[v1.x] ONNX fix embedding and slice (#19695)

* fix slice

* Update _op_translations.py

python/mxnet/contrib/onnx/mx2onnx/_op_translations.py

@@ -113,7 +113,9 @@ def convert_string_to_list(string_val):
         val = val.replace("L", "")
         val = val.replace("[", "")
         val = val.replace("]", "")
-        if val not in ("", "None"):
+        if val == "None":
+            result_list.append(None)
+        elif val != "":
             result_list.append(int(val))
 
     return result_list
@@ -2516,17 +2518,17 @@ def convert_sequencemask(node, **kwargs):
 def convert_embedding(node, **kwargs):
     """Map MXNet's Embedding operator attributes to onnx's
     Gather operator."""
+    from onnx.helper import make_node
+    from onnx import TensorProto
+
     name, input_nodes, attrs = get_inputs(node, kwargs)
     axis = int(attrs.get('axis', 0))
-    node = onnx.helper.make_node(
-        "Gather",
-        [input_nodes[1], input_nodes[0]],
-        [name],
-        axis=axis,
-        name=name
-    )
-    return [node]
 
+    nodes = [
+        make_node('Cast', [input_nodes[0]], [name+'_indices_casted'], to=int(TensorProto.INT64)),
+        make_node('Gather', [input_nodes[1], name+'_indices_casted'], [name], axis=axis, name=name)
+        ]
+    return nodes
 
 @mx_op.register("stack")
 def convert_stack(node, **kwargs):
@@ -2558,19 +2560,40 @@ def convert_stack(node, **kwargs):
 @mx_op.register("slice")
 def convert_slice(node, **kwargs):
     """Map MXNet's slice operator to onnx Slice operator."""
+    from onnx.helper import make_node
+
     name, input_nodes, attrs = get_inputs(node, kwargs)
-    starts = convert_string_to_list(attrs.get("begin"))
-    ends = convert_string_to_list(attrs.get("end"))
-    steps = attrs.get("step", [])
+
+    starts = convert_string_to_list(attrs.get('begin'))
+    ends = convert_string_to_list(attrs.get('end'))
+    steps = convert_string_to_list(attrs.get('step', '[]'))
+
+    assert len(starts) == len(ends)
+    if len(steps) == 0 or (len(steps) == 1 and steps[0] is None):
+        steps = [1 for x in starts]
+    else:
+        assert len(steps) == len(starts)
+    steps = [1 if x is None else x for x in steps]
+    for i, s in enumerate(steps):
+        if s < 0:
+            raise NotImplementedError('slice operator does not support negative steps yet')
+        if starts[i] is None:
+            starts[i] = 0
+        if ends[i] is None:
+            ends[i] = 2**63-1
+
     nodes = [
-        create_const_node(name+"_begin", np.array(starts), kwargs),
-        create_const_node(name+"_end", np.array(ends), kwargs)
+        create_const_scalar_node(name+'_0_s', np.int64(0), kwargs),
+        create_const_scalar_node(name+'_1_s', np.int64(1), kwargs),
+        create_const_scalar_node(name+'_len_s', np.int64(len(starts)), kwargs),
+        make_node('Range', [name+'_0_s', name+'_len_s', name+'_1_s'], [name+'_axes']),
+        create_tensor(starts, name+'_starts', kwargs['initializer']),
+        create_tensor(ends, name+'_ends', kwargs['initializer']),
+        create_tensor(steps, name+'_steps', kwargs['initializer']),
+        make_node("Slice", [input_nodes[0], name+'_starts', name+'_ends', name+'_axes',
+                            name+'_steps'], [name], name=name)
     ]
-    inputs = [input_nodes[0], name+"_begin", name+"_end"]
-    if len(steps) > 0:
-        nodes.append(create_const_node(name+"_steps", np.array(steps, dtype='int64'), kwargs))
-        inputs.append(name+"_steps")
-    nodes.append(onnx.helper.make_node("Slice", inputs, [name], name=name))
+
     return nodes
 
 

tests/python-pytest/onnx/test_operators.py

@@ -71,9 +71,13 @@ def test_onnx_export_abs(tmp_path):
     op_export_test('abs', M, [x], tmp_path)
 
 
-def test_onnx_export_slice(tmp_path):
-    M = def_model('slice', begin=(0,1), end=(2,4))
-    x = mx.nd.array([[1,2,3,4],[5,6,7,8],[9,10,11,12]], dtype='float32')
+@pytest.mark.parametrize('dtype', ['float32', 'float64', 'float16', 'int32', 'int64'])
+@pytest.mark.parametrize('params', [[(0, 1), (2,3), (1, 1)],
+                                    [(None, 1), (2, None), None],
+                                    [(0, 0, 0), (None, 4, 5), (None, 1, 2)]])
+def test_onnx_export_slice(tmp_path, dtype, params):
+    M = def_model('slice', begin=params[0], end=params[1], step=params[2])
+    x = mx.nd.arange(start=0, stop=60, dtype=dtype).reshape((3, 4, 5))
     op_export_test('slice', M, [x], tmp_path)