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#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
# Copyright (C) 2018-2024 Free Software Foundation, Inc.
# Contributed by Bernhard Reutner-Fischer <aldot@gcc.gnu.org>
# Inspired by bloat-o-meter from busybox.
# This software may be used and distributed according to the terms and
# conditions of the GNU General Public License as published by the Free
# Software Foundation.
# For a set of object-files, determine symbols that are
# - public but should be static
# Examples:
# unused_functions.py ./gcc/fortran
# unused_functions.py gcc/c gcc/c-family/ gcc/*-c.o | grep -v "'gt_"
# unused_functions.py gcc/cp gcc/c-family/ gcc/*-c.o | grep -v "'gt_"
import sys, os
from tempfile import mkdtemp
from subprocess import Popen, PIPE
def usage():
sys.stderr.write("usage: %s [-v] [dirs | files] [-- <readelf options>]\n"
% sys.argv[0])
sys.stderr.write("\t-v\tVerbose output\n");
sys.exit(1)
(odir, sym_args, tmpd, verbose) = (set(), "", None, False)
for i in range(1, len(sys.argv)):
f = sys.argv[i]
if f == '--': # sym_args
sym_args = ' '.join(sys.argv[i + 1:])
break
if f == '-v':
verbose = True
continue
if not os.path.exists(f):
sys.stderr.write("Error: No such file or directory '%s'\n" % f)
usage()
else:
if f.endswith('.a') and tmpd is None:
tmpd = mkdtemp(prefix='unused_fun')
odir.add(f)
def dbg(args):
if not verbose: return
print(args)
def get_symbols(file):
syms = {}
rargs = "readelf -W -s %s %s" % (sym_args, file)
p0 = Popen((a for a in rargs.split(' ') if a.strip() != ''), stdout=PIPE)
p1 = Popen(["c++filt"], stdin=p0.stdout, stdout=PIPE,
universal_newlines=True)
lines = p1.communicate()[0]
for l in lines.split('\n'):
l = l.strip()
if not len(l) or not l[0].isdigit(): continue
larr = l.split()
if len(larr) != 8: continue
num, value, size, typ, bind, vis, ndx, name = larr
if typ == 'SECTION' or typ == 'FILE': continue
# I don't think we have many aliases in gcc, re-instate the addr
# lut otherwise.
if vis != 'DEFAULT': continue
#value = int(value, 16)
#size = int(size, 16) if size.startswith('0x') else int(size)
defined = ndx != 'UND'
globl = bind == 'GLOBAL'
# c++ RID_FUNCTION_NAME dance. FORNOW: Handled as local use
# Is that correct?
if name.endswith('::__FUNCTION__') and typ == 'OBJECT':
name = name[0:(len(name) - len('::__FUNCTION__'))]
if defined: defined = False
if defined and not globl: continue
syms.setdefault(name, {})
syms[name][['use','def'][defined]] = True
syms[name][['local','global'][globl]] = True
# Note: we could filter out e.g. debug_* symbols by looking for
# value in the debug_macro sections.
if p1.returncode != 0:
print("Warning: Reading file '%s' exited with %r|%r"
% (file, p0.returncode, p1.returncode))
p0.kill()
return syms
(oprog, nprog) = ({}, {})
def walker(paths):
def ar_x(archive):
dbg("Archive %s" % path)
f = os.path.abspath(archive)
f = os.path.splitdrive(f)[1]
d = tmpd + os.path.sep + f
d = os.path.normpath(d)
owd = os.getcwd()
try:
os.makedirs(d)
os.chdir(d)
p0 = Popen(["ar", "x", "%s" % os.path.join(owd, archive)],
stderr=PIPE, universal_newlines=True)
p0.communicate()
if p0.returncode > 0: d = None # assume thin archive
except:
dbg("ar x: Error: %s: %s" % (archive, sys.exc_info()[0]))
os.chdir(owd)
raise
os.chdir(owd)
if d: dbg("Extracted to %s" % (d))
return (archive, d)
def ar_t(archive):
dbg("Thin archive, using existing files:")
try:
p0 = Popen(["ar", "t", "%s" % archive], stdout=PIPE,
universal_newlines=True)
ret = p0.communicate()[0]
return ret.split('\n')
except:
dbg("ar t: Error: %s: %s" % (archive, sys.exc_info()[0]))
raise
prog = {}
for path in paths:
if os.path.isdir(path):
for r, dirs, files in os.walk(path):
if files: dbg("Files %s" % ", ".join(files))
if dirs: dbg("Dirs %s" % ", ".join(dirs))
prog.update(walker([os.path.join(r, f) for f in files]))
prog.update(walker([os.path.join(r, d) for d in dirs]))
else:
if path.endswith('.a'):
if ar_x(path)[1] is not None: continue # extract worked
prog.update(walker(ar_t(path)))
if not path.endswith('.o'): continue
dbg("Reading symbols from %s" % (path))
prog[os.path.normpath(path)] = get_symbols(path)
return prog
def resolve(prog):
x = prog.keys()
use = set()
# for each unique pair of different files
for (f, g) in ((f,g) for f in x for g in x if f != g):
refs = set()
# for each defined symbol
for s in (s for s in prog[f] if prog[f][s].get('def') and s in prog[g]):
if prog[g][s].get('use'):
refs.add(s)
for s in refs:
# Prune externally referenced symbols as speed optimization only
for i in (i for i in x if s in prog[i]): del prog[i][s]
use |= refs
return use
try:
oprog = walker(odir)
if tmpd is not None:
oprog.update(walker([tmpd]))
oused = resolve(oprog)
finally:
try:
p0 = Popen(["rm", "-r", "-f", "%s" % (tmpd)], stderr=PIPE, stdout=PIPE)
p0.communicate()
if p0.returncode != 0: raise "rm '%s' didn't work out" % (tmpd)
except:
from shutil import rmtree
rmtree(tmpd, ignore_errors=True)
for (i,s) in ((i,s) for i in oprog.keys() for s in oprog[i] if oprog[i][s]):
if oprog[i][s].get('def') and not oprog[i][s].get('use'):
print("%s: Symbol '%s' declared extern but never referenced externally"
% (i,s))
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