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OSACA/osaca/semantics/kernel_dg.py
2025-03-27 23:12:25 +01:00

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#!/usr/bin/env python3
import copy
import time
from itertools import chain, groupby
from multiprocessing import Manager, Process, cpu_count
import networkx as nx
from osaca.semantics import INSTR_FLAGS, ArchSemantics, MachineModel
from osaca.parser.memory import MemoryOperand
from osaca.parser.register import RegisterOperand
from osaca.parser.immediate import ImmediateOperand
from osaca.parser.flag import FlagOperand
class KernelDG(nx.DiGraph):
# threshold for checking dependency graph sequential or in parallel
INSTRUCTION_THRESHOLD = 50
def __init__(
self,
parsed_kernel,
parser,
hw_model: MachineModel,
semantics: ArchSemantics,
timeout=10,
flag_dependencies=False,
):
self.timed_out = False
self.kernel = parsed_kernel
self.parser = parser
self.model = hw_model
self.arch_sem = semantics
self.dg = self.create_DG(self.kernel, flag_dependencies)
self.loopcarried_deps = self.check_for_loopcarried_dep(
self.kernel, timeout, flag_dependencies
)
@classmethod
def _extend_path(cls, dst_list, kernel, dg, offset):
for instr in kernel:
generator_path = nx.algorithms.simple_paths.all_simple_paths(
dg, instr.line_number, instr.line_number + offset
)
tmp_list = list(generator_path)
dst_list.extend(tmp_list)
# print('Thread [{}-{}] done'.format(kernel[0]['line_number'], kernel[-1]['line_number']))
def create_DG(self, kernel, flag_dependencies=False):
"""
Create directed graph from given kernel
:param kernel: Parsed asm kernel with assigned semantic information
:type kerne: list
:param flag_dependencies: indicating if dependencies of flags should be considered,
defaults to `False`
:type flag_dependencies: boolean, optional
:returns: :class:`~nx.DiGraph` -- directed graph object
"""
# 1. go through kernel instruction forms and add them as node attribute
# 2. find edges (to dependend further instruction)
# 3. get LT value and set as edge weight
dg = nx.DiGraph()
for i, instruction_form in enumerate(kernel):
dg.add_node(instruction_form.line_number)
dg.nodes[instruction_form.line_number]["instruction_form"] = instruction_form
# add load as separate node if existent
if (
INSTR_FLAGS.HAS_LD in instruction_form.flags
and INSTR_FLAGS.LD not in instruction_form.flags
):
# add new node
dg.add_node(instruction_form.line_number + 0.1)
dg.nodes[instruction_form.line_number + 0.1]["instruction_form"] = instruction_form
# and set LD latency as edge weight
dg.add_edge(
instruction_form.line_number + 0.1,
instruction_form.line_number,
latency=instruction_form.latency - instruction_form.latency_wo_load,
)
for dep, dep_flags in self.find_depending(
instruction_form, kernel[i + 1 :], flag_dependencies
):
# print(instruction_form.line_number,"\t",dep.line_number,"\n")
edge_weight = (
instruction_form.latency
if "mem_dep" in dep_flags or instruction_form.latency_wo_load is None
else instruction_form.latency_wo_load
)
if "storeload_dep" in dep_flags and self.model is not None:
edge_weight += self.model.get("store_to_load_forward_latency", 0)
if "p_indexed" in dep_flags and self.model is not None:
edge_weight = self.model.get("p_index_latency", 1)
dg.add_edge(
instruction_form.line_number,
dep.line_number,
latency=edge_weight,
)
dg.nodes[dep.line_number]["instruction_form"] = dep
return dg
def check_for_loopcarried_dep(self, kernel, timeout=10, flag_dependencies=False):
"""
Try to find loop-carried dependencies in given kernel.
