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#!/usr/bin/env python
#
# Copyright (c) 2018 Free Software Foundation
# 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
def usage():
sys.stderr.write("usage: %s [dirs | files] [-- <readelf options>]\n"
% sys.argv[0])
sys.exit(1)
(odir, sym_args) = (set(), "")
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 not os.path.exists(f):
sys.stderr.write("Error: No such file or directory '%s'\n" % f)
usage()
else:
odir.add(f)
def get_symbols(file):
syms = {}
for l in os.popen("readelf -W -s %s %s | c++filt" % (sym_args, file)).readlines():
l = l.strip()
if not (len(l) and l[0].isdigit() and len(l.split()) == 8):
continue
num, value, size, typ, bind, vis, ndx, name = l.split()
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.
return syms
(oprog, nprog) = ({}, {})
def walker(paths):
prog = {}
for path in paths:
if os.path.isdir(path):
for r, dirs, files in os.walk(path):
for f in files:
# TODO: maybe extract .a to a tmpdir and walk that, too
# maybe /there/foolib.a(file.o) as name?
if not f.endswith(".o"): continue
p = os.path.join(r, f)
prog[os.path.normpath(p)] = get_symbols(p)
for d in dirs:
tem = prog.copy()
tem.update(walker([os.path.join(r, d)]))
prog = tem
else:
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
oprog = walker(odir)
oused = resolve(oprog)
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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