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1 #!/usr/bin/env python
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2 # -*- coding: utf-8 -*-
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3 #
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4 # Copyright (c) 2018 Free Software Foundation
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5 # Contributed by Bernhard Reutner-Fischer <aldot@gcc.gnu.org>
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6 # Inspired by bloat-o-meter from busybox.
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7
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8 # This software may be used and distributed according to the terms and
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9 # conditions of the GNU General Public License as published by the Free
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10 # Software Foundation.
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11
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12 # For a set of object-files, determine symbols that are
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13 # - public but should be static
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14
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15 # Examples:
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16 # unused_functions.py ./gcc/fortran
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17 # unused_functions.py gcc/c gcc/c-family/ gcc/*-c.o | grep -v "'gt_"
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18 # unused_functions.py gcc/cp gcc/c-family/ gcc/*-c.o | grep -v "'gt_"
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19
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20 import sys, os
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21 from tempfile import mkdtemp
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22 from subprocess import Popen, PIPE
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23
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24 def usage():
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25 sys.stderr.write("usage: %s [-v] [dirs | files] [-- <readelf options>]\n"
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26 % sys.argv[0])
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27 sys.stderr.write("\t-v\tVerbose output\n");
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28 sys.exit(1)
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29
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30 (odir, sym_args, tmpd, verbose) = (set(), "", None, False)
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31
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32 for i in range(1, len(sys.argv)):
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33 f = sys.argv[i]
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34 if f == '--': # sym_args
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35 sym_args = ' '.join(sys.argv[i + 1:])
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36 break
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37 if f == '-v':
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38 verbose = True
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39 continue
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40 if not os.path.exists(f):
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41 sys.stderr.write("Error: No such file or directory '%s'\n" % f)
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42 usage()
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43 else:
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44 if f.endswith('.a') and tmpd is None:
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45 tmpd = mkdtemp(prefix='unused_fun')
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46 odir.add(f)
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47
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48 def dbg(args):
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49 if not verbose: return
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50 print(args)
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51
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52 def get_symbols(file):
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53 syms = {}
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54 rargs = "readelf -W -s %s %s" % (sym_args, file)
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55 p0 = Popen((a for a in rargs.split(' ') if a.strip() != ''), stdout=PIPE)
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56 p1 = Popen(["c++filt"], stdin=p0.stdout, stdout=PIPE,
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57 universal_newlines=True)
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58 lines = p1.communicate()[0]
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59 for l in lines.split('\n'):
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60 l = l.strip()
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61 if not len(l) or not l[0].isdigit(): continue
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62 larr = l.split()
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63 if len(larr) != 8: continue
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64 num, value, size, typ, bind, vis, ndx, name = larr
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65 if typ == 'SECTION' or typ == 'FILE': continue
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66 # I don't think we have many aliases in gcc, re-instate the addr
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67 # lut otherwise.
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68 if vis != 'DEFAULT': continue
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69 #value = int(value, 16)
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70 #size = int(size, 16) if size.startswith('0x') else int(size)
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71 defined = ndx != 'UND'
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72 globl = bind == 'GLOBAL'
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73 # c++ RID_FUNCTION_NAME dance. FORNOW: Handled as local use
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74 # Is that correct?
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75 if name.endswith('::__FUNCTION__') and typ == 'OBJECT':
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76 name = name[0:(len(name) - len('::__FUNCTION__'))]
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77 if defined: defined = False
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78 if defined and not globl: continue
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79 syms.setdefault(name, {})
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80 syms[name][['use','def'][defined]] = True
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81 syms[name][['local','global'][globl]] = True
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82 # Note: we could filter out e.g. debug_* symbols by looking for
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83 # value in the debug_macro sections.
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84 if p1.returncode != 0:
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85 print("Warning: Reading file '%s' exited with %r|%r"
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86 % (file, p0.returncode, p1.returncode))
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87 p0.kill()
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88 return syms
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89
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90 (oprog, nprog) = ({}, {})
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91
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92 def walker(paths):
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93 def ar_x(archive):
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94 dbg("Archive %s" % path)
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95 f = os.path.abspath(archive)
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96 f = os.path.splitdrive(f)[1]
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97 d = tmpd + os.path.sep + f
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98 d = os.path.normpath(d)
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99 owd = os.getcwd()
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100 try:
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101 os.makedirs(d)
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102 os.chdir(d)
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103 p0 = Popen(["ar", "x", "%s" % os.path.join(owd, archive)],
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104 stderr=PIPE, universal_newlines=True)
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105 p0.communicate()
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106 if p0.returncode > 0: d = None # assume thin archive
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107 except:
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108 dbg("ar x: Error: %s: %s" % (archive, sys.exc_info()[0]))
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109 os.chdir(owd)
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110 raise
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111 os.chdir(owd)
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112 if d: dbg("Extracted to %s" % (d))
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113 return (archive, d)
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114
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115 def ar_t(archive):
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116 dbg("Thin archive, using existing files:")
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117 try:
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118 p0 = Popen(["ar", "t", "%s" % archive], stdout=PIPE,
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119 universal_newlines=True)
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120 ret = p0.communicate()[0]
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121 return ret.split('\n')
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122 except:
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123 dbg("ar t: Error: %s: %s" % (archive, sys.exc_info()[0]))
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124 raise
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125
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126 prog = {}
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127 for path in paths:
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128 if os.path.isdir(path):
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129 for r, dirs, files in os.walk(path):
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130 if files: dbg("Files %s" % ", ".join(files))
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131 if dirs: dbg("Dirs %s" % ", ".join(dirs))
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132 prog.update(walker([os.path.join(r, f) for f in files]))
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133 prog.update(walker([os.path.join(r, d) for d in dirs]))
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134 else:
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135 if path.endswith('.a'):
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136 if ar_x(path)[1] is not None: continue # extract worked
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137 prog.update(walker(ar_t(path)))
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138 if not path.endswith('.o'): continue
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139 dbg("Reading symbols from %s" % (path))
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140 prog[os.path.normpath(path)] = get_symbols(path)
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141 return prog
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142
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143 def resolve(prog):
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144 x = prog.keys()
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145 use = set()
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146 # for each unique pair of different files
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147 for (f, g) in ((f,g) for f in x for g in x if f != g):
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148 refs = set()
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149 # for each defined symbol
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150 for s in (s for s in prog[f] if prog[f][s].get('def') and s in prog[g]):
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151 if prog[g][s].get('use'):
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152 refs.add(s)
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153 for s in refs:
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154 # Prune externally referenced symbols as speed optimization only
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155 for i in (i for i in x if s in prog[i]): del prog[i][s]
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156 use |= refs
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157 return use
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158
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159 try:
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160 oprog = walker(odir)
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161 if tmpd is not None:
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162 oprog.update(walker([tmpd]))
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163 oused = resolve(oprog)
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164 finally:
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165 try:
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166 p0 = Popen(["rm", "-r", "-f", "%s" % (tmpd)], stderr=PIPE, stdout=PIPE)
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167 p0.communicate()
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168 if p0.returncode != 0: raise "rm '%s' didn't work out" % (tmpd)
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169 except:
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170 from shutil import rmtree
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171 rmtree(tmpd, ignore_errors=True)
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172
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173 for (i,s) in ((i,s) for i in oprog.keys() for s in oprog[i] if oprog[i][s]):
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174 if oprog[i][s].get('def') and not oprog[i][s].get('use'):
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175 print("%s: Symbol '%s' declared extern but never referenced externally"
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176 % (i,s))
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177
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178
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