:param kernel: Parsed asm kernel with assigned semantic information
:type kernel: list
:param timeout: Timeout in seconds for parallel execution, defaults
to `10`. Set to `0` for no timeout
:type timeout: int
:returns: `dict` -- dependency dictionary with all cyclic LCDs
"""
# increase line number for second kernel loop
offset = max(1000, max([i.line_number for i in kernel]))
tmp_kernel = [] + kernel
for orig_iform in kernel:
temp_iform = copy.copy(orig_iform)
temp_iform.line_number += offset
tmp_kernel.append(temp_iform)
# get dependency graph
dg = self.create_DG(tmp_kernel, flag_dependencies)
# build cyclic loop-carried dependencies
loopcarried_deps = []
all_paths = []
klen = len(kernel)
if klen >= self.INSTRUCTION_THRESHOLD:
# parallel execution with static scheduling
num_cores = cpu_count()
workload = int((klen - 1) / num_cores) + 1
starts = [tid * workload for tid in range(num_cores)]
ends = [min((tid + 1) * workload, klen) for tid in range(num_cores)]
instrs = [kernel[s:e] for s, e in zip(starts, ends)]
with Manager() as manager:
all_paths = manager.list()
processes = [
Process(
target=KernelDG._extend_path,
args=(all_paths, instr_section, dg, offset),
)
for instr_section in instrs
]
for p in processes:
p.start()
if timeout == -1:
# no timeout
for p in processes:
p.join()
else:
start_time = time.time()
while time.time() - start_time <= timeout:
if any(p.is_alive() for p in processes):
time.sleep(0.2)
else:
# all procs done
for p in processes:
p.join()
break
else:
self.timed_out = True
# terminate running processes
for p in processes:
if p.is_alive():
p.kill()
p.join()
all_paths = list(all_paths)
else:
# sequential execution to avoid overhead when analyzing smaller kernels
for instr in kernel:
all_paths.extend(
nx.algorithms.simple_paths.all_simple_paths(
dg, instr.line_number, instr.line_number + offset
)
)
paths_set = set()
for path in all_paths:
lat_sum = 0.0
# extend path by edge bound latencies (e.g., store-to-load latency)
lat_path = []
for s, d in nx.utils.pairwise(path):
edge_lat = dg.edges[s, d]["latency"]
# map source node back to original line numbers
if s > offset:
s -= offset
lat_path.append((s, edge_lat))
lat_sum += edge_lat
if d > offset:
d -= offset
lat_path.sort()
# Ignore duplicate paths which differ only in the root node
if tuple(lat_path) in paths_set:
continue
paths_set.add(tuple(lat_path))
loopcarried_deps.append((lat_sum, lat_path))
loopcarried_deps.sort(reverse=True)
# map lcd back to nodes
loopcarried_deps_dict = {}
for lat_sum, involved_lines in loopcarried_deps:
dict_key = "-".join([str(il[0]) for il in involved_lines])
loopcarried_deps_dict[dict_key] = {
"root": self._get_node_by_lineno(involved_lines[0][0]),
"dependencies": [
(self._get_node_by_lineno(ln), lat) for ln, lat in involved_lines
],
"latency": lat_sum,
}
return loopcarried_deps_dict
def _get_node_by_lineno(self, lineno, kernel=None, all=False):
"""Return instruction form with line number ``lineno`` from kernel"""
if kernel is None:
kernel = self.kernel
result = [instr for instr in kernel if instr.line_number == lineno]
if not all:
return result[0]
else:
return result
def get_critical_path(self):
"""Find and return critical path after the creation of a directed graph."""
max_latency_instr = max(self.kernel, key=lambda k: k.latency)
if nx.algorithms.dag.is_directed_acyclic_graph(self.dg):
longest_path = nx.algorithms.dag.dag_longest_path(self.dg, weight="latency")
# TODO verify that we can remove the next two lince due to earlier initialization
for line_number in longest_path:
self._get_node_by_lineno(int(line_number)).latency_cp = 0
# set cp latency to instruction
path_latency = 0.0
for s, d in nx.utils.pairwise(longest_path):
node = self._get_node_by_lineno(int(s))
node.latency_cp = self.dg.edges[(s, d)]["latency"]
path_latency += node.latency_cp
# add latency for last instruction
node = self._get_node_by_lineno(int(longest_path[-1]))
node.latency_cp = node.latency
if max_latency_instr.latency > path_latency:
max_latency_instr.latency_cp = float(max_latency_instr.latency)
return [max_latency_instr]
else:
return [x for x in self.kernel if x.line_number in longest_path]
else:
# split to DAG
raise NotImplementedError("Kernel is cyclic.")
def get_loopcarried_dependencies(self):
"""
Return all LCDs from kernel (after :func:`~KernelDG.check_for_loopcarried_dep` was run)
"""
if nx.algorithms.dag.is_directed_acyclic_graph(self.dg):
return self.loopcarried_deps
else:
# split to DAG
raise NotImplementedError("Kernel is cyclic.")
def find_depending(self, instruction_form, instructions, flag_dependencies=False):
"""
Find instructions in `instructions` depending on a given instruction form's results.
