GH-98831: Support cache effects in super- and macro instructions (#99601)

This commit is contained in:
Guido van Rossum 2022-12-02 19:57:30 -08:00 committed by GitHub
parent 0547a981ae
commit acf9184e6b
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4 changed files with 474 additions and 264 deletions

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@ -14,23 +14,76 @@ import typing
import parser
DEFAULT_INPUT = "Python/bytecodes.c"
DEFAULT_OUTPUT = "Python/generated_cases.c.h"
DEFAULT_INPUT = os.path.relpath(
os.path.join(os.path.dirname(__file__), "../../Python/bytecodes.c")
)
DEFAULT_OUTPUT = os.path.relpath(
os.path.join(os.path.dirname(__file__), "../../Python/generated_cases.c.h")
)
BEGIN_MARKER = "// BEGIN BYTECODES //"
END_MARKER = "// END BYTECODES //"
RE_PREDICTED = r"(?s)(?:PREDICT\(|GO_TO_INSTRUCTION\(|DEOPT_IF\(.*?,\s*)(\w+)\);"
UNUSED = "unused"
BITS_PER_CODE_UNIT = 16
arg_parser = argparse.ArgumentParser()
arg_parser.add_argument("-i", "--input", type=str, default=DEFAULT_INPUT)
arg_parser.add_argument("-o", "--output", type=str, default=DEFAULT_OUTPUT)
arg_parser = argparse.ArgumentParser(
description="Generate the code for the interpreter switch.",
formatter_class=argparse.ArgumentDefaultsHelpFormatter,
)
arg_parser.add_argument(
"-i", "--input", type=str, help="Instruction definitions", default=DEFAULT_INPUT
)
arg_parser.add_argument(
"-o", "--output", type=str, help="Generated code", default=DEFAULT_OUTPUT
)
# This is not a data class
class Instruction(parser.InstDef):
class Formatter:
"""Wraps an output stream with the ability to indent etc."""
stream: typing.TextIO
prefix: str
def __init__(self, stream: typing.TextIO, indent: int) -> None:
self.stream = stream
self.prefix = " " * indent
def write_raw(self, s: str) -> None:
self.stream.write(s)
def emit(self, arg: str) -> None:
if arg:
self.write_raw(f"{self.prefix}{arg}\n")
else:
self.write_raw("\n")
@contextlib.contextmanager
def indent(self):
self.prefix += " "
yield
self.prefix = self.prefix[:-4]
@contextlib.contextmanager
def block(self, head: str):
if head:
self.emit(head + " {")
else:
self.emit("{")
with self.indent():
yield
self.emit("}")
@dataclasses.dataclass
class Instruction:
"""An instruction with additional data and code."""
# Parts of the underlying instruction definition
inst: parser.InstDef
kind: typing.Literal["inst", "op"]
name: str
block: parser.Block
# Computed by constructor
always_exits: bool
cache_offset: int
@ -43,65 +96,44 @@ class Instruction(parser.InstDef):
predicted: bool = False
def __init__(self, inst: parser.InstDef):
super().__init__(inst.header, inst.block)
self.context = inst.context
self.inst = inst
self.kind = inst.kind
self.name = inst.name
self.block = inst.block
self.always_exits = always_exits(self.block)
self.cache_effects = [
effect for effect in self.inputs if isinstance(effect, parser.CacheEffect)
effect for effect in inst.inputs if isinstance(effect, parser.CacheEffect)
]
self.cache_offset = sum(c.size for c in self.cache_effects)
self.input_effects = [
effect for effect in self.inputs if isinstance(effect, parser.StackEffect)
effect for effect in inst.inputs if isinstance(effect, parser.StackEffect)
]
self.output_effects = self.outputs # For consistency/completeness
self.output_effects = inst.outputs # For consistency/completeness
def write(self, f: typing.TextIO, indent: str, dedent: int = 0) -> None:
def write(self, out: Formatter) -> None:
"""Write one instruction, sans prologue and epilogue."""
if dedent < 0:
indent += " " * -dedent # DO WE NEED THIS?
