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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:
# Build a live range graph for tensors in one or more subgraphs. Used for tensor allocation as well as in the scheduler.
# Can work with either a pass packed subgraph or a scheduled subgraph.
from .tensor import Tensor, MemArea
from .nn_graph import TensorPurpose, PassPlacement
from .high_level_command_stream_generator import calc_allowed_ofm_ifm_overlap_for_cascaded_pass
class LiveRange:
def __init__(self, tens):
self.tensors = [] # Tensors that are assigned to the same LiveRange will be allocated to the same address
self.start_time = 99999999999
self.end_time = -1
self.size = 0
self.name = ""
if tens:
self.add_tensor(tens)
def __str__(self):
return "<live_range.LiveRange: '%s' start_time=%s, end_time=%s>" % (self.name, self.start_time, self.end_time)
__repr__ = __str__
def add_tensor(self, tens):
if self.size == 0:
self.size = tens.storage_size()
self.name = tens.name # LiveRange will be named after the first tensor added
else:
assert (
self.size >= tens.storage_size()
), "Tensors assigned to the same LiveRange need to fit the size of the LiveRange."
self.tensors.append(tens)
def mark_usage(self, op_time):
if op_time == -1:
return
op_time_start = op_time
op_time_end = op_time + 1
self.start_time = min(self.start_time, op_time_start)
self.end_time = max(self.end_time, op_time_end)
def overlaps_ranges(self, other):
return max(self.start_time, other.start_time) < min(self.end_time, other.end_time)
def overlaps_address(self, other):
# Returns the first pair of tensors in this LiveRange and 'other' which have
# overlapping addresses
for tens in self.tensors:
for other_tens in other.tensors:
if max(tens.address, other_tens.address) < min(
tens.address + self.size, other_tens.address + other.size
):
return True, tens, other_tens
return False, None, None
def __lt__(self, other):
if self.start_time != other.start_time:
return self.start_time < other.start_time
if self.end_time != other.end_time:
return self.end_time < other.end_time
if self.size != other.size:
return self.size < other.size
return self.name < other.name
def set_address(self, address):
# Set address of all unaddressed tensors in LiveRange
for tens in self.tensors:
if tens.address == 0:
tens.address = address
# Also need to set the address to the tensor's cpu/npu clones
if tens.cpu_tensor != None:
tens.cpu_tensor.address = address
if tens.npu_tensor != None:
tens.npu_tensor.address = address
def get_alignment(self):
# Get max alignment of LiveRange's tensors
if self.tensors:
alignment = 0
for tens in self.tensors:
alignment = max(alignment, tens.alignment)
return alignment
return Tensor.AllocationQuantum
def merge_memory_op_ranges(sg, lr_graph, tensor_should_be_ignored, target_mem_area):
for ps in sg.passes:
if ps.placement == PassPlacement.MemoryOnly:
# For memory only passes, e.g. Reshape. Add input and output tensor to the same LiveRange
input_tensor = ps.inputs[0]
output_tensor = ps.outputs[0]
# If the input or output tensor is tied to a Cpu tensor, i.e. a subgraph input
# or output, fuse the live-range with the Cpu tensors' live-range instead.
input_tensor = input_tensor.cpu_tensor if input_tensor.cpu_tensor != None else input_tensor
output_tensor = output_tensor.cpu_tensor if output_tensor.cpu_tensor != None else output_tensor
if not tensor_should_be_ignored(input_tensor, target_mem_area) and not tensor_should_be_ignored(
output_tensor, target_mem_area
):
lr_graph.fuse_ranges(input_tensor, output_tensor)
class LiveRangeGraph:
def __init__(self):
self.ranges = {} # tens -> range
self.allowed_overlaps = {} # (tens,tens) -> overlap_int
self.ignore_tensors = set()
self.processed_subgraphs = set()
self.current_time = 0
def get_or_create_range(self, tens):
for rng in self.ranges.values():
# Return the live range of the tensor (or it's cpu/npu clone)
if any(tensor in rng.tensors for tensor in [tens, tens.npu_tensor, tens.cpu_tensor]):
return rng
# No live range found for the tensor, create a new one
rng = LiveRange(tens)
self.ranges[tens] = rng
return rng
def fuse_ranges(self, in_tens, out_tens):
live_range = self.get_or_create_range(in_tens)
assert out_tens not in self.ranges, out_tens
live_range.add_tensor(out_tens)
self.ranges[out_tens] = live_range
return live_range
def extract_live_ranges_from_passes(
sg,
target_mem_area,
mark_output_tensors_overlapping_with_input_tensors=False,
ignore_subgraph_input_output_tensors=False,
):
lr_graph = LiveRangeGraph()
if ignore_subgraph_input_output_tensors:
lr_graph.ignore_tensors.update(sg.input_tensors)
