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