# Get cache offset and maybe assert that it is correct
# Write a static assertion that a family's cache size is correct
if family := self.family:
if self.name == family.members[0]:
if cache_size := family.size:
f.write(
f"{indent} static_assert({cache_size} == "
f'{self.cache_offset}, "incorrect cache size");\n'
out.emit(
f"static_assert({cache_size} == "
f'{self.cache_offset}, "incorrect cache size");'
)
# Write cache effect variable declarations
cache_offset = 0
for ceffect in self.cache_effects:
if ceffect.name != UNUSED:
bits = ceffect.size * BITS_PER_CODE_UNIT
if bits == 64:
# NOTE: We assume that 64-bit data in the cache
# is always an object pointer.
# If this becomes false, we need a way to specify
# syntactically what type the cache data is.
f.write(
f"{indent} PyObject *{ceffect.name} = "
f"read_obj(next_instr + {cache_offset});\n"
)
else:
f.write(f"{indent} uint{bits}_t {ceffect.name} = "
f"read_u{bits}(next_instr + {cache_offset});\n")
cache_offset += ceffect.size
assert cache_offset == self.cache_offset
# Write input stack effect variable declarations and initializations
for i, seffect in enumerate(reversed(self.input_effects), 1):
if seffect.name != UNUSED:
f.write(f"{indent} PyObject *{seffect.name} = PEEK({i});\n")
out.emit(f"PyObject *{seffect.name} = PEEK({i});")
# Write output stack effect variable declarations
input_names = {seffect.name for seffect in self.input_effects}
input_names.add(UNUSED)
for seffect in self.output_effects:
if seffect.name not in input_names:
f.write(f"{indent} PyObject *{seffect.name};\n")
out.emit(f"PyObject *{seffect.name};")
self.write_body(f, indent, dedent)
self.write_body(out, 0)
# Skip the rest if the block always exits
if always_exits(self.block):
@ -110,9 +142,9 @@ class Instruction(parser.InstDef):
# Write net stack growth/shrinkage
diff = len(self.output_effects) - len(self.input_effects)
if diff > 0:
f.write(f"{indent} STACK_GROW({diff});\n")
out.emit(f"STACK_GROW({diff});")
elif diff < 0:
f.write(f"{indent} STACK_SHRINK({-diff});\n")
out.emit(f"STACK_SHRINK({-diff});")
# Write output stack effect assignments
unmoved_names = {UNUSED}
@ -121,14 +153,32 @@ class Instruction(parser.InstDef):
unmoved_names.add(ieffect.name)
for i, seffect in enumerate(reversed(self.output_effects)):
if seffect.name not in unmoved_names:
f.write(f"{indent} POKE({i+1}, {seffect.name});\n")
out.emit(f"POKE({i+1}, {seffect.name});")
# Write cache effect
if self.cache_offset:
f.write(f"{indent} next_instr += {self.cache_offset};\n")
out.emit(f"next_instr += {self.cache_offset};")
def write_body(self, f: typing.TextIO, ndent: str, dedent: int) -> None:
def write_body(self, out: Formatter, dedent: int, cache_adjust: int = 0) -> None:
"""Write the instruction body."""
# Write cache effect variable declarations and initializations
cache_offset = cache_adjust
for ceffect in self.cache_effects:
if ceffect.name != UNUSED:
bits = ceffect.size * BITS_PER_CODE_UNIT
if bits == 64:
# NOTE: We assume that 64-bit data in the cache
# is always an object pointer.
# If this becomes false, we need a way to specify
# syntactically what type the cache data is.
type = "PyObject *"
func = "read_obj"
else:
type = f"uint{bits}_t "
func = f"read_u{bits}"
out.emit(f"{type}{ceffect.name} = {func}(next_instr + {cache_offset});")
cache_offset += ceffect.size
assert cache_offset == self.cache_offset + cache_adjust
# Get lines of text with proper dedent
blocklines = self.block.to_text(dedent=dedent).splitlines(True)
@ -165,122 +215,101 @@ class Instruction(parser.InstDef):
else:
break
if ninputs:
f.write(f"{space}if ({cond}) goto pop_{ninputs}_{label};\n")
out.write_raw(f"{space}if ({cond}) goto pop_{ninputs}_{label};\n")
else:
f.write(f"{space}if ({cond}) goto {label};\n")
out.write_raw(f"{space}if ({cond}) goto {label};\n")
else:
f.write(line)
out.write_raw(line)
InstructionOrCacheEffect = Instruction | parser.CacheEffect
@dataclasses.dataclass
class SuperComponent:
class Component:
instr: Instruction
input_mapping: dict[str, parser.StackEffect]
output_mapping: dict[str, parser.StackEffect]
def write_body(self, out: Formatter, cache_adjust: int) -> None:
with out.block(""):
for var, ieffect in self.input_mapping.items():
out.emit(f"PyObject *{ieffect.name} = {var};")
for oeffect in self.output_mapping.values():
out.emit(f"PyObject *{oeffect.name};")
self.instr.write_body(out, dedent=-4, cache_adjust=cache_adjust)
for var, oeffect in self.output_mapping.items():
out.emit(f"{var} = {oeffect.name};")
class SuperInstruction(parser.Super):
# TODO: Use a common base class for {Super,Macro}Instruction
@dataclasses.dataclass
class SuperOrMacroInstruction:
"""Common fields for super- and macro instructions."""
