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# Copyright (C) 2020 Arm Limited or its affiliates. All rights reserved.
#
# SPDX-License-Identifier: Apache-2.0
#
# 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
#
# 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.
# Description:
# Early optimisation of the network graph, using the rewrite_graph module to do the traversal of the graph. These are
# split into two parts optimise_graph_a and optimise_graph_b.
from .nn_graph import Operation, NpuBlockType, Tensor
from . import rewrite_graph
from .data_type import BaseType, DataType
import numpy as np
import math
from .numeric_util import round_up_divide
passthrough_nodes = set(("Identity",))
def remove_passthrough_tensor(tens, arch):
if len(tens.ops) == 1 and tens.ops[0].type in passthrough_nodes:
assert len(tens.ops[0].inputs) == 1
tens = tens.ops[0].inputs[0]
return tens
def rewrite_concat(tens, arch):
if len(tens.ops) == 1 and tens.ops[0].is_concat_op():
concat_op = tens.ops[0]
if tens != concat_op.outputs[0]:
return tens # don't attempt to rewrite the min/max outputs of QuantizedConcat
# Not supported so leave it and run on CPU
if not concat_op.run_on_npu:
return tens
inputs, axis = concat_op.get_concat_inputs_axis()
tens.ops = []
offset = 0
for idx, inp in enumerate(inputs):
new_op = Operation("ConcatSliceWrite", concat_op.name + str(idx))
new_op.inputs = [inp]
new_op.outputs = [tens]
new_op.attrs["concat_axis"] = axis
new_op.attrs["concat_start"] = offset
offset += inp.shape[axis]
new_op.attrs["concat_end"] = offset
new_op.run_on_npu = True
tens.ops.append(new_op)
assert tens.shape[axis] == offset
return tens
def rewrite_split(tens, arch):
if len(tens.ops) == 1 and tens.ops[0].is_split_op():
split_op = tens.ops[0]
# Not supported so leave it and run on CPU
if not split_op.run_on_npu:
return tens
inp, outputs, axis, offset_start, offset_end = split_op.get_split_inputs_axis()
tens.ops = []
new_op = Operation("SplitSliceRead", split_op.name)
new_op.inputs = [inp]
new_op.outputs = [tens]
# For Split the offset cannot be extracted from the tensor so it has to
# be calculated from the index of the output tensor
if axis != None:
# Get the start and end of the split
offset_start = [0] * len(tens.shape)
offset_end = [0] * len(tens.shape)
for out in outputs:
if out == tens:
break
offset_start[axis] += out.shape[axis]
offset_end[axis] = offset_start[axis] + tens.shape[axis]
new_op.attrs["split_start"] = offset_start
new_op.attrs["split_end"] = offset_end
new_op.run_on_npu = True
tens.ops.append(new_op)
return tens
def needed_total_padding(input_size, stride, filter_size):
out_size = (input_size + stride - 1) // stride
needed_input = (out_size - 1) * stride + filter_size
total_padding = max(0, needed_input - input_size)
return total_padding
def calc_padding_and_skirt(padding_type, kernel_size, stride, input_dims):
ypad = needed_total_padding(int(input_dims[1]), int(stride[1]), int(kernel_size[0]))
xpad = needed_total_padding(int(input_dims[2]), int(stride[2]), int(kernel_size[1]))
if padding_type == b"SAME":
left_pad = (xpad + 0) // 2
right_pad = (xpad + 1) // 2
top_pad = (ypad + 0) // 2
bottom_pad = (ypad + 1) // 2
elif padding_type == b"VALID":
left_pad = 0
right_pad = 0
top_pad = 0
bottom_pad = 0
else:
assert 0, "Unknown padding"
padding = (top_pad, left_pad, bottom_pad, right_pad)
skirt = (top_pad, left_pad, ypad - top_pad, xpad - left_pad)
return padding, skirt
def fixup_conv2d_backprop(op, arch):
if op.type == "Conv2DBackpropInput":
# flip the inputs
op.inputs[0], op.inputs[2] = op.inputs[2], op.inputs[0]
op.type = "Conv2DBackpropInputSwitched"
return op
def fixup_fully_connected_input(op, arch):
if op.type == "FullyConnectedAct":
inp = op.inputs[0]
weights = op.inputs[1]
n_in_elems = weights.shape[-2]
elms = inp.elements()
batch_size = elms // n_in_elems
assert batch_size * n_in_elems == elms
desired_shape = [batch_size, n_in_elems]
if inp.shape != desired_shape:
