[TOPI][Relay][OP] support dynamic NMS(Non Maximum Suppression), symbo…

…lic begin, end, and strides for strided_slice (apache#4312)

* [TOPI][Relay][OP] Dynamic NMS and strided_slice

* Incorporate comments

* fix nnvm compatibility issues

* fix InferCorrectLayout

* Minor fix

* fix for fuse

* Workaround to pass batch_size into hybrid function to handle dynamic shape

* Seperate rearrange

* fix lint

* fix ci, comments

* change attr to Optional<T>

* clang format

* remove empty lines

* partial ignore for end of strided_slice

* pylint

* add out_indices for gpu get_valid_counts

* change to slice_mode

* clang-format, fix comments

* fix comment

* change slice_mode to string

* fix CI

* update docstring

Co-authored-by: Yao Wang <kevinthesunwy@gmail.com>

include/tvm/relay/attrs/transform.h

@@ -210,14 +210,24 @@ struct SplitAttrs : public tvm::AttrsNode<SplitAttrs> {
 
 /*! \brief Attributes for StridedSlice operator */
 struct StridedSliceAttrs : public tvm::AttrsNode<StridedSliceAttrs> {
-  Array<Integer> begin;
-  Array<Integer> end;
-  Array<Integer> strides;
+  Optional<Array<Integer>> begin;
+  Optional<Array<Integer>> end;
+  Optional<Array<Integer>> strides;
+  std::string slice_mode;
 
   TVM_DECLARE_ATTRS(StridedSliceAttrs, "relay.attrs.StridedSliceAttrs") {
     TVM_ATTR_FIELD(begin).describe("Indices for begin of slice, begin index is also inclusive");
     TVM_ATTR_FIELD(end).describe("Indices for end of slice, end index is exclusive");
-    TVM_ATTR_FIELD(strides).set_default(Array<Integer>({})).describe("Stride values of the slice");
+    TVM_ATTR_FIELD(strides).describe(
+        "Stride values of the slice, a stride can be negative, which causes a reverse slice.");
+    TVM_ATTR_FIELD(slice_mode)
+        .set_default("end")
+        .describe(
+            "The slice mode [end, size]."
+            "end - The default slice mode, ending indices for the slice."
+            "size - The input strides will be ignored, input end in this mode indicates the size"
+            "of a slice starting at the location specified by begin. If end[i] is -1,"
+            "all remaining elements in that dimension are included in the slice");
   }
 };
 

include/tvm/relay/attrs/vision.h

@@ -104,7 +104,9 @@ struct NonMaximumSuppressionAttrs : public tvm::AttrsNode<NonMaximumSuppressionA
         .describe(
             "Max number of output valid boxes for each instance."
             "By default all valid boxes are returned.");
-    TVM_ATTR_FIELD(iou_threshold).set_default(0.5).describe("Non-maximum suppression threshold.");
+    TVM_ATTR_FIELD(iou_threshold)
+        .set_default(0.5)
+        .describe("Non-maximum suppression iou threshold.");
     TVM_ATTR_FIELD(force_suppress)
         .set_default(false)
         .describe("Suppress all detections regardless of class_id.");

python/tvm/relay/_parser.py

@@ -114,7 +114,7 @@ def convert(self, v):
     def __call__(self, args, attrs, type_args):
         if attrs is None:
             attrs = {}
-        if self.operator is op.reshape:
+        if self.operator in (op.reshape, op.strided_slice):
             x = self.operator(*args)
         elif self.operator in (op.zeros, op.ones, op.full, op.broadcast_to):
             x = self.operator(*args, dtype=attrs["dtype"])

python/tvm/relay/frontend/keras.py

@@ -611,8 +611,8 @@ def _convert_cropping(inexpr, keras_layer, _):
         raise tvm.error.OpNotImplemented(
             'Operator {} is not supported for frontend Keras.'.format(crop_type))
     int32_max = np.iinfo(np.int32).max
-    return _op.strided_slice(inexpr, begin=[0, 0, crop_t, crop_l], \
-        end=[int32_max, int32_max, in_h-crop_b, in_w-crop_r])
+    return _op.strided_slice(inexpr, begin=_expr.const([0, 0, crop_t, crop_l]), \
+        end=_expr.const([int32_max, int32_max, in_h-crop_b, in_w-crop_r]))
 