name: str
stack: list[str]
initial_sp: int
final_sp: int
parts: list[SuperComponent]
def __init__(self, sup: parser.Super):
super().__init__(sup.kind, sup.name, sup.ops)
self.context = sup.context
def analyze(self, a: "Analyzer") -> None:
components = self.check_components(a)
self.stack, self.initial_sp = self.super_macro_analysis(a, components)
sp = self.initial_sp
self.parts = []
for instr in components:
input_mapping = {}
for ieffect in reversed(instr.input_effects):
sp -= 1
if ieffect.name != UNUSED:
input_mapping[self.stack[sp]] = ieffect
output_mapping = {}
for oeffect in instr.output_effects:
if oeffect.name != UNUSED:
output_mapping[self.stack[sp]] = oeffect
sp += 1
self.parts.append(SuperComponent(instr, input_mapping, output_mapping))
self.final_sp = sp
@dataclasses.dataclass
class SuperInstruction(SuperOrMacroInstruction):
"""A super-instruction."""
def check_components(self, a: "Analyzer") -> list[Instruction]:
components: list[Instruction] = []
if not self.ops:
a.error(f"{self.kind.capitalize()}-instruction has no operands", self)
for name in self.ops:
if name not in a.instrs:
a.error(f"Unknown instruction {name!r}", self)
else:
instr = a.instrs[name]
if self.kind == "super" and instr.kind != "inst":
a.error(f"Super-instruction operand {instr.name} must be inst, not op", instr)
components.append(instr)
return components
super: parser.Super
parts: list[Component]
def super_macro_analysis(
self, a: "Analyzer", components: list[Instruction]
) -> tuple[list[str], int]:
"""Analyze a super-instruction or macro.
Print an error if there's a cache effect (which we don't support yet).
@dataclasses.dataclass
class MacroInstruction(SuperOrMacroInstruction):
"""A macro instruction."""
Return the list of variable names and the initial stack pointer.
"""
lowest = current = highest = 0
for instr in components:
if instr.cache_effects:
a.error(
f"Super-instruction {self.name!r} has cache effects in {instr.name!r}",
instr,
)
current -= len(instr.input_effects)
lowest = min(lowest, current)
current += len(instr.output_effects)
highest = max(highest, current)
# At this point, 'current' is the net stack effect,
# and 'lowest' and 'highest' are the extremes.
# Note that 'lowest' may be negative.
stack = [f"_tmp_{i+1}" for i in range(highest - lowest)]
return stack, -lowest
macro: parser.Macro
parts: list[Component | parser.CacheEffect]
class Analyzer:
"""Parse input, analyze it, and write to output."""
filename: str
output_filename: str
src: str
errors: int = 0
def __init__(self, filename: str, output_filename: str):
"""Read the input file."""
self.filename = filename
self.output_filename = output_filename
with open(filename) as f:
self.src = f.read()
def error(self, msg: str, node: parser.Node) -> None:
lineno = 0
if context := node.context:
# Use line number of first non-comment in the node
for token in context.owner.tokens[context.begin : context.end]:
for token in context.owner.tokens[context.begin : context.end]:
lineno = token.line
if token.kind != "COMMENT":
break
print(f"{self.filename}:{lineno}: {msg}", file=sys.stderr)
self.errors += 1
def __init__(self, filename: str):
"""Read the input file."""
self.filename = filename
with open(filename) as f:
self.src = f.read()
instrs: dict[str, Instruction] # Includes ops
supers: dict[str, parser.Super] # Includes macros
supers: dict[str, parser.Super]
super_instrs: dict[str, SuperInstruction]
macros: dict[str, parser.Macro]
macro_instrs: dict[str, MacroInstruction]
families: dict[str, parser.Family]
def parse(self) -> None:
"""Parse the source text."""