:param dict instruction_form: instruction form to check for dependencies
:param list instructions: instructions to check
:param flag_dependencies: indicating if dependencies of flags should be considered,
defaults to `False`
:type flag_dependencies: boolean, optional
:returns: iterator if all directly dependent instruction forms and according flags
"""
if instruction_form.semantic_operands is None:
return
for dst in chain(
instruction_form.semantic_operands["destination"],
instruction_form.semantic_operands["src_dst"],
):
# TODO instructions before must be considered as well, if they update registers
# not used by insruction_form. E.g., validation/build/A64FX/gcc/O1/gs-2d-5pt.marked.s
register_changes = self._update_reg_changes(instruction_form)
# print("FROM", instruction_form.line, register_changes)
for i, instr_form in enumerate(instructions):
self._update_reg_changes(instr_form, register_changes)
# print(" TO", instr_form.line, register_changes)
if isinstance(dst, RegisterOperand):
# read of register
if self.is_read(dst, instr_form):
if (
dst.pre_indexed
or dst.post_indexed
or (isinstance(dst.post_indexed, dict))
):
yield instr_form, ["p_indexed"]
else:
yield instr_form, []
# write to register -> abort
if self.is_written(dst, instr_form):
break
if isinstance(dst, FlagOperand) and flag_dependencies:
# read of flag
if self.is_read(dst, instr_form):
yield instr_form, []
# write to flag -> abort
if self.is_written(dst, instr_form):
break
if isinstance(dst, MemoryOperand):
# base register is altered during memory access
if dst.pre_indexed:
if self.is_written(dst.base, instr_form):
break
# if dst.memory.base:
# if self.is_read(dst.memory.base, instr_form):
# yield instr_form, []
# if dst.memory.index:
# if self.is_read(dst.memory.index, instr_form):
# yield instr_form, []
if dst.post_indexed:
# Check for read of base register until overwrite
if self.is_written(dst.base, instr_form):
break
# TODO record register changes
# (e.g., mov, leaadd, sub, inc, dec) in instructions[:i]
# and pass to is_memload and is_memstore to consider relevance.
# load from same location (presumed)
if self.is_memload(dst, instr_form, register_changes):
yield instr_form, ["storeload_dep"]
# store to same location (presumed)
if self.is_memstore(dst, instr_form, register_changes):
break
self._update_reg_changes(instr_form, register_changes, only_postindexed=True)
def _update_reg_changes(self, iform, reg_state=None, only_postindexed=False):
if self.arch_sem is None:
# This analysis requires semenatics to be available
return {}
if reg_state is None:
reg_state = {}
for reg, change in self.arch_sem.get_reg_changes(iform, only_postindexed).items():
if change is None or reg_state.get(reg, {}) is None:
reg_state[reg] = None
else:
reg_state.setdefault(reg, {"name": reg, "value": 0})
if change["name"] != reg:
# renaming occured, ovrwrite value with up-to-now change of source register
reg_state[reg]["name"] = change["name"]
src_reg_state = reg_state.get(change["name"], {"value": 0})
if src_reg_state is None:
# original register's state was changed beyond reconstruction
reg_state[reg] = None
continue
reg_state[reg]["value"] = src_reg_state["value"]
reg_state[reg]["value"] += change["value"]
return reg_state
def get_dependent_instruction_forms(self, instr_form=None, line_number=None):
"""
Returns iterator
"""
if not instr_form and not line_number:
raise ValueError("Either instruction form or line_number required.")