# mismatch, insert a reshape to fix this.
reshape_name = op.name + "_reshape"
new_shape_tens = Tensor([1], DataType.int32, reshape_name + "_shape")
new_shape_tens.values = np.array(desired_shape)
new_shape_tens_const = Operation("Const", new_shape_tens.name + "_const")
new_shape_tens.ops = [new_shape_tens_const]
new_shape_tens_const.outputs = [new_shape_tens]
reshape_op = Operation("Reshape", reshape_name)
reshape_op.inputs = [inp, new_shape_tens]
reshape_op.attrs["new_shape"] = desired_shape
reshape_out = inp.clone("_reshaped")
reshape_out.shape = reshape_out.storage_shape = reshape_out.bandwidth_shape = desired_shape
reshape_out.ops = [reshape_op]
reshape_op.outputs = [reshape_out]
op.inputs[0] = reshape_out
return op
def fixup_pack_input(op, arch):
if op.type == "Pack":
# Pack is also referred to as Stack
# Requires the rewrite_concat function to be called on the op afterwards
axis = int(op.attrs["axis"])
desired_shape = op.inputs[0].shape[:axis] + [1] + op.inputs[0].shape[axis:]
# Construct 1 shape tensor to be used by all inserted reshape ops
new_shape_name = op.name + "_reshape_shape"
new_shape_tens = Tensor([1], DataType.int32, new_shape_name)
new_shape_tens.values = np.array(desired_shape)
new_shape_tens_const = Operation("Const", new_shape_tens.name + "_const")
new_shape_tens.ops = [new_shape_tens_const]
new_shape_tens_const.outputs = [new_shape_tens]
for idx, inp in enumerate(op.inputs):
reshape_name = op.name + str(idx) + "_reshape"
reshape_op = Operation("Reshape", reshape_name)
reshape_op.inputs = [inp, new_shape_tens]
reshape_op.attrs["new_shape"] = desired_shape
reshape_out = inp.clone("_reshaped")
reshape_out.shape = reshape_out.storage_shape = reshape_out.bandwidth_shape = desired_shape
reshape_out.ops = [reshape_op]
reshape_op.outputs = [reshape_out]
op.inputs[idx] = reshape_out
op.type = "PackReshaped"
return op
def fixup_unpack_output(tens, arch):
op = tens.ops[0]
if op.type in set(("Unpack", "StridedSlice")):
# Unpack is also referred to as Unstack
# Requires the rewrite_split function to be called on the op afterwards
if op.type == "StridedSlice":
shrink_axis_mask = op.attrs["shrink_axis_mask"]
if shrink_axis_mask == 0:
# Equal Rank StridedSlice, no need to insert reshape
return tens
# Only allow shrinking 1 axis for now
assert shrink_axis_mask & (shrink_axis_mask - 1) == 0
assert len(tens.shape) == (len(op.inputs[0].shape) - 1)
axis = int(math.log2(shrink_axis_mask))
op.attrs["shrink_axis_mask"] = 0
else:
axis = int(op.attrs["axis"])
op.type = "UnpackReshaped"
desired_shape = tens.shape[:axis] + [1] + tens.shape[axis:]
# Construct 1 shape tensor to be used by all inserted reshape ops
new_shape_name = op.name + "_reshape_shape"
new_shape_tens = Tensor([1], DataType.int32, new_shape_name)
new_shape_tens.values = np.array(tens.shape)
new_shape_tens_const = Operation("Const", new_shape_tens.name + "_const")