"""Parse the source text.
We only want the parser to see the stuff between the
begin and end markers.
"""
psr = parser.Parser(self.src, filename=self.filename)
# Skip until begin marker
@ -291,24 +320,38 @@ class Analyzer:
raise psr.make_syntax_error(
f"Couldn't find {BEGIN_MARKER!r} in {psr.filename}"
)
start = psr.getpos()
# Parse until end marker
# Find end marker, then delete everything after it
while tkn := psr.next(raw=True):
if tkn.text == END_MARKER:
break
del psr.tokens[psr.getpos() - 1 :]
# Parse from start
psr.setpos(start)
self.instrs = {}
self.supers = {}
self.macros = {}
self.families = {}
while (tkn := psr.peek(raw=True)) and tkn.text != END_MARKER:
if inst := psr.inst_def():
self.instrs[inst.name] = instr = Instruction(inst)
elif super := psr.super_def():
self.supers[super.name] = super
elif family := psr.family_def():
self.families[family.name] = family
else:
raise psr.make_syntax_error(f"Unexpected token")
while thing := psr.definition():
match thing:
case parser.InstDef(name=name):
self.instrs[name] = Instruction(thing)
case parser.Super(name):
self.supers[name] = thing
case parser.Macro(name):
self.macros[name] = thing
case parser.Family(name):
self.families[name] = thing
case _:
typing.assert_never(thing)
if not psr.eof():
raise psr.make_syntax_error("Extra stuff at the end")
print(
f"Read {len(self.instrs)} instructions, "
f"{len(self.supers)} supers/macros, "
f"Read {len(self.instrs)} instructions/ops, "
f"{len(self.supers)} supers, {len(self.macros)} macros, "
f"and {len(self.families)} families from {self.filename}",
file=sys.stderr,
)
@ -321,7 +364,7 @@ class Analyzer:
self.find_predictions()
self.map_families()
self.check_families()
self.analyze_supers()
self.analyze_supers_and_macros()
def find_predictions(self) -> None:
"""Find the instructions that need PREDICTED() labels."""
@ -332,7 +375,7 @@ class Analyzer:
else:
self.error(
f"Unknown instruction {target!r} predicted in {instr.name!r}",
instr, # TODO: Use better location
instr.inst, # TODO: Use better location
)
def map_families(self) -> None:
@ -360,7 +403,9 @@ class Analyzer:
members = [member for member in family.members if member in self.instrs]
if members != family.members:
unknown = set(family.members) - set(members)
self.error(f"Family {family.name!r} has unknown members: {unknown}", family)
self.error(
f"Family {family.name!r} has unknown members: {unknown}", family
)
if len(members) < 2:
continue
head = self.instrs[members[0]]
@ -381,105 +426,211 @@ class Analyzer:
family,
)
def analyze_supers(self) -> None:
"""Analyze each super instruction."""
def analyze_supers_and_macros(self) -> None:
"""Analyze each super- and macro instruction."""
