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#!/usr/bin/env python3
"""
strip_asm.py - Cleanup ASM output for the specified file
"""
import os
import re
import sys
from argparse import ArgumentParser
def find_used_labels(asm):
found = set()
label_re = re.compile(r"\s*j[a-z]+\s+\.L([a-zA-Z0-9][a-zA-Z0-9_]*)")
for line in asm.splitlines():
m = label_re.match(line)
if m:
found.add(".L%s" % m.group(1))
return found
def normalize_labels(asm):
decls = set()
label_decl = re.compile("^[.]{0,1}L([a-zA-Z0-9][a-zA-Z0-9_]*)(?=:)")
for line in asm.splitlines():
m = label_decl.match(line)
if m:
decls.add(m.group(0))
if len(decls) == 0:
return asm
needs_dot = next(iter(decls))[0] != "."
if not needs_dot:
return asm
for ld in decls:
asm = re.sub(r"(^|\s+)" + ld + r"(?=:|\s)", "\\1." + ld, asm)
return asm
def transform_labels(asm):
asm = normalize_labels(asm)
used_decls = find_used_labels(asm)
new_asm = ""
label_decl = re.compile(r"^\.L([a-zA-Z0-9][a-zA-Z0-9_]*)(?=:)")
for line in asm.splitlines():
m = label_decl.match(line)
if not m or m.group(0) in used_decls:
new_asm += line
new_asm += "\n"
return new_asm
def is_identifier(tk):
if len(tk) == 0:
return False
first = tk[0]
if not first.isalpha() and first != "_":
return False
for i in range(1, len(tk)):
c = tk[i]
if not c.isalnum() and c != "_":
return False
return True
def process_identifiers(line):
"""
process_identifiers - process all identifiers and modify them to have
consistent names across all platforms; specifically across ELF and MachO.
For example, MachO inserts an additional understore at the beginning of
names. This function removes that.
"""
parts = re.split(r"([a-zA-Z0-9_]+)", line)
new_line = ""
for tk in parts:
if is_identifier(tk):
if tk.startswith("__Z"):
tk = tk[1:]
elif (
tk.startswith("_")
and len(tk) > 1
and tk[1].isalpha()
and tk[1] != "Z"
):
tk = tk[1:]
new_line += tk
return new_line
def process_asm(asm):
"""
Strip the ASM of unwanted directives and lines
"""
new_contents = ""
asm = transform_labels(asm)
# TODO: Add more things we want to remove
discard_regexes = [
re.compile(r"\s+\..*$"), # directive
re.compile(r"\s*#(NO_APP|APP)$"), # inline ASM
re.compile(r"\s*#.*$"), # comment line
re.compile(
r"\s*\.globa?l\s*([.a-zA-Z_][a-zA-Z0-9$_.]*)"
), # global directive
re.compile(
r"\s*\.(string|asciz|ascii|[1248]?byte|short|word|long|quad|value|zero)"
),
]
keep_regexes: list[re.Pattern] = []
fn_label_def = re.compile("^[a-zA-Z_][a-zA-Z0-9_.]*:")
for line in asm.splitlines():
# Remove Mach-O attribute
line = line.replace("@GOTPCREL", "")
add_line = True
for reg in discard_regexes:
if reg.match(line) is not None:
add_line = False
break
for reg in keep_regexes:
if reg.match(line) is not None:
add_line = True
break
if add_line:
if fn_label_def.match(line) and len(new_contents) != 0:
new_contents += "\n"
line = process_identifiers(line)
new_contents += line
new_contents += "\n"
return new_contents
def main():
parser = ArgumentParser(description="generate a stripped assembly file")
parser.add_argument(
"input",
metavar="input",
type=str,
nargs=1,
help="An input assembly file",
)
parser.add_argument(
"out", metavar="output", type=str, nargs=1, help="The output file"
)
args, unknown_args = parser.parse_known_args()
input = args.input[0]
output = args.out[0]
if not os.path.isfile(input):
print("ERROR: input file '%s' does not exist" % input)
sys.exit(1)
with open(input, "r") as f:
contents = f.read()
new_contents = process_asm(contents)
with open(output, "w") as f:
f.write(new_contents)
if __name__ == "__main__":
main()
# vim: tabstop=4 expandtab shiftwidth=4 softtabstop=4
# kate: tab-width: 4; replace-tabs on; indent-width 4; tab-indents: off;
# kate: indent-mode python; remove-trailing-spaces modified;
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