line_number = line_number if line_number else instr_form["line_number"]
if self.dg.has_node(line_number):
return self.dg.successors(line_number)
return iter([])
def is_read(self, register, instruction_form):
"""Check if instruction form reads from given register"""
is_read = False
if instruction_form.semantic_operands is None:
return is_read
for src in chain(
instruction_form.semantic_operands["source"],
instruction_form.semantic_operands["src_dst"],
):
if isinstance(src, RegisterOperand):
is_read = self.parser.is_reg_dependend_of(register, src) or is_read
if isinstance(src, FlagOperand):
is_read = self.parser.is_flag_dependend_of(register, src) or is_read
if isinstance(src, MemoryOperand):
if src.base is not None:
is_read = self.parser.is_reg_dependend_of(register, src.base) or is_read
if src.index is not None and isinstance(src.index, RegisterOperand):
is_read = self.parser.is_reg_dependend_of(register, src.index) or is_read
# Check also if read in destination memory address
for dst in chain(
instruction_form.semantic_operands["destination"],
instruction_form.semantic_operands["src_dst"],
):
if isinstance(dst, MemoryOperand):
if dst.base is not None:
is_read = self.parser.is_reg_dependend_of(register, dst.base) or is_read
if dst.index is not None:
is_read = self.parser.is_reg_dependend_of(register, dst.index) or is_read
return is_read
def is_memload(self, mem, instruction_form, register_changes={}):
"""Check if instruction form loads from given location, assuming register_changes"""
if instruction_form.semantic_operands is None:
return False
for src in chain(
instruction_form.semantic_operands["source"],
instruction_form.semantic_operands["src_dst"],
):
# Here we check for mem dependecies only
if not isinstance(src, MemoryOperand):
continue
# src = src.memory
# determine absolute address change
addr_change = 0
if isinstance(src.offset, ImmediateOperand) and src.offset.value is not None:
addr_change += src.offset.value
if isinstance(mem.offset, ImmediateOperand) and mem.offset.value is not None:
addr_change -= mem.offset.value
if mem.base and src.base:
base_change = register_changes.get(
(src.base.prefix if src.base.prefix is not None else "") + src.base.name,
{
"name": (src.base.prefix if src.base.prefix is not None else "")
+ src.base.name,
"value": 0,
},
)
if base_change is None:
# Unknown change occurred
continue
if (
mem.base.prefix
if mem.base.prefix is not None
else "" + mem.base.name != base_change["name"]
):
# base registers do not match
continue
addr_change += base_change["value"]
elif mem.base or src.base:
# base registers do not match
continue
if mem.index and src.index:
index_change = register_changes.get(
(src.index.prefix if src.index.prefix is not None else "") + src.index.name,
{
"name": (src.index.prefix if src.index.prefix is not None else "")
+ src.index.name,
"value": 0,
},
)
if index_change is None:
# Unknown change occurred
continue
if mem.scale != src.scale:
# scale factors do not match
continue
if (
mem.index.prefix
if mem.index.prefix is not None
else "" + mem.index.name != index_change["name"]
):
# index registers do not match
continue
addr_change += index_change["value"] * src.scale
elif mem.index or src.index:
# index registers do not match
continue
# if instruction_form.line_number == 3:
if addr_change == 0:
return True
return False
def is_written(self, register, instruction_form):
"""Check if instruction form writes in given register"""
is_written = False
if instruction_form.semantic_operands is None:
return is_written
for dst in chain(
instruction_form.semantic_operands["destination"],
instruction_form.semantic_operands["src_dst"],
):
if isinstance(dst, RegisterOperand):
is_written = self.parser.is_reg_dependend_of(register, dst) or is_written
if isinstance(dst, FlagOperand):
is_written = self.parser.is_flag_dependend_of(register, dst) or is_written
if isinstance(dst, MemoryOperand):
if dst.pre_indexed or dst.post_indexed:
is_written = self.parser.is_reg_dependend_of(register, dst.base) or is_written
# Check also for possible pre- or post-indexing in memory addresses
for src in chain(
instruction_form.semantic_operands["source"],
instruction_form.semantic_operands["src_dst"],
):
if isinstance(src, MemoryOperand):
if src.pre_indexed or src.post_indexed:
is_written = self.parser.is_reg_dependend_of(register, src.base) or is_written
return is_written
def is_memstore(self, mem, instruction_form, register_changes={}):
"""Check if instruction form stores to given location, assuming unchanged registers"""
is_store = False
if instruction_form.semantic_operands is None:
return is_store
for dst in chain(
instruction_form.semantic_operands["destination"],
instruction_form.semantic_operands["src_dst"],
):
if isinstance(dst, MemoryOperand):
is_store = mem == dst or is_store
return is_store
def export_graph(self, filepath=None):
"""
Export graph with highlighted CP and LCDs as DOT file. Writes it to 'osaca_dg.dot'
if no other path is given.
:param filepath: path to write DOT file, defaults to None.