 
 def _convert_batchnorm(inexpr, keras_layer, etab):

python/tvm/relay/frontend/mxnet.py

@@ -411,16 +411,22 @@ def _mx_slice(inputs, attrs):
     begin = list(attrs.get_int_tuple('begin', None))
     end = list(attrs.get_int_tuple('end', None))
     stride = attrs.get_int_tuple('step', None)
+    input_shape = _infer_type(inputs[0]).checked_type.shape
     if begin is None:
         raise tvm.error.OpAttributeRequired(
             'Attribute "begin" not found in operator Slice.')
     if end is None:
         raise tvm.error.OpAttributeRequired(
             'Attribute "end" not found in operator Slice.')
-    begin = tuple(x if x is not None else 0 for x in begin)
-    new_attrs = {'begin': begin, 'end': end}
+    begin = (x if x is not None else 0 for x in begin)
+    for i, ed in enumerate(end):
+        if ed is None:
+            end[i] = input_shape[i]
+    new_attrs = {'begin': _expr.const(list(begin), dtype="int32"),
+                 'end': _expr.const(list(end), dtype="int32")}
     if stride is not None:
-        new_attrs['strides'] = stride
+        stride = (x if x is not None else 1 for x in stride)
+        new_attrs['strides'] = _expr.const(list(stride), dtype="int32")
     return _op.strided_slice(inputs[0], **new_attrs)
 
 
@@ -460,7 +466,9 @@ def _mx_slice_axis(inputs, attrs):
         else:
             begin.append(ax_beg)
             end.append(ax_end)
-    return _op.strided_slice(inputs[0], begin, end)
+    return _op.strided_slice(inputs[0],
+                             _expr.const(begin, dtype="int32"),
+                             _expr.const(end, dtype="int32"))
 
 
 def _mx_crop_like(inputs, attrs):
@@ -480,9 +488,9 @@ def _mx_crop_like(inputs, attrs):
         return _op.slice_like(*inputs, **new_attrs)
     expr = _infer_type(inputs[1])
     like_shape = expr.checked_type.shape
-    new_attrs['begin'] = [0, 0, offset[0], offset[1]]
-    new_attrs['end'] = [like_shape[0], like_shape[1], offset[0]+like_shape[2],
-                        offset[1]+like_shape[3]]
+    new_attrs['begin'] = _expr.const([0, 0, offset[0], offset[1]], dtype="int32")
+    new_attrs['end'] = _expr.const([like_shape[0], like_shape[1], offset[0]+like_shape[2],
+                                    offset[1]+like_shape[3]], dtype="int32")
     return _op.strided_slice(inputs[0], **new_attrs)
 
 
@@ -656,7 +664,7 @@ def _mx_multibox_detection(inputs, attrs):
 
     ret = _op.vision.multibox_transform_loc(inputs[0], inputs[1],
                                             inputs[2], **new_attrs0)
-    return _op.vision.non_max_suppression(ret[0], ret[1], **new_attrs1)
+    return _op.vision.non_max_suppression(ret[0], ret[1], ret[1], **new_attrs1)
 
 
 def _mx_batch_dot(inputs, attrs):
@@ -820,6 +828,7 @@ def _mx_box_nms(inputs, attrs):
                                       id_index=id_index, score_index=score_index)
     nms_out = _op.vision.non_max_suppression(ret[1],
                                              ret[0],
+                                             ret[2],
                                              iou_threshold=iou_thresh,
                                              force_suppress=force_suppress,
                                              top_k=top_k,

python/tvm/relay/frontend/onnx.py

@@ -1014,11 +1014,12 @@ def _impl_v1(cls, inputs, attr, params):
                 attr['ends'] = new_ends
         except KeyError:
             pass
+        begin = list(attr['starts'])
+        end = list(attr['ends'])
 
-        return AttrCvt('strided_slice',
-                       transforms={'starts': 'begin',
-                                   'ends': 'end'},
-                       ignores=['axes'])(inputs, attr)
+        return _op.strided_slice(inputs[0],
+                                 begin=_expr.const(begin, dtype="int32"),
+                                 end=_expr.const(end, dtype="int32"))
 