new_shape_tens.ops = [new_shape_tens_const]
new_shape_tens_const.outputs = [new_shape_tens]
for idx, out_tens in enumerate(op.outputs):
reshape_name = op.name + str(idx) + "_reshape"
reshape_op = Operation("Reshape", reshape_name)
reshape_op.outputs = [out_tens]
reshape_in = out_tens.clone("_reshaped")
reshape_in.shape = reshape_in.storage_shape = reshape_in.bandwidth_shape = desired_shape
reshape_in.ops = [op]
out_tens.ops = [reshape_op]
reshape_op.inputs = [reshape_in, new_shape_tens]
op.outputs[idx] = reshape_in
return tens
def add_padding_fields(op, arch):
if "padding" in op.attrs:
if "Conv" in op.type:
kernel_size = op.inputs[1].shape[:2]
input_shape = op.inputs[0].shape
elif "Pool" in op.type:
kernel_size = op.attrs["ksize"][1:3]
input_shape = op.inputs[0].shape
elif op.type == "ExtractImagePatches":
kernel_size = op.attrs["ksizes"][1:3]
input_shape = op.inputs[0].shape
else:
assert 0, "Unknown operation that uses padding"
padding, skirt = calc_padding_and_skirt(op.attrs["padding"], kernel_size, op.attrs["strides"], input_shape)
op.attrs["explicit_padding"] = padding
op.attrs["skirt"] = skirt
return op
conv_op = set(("Conv2D", "QuantizedConv2D", "Conv2DBackpropInputSwitched", "Conv2DBiasAct"))
fc_op = set(
(
"MatMul",
"QuantizedMatMul",
"BlockLSTM",
"RnnAct",
"UnidirectionalSequenceRnnAct",
"BidirectionalSequenceRnnAct",
"LstmAct",
"UnidirectionalSequenceLstmAct",
"BidirectionalSequenceLstmAct",
"FullyConnectedAct",
)
)
depthwise_op = set(("DepthwiseConv2dNative", "DepthwiseConv2dBiasAct",))
pool_op = set(("AvgPool", "MaxPool", "QuantizedAvgPool", "QuantizedMaxPool", "AvgPoolAct", "MaxPoolAct"))
elementwise_op = set(("AddAct", "MulAct", "SubAct", "Maximum", "Minimum", "LeakyRelu", "Abs"))
activation_ops = set(("Relu", "Relu6", "ReluN1To1", "Sigmoid", "Tanh"))
memory_only_ops = set(("Reshape",))
# Check if the op can be reordered
def get_prepend_op(op):
inp = op.inputs[0]
# The op should be reordered between prev_op and prep_op
prev_op = inp.ops[-1]
prep_op = None
while prev_op.type in memory_only_ops and len(prev_op.outputs) == 1 and len(prev_op.outputs[0].consumers()) == 1:
prep_op = prev_op
inp = prev_op.inputs[0]
prev_op = inp.ops[-1]
if prev_op != None and len(prev_op.outputs) == 1 and len(prev_op.outputs[0].consumers()) == 1:
return prep_op
return None
def mark_npu_block_type(op, arch):
npu_block_type = NpuBlockType.Default
if op.type in conv_op:
npu_block_type = NpuBlockType.ConvolutionMxN
elif op.type in fc_op:
npu_block_type = NpuBlockType.VectorProduct
elif op.type in depthwise_op:
npu_block_type = NpuBlockType.ConvolutionDepthWise
elif op.type in pool_op:
npu_block_type = NpuBlockType.Pooling
elif op.type in elementwise_op:
npu_block_type = NpuBlockType.ElementWise
op.attrs["npu_block_type"] = npu_block_type
return op
def convert_depthwise_to_conv(op, arch):
