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