_names:
+        hdl = OpHandle()
+        check_call(_LIB.NNGetOpHandle(c_str(name), ctypes.byref(hdl)))
+        submodule_name = _get_np_op_submodule_name(name)
+        module_name_local = module_name
+        if len(submodule_name) > 0:
+            func_name = name[(len(_NP_OP_PREFIX) + len(submodule_name)):]
+            cur_module = submodule_dict[submodule_name]
+            module_name_local = submodule_pattern % (root_namespace,
+                                                     module_name, submodule_name[1:-1])
+        else:
+            func_name = name[len(_NP_OP_PREFIX):]
+            cur_module = module_np_op
+
+        function = make_op_func(hdl, name, func_name)
+        function.__module__ = module_name_local
+        setattr(cur_module, function.__name__, function)
+        cur_module.__all__.append(function.__name__)

python/mxnet/gluon/block.py

@@ -34,6 +34,7 @@
 from .. import name as _name
 from .parameter import Parameter, ParameterDict, DeferredInitializationError
 from .utils import _indent, _brief_print_list, HookHandle
+from .. import numpy as _mx_np
 
 
 class _BlockScope(object):
@@ -739,9 +740,13 @@ def _get_graph(self, *args):
         if not self._cached_graph:
             args, self._in_format = _flatten(args, "input")
             if len(args) > 1:
-                inputs = [symbol.var('data%d'%i) for i in range(len(args))]
+                inputs = [symbol.var('data%d' % i).as_np_ndarray()
+                          if isinstance(args[i], _mx_np.ndarray)
+                          else symbol.var('data%d' % i) for i in range(len(args))]
             else:
-                inputs = [symbol.var('data')]
+                inputs = [symbol.var('data').as_np_ndarray()
+                          if isinstance(args[0], _mx_np.ndarray)
+                          else symbol.var('data')]
             grouped_inputs = _regroup(inputs, self._in_format)[0]
 
             params = {i: j.var() for i, j in self._reg_params.items()}

python/mxnet/ndarray/__init__.py

@@ -30,6 +30,7 @@
 from .utils import load, load_frombuffer, save, zeros, empty, array
 from .sparse import _ndarray_cls
 from .ndarray import _GRAD_REQ_MAP, _DTYPE_MX_TO_NP, _DTYPE_NP_TO_MX, _new_empty_handle
+from . import numpy as np
 
 __all__ = op.__all__ + ndarray.__all__ + utils.__all__ + \
           ['contrib', 'linalg', 'random', 'sparse', 'image']

python/mxnet/ndarray/_internal.py

@@ -23,23 +23,24 @@
 try:
     if int(_os.environ.get("MXNET_ENABLE_CYTHON", True)) == 0:
         from .._ctypes.ndarray import NDArrayBase, CachedOp
-        from .._ctypes.ndarray import _set_ndarray_class, _imperative_invoke
+        from .._ctypes.ndarray import _set_ndarray_class, _imperative_invoke, _set_np_ndarray_class
     elif _sys.version_info >= (3, 0):
         from .._cy3.ndarray import NDArrayBase, CachedOp
-        from .._cy3.ndarray import _set_ndarray_class, _imperative_invoke
+        from .._cy3.ndarray import _set_ndarray_class, _imperative_invoke, _set_np_ndarray_class
     else:
         from .._cy2.ndarray import NDArrayBase, CachedOp
-        from .._cy2.ndarray import _set_ndarray_class, _imperative_invoke
+        from .._cy2.ndarray import _set_ndarray_class, _imperative_invoke, _set_np_ndarray_class
 except ImportError:
     if int(_os.environ.get("MXNET_ENFORCE_CYTHON", False)) != 0:
         raise ImportError("Cython Module cannot be loaded but MXNET_ENFORCE_CYTHON=1")
     from .._ctypes.ndarray import NDArrayBase, CachedOp
-    from .._ctypes.ndarray import _set_ndarray_class, _imperative_invoke
+    from .._ctypes.ndarray import _set_ndarray_class, _imperative_invoke, _set_np_ndarray_class
 
 from ..base import _Null
 try:
     from .gen__internal import * # pylint: disable=unused-wildcard-import
 except ImportError:
     pass
 
-__all__ = ['NDArrayBase', 'CachedOp', '_imperative_invoke', '_set_ndarray_class']
+__all__ = ['NDArrayBase', 'CachedOp', '_imperative_invoke', '_set_ndarray_class',
+           '_set_np_ndarray_class']