[FRONTEND][TFLITE]Gather, StridedSlice op support added (#4788)

* [FRONTEND][TFLITE]Gather, StridedSlice op added

* Review comments fixed

tests/python/frontend/tflite/test_forward.py

@@ -292,6 +292,79 @@ def test_forward_topk():
     _test_topk((3, 5, 7), 3)
 
 #######################################################################
+# Gather
+# ------
+
+def _test_gather(dshape, indices, axis, dtype, quantized=False, oob=False):
+    """ One iteration of Gather """
+    indices = np.asarray(indices).astype('int32')
+    data = np.random.uniform(1, 10, size=dshape)
+    data = data.astype(np.uint8) if quantized else data.astype(dtype)
+    with tf.Graph().as_default():
+        in_data = array_ops.placeholder(shape=data.shape, dtype=data.dtype, name="in_data")
+        if axis:
+            out = array_ops.gather(in_data, indices, axis=axis)
+        else:
+            out = array_ops.gather(in_data, indices) #tflite conversion fails for None axis
+        input_range = {'in_data': (-100, 100)} if quantized else None
+        try:
+            compare_tflite_with_tvm([data], ['in_data:0'], [in_data], [out],
+                                      quantized=quantized, input_range=input_range)
+        except ValueError as e:
+            if not oob:
+                raise e
+        except Exception as e:
+            raise e
+
+def test_forward_gather():
+    """ GATHER """
+    for quantized in [False, True]:
+        _test_gather((4,), [1], 0, 'float32', quantized)
+        _test_gather((4,), [1], None, 'int32', quantized)
+        _test_gather((1, 4), [0], 0, 'int32', quantized)
+        _test_gather((4,), [[[1, 0], [0, 1]]], 0, 'float32', quantized)
+        _test_gather((2, 2), [[[1, 0], [0, 1]]], 1, 'int32', quantized)
+        _test_gather((2, 2), [[[1, 0], [0, 1]]], None, 'float32', quantized)
+        _test_gather((3, 3, 3),  [[[1, 0]]], 0, 'int32', quantized)
+        _test_gather((3, 3, 3), [[[1, 0]]], 2, 'int32', quantized)
+        _test_gather((4, 3, 5, 6),  [[2, 1, 0, 0]], 0, 'float32', quantized)
+        _test_gather((3, 3, 3), [[[2, 1]]], -1, 'int32', quantized)
+        _test_gather((4,), [16], 0, 'float32', quantized, oob=True)
+        _test_gather((1, 3, 3), [12], 0, 'int32', quantized, oob=True)
+        _test_gather((1, 3, 3), [20], 1, 'float32', quantized, oob=True)
+        _test_gather((1, 3, 3), [20, 20], 2, 'float32', quantized, oob=True)
+
+#######################################################################
+# StridedSlice
+# ------------
+
+def _test_stridedslice(ip_shape, begin, end, stride, dtype,
+                       begin_mask=0, end_mask=0, new_axis_mask=0,
+                       shrink_axis_mask=0, ellipsis_mask=0, quantized=False):
+    """ One iteration of a Stridedslice """
+    data = np.random.uniform(size=ip_shape).astype(dtype)
+    data = data.astype(np.uint8) if quantized else data.astype(dtype)
+    with tf.Graph().as_default():
+        in_data = tf.placeholder(dtype, ip_shape, name="in_data")
+        out = array_ops.strided_slice(in_data, begin, end, stride,
+                                      begin_mask=begin_mask,
+                                      end_mask=end_mask,
+                                      new_axis_mask=new_axis_mask,
+                                      shrink_axis_mask=shrink_axis_mask,
+                                      ellipsis_mask=ellipsis_mask)
+        input_range = {'in_data': (-100, 100)} if quantized else None
+        compare_tflite_with_tvm([data], ['in_data:0'], [in_data], [out], quantized=quantized,
+                                  input_range=input_range)
+
+def test_forward_stridedslice():
+    '''test StridedSlice'''
+    for quantized in [False, True]:
+        _test_stridedslice((2), [1], [1], [1], 'float32', shrink_axis_mask=1, quantized=quantized)
+        _test_stridedslice((3, 4, 3), [1, -1, 0], [4, -5, 3], [2, -1, 1], 'float32', quantized=quantized)
+        _test_stridedslice((3, 4), [1, 0], [4, 4], [1, 1], 'float32', shrink_axis_mask=0, quantized=quantized)
+        _test_stridedslice((4, 4), [1, 0], [4, 4], [1, 1], 'float32', shrink_axis_mask=2, quantized=quantized)
+
+#######################################################################
 # transpose
 # ---------
 
@@ -1855,6 +1928,8 @@ if __name__ == '__main__':
     test_forward_squeeze()
     test_forward_slice()
     test_forward_topk()
+    test_forward_gather()
+    test_forward_stridedslice()
     test_forward_depthtospace()
     test_forward_spacetodepth()