self.super_instrs = {}
for name, sup in self.supers.items():
dup = SuperInstruction(sup)
dup.analyze(self)
self.super_instrs[name] = dup
self.macro_instrs = {}
for name, super in self.supers.items():
self.super_instrs[name] = self.analyze_super(super)
for name, macro in self.macros.items():
self.macro_instrs[name] = self.analyze_macro(macro)
def write_instructions(self, filename: str) -> None:
def analyze_super(self, super: parser.Super) -> SuperInstruction:
components = self.check_super_components(super)
stack, initial_sp = self.stack_analysis(components)
sp = initial_sp
parts: list[Component] = []
for component in components:
match component:
case parser.CacheEffect() as ceffect:
parts.append(ceffect)
case Instruction() as instr:
input_mapping = {}
for ieffect in reversed(instr.input_effects):
sp -= 1
if ieffect.name != UNUSED:
input_mapping[stack[sp]] = ieffect
output_mapping = {}
for oeffect in instr.output_effects:
if oeffect.name != UNUSED:
output_mapping[stack[sp]] = oeffect
sp += 1
parts.append(Component(instr, input_mapping, output_mapping))
case _:
typing.assert_never(component)
final_sp = sp
return SuperInstruction(super.name, stack, initial_sp, final_sp, super, parts)
def analyze_macro(self, macro: parser.Macro) -> MacroInstruction:
components = self.check_macro_components(macro)
stack, initial_sp = self.stack_analysis(components)
sp = initial_sp
parts: list[Component | parser.CacheEffect] = []
for component in components:
match component:
case parser.CacheEffect() as ceffect:
parts.append(ceffect)
case Instruction() as instr:
input_mapping = {}
for ieffect in reversed(instr.input_effects):
sp -= 1
if ieffect.name != UNUSED:
input_mapping[stack[sp]] = ieffect
output_mapping = {}
for oeffect in instr.output_effects:
if oeffect.name != UNUSED:
output_mapping[stack[sp]] = oeffect
sp += 1
parts.append(Component(instr, input_mapping, output_mapping))
case _:
typing.assert_never(component)
final_sp = sp
return MacroInstruction(macro.name, stack, initial_sp, final_sp, macro, parts)
def check_super_components(self, super: parser.Super) -> list[Instruction]:
components: list[Instruction] = []
for op in super.ops:
if op.name not in self.instrs:
self.error(f"Unknown instruction {op.name!r}", super)
else:
components.append(self.instrs[op.name])
return components
def check_macro_components(
self, macro: parser.Macro
) -> list[InstructionOrCacheEffect]:
components: list[InstructionOrCacheEffect] = []
for uop in macro.uops:
match uop:
case parser.OpName(name):
if name not in self.instrs:
self.error(f"Unknown instruction {name!r}", macro)
components.append(self.instrs[name])
case parser.CacheEffect():
components.append(uop)
case _:
typing.assert_never(uop)
return components
def stack_analysis(
self, components: typing.Iterable[InstructionOrCacheEffect]
) -> tuple[list[str], int]:
"""Analyze a super-instruction or macro.
Print an error if there's a cache effect (which we don't support yet).
Return the list of variable names and the initial stack pointer.
"""
lowest = current = highest = 0
for thing in components:
match thing:
case Instruction() as instr:
current -= len(instr.input_effects)
lowest = min(lowest, current)
current += len(instr.output_effects)
highest = max(highest, current)
case parser.CacheEffect():
pass
case _:
typing.assert_never(thing)
# At this point, 'current' is the net stack effect,
# and 'lowest' and 'highest' are the extremes.
# Note that 'lowest' may be negative.
stack = [f"_tmp_{i+1}" for i in range(highest - lowest)]
return stack, -lowest
def write_instructions(self) -> None:
"""Write instructions to output file."""
indent = " " * 8
with open(filename, "w") as f:
with open(self.output_filename, "w") as f:
# Write provenance header
f.write(f"// This file is generated by {os.path.relpath(__file__)}\n")
f.write(f"// from {os.path.relpath(self.filename)}\n")
f.write(f"// Do not edit!\n")
# Write regular instructions
# Create formatter; the rest of the code uses this.
self.out = Formatter(f, 8)
# Write and count regular instructions
n_instrs = 0
for name, instr in self.instrs.items():
if instr.kind != "inst":
continue # ops are not real instructions
n_instrs += 1
f.write(f"\n{indent}TARGET({name}) {{\n")
if instr.predicted:
f.write(f"{indent} PREDICTED({name});\n")
instr.write(f, indent)
if not always_exits(instr.block):
f.write(f"{indent} DISPATCH();\n")
f.write(f"{indent}}}\n")
self.out.emit("")
with self.out.block(f"TARGET({name})"):
if instr.predicted:
self.out.emit(f"PREDICTED({name});")
instr.write(self.out)
if not always_exits(instr.block):
self.out.emit(f"DISPATCH();")
# Write super-instructions and macros
# Write and count super-instructions
n_supers = 0
n_macros = 0
for sup in self.super_instrs.values():
if sup.kind == "super":
n_supers += 1
elif sup.kind == "macro":
n_macros += 1
self.write_super_macro(f, sup, indent)
n_supers += 1
self.write_super(sup)
print(
f"Wrote {n_instrs} instructions, {n_supers} supers, "
f"and {n_macros} macros to {filename}",
file=sys.stderr,
)
# Write and count macro instructions
n_macros = 0
for macro in self.macro_instrs.values():
n_macros += 1
self.write_macro(macro)
def write_super_macro(
self, f: typing.TextIO, sup: SuperInstruction, indent: str = ""
) -> None:
print(
f"Wrote {n_instrs} instructions, {n_supers} supers, "
f"and {n_macros} macros to {self.output_filename}",
file=sys.stderr,
)
# TODO: Make write() and block() methods of some Formatter class
def write(arg: str) -> None:
if arg:
f.write(f"{indent}{arg}\n")
else:
f.write("\n")
def write_super(self, sup: SuperInstruction) -> None:
"""Write code for a super-instruction."""