     @classmethod
     def _impl_v10(cls, inputs, attr, params):
@@ -1034,7 +1035,9 @@ def _impl_v10(cls, inputs, attr, params):
                     starts, ends, axes)
                 starts = new_starts
                 ends = new_ends
-        return _op.strided_slice(inputs[0], begin=starts, end=ends)
+        return _op.strided_slice(inputs[0],
+                                 begin=_expr.const(starts, dtype="int32"),
+                                 end=_expr.const(ends, dtype="int32"))
 
 
 class Gather(OnnxOpConverter):

python/tvm/relay/frontend/pytorch.py

@@ -264,7 +264,11 @@ def _impl(inputs, input_types):
                 end[dim] = inputs[3]
 
         strides.append(int(inputs[4]))
-        return _op.transform.strided_slice(data, begin, end, strides)
+        return _op.transform.strided_slice(data,
+                                           begin=_expr.const(begin),
+                                           end=_expr.const(end),
+                                           strides=_expr.const(strides),
+                                           slice_mode="size")
     return _impl
 
 def _split():
@@ -1263,7 +1267,10 @@ def _impl(inputs, input_types):
             end[axis] = i + unif_size
             stride = [1] * len(shape)
 
-            chunk_out = _op.transform.strided_slice(data, begin, end, stride)
+            chunk_out = _op.transform.strided_slice(data,
+                                                    begin=_expr.const(begin),
+                                                    end=_expr.const(end),
+                                                    strides=_expr.const(stride))
             chunks.append(chunk_out)
 
         if dim % num_chunks:
@@ -1273,7 +1280,10 @@ def _impl(inputs, input_types):
             end[axis] = dim
             stride = [1] * len(shape)
 
-            chunk_out = _op.transform.strided_slice(data, begin, end, stride)
+            chunk_out = _op.transform.strided_slice(data,
+                                                    begin=_expr.const(begin),
+                                                    end=_expr.const(end),
+                                                    strides=_expr.const(stride))
             chunks.append(chunk_out)
 
         return chunks

python/tvm/relay/frontend/tensorflow.py

@@ -614,6 +614,62 @@ def _impl(inputs, attr, params, mod):
         return out
     return _impl
 
+def _nms():
+    def _impl(inputs, attr, params, mod):
+        # Get parameter values
+        # TODO(yongwww) change nms in relay to support symbolic max_output_size
+        try:
+            max_output_size = int(np.atleast_1d(inputs[2].data.asnumpy()
+                                                .astype("int64"))[0])
+        except Exception:
+            try:
+                max_output_size = _infer_value(inputs[2], params,
+                                               mod).asnumpy().astype("int64").tolist()[0]
+            except Exception:
+                max_output_size = -1
+        iou_threshold = np.atleast_1d(inputs[3].data.asnumpy())[0]
+        # score_threshold was introduced from V3
+        score_threshold = np.atleast_1d(inputs[4].data.asnumpy())[0] if len(inputs) > 4 else 0.0
+
+        # Generate data with shape (1, num_anchors, 5)
+        scores = AttrCvt(op_name="expand_dims",
+                         ignores=['T_threshold'],
+                         extras={'axis': -1, 'num_newaxis': 1})([inputs[1]], attr)
+        data = get_relay_op('concatenate')([scores, inputs[0]], -1)
+        data = get_relay_op('expand_dims')(data, 0, 1)
+
+        # reason why using get_valid_counts is for inference performance
+        ct, data, indices = get_relay_op('get_valid_counts')(data,
+                                                             score_threshold=score_threshold,
+                                                             id_index=-1,
+                                                             score_index=0)
+        # TensorFlow NMS doesn't have parameter top_k
+        top_k = -1
+        # TF doesn't have class id for nms input
+        score_index = 0
+        nms_ret = get_relay_op('non_max_suppression')(data=data,
+                                                      valid_count=ct,
+                                                      indices=indices,
+                                                      max_output_size=max_output_size,
+                                                      iou_threshold=iou_threshold,
+                                                      force_suppress=True,
+                                                      top_k=top_k,
+                                                      coord_start=1,
+                                                      score_index=score_index,
+                                                      id_index=-1,
+                                                      return_indices=True,
+                                                      invalid_to_bottom=False)
+
+        # squeeze it, TF NMS is not batched
+        size = get_relay_op("squeeze")(nms_ret[1], axis=[1])
+        data_slice = get_relay_op("squeeze")(nms_ret[0], axis=[0])
+
+        # slice to get the dynamic result
+        ret = get_relay_op("strided_slice")(data_slice, begin=_expr.const([0]),
+                                            end=size, slice_mode="size")
+        return ret
+    return _impl
+
 def _decode_image():
     def _impl(inputs, attr, params, mod):
         # Image decode wrapper: Expecting user to feed decoded input to next layer drop this layer.
@@ -1119,25 +1175,20 @@ def _impl(inputs, attr, params, mod):
         try:
             begin = _get_list_param(params, inputs[1])
         except (IndexError, KeyError, AttributeError):
-            begin = _infer_value(inputs[1], params).asnumpy().tolist()[0]
+            # Handle symbolic begin
+            try:
+                begin = _infer_value(inputs[1], params).asnumpy().tolist()
+            except Exception:
+                begin = inputs[1]
         try:
             size = _get_list_param(params, inputs[2])
         except (IndexError, KeyError, AttributeError):
             # Handle symbolic size
             try:
-                size = _infer_value(inputs[2], params).asnumpy().tolist()[0]
+                size = _infer_value(inputs[2], params).asnumpy().tolist()
             except Exception:
                 size = inputs[2]
-        data_shape = _infer_shape(inputs[0], mod)
-        data_dim = len(data_shape)
-        end = size
-        if not isinstance(end, (_expr.Call, _expr.Var)):
-            for i in range(data_dim):
-                if size[i] == -1:
-                    end[i] = data_shape[i]
-                else:
-                    end[i] += begin[i]
-        return _op.strided_slice(inputs[0], begin=begin, end=end)
+        return _op.strided_slice(inputs[0], begin=begin, end=size, slice_mode="size")
     return _impl
 
