utils/codegen-diff

   1 #!/usr/bin/perl
   2
   3 use Getopt::Std;
   4 $DEBUG = 0;
   5
   6 sub parse_objdump_file {
   7   my ($filename) = @_;
   8   my @result;
   9   open (INPUT, $filename) or die "$filename: $!\n";
  10   print "opened objdump output file $filename\n" if $DEBUG;
  11   while (<INPUT>) {
  12     if (/\s*([0-9a-f]*):\t(([0-9a-f]{2} )+) *\t(.*)$/) {
  13       my ($addr, $bytes, $instr) = ($1, $2, $4);
  14       $addr = "0x" . $addr;
  15       $bytes =~ s/\s*(.*\S)\s*/$1/; # trim any remaining whitespace
  16       $instr =~ s/\s*(.*\S)\s*/$1/;
  17       push (@result, {'addr' => $addr, 'bytes' => $bytes, 'instr' => $instr});
  18       print "addr=$addr bytes='$bytes' instr='$instr'\n" if $DEBUG;
  19     }
  20   }
  21   close INPUT;
  22   return @result;
  23 }
  24
  25 sub parse_gdb_file {
  26   my ($filename) = @_;
  27   my @result;
  28   my $got_addr;
  29   open (INPUT, $filename) or die "$filename: $!\n";
  30   print "opened gdb output file $filename\n" if $DEBUG;
  31   while (<INPUT>) {
  32     if (/^(0x[0-9a-f]*):\t([^\t]*)\t[^:]*:\t((0x[0-9a-f]{2}\s*)+)\s*$/) {
  33       my ($addr, $bytes, $instr) = ($1, $3, $2);
  34       $bytes =~ s/0x//g;
  35       $bytes =~ s/\s+/ /g;           # regularize whitespace
  36       $bytes =~ s/\s*(.*\S)\s*/$1/;  # trim any remaining whitespace
  37       $instr =~ s/\s*(.*\S)\s*/$1/;
  38       push (@result, {'addr' => $addr, 'bytes' => $bytes, 'instr' => $instr});
  39       print "addr=$addr bytes='$bytes' instr='$instr'\n" if $DEBUG;
  40     } elsif (/^(0x[0-9a-f]*):\t$/) { # deal with gdb's line breaker
  41       $got_addr = $1;
  42     } elsif ($got_addr && /^    ([^\t]*)\t[^:]*:\t((0x[0-9a-f]{2}\s*)+)\s*$/) {
  43       my ($addr, $bytes, $instr) = ($got_addr, $2, $1);
  44       $bytes =~ s/0x//g;
  45       $bytes =~ s/\s+/ /g;           # regularize whitespace
  46       $bytes =~ s/\s*(.*\S)\s*/$1/;  # trim any remaining whitespace
  47       $instr =~ s/\s*(.*\S)\s*/$1/;
  48       push (@result, {'addr' => $addr, 'bytes' => $bytes, 'instr' => $instr});
  49       print "addr=$addr bytes='$bytes' instr='$instr'\n" if $DEBUG;
  50       undef $got_addr;
  51     }
  52   }
  53   close INPUT;
  54   return @result;
  55 }
  56
  57 sub binary_diffs {
  58   my ($objdump_file, $gdb_file) = @_;
  59   my @file1 = parse_objdump_file ($objdump_file);
  60   my @file2 = parse_gdb_file ($gdb_file);
  61   my $lastrecord = ($#file1 >= $#file2) ? ($#file1) : ($#file2);
  62   for (my $i = 0; $i <= $lastrecord; ++$i) {
  63     my $d1 = $file1[$i];
  64     my $d2 = $file2[$i];
  65     if ($d1->{'bytes'} ne $d2->{'bytes'}) {
  66       next if (($d1->{'instr'} eq $d2->{'instr'}) && $opt_d);
  67       printf "0x%08x:\t%30s \t%s\n", 0+$d1->{'addr'}, $d1->{'bytes'}, $d1->{'instr'};
  68       printf "0x%08x:\t%30s \t%s\n\n", 0+$d2->{'addr'}, $d2->{'bytes'}, $d2->{'instr'};
  69     }
  70   }
  71 }
  72
  73 &getopts('d');
  74 $objdump_file = $ARGV[0];
  75 $gdb_file = $ARGV[1];
  76 binary_diffs ($objdump_file, $gdb_file);
  77 exit (0);
  78 __END__
  79 =pod
  80
  81 =head1 NAME
  82
  83 codegen-diff
  84
  85 =head1 SYNOPSIS
  86
  87 codegen-diff [-d] I<OBJDUMP-OUTPUT-FILE> I<GDB-DISASSEMBLY-FILE>
  88
  89 =head1 DESCRIPTION
  90
  91 B<codegen-diff> is a program that tries to show you the differences
  92 between the code that B<llc> generated and the code that B<lli> generated.
  93
  94 The way you use it is as follows: first, you create I<OBJDUMP-OUTPUT-FILE>
  95 by running B<objdump> on the B<llc> compiled and linked binary. You need to
  96 trim down the result so it contains only the function of interest.
  97
  98 Second, you create I<GDB-DISASSEMBLY-FILE> by running B<gdb>, with my patch
  99 to print out hex bytes in the B<disassemble> command output, on
 100 B<lli>.  Set a breakpoint in C<Emitter::finishFunction()> and wait until
 101 the function you want is compiled.  Then use the B<disassemble> command
 102 to print out the assembly dump of the function B<lli> just compiled.
 103 (Use C<lli -debug> to find out where the function starts and ends in memory.)
 104 It's easiest to save this output by using B<script>.
 105
 106 Finally, you run B<codegen-diff>, as indicated in the Synopsis section of
 107 this manpage. It will print out a two-line stanza for each mismatched
 108 instruction, with the  B<llc> version first, and the  B<lli> version second.
 109
 110 =head1 OPTIONS
 111
 112 =over 4
 113
 114 =item -d
 115
 116 Don't show instructions where the bytes are different but they
 117 disassemble to the same thing. This puts a lot of trust in the
 118 disassembler, but it might help you highlight the more egregious cases
 119 of misassembly.
 120
 121 =back
 122
 123 =head1 AUTHOR
 124
 125 B<codegen-diff> was written by Brian Gaeke.
 126
 127 =head1 SEE ALSO
 128
 129 L<gdb(1)>, L<objdump(1)>, L<script(1)>.
 130
 131 You will need my B<gdb> patch:
 132
 133   http://llvm.cs.uiuc.edu/~gaeke/gdb-disassembly-print-bytes.patch
 134
 135 =cut