:type filepath: str, optional
"""
graph = copy.deepcopy(self.dg)
cp = self.get_critical_path()
cp_line_numbers = [x.line_number for x in cp]
lcd = self.get_loopcarried_dependencies()
lcd_line_numbers = {}
for dep in lcd:
lcd_line_numbers[dep] = [x.line_number for x, lat in lcd[dep]["dependencies"]]
# create LCD edges
for dep in lcd_line_numbers:
min_line_number = min(lcd_line_numbers[dep])
max_line_number = max(lcd_line_numbers[dep])
graph.add_edge(min_line_number, max_line_number, dir="back")
graph.edges[min_line_number, max_line_number]["latency"] = [
lat for x, lat in lcd[dep]["dependencies"] if x.line_number == max_line_number
]
# add label to edges
for e in graph.edges:
graph.edges[e]["label"] = graph.edges[e]["latency"]
# add CP values to graph
for n in cp:
graph.nodes[n.line_number]["instruction_form"].latency_cp = n.latency_cp
# Make the critical path bold.
for n in graph.nodes:
if n in cp_line_numbers:
# graph.nodes[n]['color'] = 1
graph.nodes[n]["style"] = "bold"
graph.nodes[n]["penwidth"] = 4
# Make critical path edges bold.
for e in graph.edges:
if (
graph.nodes[e[0]]["instruction_form"].line_number in cp_line_numbers
and graph.nodes[e[1]]["instruction_form"].line_number in cp_line_numbers
and e[0] < e[1]
):
bold_edge = True
for i in range(e[0] + 1, e[1]):
if i in cp_line_numbers:
bold_edge = False
if bold_edge:
graph.edges[e]["style"] = "bold"
graph.edges[e]["penwidth"] = 3
# Color the cycles created by loop-carried dependencies, longest first, never recoloring
# any node or edge, so that the longest LCD and most long chains that are involved in the
# loop are legible.
lcd_by_latencies = sorted(
(
(latency, list(deps))
for latency, deps in groupby(lcd, lambda dep: lcd[dep]["latency"])
),
reverse=True
)
node_colors = {}
edge_colors = {}
colors_used = 0
for i, (latency, deps) in enumerate(lcd_by_latencies):
color = None
for dep in deps:
path = lcd_line_numbers[dep]
for n in path:
if n not in node_colors:
if not color:
color = colors_used + 1
colors_used += 1
node_colors[n] = color
for u, v in zip(path, path[1:] + [path[0]]):
if (u, v) not in edge_colors:
# Dont introduce a color just for an edge.
if not color:
color = colors_used
edge_colors[u, v] = color
max_color = min(11, colors_used)
colorscheme = f"spectral{max(3, max_color)}"
graph.graph["node"] = {"colorscheme" : colorscheme}
graph.graph["edge"] = {"colorscheme" : colorscheme}
for n, color in node_colors.items():
if "style" not in graph.nodes[n]:
graph.nodes[n]["style"] = "filled"
else:
graph.nodes[n]["style"] += ",filled"
graph.nodes[n]["fillcolor"] = color
if (
(max_color >= 4 and color in (1, max_color)) or
(max_color >= 10 and color in (1, 2, max_color - 1 , max_color))
):
graph.nodes[n]["fontcolor"] = "white"
for (u, v), color in edge_colors.items():
# The backward edge of the cycle is represented as the corresponding forward
# edge with the attribute dir=back.
edge = graph.edges[u, v] if (u, v) in graph.edges else graph.edges[v, u]
edge["color"] = color
# rename node from [idx] to [idx mnemonic] and add shape
mapping = {}
for n in graph.nodes:
if int(n) != n:
mapping[n] = "{}: LOAD".format(int(n))
graph.nodes[n]["fontname"] = "italic"
graph.nodes[n]["fontsize"] = 11.0
else:
node = graph.nodes[n]["instruction_form"]
if node.mnemonic is not None:
mapping[n] = "{}: {}".format(n, node.mnemonic)
else:
label = "label" if node.label is not None else None
label = "directive" if node.directive is not None else label
label = "comment" if node.comment is not None and label is None else label
mapping[n] = "{}: {}".format(n, label)
graph.nodes[n]["fontname"] = "italic"
graph.nodes[n]["fontsize"] = 11.0
graph.nodes[n]["shape"] = "rectangle"
nx.relabel.relabel_nodes(graph, mapping, copy=False)
if filepath:
nx.drawing.nx_agraph.write_dot(graph, filepath)
else:
nx.drawing.nx_agraph.write_dot(graph, "osaca_dg.dot")