lr_graph.ignore_tensors.update(sg.output_tensors)
def tensor_should_be_ignored(tens, target_mem_area):
if tens.mem_area != target_mem_area:
return True
if tens in lr_graph.ignore_tensors:
return True
if tens.name.endswith("reshape_shape_npu"):
# Reshape tensor, no need to allocate
lr_graph.ignore_tensors.add(tens)
return True
return False
# Merge only memory operations in the NPU subgraphs
if sg.placement == PassPlacement.Npu:
merge_memory_op_ranges(sg, lr_graph, tensor_should_be_ignored, target_mem_area)
for idx, ps in enumerate(sg.passes):
ps.time = 2 * idx
time_for_pass = ps.time
for tens in ps.inputs:
if tensor_should_be_ignored(tens, target_mem_area):
continue
rng = lr_graph.get_or_create_range(tens)
rng.mark_usage(time_for_pass)
for tens in ps.intermediates:
if tensor_should_be_ignored(tens, target_mem_area):
continue
rng = lr_graph.get_or_create_range(tens)
rng.mark_usage(time_for_pass)
for tens in ps.outputs:
if tensor_should_be_ignored(tens, target_mem_area):
continue
rng = lr_graph.get_or_create_range(tens)
output_time = time_for_pass
if not mark_output_tensors_overlapping_with_input_tensors and ps.is_element_wise:
output_time += 1
rng.mark_usage(output_time)
end_time = len(sg.passes) * 2
for tens in sg.output_tensors:
if tensor_should_be_ignored(tens, target_mem_area):
continue
rng = lr_graph.get_or_create_range(tens)
rng.mark_usage(end_time)
return lr_graph
def extract_live_ranges_from_cascaded_passes(
sg,
target_mem_area,
mark_output_tensors_overlapping_with_input_tensors=False,
use_ifm_ofm_overlap=True,
ignore_subgraph_input_output_tensors=False,
lr_graph=None,
):
if lr_graph == None:
lr_graph = LiveRangeGraph()
if sg in lr_graph.processed_subgraphs:
# if subgraph has been processed already, return the lr_graph as is
return lr_graph
if ignore_subgraph_input_output_tensors:
lr_graph.ignore_tensors.update(sg.input_tensors)
lr_graph.ignore_tensors.update(sg.output_tensors)
def tensor_should_be_ignored(tens, target_mem_area):
if tens.mem_area != target_mem_area:
return True
if tens in lr_graph.ignore_tensors:
return True
if tens.name.endswith("reshape_shape_npu"):
# Reshape tensor, no need to allocate
lr_graph.ignore_tensors.add(tens)
return True
return False
# Merge only memory operations in the NPU subgraphs
if sg.placement == PassPlacement.Npu:
merge_memory_op_ranges(sg, lr_graph, tensor_should_be_ignored, target_mem_area)
for cps in sg.cascaded_passes:
cps.time = lr_graph.current_time
time_for_pass = cps.time
is_element_wise = cps.is_element_wise
for tens in cps.inputs:
if tensor_should_be_ignored(tens, target_mem_area):
continue
rng = lr_graph.get_or_create_range(tens)
rng.mark_usage(time_for_pass)
cps_primary_op = cps.passes[0].primary_op
if cps_primary_op and cps_primary_op.type == "NpuOp" and target_mem_area in set((MemArea.Sram, MemArea.Dram)):
# If the primary-op is an NpuOp that means this is where an Npu subgraph
# is called. Go into said subgraph and extract live ranges before continuing.
npu_sg = cps_primary_op.attrs["subgraph"]
lr_graph = extract_live_ranges_from_cascaded_passes(
npu_sg,
target_mem_area,
mark_output_tensors_overlapping_with_input_tensors,
use_ifm_ofm_overlap,
False,
lr_graph,
)
# Set the new time after handling the Npu subgraph
time_for_pass = lr_graph.current_time
cps.time = time_for_pass
for tens in cps.intermediates:
if tensor_should_be_ignored(tens, target_mem_area):
continue
rng = lr_graph.get_or_create_range(tens)
rng.mark_usage(time_for_pass)
for tens in cps.outputs:
if tensor_should_be_ignored(tens, target_mem_area):
continue
rng = lr_graph.get_or_create_range(tens)
output_time = time_for_pass
if not mark_output_tensors_overlapping_with_input_tensors and is_element_wise:
output_time += 1
rng.mark_usage(output_time)
if use_ifm_ofm_overlap:
# fill allowed overlap for ifm and ofm tensor
ifm_tensor = cps.passes[0].ifm_tensor
ofm_tensor = cps.passes[-1].ofm_tensor
if (
ifm_tensor is not None
and ofm_tensor is not None
and not tensor_should_be_ignored(ifm_tensor, target_mem_area)
and not tensor_should_be_ignored(ofm_tensor, target_mem_area)
):
lr_graph.allowed_overlaps[(ifm_tensor, ofm_tensor)] = calc_allowed_ofm_ifm_overlap_for_cascaded_pass(
cps
)
lr_graph.current_time += 2
end_time = 0
for rng in lr_graph.ranges.values():
# Find the maximum end time of all live-ranges in the graph
end_time = max(end_time, rng.end_time)
for tens in sg.output_tensors:
if tensor_should_be_ignored(tens, target_mem_area):
continue
rng = lr_graph.get_or_create_range(tens)
rng.mark_usage(end_time)
# Add subgraph to set of processed subgraphs
lr_graph.processed_subgraphs.add(sg)
return lr_graph