blob: c07229fb1572f2516a494379ea0a6974ec3f08b4 [file] [log] [blame]
# 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:
# Compresses and pads the weigths. It also calculates the scales and packs with the biases.
import math
from collections import namedtuple
import numpy as np
from .api import NpuBlockTraversal
from .architecture_features import Accelerator
from .architecture_features import ArchitectureFeatures
from .data_type import DataType
from .errors import UnsupportedFeatureError
from .nn_graph import SchedulingStrategy
from .numeric_util import round_up
from .numeric_util import round_up_divide
from .operation import NpuBlockType
from .operation import Op
from .scaling import quantise_scale
from .scaling import reduced_quantise_scale
from .tensor import create_equivalence_id
from .tensor import TensorBlockTraversal
from .tensor import TensorFormat
from .tensor import TensorPurpose
from .tensor import TensorSubPurpose
from ethosu import mlw_codec
# Contains meta info for a weight compression. If two tensors have identical weight compression config,
# then they also will have identical compressed weights.
WeightCompressionConfig = namedtuple(
"WeightCompressionConfig", ["npu_block_type", "ofm_block_depth", "ofm_depth_step", "dilation", "value_id"]
)
def encode_weights(
accelerator: Accelerator,
weights_volume: np.ndarray,
dilation_xy: tuple,
ifm_bitdepth: int,
ofm_block_depth: int,
is_depthwise: bool,
block_traversal: NpuBlockTraversal,
):
"""
Public facing API to use the ethosu weight encoding.
:param accelerator: architecture_features.Accelerator enum to pick the correct ethosu accelerator
:param weights_volume: numpy.ndarray in OHWI layout with a shape of four
:param dilation_xy: a two element tuple of dilation attributes in x,y dimension
:param ifm_bitdepth: the bitdepth of input feature map
:param ofm_block_depth: the depth of blocks for ethosu processing
:param is_depthwise: a boolean indicating these weights are used for a depthwise traversal
:param block_traversal: indicates how these weights are traversed on sub-kernal basis
:return: a bytearray of compressed weights
"""
# Check arg types
assert isinstance(accelerator, Accelerator)
assert isinstance(weights_volume, np.ndarray)
assert isinstance(dilation_xy, tuple)
assert isinstance(ifm_bitdepth, int)
assert isinstance(ofm_block_depth, int)
assert isinstance(is_depthwise, bool)
assert isinstance(block_traversal, NpuBlockTraversal)
# Checks for weight layout
assert len(weights_volume.shape) == 4, "weights ndarray should have a shape of 4"
# It cannot be both partkernel and depthwise
assert not (
is_depthwise and block_traversal == NpuBlockTraversal.PART_KERNEL_FIRST
), "encode_weights :: partkernel and depthwise are mutually exclusive"
# Check valid values for dilation
assert dilation_xy[0] in (1, 2), "encode_weights :: dilation x should be 1 or 2 not {}".format(dilation_xy[0])
assert dilation_xy[1] in (1, 2), "encode_weights :: dilation y should be 1 or 2 not {}".format(dilation_xy[1])
ifm_ublock = ArchitectureFeatures.accelerator_configs[accelerator].ifm_ublock
ofm_ublock = ArchitectureFeatures.accelerator_configs[accelerator].ofm_ublock
raw_stream = generate_brick(
ifm_ublock=ifm_ublock,
ofm_ublock=ofm_ublock,
brick_weights=weights_volume,
ofm_block_depth=ofm_block_depth,
is_depthwise=is_depthwise,
is_partkernel=block_traversal == NpuBlockTraversal.PART_KERNEL_FIRST,
ifm_bitdepth=ifm_bitdepth,
dilation=dilation_xy,
)
encoded_stream = encode(raw_stream)
return encoded_stream
def encode_bias(bias: np.int64, scale: int, shift: int):
"""
Public facing API to pack bias and scale values as required by the hardware
:param bias: 64bit signed number that includes 40bit signed bias
:param scale: 32bit scale value
:param shift: 6bit shift value
:return: packed 80bit [0(2-bits),shift(6-bits),scale(32-bits),bias(40-bits)]
"""
# Check arg types
assert isinstance(bias, np.int64)
assert isinstance(scale, int)
assert isinstance(shift, int)
assert -(1 << (40 - 1)) <= bias < (1 << (40 - 1)) # signed 40-bit range
assert 0 <= scale < (1 << 32) # unsigned 32-bit range
assert 0 <= shift < (1 << 6) # unsigned 6-bit range
data = bytearray(10)
data[0] = (bias >> (0 * 8)) & 0xFF
data[1] = (bias >> (1 * 8)) & 0xFF
data[2] = (bias >> (2 * 8)) & 0xFF
data[3] = (bias >> (3 * 8)) & 0xFF
data[4] = (bias >> (4 * 8)) & 0xFF
data[5] = (scale >> (0 * 8)) & 0xFF
data[6] = (scale >> (1 * 8)) & 0xFF
data[7] = (scale >> (2 * 8)) & 0xFF
data[8] = (scale >> (3 * 8)) & 0xFF
data[9] = shift & 0x3F
return data
def create_weight_compression_config(tens, npu_block_type, ofm_block_depth, ofm_depth_step, dilation):
