#!/usr/bin/env python
"""
strip_asm.py - Cleanup ASM output for the specified file
"""
from argparse import ArgumentParser
import sys
import os
import re
def find_used_labels(asm):
found = set()
label_re = re.compile("\s*j[a-z]+\s+\.L([a-zA-Z0-9][a-zA-Z0-9_]*)")
for l in asm.splitlines():
m = label_re.match(l)
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 l in asm.splitlines():
m = label_decl.match(l)
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("(^|\s+)" + ld + "(?=:|\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("^\.L([a-zA-Z0-9][a-zA-Z0-9_]*)(?=:)")
for l in asm.splitlines():
m = label_decl.match(l)
if not m or m.group(0) in used_decls:
new_asm += l
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(l):
"""
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_]+)', l)
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("\s+\..*$"), # directive
re.compile("\s*#(NO_APP|APP)$"), #inline ASM
re.compile("\s*#.*$"), # comment line
re.compile("\s*\.globa?l\s*([.a-zA-Z_][a-zA-Z0-9$_.]*)"), #global directive
re.compile("\s*\.(string|asciz|ascii|[1248]?byte|short|word|long|quad|value|zero)"),
]
keep_regexes = [
]
fn_label_def = re.compile("^[a-zA-Z_][a-zA-Z0-9_.]*:")
for l in asm.splitlines():
# Remove Mach-O attribute
l = l.replace('@GOTPCREL', '')
add_line = True
for reg in discard_regexes:
if reg.match(l) is not None:
add_line = False
break
for reg in keep_regexes:
if reg.match(l) is not None:
add_line = True
break
if add_line:
if fn_label_def.match(l) and len(new_contents) != 0:
new_contents += '\n'
l = process_identifiers(l)
new_contents += l
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)
contents = None
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()
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