[Topi]Allow empty tensor for reshape, tile and strided_slice (#4618)

* Support empty tensor

* Fix schedule

* Refactor

* Minor fix

* Fix pylint

* Merge cpp and python is_empty_shape

src/relay/op/tensor/transform.cc

@@ -888,6 +888,7 @@ bool TakeRel(const Array<Type>& types,
   CHECK(data != nullptr);
   const auto* indices = types[1].as<TensorTypeNode>();
   CHECK(indices != nullptr);
+  CHECK(indices->dtype.is_int()) << "indices of take must be tensor of integer";
   const auto param = attrs.as<TakeAttrs>();
   CHECK(param != nullptr);
 
@@ -1648,6 +1649,9 @@ bool SqueezeRel(const Array<Type>& types,
   // if axes is None, squeeze all axes of dimension 1
   if (!param->axis.defined()) {
     for (const auto& e : data->shape) {
+      if (!e.as<IntImm>()) {
+        LOG(FATAL) << "axis needs to be defined for dynamic input.";
+      }
       const int64_t* axis_ptr = as_const_int(e);
       CHECK(axis_ptr != nullptr) << "the axes attribute must be concrete";
       if (*axis_ptr != 1) {

topi/include/topi/detail/tensor_utils.h

+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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.
+ */
+
+/*!
+ * \file tensor_utils.h
+ * \brief Utility functions for handling tensor
+ */
+#ifndef TOPI_DETAIL_TENSOR_UTILS_H_
+#define TOPI_DETAIL_TENSOR_UTILS_H_
+
+
+namespace topi {
+namespace detail {
+using namespace tvm;
+
+/*!
+ * \brief Check whether input shape has dimension of size 0;
+ *
+ * \param x Input shape
+ *
+ * \return True if the input shape is empty.
+ */
+inline bool is_empty_shape(const Array<Expr>& x) {
+  bool is_empty = false;
+  for (const auto& dim : x) {
+    if (auto int_dim = dim.as<IntImm>()) {
+      if (int_dim->value == 0) {
+        is_empty = true;
+        break;
+      }
+    }
+  }
+  return is_empty;
+}
+
+}  // namespace detail
+}  // namespace topi
+#endif  // TOPI_DETAIL_TENSOR_UTILS_H_
+

topi/include/topi/transform.h

@@ -34,6 +34,7 @@
 #include "topi/tags.h"
 #include "topi/detail/ravel_unravel.h"
 #include "topi/detail/constant_utils.h"
+#include "topi/detail/tensor_utils.h"
 #include "tvm/operation.h"
 #include "tvm/expr_operator.h"
 #include "tvm/data_layout.h"
@@ -207,16 +208,28 @@ inline Tensor reshape(const Tensor& x,
                       std::string name = "T_reshape",
                       std::string tag = kInjective) {
   auto x_shape = x->shape;
-  Array<Expr> newshape_int32;
+  Array<Expr> target_shape;
 
   for (const auto &ele : newshape) {
-    newshape_int32.push_back(cast(DataType::Int(32), ele));
+    if (ele.as<IntImm>()) {
+      target_shape.push_back(cast(DataType::Int(32), ele));
+    } else {
+      target_shape.push_back(ele);
+    }
   }
+
+  if (is_empty_shape(target_shape)) {
+    return compute(target_shape,
+                   [&](const Array<Var> &indices) { return tvm::cast(x->dtype, 0); },
+                   name, tag);
+  } else {
     return compute(
-    newshape_int32, [&](const Array<Var>& indices) {
-      return x(UnravelIndex(RavelIndex(Array<Expr>{indices.begin(), indices.end()}, newshape_int32),
+      target_shape, [&](const Array<Var>& indices) {
+        return x(UnravelIndex(
+          RavelIndex(Array<Expr>{indices.begin(), indices.end()}, target_shape),
           x_shape));
       }, name, tag);
+  }
 }
 
 /*!
@@ -556,7 +569,7 @@ inline Tensor strided_slice(const Tensor& x,
     int interval = std::abs(end_i - begin_i);
     int slice_size = static_cast<int>((interval
                                      + std::abs(stride_vec[i]) - 1) / std::abs(stride_vec[i]));
-    CHECK(stride_vec[i] < 0 ? (end_i < begin_i) : (begin_i < end_i))
+    CHECK(stride_vec[i] < 0 ? (end_i <= begin_i) : (begin_i <= end_i))
       << ": Input [Begin=" << begin_vec[i] << ", End=" << end_vec[i]
       << "] is invalid for axis=" << i;
 
@@ -938,6 +951,11 @@ inline Tensor tile(const Tensor& x,
   for (size_t i = 0; i < tdim; ++i)
     new_shape.push_back(data_shape[i] * reps_shape[i]);
 
+  if (is_empty_shape(new_shape)) {
+    return compute(new_shape,
+                   [&](const Array<Var>& indices) { return tvm::cast(x->dtype, 0);},
+                   name, tag);
+  } else {
     return compute(
       new_shape, [&](const Array<Var>& indices) {
         Array<Expr> idx;
@@ -950,6 +968,7 @@ inline Tensor tile(const Tensor& x,
         }
         return x(idx);
       }, name, tag);
+  }
 }
 
 /*!

topi/python/topi/arm_cpu/injective.py

@@ -18,6 +18,7 @@
 """Schedule for pooling operators"""
 import tvm
 from .. import generic
+from ..util import is_empty_shape
 