 
@@ -1466,8 +1517,11 @@ def _transform_mask(stride_dim, ellipsis_mask):
         fshape_indices = None
         if begin_mask or end_mask or ellipsis_mask or new_axis_mask or shrink_axis_mask:
             begin, end, stride, fshape_indices = _transform_mask(stride_dim, ellipsis_mask)
-        out = _op.strided_slice(inputs[0], begin=begin, end=end, strides=stride)
-        out_shape = _infer_shape(out, mod)
+        out = _op.strided_slice(inputs[0],
+                                begin=begin,
+                                end=end,
+                                strides=stride)
+        out_shape = _infer_shape(out, mod=mod)
         if not fshape_indices:
             fshape_indices = range(len(out_shape))
 
@@ -2026,6 +2080,8 @@ def _impl(inputs, attr, params, mod):
     'Mod'                               : _elemwise('mod'),
     'Mul'                               : _elemwise('multiply'),
     'Neg'                               : AttrCvt('negative'),
+    'NonMaxSuppressionV2'               : _nms(),
+    'NonMaxSuppressionV3'               : _nms(),
     'NoOp'                              : _no_op(),
     'NotEqual'                          : _broadcast('not_equal'),
     'OneHot'                            : _one_hot(),

python/tvm/relay/frontend/tflite.py

@@ -2544,7 +2544,7 @@ def convert_detection_postprocess(self, op):
 
         ret = _op.vision.multibox_transform_loc(cls_pred, loc_prob,
                                                 anchor_expr, **multibox_transform_loc_attrs)
-        ret = _op.vision.non_max_suppression(ret[0], ret[1], **non_max_suppression_attrs)
+        ret = _op.vision.non_max_suppression(ret[0], ret[1], ret[1], **non_max_suppression_attrs)
         ret = _op.vision.get_valid_counts(ret, 0)
         valid_count = ret[0]
         # keep only the top 'max_detections' rows

python/tvm/relay/op/_tensor_grad.py

@@ -390,8 +390,10 @@ def conv2d_grad(orig, grad):
     assert padded_weight_grad_h >= filter_h
     assert padded_weight_grad_w >= filter_w
     if padded_weight_grad_h > filter_h or padded_weight_grad_w > filter_w:
-        backward_weight = strided_slice(backward_weight, begin=[0, 0, 0, 0],
-                                        end=[None, None, filter_h, filter_w])
+        backward_weight = strided_slice(backward_weight,
+                                        begin=const([0, 0, 0, 0], dtype="int64"),
+                                        end=const([out_channel, in_channel // attrs.groups,
+                                                   filter_h, filter_w], dtype="int64"))
 
     return [backward_data, backward_weight]