# Depthwise is equivalent to a single conv2d if the ifm depth is 1 and
# the ofm depth equals the depth multipler.
# If those conditions are true, then we can perform a simple
# switch of the operator type (and weight order)
if ("DepthwiseConv2d" in op.type) and (op.attrs["depth_multiplier"] != 1):
ifm_tensor = op.inputs[0]
weight_tensor = op.inputs[1]
ofm_tensor = op.outputs[0]
if (ifm_tensor.shape[3] == 1) and (ofm_tensor.shape[3] == op.attrs["depth_multiplier"]):
# Change op type to Conv2d
op.type = op.type.replace("DepthwiseConv2d", "Conv2D")
del op.attrs["channel_multiplier"]
del op.attrs["depth_multiplier"]
weight_tensor.quant_values = np.transpose(weight_tensor.quant_values, (0, 1, 3, 2))
weight_tensor.shape = weight_tensor.storage_shape = weight_tensor.bandwidth_shape = list(
weight_tensor.quant_values.shape
)
else:
print(
"Error: Unsupported DepthwiseConv2d with depth_multiplier = {0}, "
"ifm channels = {1}, ofm channels = {2}".format(
op.attrs["depth_multiplier"], ifm_tensor.shape[3], ofm_tensor.shape[3]
)
)
assert False
return op
# Reorder activation op if it's after the memory only operations
def fixup_act_reorder(op, arch):
if op.type in activation_ops:
prep_op = get_prepend_op(op)
if prep_op != None:
act_op = op.clone("_reordered")
act_op.inputs = [prep_op.inputs[0]]
act_op_out = act_op.inputs[0].clone("_acted")
act_op_out.quantization = op.outputs[0].quantization.clone()
act_op_out.ops = [act_op]
act_op.outputs = [act_op_out]
prep_op.inputs[0] = act_op_out
prep_op.outputs[0].quantization = act_op_out.quantization.clone()
# Mark the op so that it will be removed as passthrough later on
op.type = "Identity"
return op
def convert_mul_max_to_abs_or_lrelu(op, arch):
"""Whenever there is a subgraph with this topology:
Input X For X = -1 or X > 0
| \ / This subgraph can be replaced with either
| Mul an Abs (if X = -1) or a LeakyReLU (if X > 0)
| /
Max
"""
if op.type == "Maximum":
# finds the Mul input(s) to the Max
muls = [i for i in op.inputs if i.ops[0].type == "MulAct"]
if len(muls) == 1:
mul = muls[0].ops[0]
elif len(muls) == 2:
# In the case both inputs are Muls, find the one with the same input as the Max
mul = [m for m in muls if len(set(op.inputs + m.ops[0].inputs)) == 1][0].ops[0]
else:
# No Mul inputs
return op
# make sure the Mul doesn't have any other consumers
if len(mul.outputs[0].consumers()) != 1:
return op
# make sure the Mul doesn't have a faf
if mul.attrs["fused_activation_function"]:
return op
# finds the branched input that goes to both the Max and the Mul
shared = set(op.inputs) & set(mul.inputs)
if len(shared) == 1:
shared_in = shared.pop()
# find the constant scalar input to the Mul
const_tens = (set(mul.inputs) - {shared_in}).pop()
# check that it is a scalar
if const_tens.shape != []:
return op
const = const_tens.ops[0]
# check that it is a constant
if const.type != "Const":
return op
else:
return op
val = const.outputs[0].values
if val >= 0:
new_op = "LeakyRelu"
op.attrs["alpha"] = val
elif val == -1:
new_op = "Abs"
else:
return op
op.type = op.type.replace("Maximum", new_op)
op.name = op.name.replace("Maximum", new_op)
op.outputs[0].name = op.outputs[0].name.replace("Maximum", new_op)
op.inputs = [shared_in]
return op
def supported_operator_check(op, arch):
op.run_on_npu = arch.supported_operators.is_operator_supported(op)
return op
def optimise_graph_a(nng, arch, verbose_graph=False):
if verbose_graph:
nng.print_graph()
op_rewrite_list = [
# mark block type and check if the operations are supported
mark_npu_block_type,
supported_operator_check,
# then do any rewrites of supported operators
convert_depthwise_to_conv,
fixup_fully_connected_input,
fixup_pack_input,
fixup_conv2d_backprop,
fixup_act_reorder,
add_padding_fields,
mark_npu_block_type,
# convert_mul_max_to_abs_or_lrelu # TODO: enable optimisation once quantisation issues are resolved
]
for idx, sg in enumerate(nng.subgraphs):
# rewrite graph pass
nng.subgraphs[idx] = rewrite_graph.rewrite_graph_pre_order(
sg, arch, [fixup_unpack_output,], op_rewrite_list, rewrite_unsupported=False
)
for idx, sg in enumerate(nng.subgraphs):
# remove passthrough tensors
nng.subgraphs[idx] = rewrite_graph.rewrite_graph_pre_order(sg, arch, [remove_passthrough_tensor,], [])
if verbose_graph:
nng.print_graph()
return nng
def optimise_graph_b(nng, arch, verbose_graph=False):
if verbose_graph:
nng.print_graph()
for idx, sg in enumerate(nng.subgraphs):
# combined rewrite graph pass
nng.subgraphs[idx] = rewrite_graph.rewrite_graph_pre_order(sg, arch, [rewrite_concat, rewrite_split,], [])
if verbose_graph:
nng.print_graph()
return nng