# Note: for an ofm block only its depth is used in weight compression.
# And block depth > ofm depth gives same result as block depth == ofm depth
block_depth = min(ofm_block_depth, tens.quant_values.shape[-1])
return WeightCompressionConfig(npu_block_type, block_depth, ofm_depth_step, dilation, tens.value_id)
def set_storage_shape(tens):
# Sets the storage shape depending on the tensor's sub purpose
if tens.sub_purpose == TensorSubPurpose.DoubleBuffer and len(tens.compressed_values) > 2:
offset = 2 * np.amax([len(x) for x in tens.compressed_values])
assert offset % 16 == 0
else:
offset = tens.weight_compressed_offsets[-1]
tens.storage_shape = [1, 1, 1, offset]
class CompressedWeightCache:
# Contains weight compressions for all weight tensors in a graph
def __init__(self):
self.cache = {} # maps from WeightCompressionConfig to a tensor clone containing compressed weights
def get_tensor_with_same_compression(self, wcc):
return self.cache.get(wcc)
def add(self, tens):
# Adds the compressed weights from the tensor to the cache
wcc = tens.weight_compression_config
# Clone the tensor to make sure that nothing related to the weight compression is modified
tens_clone = tens.clone("_weights{}_{}".format(wcc.ofm_block_depth, wcc.ofm_depth_step))
self.cache[wcc] = tens_clone
def encode(weight_stream):
if len(weight_stream) == 0:
return []
assert np.amin(weight_stream) >= -255
assert np.amax(weight_stream) <= 255
# Encode flattened signed weight stream
compressed = mlw_codec.encode(weight_stream)
# pad with 0xFF as needed so the length of the weight stream
# is a multiple of 16
while (len(compressed) % 16) != 0:
compressed.append(0xFF)
return compressed
def generate_brick(
ifm_ublock, ofm_ublock, brick_weights, ofm_block_depth, is_depthwise, is_partkernel, ifm_bitdepth, dilation
):
decomp_h = ArchitectureFeatures.SubKernelMax.height // dilation[0]
decomp_w = ArchitectureFeatures.SubKernelMax.width // dilation[1]
# Expect weights formatted OHWI
ofm_depth = brick_weights.shape[-4]
ifm_depth = brick_weights.shape[-1]
kernel_width = brick_weights.shape[-2]
kernel_height = brick_weights.shape[-3]
# IFM block depth
if is_partkernel or (ifm_bitdepth == 16):
# IFM block depth is always 16 for part-kernel-first
ifm_block_depth = 16
elif ifm_bitdepth == 8:
ifm_block_depth = 32
else:
assert False
stream = []
# Top level striping - OFM blocks in the entire brick's depth
for ofm_block_z in range(0, ofm_depth, ofm_block_depth):
clipped_ofm_block_depth = min(ofm_block_depth, ofm_depth - ofm_block_z)
# IFM blocks required for the brick
for ifm_block_z in range(0, (1 if is_depthwise else ifm_depth), ifm_block_depth):
if is_depthwise:
clipped_ifm_block_depth = ifm_ublock.depth
else:
clipped_ifm_block_depth = (
min(ifm_block_depth, ifm_depth - ifm_block_z) if is_partkernel else ifm_block_depth
)
# Weight decomposition
# Subkernel Splitting (H)
for subkernel_y in range(0, kernel_height, decomp_h):
sub_height = min(kernel_height - subkernel_y, decomp_h)
# Subkernel splitting (W)
for subkernel_x in range(0, kernel_width, decomp_w):
sub_width = min(kernel_width - subkernel_x, decomp_w)
subkernel_elements = sub_width * sub_height
# Part kernel first works across the kernel H/W and needs padding
if is_partkernel:
if ifm_bitdepth == 16 and subkernel_elements % 2 != 0:
subkernel_elements = int(math.ceil(subkernel_elements / 2) * 2)
elif ifm_bitdepth == 8 and subkernel_elements % 4 != 0:
subkernel_elements = int(math.ceil(subkernel_elements / 4) * 4)
# Depthwise Conv requires multiple of 4 kernel elements in its weight block
# this is different from normal conv which is considered "weights depth-first"
elif is_depthwise:
subkernel_elements = int(math.ceil(subkernel_elements / 4.0) * 4)