 @generic.schedule_injective_from_existing.register(["arm_cpu"])
 def schedule_injective_from_existing(sch, out):
@@ -68,6 +69,8 @@ def schedule_injective(outs):
         (io, ii) = s[x].split(list(s[x].op.axis)[-1], 8)
         s[x].vectorize(ii)
     tvm.schedule.AutoInlineInjective(s)
+
+    if not is_empty_shape(x.shape):
         schedule_injective_from_existing(s, x)
     return s
 

topi/python/topi/cpp/__init__.py

@@ -24,3 +24,4 @@ from . import x86
 from . import generic
 from . import rocm
 from . import image
+from . import util

topi/python/topi/cpp/util.py

+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you 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.
+"""FFI for TOPI utility functions"""
+
+from tvm._ffi.function import _init_api_prefix
+
+_init_api_prefix("topi.cpp.util", "topi.util")

topi/python/topi/cuda/injective.py

@@ -18,6 +18,7 @@
 """Schedule for composition of injective operator"""
 import tvm
 from .. import generic, util
+from ..util import is_empty_shape
 
 @generic.schedule_injective_from_existing.register(["cuda", "gpu"])
 def schedule_injective_from_existing(sch, out):
@@ -79,6 +80,7 @@ def schedule_injective(outs):
 
     tvm.schedule.AutoInlineInjective(s)
     for out in outs:
+        if not is_empty_shape(out.shape):
             schedule_injective_from_existing(s, out)
     return s
 

topi/python/topi/util.py

@@ -21,7 +21,7 @@ from numbers import Integral
 
 import tvm
 from tvm.api import layout, bijective_layout
-from . import tag
+from . import tag, cpp
 
 class InvalidShapeError(ValueError):
     """Invalid shape for a topi function. i.e. call winograd template for non-3x3 kernel)"""
@@ -417,3 +417,19 @@ def make_idx(b, e, s, z, i):
                           (b - i) // tvm.abs(s),
                           (i - b) // s)
     return tvm.if_then_else(tvm.expr.Or(bc, ec), 88, ss)
+
+
+def is_empty_shape(shape):
+    """Check whether an input shape has dimesion with size 0.
+
+    Parameter
+    ---------
+    shape : list of Expr
+      Input shape
+
+    Returns
+    -------
+    is_empty: bool
+      Whether input shape is empty or has dimesion with size 0.
+    """
+    return cpp.util.is_empty_shape(shape)

topi/python/topi/x86/injective.py

@@ -19,6 +19,7 @@
 from __future__ import absolute_import as _abs
 import tvm
 from .. import generic
+from ..util import is_empty_shape
 
 @generic.schedule_injective_from_existing.register(["cpu"])
 def schedule_injective_from_existing(sch, out):
@@ -65,6 +66,8 @@ def schedule_injective(outs):
     x = outs[0]
     s = tvm.create_schedule([x.op for x in outs])
     tvm.schedule.AutoInlineInjective(s)
+
+    if not is_empty_shape(x.shape):
         schedule_injective_from_existing(s, x)
     return s
 

topi/src/topi.cc

@@ -72,6 +72,8 @@
 #include <topi/rocm/softmax.h>
 #include <topi/rocm/normalization.h>
 
+#include <topi/detail/tensor_utils.h>
+
 namespace topi {
 
 using namespace tvm;
@@ -740,6 +742,12 @@ TVM_REGISTER_GLOBAL("topi.cuda.schedule_l2_normalize")
   *rv = topi::cuda::schedule_l2_normalize(args[0], args[1]);
   });
 
+/* Utility functions */
+TVM_REGISTER_GLOBAL("topi.util.is_empty_shape")
+.set_body([](TVMArgs args, TVMRetValue *rv) {
+  *rv = topi::detail::is_empty_shape(args[0]);
+  });
+
 /*! \brief Builder function for instantiating schedules. */
 using FTVMScheduleBuilder = std::function<
   tvm::Schedule(const tvm::Target& target, const tvm::Array<tvm::Tensor>& outs)>;

topi/tests/python/test_topi_transform.py

@@ -555,6 +555,7 @@ def test_strided_slice():
     verify_strided_slice((3, 4, 3), [1, 0, 0], [2, 2, 3], [1, 1, 2])
     verify_strided_slice((3, 4, 3), [1, -1, 0], [2, -3, 3], [1, -1, 1])
     verify_strided_slice((3, 4, 3), [1, 1, 0], [4, 4, 3])
+    verify_strided_slice((3, 4, 3), [0, 2, 0], [1, 2, 3])
 
 def test_strided_set():
     verify_strided_set((3, 4, 3), (3, 2, 2), [0, 3, 0], [4, 1, 4], [1, -1, 2])
@@ -596,6 +597,7 @@ def test_reshape():
     verify_reshape((4, 2, 3, 4), (2, 4, 12))
     verify_reshape((4, 2, 3, 4), (2, 48))
     verify_reshape((16, ), (2, 2, 2, 2))
+    verify_reshape((4, 0), (2, 0, 2))
 
 
 def test_where():
@@ -718,6 +720,7 @@ def test_tile():
     verify_tile((3, 2), (2, 3))
     verify_tile((3, 2, 5), (2,))
     verify_tile((3, ), (2, 3, 3))
+    verify_tile((4, 0), (5,))
 
 def test_layout_transform():
     in_shape = (1, 32, 8, 8)