with self.wrap_super_or_macro(sup):
first = True
for comp in sup.parts:
if not first:
self.out.emit("NEXTOPARG();")
self.out.emit("next_instr++;")
first = False
comp.write_body(self.out, 0)
if comp.instr.cache_offset:
self.out.emit(f"next_instr += {comp.instr.cache_offset};")
@contextlib.contextmanager
def block(head: str):
if head:
write(head + " {")
else:
write("{")
nonlocal indent
indent += " "
yield
indent = indent[:-4]
write("}")
def write_macro(self, mac: MacroInstruction) -> None:
"""Write code for a macro instruction."""
with self.wrap_super_or_macro(mac):
cache_adjust = 0
for part in mac.parts:
match part:
case parser.CacheEffect(size=size):
cache_adjust += size
case Component() as comp:
comp.write_body(self.out, cache_adjust)
cache_adjust += comp.instr.cache_offset
write("")
with block(f"TARGET({sup.name})"):
for i, var in enumerate(sup.stack):
if i < sup.initial_sp:
write(f"PyObject *{var} = PEEK({sup.initial_sp - i});")
if cache_adjust:
self.out.emit(f"next_instr += {cache_adjust};")
@contextlib.contextmanager
def wrap_super_or_macro(self, up: SuperOrMacroInstruction):
"""Shared boilerplate for super- and macro instructions."""
self.out.emit("")
with self.out.block(f"TARGET({up.name})"):
for i, var in enumerate(up.stack):
if i < up.initial_sp:
self.out.emit(f"PyObject *{var} = PEEK({up.initial_sp - i});")
else:
write(f"PyObject *{var};")
self.out.emit(f"PyObject *{var};")
for i, comp in enumerate(sup.parts):
if i > 0 and sup.kind == "super":
write("NEXTOPARG();")
write("next_instr++;")
yield
with block(""):
for var, ieffect in comp.input_mapping.items():
write(f"PyObject *{ieffect.name} = {var};")
for oeffect in comp.output_mapping.values():
write(f"PyObject *{oeffect.name};")
comp.instr.write_body(f, indent, dedent=-4)
for var, oeffect in comp.output_mapping.items():
write(f"{var} = {oeffect.name};")
if up.final_sp > up.initial_sp:
self.out.emit(f"STACK_GROW({up.final_sp - up.initial_sp});")
elif up.final_sp < up.initial_sp:
self.out.emit(f"STACK_SHRINK({up.initial_sp - up.final_sp});")
for i, var in enumerate(reversed(up.stack[: up.final_sp]), 1):
self.out.emit(f"POKE({i}, {var});")
if sup.final_sp > sup.initial_sp:
write(f"STACK_GROW({sup.final_sp - sup.initial_sp});")
elif sup.final_sp < sup.initial_sp:
write(f"STACK_SHRINK({sup.initial_sp - sup.final_sp});")
for i, var in enumerate(reversed(sup.stack[:sup.final_sp]), 1):
write(f"POKE({i}, {var});")
write("DISPATCH();")
self.out.emit(f"DISPATCH();")
def always_exits(block: parser.Block) -> bool:
@ -506,13 +657,12 @@ def always_exits(block: parser.Block) -> bool:
def main():
"""Parse command line, parse input, analyze, write output."""
args = arg_parser.parse_args() # Prints message and sys.exit(2) on error
a = Analyzer(args.input) # Raises OSError if file not found
a = Analyzer(args.input, args.output) # Raises OSError if input unreadable
a.parse() # Raises SyntaxError on failure
a.analyze() # Prints messages and raises SystemExit on failure
a.analyze() # Prints messages and sets a.errors on failure
if a.errors:
sys.exit(f"Found {a.errors} errors")
a.write_instructions(args.output) # Raises OSError if file can't be written
a.write_instructions() # Raises OSError if output can't be written
if __name__ == "__main__":