ifm_block_depth_outer = clipped_ifm_block_depth if is_partkernel else 1
ifm_block_depth_inner = 1 if is_partkernel else clipped_ifm_block_depth
# IFM Ublocks in IFM-block over depth for part-kernel-first mode
# For depth-first IFM Ublocks are traversed after subkernel elements so this loop is ignored.
for ifm_ublk_outer in range(0, ifm_block_depth_outer, ifm_ublock.depth):
# OFM Ublocks in OFM-block over depth
for ofm_ublk in range(0, clipped_ofm_block_depth, ofm_ublock.depth):
# HW Kernel element traversal - cannot be a H/W loop due to element
# padding requirement on depthwise/part-kernel configurations
for element in range(subkernel_elements):
kx = element % sub_width
ky = element // sub_width
# IFM Ublocks in IFM-block over depth (only 1 ublock if depthwise)
# In case of part-kernel-first IFM Ublock traversal have already been handled
# and this loop is ignored.
for ifm_ublk_inner in range(0, ifm_block_depth_inner, ifm_ublock.depth):
# Feed OFM ublock elements
for ofm_ublock_z in range(ofm_ublock.depth):
# Source IFM ublock elements (only 1 element deep if depthwise)
for ifm_ublock_z in range(1 if is_depthwise else ifm_ublock.depth):
# Source position within the current subkernel
wx = subkernel_x + kx
wy = subkernel_y + ky
# Source IFM/OFM slices
ifm_ublk = ifm_ublk_inner + ifm_ublk_outer
ifm_z = ifm_block_z + ifm_ublk + ifm_ublock_z
ofm_z = ofm_block_z + ofm_ublk + ofm_ublock_z
if (ifm_z >= ifm_depth) or (ofm_z >= ofm_depth) or (ky >= sub_height):
stream.append(0)
else:
stream.append(brick_weights[ofm_z][wy][wx][ifm_z])
return stream
def core_deinterleave(hwio, core, ncores):
# Put weights back into OHWI
ohwi = np.transpose(hwio, (3, 0, 1, 2))
return ohwi[core : ohwi.shape[0] : ncores]
# Compress the weights
def compress_weights(arch, nng, tens, npu_block_type, ofm_block_depth, ofm_depth_step, dilation):
assert tens.purpose == TensorPurpose.Weights
# Check the weight cache
if nng.weight_cache is None:
nng.weight_cache = CompressedWeightCache()
wcc = create_weight_compression_config(tens, npu_block_type, ofm_block_depth, ofm_depth_step, dilation)
tens.weight_compression_config = wcc
# Reassign equivalence id such that tensors with same weight compression get identical equivalence ids,
# but tensors with the same values but different compression get different equivalence ids
tens.equivalence_id = create_equivalence_id(wcc)
tens_cached = nng.weight_cache.get_tensor_with_same_compression(wcc)
if tens_cached is not None:
# Cache hit, copy weights from the cache
tens.copy_compressed_weight_info(tens_cached)
set_storage_shape(tens)
return
# No cache hit, perform the compression
assert tens.quantization is not None
assert tens.quantization.scale_f32 is not None
assert tens.quantization.zero_point is not None
zero_point = tens.quantization.zero_point
quant_buf = tens.quant_values.astype(np.int64)
# Early zero-point correction
weights = quant_buf - zero_point
if len(weights.shape) == 2:
weights = np.expand_dims(np.expand_dims(weights, axis=0), axis=0)
compression_scales = []
compressed_offsets = []
encoded_streams = []
encoded_streams_substream_offsets = []
offset = 0
max_single_buffer_len = 0
ifm_bitdepth = tens.consumer_list[0].inputs[0].dtype.size_in_bits()
ifm_depth = weights.shape[-2]
if npu_block_type == NpuBlockType.ConvolutionDepthWise:
tens.block_traversal = TensorBlockTraversal.DepthWise
if npu_block_type == NpuBlockType.ConvolutionMxN:
# Determine which block traversal strategy has better DPU utilization
kernel_size = weights.shape[0] * weights.shape[1]
depth_utilization = weights.shape[2] / round_up(weights.shape[2], 32 if ifm_bitdepth == 8 else 16)
part_kernel_utilization = (weights.shape[2] / round_up(weights.shape[2], 8)) * (
kernel_size / round_up(kernel_size, 4 if ifm_bitdepth == 8 else 2)
)
if part_kernel_utilization >= depth_utilization or ifm_depth <= 8:
# Part-kernel first is always better for ifm depths <= 8
tens.block_traversal = TensorBlockTraversal.PartKernelFirst
else:
