#!/usr/bin/env python
# ******************************************************************************
# Copyright 2023 Brainchip Holdings Ltd.
#
# Licensed 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.
# ******************************************************************************
__all__ = ["QuantizedAdd", "get_qadd"]
import numpy as np
from onnx import TensorProto as TP
from onnx.helper import make_node
from .base_layer import OnnxLayer
from .subgraph_ops import cast_tensors_to, get_scale_out_ops, get_input_shift_ops
from ..graph_tools import TENSOR_SHAPE, value_info_to_tensor_shape
from ..quantization.weights import align_to
from ..quantization.outputs import downscale_fp
def get_qadd(nodes, graph):
# Both inputs should not be constants
weight_names = [x.name for x in graph.initializer]
if nodes[0].input[0] in weight_names or nodes[0].input[1] in weight_names:
raise ValueError("Unsupported Add: inputs should be tensors.")
add_node = nodes[0]
add_name = add_node.name
qadd = QuantizedAdd(name=add_name)
return qadd
[docs]class QuantizedAdd(OnnxLayer):
"""Intermediate representation of Add() as an exportable node."""
def __init__(self, name=''):
super().__init__("QuantizedAdd", name=name)
def __build__(self, a_input_ts, b_input_ts, downscale=True):
assert a_input_ts.dtype == b_input_ts.dtype == np.int8
assert a_input_ts.shape == b_input_ts.shape
# The chain of operations is modified if downscale is needed
self.serialize_attr["scale"] = downscale
# Compute output shape
output_type = "int8" if downscale else "int32"
output_ts = TENSOR_SHAPE(a_input_ts.shape, np.dtype(output_type))
return output_ts
def __quantize__(self, a_qinput, b_qinput, out_tensor_range, force_fp=False):
def _round_pot(x):
return 2.0**np.round(np.log2(x))
x1_scale = a_qinput.weights["scale"]
x2_scale = b_qinput.weights["scale"]
# This quantization is feasible if and only if input scales are power-of-two
np.testing.assert_array_equal(x1_scale, _round_pot(x1_scale), "Required a power-of-two")
np.testing.assert_array_equal(x2_scale, _round_pot(x2_scale), "Required a power-of-two")
# Prepare tensors list with unique names
prefix = self.name + "_"
# Transpose scales to align with channels
output_shape = value_info_to_tensor_shape(self.output).shape
x1_scale = align_to(x1_scale, len(output_shape))
x2_scale = align_to(x2_scale, len(output_shape))
# We expected input scales are a power-of-two. Take i_scale as a max of both scales
i_scale = np.maximum(x1_scale, x2_scale)
# Shift to apply for each input will be
weights_dict = {prefix + "x1_shift": (i_scale / x1_scale).astype("int32"),
prefix + "x2_shift": (i_scale / x2_scale).astype("int32")}
if "Scaled" not in self.op_type:
out_scale = i_scale.squeeze()
else:
# Now consider calibrated output range
scale, s_out, out_scale = downscale_fp(out_tensor_range, i_scale, bitwidth=8)
# Add does not have output scale. We fold scale into shift as a power-of-two.
# This will force an 'output scale' = 1
s_out = 2.0**(np.log2(s_out) - np.ceil(np.log2(scale)))
weights_dict.update({prefix + "S_out": s_out.astype(np.float32)})
# Return quantized weights and ouput scale
return weights_dict, out_scale
@staticmethod
def build_subgraph(op_type):
# Cast inputs and shift to float.
nodes, t_names = cast_tensors_to(["X", "Y", "Xs", "Ys"])
# Align inputs with input shift
nodes += get_input_shift_ops(t_names[0], t_names[2], "Xshifted")
nodes += get_input_shift_ops(t_names[1], t_names[3], "Yshifted")
# Perform addition
nodes.append(make_node("Add", inputs=["Xshifted", "Yshifted"], outputs=["Zi"]))
# Apply final output shift (optional)
if "Scaled" in op_type:
shift_nodes, shift_t_names = cast_tensors_to(["", "Shift"])
nodes += shift_nodes
nodes += get_scale_out_ops("Zi", "Zscaled", *shift_t_names)
nodes.append(make_node("Cast", ["Zscaled"], ["Z"], to=TP.INT8))
else:
nodes.append(make_node("Cast", ["Zi"], ["Z"], to=TP.INT32))
return nodes