clang/utils/check_cfc/obj_diff.py

   1 #!/usr/bin/env python
   2
   3 from __future__ import absolute_import, division, print_function
   4
   5 import argparse
   6 import difflib
   7 import filecmp
   8 import os
   9 import subprocess
  10 import sys
  11
  12 disassembler = "objdump"
  13
  14
  15 def keep_line(line):
  16     """Returns true for lines that should be compared in the disassembly
  17     output."""
  18     return "file format" not in line
  19
  20
  21 def disassemble(objfile):
  22     """Disassemble object to a file."""
  23     p = subprocess.Popen(
  24         [disassembler, "-d", objfile], stdout=subprocess.PIPE, stderr=subprocess.PIPE
  25     )
  26     (out, err) = p.communicate()
  27     if p.returncode or err:
  28         print("Disassemble failed: {}".format(objfile))
  29         sys.exit(1)
  30     return [line for line in out.split(os.linesep) if keep_line(line)]
  31
  32
  33 def dump_debug(objfile):
  34     """Dump all of the debug info from a file."""
  35     p = subprocess.Popen(
  36         [disassembler, "-WliaprmfsoRt", objfile],
  37         stdout=subprocess.PIPE,
  38         stderr=subprocess.PIPE,
  39     )
  40     (out, err) = p.communicate()
  41     if p.returncode or err:
  42         print("Dump debug failed: {}".format(objfile))
  43         sys.exit(1)
  44     return [line for line in out.split(os.linesep) if keep_line(line)]
  45
  46
  47 def first_diff(a, b, fromfile, tofile):
  48     """Returns the first few lines of a difference, if there is one.  Python
  49     diff can be very slow with large objects and the most interesting changes
  50     are the first ones. Truncate data before sending to difflib.  Returns None
  51     is there is no difference."""
  52
  53     # Find first diff
  54     first_diff_idx = None
  55     for idx, val in enumerate(a):
  56         if val != b[idx]:
  57             first_diff_idx = idx
  58             break
  59
  60     if first_diff_idx == None:
  61         # No difference
  62         return None
  63
  64     # Diff to first line of diff plus some lines
  65     context = 3
  66     diff = difflib.unified_diff(
  67         a[: first_diff_idx + context], b[: first_diff_idx + context], fromfile, tofile
  68     )
  69     difference = "\n".join(diff)
  70     if first_diff_idx + context < len(a):
  71         difference += "\n*** Diff truncated ***"
  72     return difference
  73
  74
  75 def compare_object_files(objfilea, objfileb):
  76     """Compare disassembly of two different files.
  77     Allowing unavoidable differences, such as filenames.
  78     Return the first difference if the disassembly differs, or None.
  79     """
  80     disa = disassemble(objfilea)
  81     disb = disassemble(objfileb)
  82     return first_diff(disa, disb, objfilea, objfileb)
  83
  84
  85 def compare_debug_info(objfilea, objfileb):
  86     """Compare debug info of two different files.
  87     Allowing unavoidable differences, such as filenames.
  88     Return the first difference if the debug info differs, or None.
  89     If there are differences in the code, there will almost certainly be differences in the debug info too.
  90     """
  91     dbga = dump_debug(objfilea)
  92     dbgb = dump_debug(objfileb)
  93     return first_diff(dbga, dbgb, objfilea, objfileb)
  94
  95
  96 def compare_exact(objfilea, objfileb):
  97     """Byte for byte comparison between object files.
  98     Returns True if equal, False otherwise.
  99     """
 100     return filecmp.cmp(objfilea, objfileb)
 101
 102
 103 if __name__ == "__main__":
 104     parser = argparse.ArgumentParser()
 105     parser.add_argument("objfilea", nargs=1)
 106     parser.add_argument("objfileb", nargs=1)
 107     parser.add_argument("-v", "--verbose", action="store_true")
 108     args = parser.parse_args()
 109     diff = compare_object_files(args.objfilea[0], args.objfileb[0])
 110     if diff:
 111         print("Difference detected")
 112         if args.verbose:
 113             print(diff)
 114         sys.exit(1)
 115     else:
 116         print("The same")