tens.block_traversal = TensorBlockTraversal.DepthFirst
is_depthwise = tens.block_traversal == TensorBlockTraversal.DepthWise
if tens.block_traversal == TensorBlockTraversal.PartKernelFirst:
block_traversal = NpuBlockTraversal.PART_KERNEL_FIRST
else:
block_traversal = NpuBlockTraversal.DEPTH_FIRST
if tens.consumer_list[0].type == Op.Conv2DBackpropInputSwitchedBias:
# Transpose Convoluion, reverse weights in H and W axes
weights = np.flip(weights, axis=(0, 1))
# Calculate brick size
brick_size = (weights.shape[0], weights.shape[1], weights.shape[2], min(tens.shape[-1], ofm_depth_step))
elements_in_brick = np.prod(brick_size)
# Slice weight stream up depth-ways into bricks and compress
full_ofm_depth = quant_buf.shape[-1]
for idx in range(0, full_ofm_depth, ofm_depth_step):
# Get the weights necessary for this brick
count = min(full_ofm_depth - idx, ofm_depth_step)
brick_weights = weights[:, :, :, idx : idx + count]
substream_offsets = [0]
encoded_stream = []
# For each core, deinterleave weights from the larger volume
# and generate separate compressed streams.
for core in range(0, min(arch.ncores, full_ofm_depth)):
core_weights = core_deinterleave(brick_weights, core, arch.ncores)
block_depth = (ofm_block_depth + arch.ncores - 1 - core) // arch.ncores
encoded_substream = []
if block_depth != 0:
encoded_substream = encode_weights(
accelerator=arch.accelerator_config,
weights_volume=core_weights,
dilation_xy=dilation,
ifm_bitdepth=ifm_bitdepth,
ofm_block_depth=block_depth,
is_depthwise=is_depthwise,
block_traversal=block_traversal,
)
encoded_stream.extend(encoded_substream)
substream_offsets.append(len(encoded_stream))
encoded_streams.append(encoded_stream)
encoded_streams_substream_offsets.append(substream_offsets)
# Remember maximum encoded length for DoubleBuffering
max_single_buffer_len = max(max_single_buffer_len, len(encoded_stream))
# Remember where we put it for linear addressing
compressed_offsets.append(offset)
offset += len(encoded_stream)
assert offset % 16 == 0
# Compression scale tracking
compression_scales.append(len(encoded_stream) / elements_in_brick)
# Track total length as last element of the offsets array
compressed_offsets.append(offset)
tens.weight_compression_scales = compression_scales
tens.weight_compressed_offsets = compressed_offsets
tens.compression_scale_for_worst_weight_stream = np.amax(compression_scales)
tens.storage_compression_scale = tens.bandwidth_compression_scale = np.average(compression_scales)
tens.compressed_values = encoded_streams
tens.compressed_values_substream_offsets = encoded_streams_substream_offsets
tens.brick_size = brick_size
set_storage_shape(tens)
nng.weight_cache.add(tens)
def calc_scales_and_pack_biases(tens, arch, ofm_depth_step, rescale_for_faf=False):
assert tens.purpose in [TensorPurpose.FeatureMap, TensorPurpose.FSBias]
assert tens.format == TensorFormat.NHWC
# the connected operator should expect a bias input unless it is a FullyConnected
assert tens.consumer_list[0].type.needs_bias()
# the input bias tensor is the same as that connected to the operator
bias_tens = tens.consumer_list[0].bias
assert tens is bias_tens
# the operator should only have a single output
assert len(tens.consumer_list[0].outputs) == 1
biases = tens.quant_values
first_consumer_op = tens.consumer_list[0]
ifm_dtype = first_consumer_op.inputs[0].dtype
ifm_scale = first_consumer_op.inputs[0].quantization.scale_f32
ofm_scale = first_consumer_op.get_output_quantization().scale_f32
weight_scales = first_consumer_op.inputs[1].quantization.scale_f32
# biases can have multiple consumers for rnn cells. if so, then check that they are all the same
for op in tens.consumer_list[1:]:
assert ifm_scale == op.inputs[0].quantization.scale_f32
assert ofm_scale == op.get_output_quantization().scale_f32
assert weight_scales == op.inputs[1].quantization.scale_f32
if not hasattr(weight_scales, "__iter__"):
# If weight_scales is not already an iterable make it into a list
weight_scales = [weight_scales]
