tools/unused-symbols-report.py

   1 #!/usr/bin/env python
   2 # Copyright (c) 2011 The Chromium Authors. All rights reserved.
   3 # Use of this source code is governed by a BSD-style license that can be
   4 # found in the LICENSE file.
   5
   6 """Prints a report of symbols stripped by the linker due to being unused.
   7
   8 To use, build with these linker flags:
   9   -Wl,--gc-sections
  10   -Wl,--print-gc-sections
  11 the first one is the default in Release; search build/common.gypi for it
  12 and to see where to add the other.
  13
  14 Then build, saving the output into a file:
  15   make chrome 2>&1 | tee buildlog
  16 and run this script on it:
  17   ./tools/unused-symbols-report.py buildlog > report.html
  18 """
  19
  20 import cgi
  21 import optparse
  22 import os
  23 import re
  24 import subprocess
  25 import sys
  26
  27 cppfilt_proc = None
  28 def Demangle(sym):
  29   """Demangle a C++ symbol by passing it through c++filt."""
  30   global cppfilt_proc
  31   if cppfilt_proc is None:
  32     cppfilt_proc = subprocess.Popen(['c++filt'], stdin=subprocess.PIPE,
  33                                     stdout=subprocess.PIPE)
  34   print >>cppfilt_proc.stdin, sym
  35   return cppfilt_proc.stdout.readline().strip()
  36
  37
  38 def Unyuck(sym):
  39   """Attempt to prettify a C++ symbol by some basic heuristics."""
  40   sym = sym.replace('std::basic_string<char, std::char_traits<char>, '
  41                     'std::allocator<char> >', 'std::string')
  42   sym = sym.replace('std::basic_string<wchar_t, std::char_traits<wchar_t>, '
  43                     'std::allocator<wchar_t> >', 'std::wstring')
  44   sym = sym.replace('std::basic_string<unsigned short, '
  45                     'base::string16_char_traits, '
  46                     'std::allocator<unsigned short> >', 'string16')
  47   sym = re.sub(r', std::allocator<\S+\s+>', '', sym)
  48   return sym
  49
  50
  51 def Parse(input, skip_paths=None, only_paths=None):
  52   """Parse the --print-gc-sections build output.
  53
  54   Args:
  55     input: iterable over the lines of the build output
  56
  57   Yields:
  58     (target name, path to .o file, demangled symbol)
  59   """
  60   symbol_re = re.compile(r"'\.text\.(\S+)' in file '(\S+)'$")
  61   path_re = re.compile(r"^out/[^/]+/[^/]+/([^/]+)/(.*)$")
  62   for line in input:
  63     match = symbol_re.search(line)
  64     if not match:
  65       continue
  66     symbol, path = match.groups()
  67     symbol = Unyuck(Demangle(symbol))
  68     path = os.path.normpath(path)
  69     if skip_paths and skip_paths in path:
  70       continue
  71     if only_paths and only_paths not in path:
  72       continue
  73     match = path_re.match(path)
  74     if not match:
  75       print >>sys.stderr, "Skipping weird path", path
  76       continue
  77     target, path = match.groups()
  78     yield target, path, symbol
  79
  80
  81 # HTML header for our output page.
  82 TEMPLATE_HEADER = """<!DOCTYPE html>
  83 <head>
  84 <style>
  85 body {
  86   font-family: sans-serif;
  87   font-size: 0.8em;
  88 }
  89 h1, h2 {
  90   font-weight: normal;
  91   margin: 0.5em 0;
  92 }
  93 h2 {
  94   margin-top: 1em;
  95 }
  96 tr:hover {
  97   background: #eee;
  98 }
  99 .permalink {
 100   padding-left: 1ex;
 101   font-size: 80%;
 102   text-decoration: none;
 103   color: #ccc;
 104 }
 105 .symbol {
 106   font-family: WebKitWorkAround, monospace;
 107   margin-left: 4ex;
 108   text-indent: -4ex;
 109   padding: 0.5ex 1ex;
 110 }
 111 .file {
 112   padding: 0.5ex 1ex;
 113   padding-left: 2ex;
 114   font-family: WebKitWorkAround, monospace;
 115   font-size: 90%;
 116   color: #777;
 117 }
 118 </style>
 119 </head>
 120 <body>
 121 <h1>chrome symbols deleted at link time</h1>
 122 """
 123
 124
 125 def Output(iter):
 126   """Print HTML given an iterable of (target, path, symbol) tuples."""
 127   targets = {}
 128   for target, path, symbol in iter:
 129     entries = targets.setdefault(target, [])
 130     entries.append((symbol, path))
 131
 132   print TEMPLATE_HEADER
 133   print "<p>jump to target:"
 134   print "<select onchange='document.location.hash = this.value'>"
 135   for target in sorted(targets.keys()):
 136     print "<option>%s</option>" % target
 137   print "</select></p>"
 138
 139   for target in sorted(targets.keys()):
 140     print "<h2>%s" % target
 141     print "<a class=permalink href='#%s' name='%s'>#</a>" % (target, target)
 142     print "</h2>"
 143     print "<table width=100% cellspacing=0>"
 144     for symbol, path in sorted(targets[target]):
 145       htmlsymbol = cgi.escape(symbol).replace('::', '::<wbr>')
 146       print "<tr><td><div class=symbol>%s</div></td>" % htmlsymbol
 147       print "<td valign=top><div class=file>%s</div></td></tr>" % path
 148     print "</table>"
 149
 150
 151 def main():
 152   parser = optparse.OptionParser(usage='%prog [options] buildoutput\n\n' +
 153                                  __doc__)
 154   parser.add_option("--skip-paths", metavar="STR", default="third_party",
 155                     help="skip paths matching STR [default=%default]")
 156   parser.add_option("--only-paths", metavar="STR",
 157                     help="only include paths matching STR [default=%default]")
 158   opts, args = parser.parse_args()
 159
 160   if len(args) < 1:
 161     parser.print_help()
 162     sys.exit(1)
 163
 164   iter = Parse(open(args[0]),
 165                skip_paths=opts.skip_paths,
 166                only_paths=opts.only_paths)
 167   Output(iter)
 168
 169
 170 if __name__ == '__main__':
 171   main()