# Convert scales to np.double (from np.float32) to conform to TensorFlow Lite which
# uses double during scaling calculations
# TensorFlow Lite casts the scales slightly differently for uint8 and int8
if not rescale_for_faf:
if ifm_dtype == DataType.uint8:
scales = [np.double(ifm_scale * weight_scale) / np.double(ofm_scale) for weight_scale in weight_scales]
elif ifm_dtype == DataType.int8 or ifm_dtype == DataType.int16:
scales = [
(np.double(ifm_scale) * np.double(weight_scale)) / np.double(ofm_scale)
for weight_scale in weight_scales
]
else:
raise UnsupportedFeatureError(
"Compression of {} is not implemented; tensor: {}".format(ifm_dtype, tens.name)
)
else:
if ifm_dtype == DataType.uint8:
scales = [np.double(ifm_scale * weight_scale * 0x3000) for weight_scale in weight_scales]
elif ifm_dtype == DataType.int8 or ifm_dtype == DataType.int16:
scales = [(np.double(ifm_scale * 0x3000) * np.double(weight_scale)) for weight_scale in weight_scales]
else:
raise UnsupportedFeatureError(
"Compression of {} is not implemented; tensor: {}".format(ifm_dtype, tens.name)
)
# quantise all of the weight scales into (scale_factor, shift)
if ifm_dtype == DataType.int16:
quantised_scales = [reduced_quantise_scale(scale) for scale in scales]
else:
quantised_scales = [quantise_scale(scale) for scale in scales]
# pack the biases and scales
if len(quantised_scales) == 1:
# If only 1 quantised scale is used, repeat that value for the length of the biases
quantised_scales = [quantised_scales[0]] * len(biases)
assert len(quantised_scales) == len(biases)
tens.element_size_bytes = 10
tens.compressed_values = []
tens.compressed_values_substream_offsets = []
total_elements = len(quantised_scales)
alignment_bytes = 0
for i in range(0, total_elements, ofm_depth_step):
# Extract streams from brick to generate substreams for each core
stream = bytearray()
substream_offsets = [0]
max_len = min(ofm_depth_step, total_elements - i)
for core in range(0, min(arch.ncores, max_len)):
core_scales = quantised_scales[i + core : i + core + max_len : arch.ncores]
core_biases = biases[i + core : i + core + max_len : arch.ncores]
for j, core_bias in enumerate(core_biases):
stream.extend(encode_bias(np.int64(core_bias), *core_scales[j]))
# Align to 16 for start for next substream
remainder = (len(stream)) % 16
if remainder > 0:
stream.extend(bytearray(16 - remainder))
alignment_bytes += 16 - remainder
substream_offsets.append(len(stream))
# Add to compressed values with their substream offset lists to the tensor
tens.compressed_values.append(stream)
tens.compressed_values_substream_offsets.append(substream_offsets)
tens.storage_shape = [total_elements + round_up_divide(alignment_bytes, tens.element_size_bytes)]
def update_pass_weight_and_scale_tensors(nng, arch):
for sg in nng.subgraphs:
for ps in sg.passes:
tens = ps.weight_tensor
if tens is not None:
op = tens.find_npu_op()
if op is None:
continue
needs_dma = tens.needs_dma()
if ps.cascade.strategy == SchedulingStrategy.WeightStream and needs_dma:
ofm_depth_step = ps.block_config[-1]
else:
ofm_depth_step = tens.shape[-1]
compress_weights(
arch, nng, tens, op.type.npu_block_type, ps.block_config[-1], ofm_depth_step, op.get_dilation_h_w()
)
# Update source tensor
if needs_dma:
src_tens = tens.get_dma_src_tensor()
src_tens.shape = tens.shape
src_tens.quant_values = tens.quant_values
src_tens.copy_compressed_weight_info(tens)
set_storage_shape(src_tens)
if ps.scale_tensor is not None:
rescale_for_faf = False
activation_ops = set((Op.Sigmoid, Op.Tanh))
if (ps.ops[-1].type in activation_ops) and (ps.npu_block_type != NpuBlockType.ElementWise):
rescale_for_faf = True
calc_scales_and_pack_biases(ps.scale_tensor, arch, ofm_depth_step, rescale_for_faf)
if ps.scale_tensor.ops[0].type == Op.DMA:
src_tens = ps.scale_tensor.get_dma_src_tensor()
src_tens.shape = ps.scale_tensor.shape
src_tens.quant_values = ps.scale_tensor.quant_values
src_tens.element_size_bytes = ps.scale_tensor.element_size_bytes
src_tens.copy_compressed_weight_info(ps.scale_tensor)