1#!/usr/bin/perl 2 3use Getopt::Std; 4$DEBUG = 0; 5 6sub parse_objdump_file { 7 my ($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 $DEBUG; 19 } 20 } 21 close INPUT; 22 return @result; 23} 24 25sub parse_gdb_file { 26 my ($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 $got_addr; 51 } 52 } 53 close INPUT; 54 return @result; 55} 56 57sub binary_diffs { 58 my ($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 = $ARGV[1]; 76binary_diffs ($objdump_file, $gdb_file); 77exit (0); 78__END__ 79=pod 80 81=head1 NAME 82 83codegen-diff 84 85=head1 SYNOPSIS 86 87codegen-diff [-d] I<OBJDUMP-OUTPUT-FILE> I<GDB-DISASSEMBLY-FILE> 88 89=head1 DESCRIPTION 90 91B<codegen-diff> is a program that tries to show you the differences 92between the code that B<llc> generated and the code that B<lli> generated. 93 94The way you use it is as follows: first, you create I<OBJDUMP-OUTPUT-FILE> 95by running B<objdump> on the B<llc> compiled and linked binary. You need to 96trim down the result so it contains only the function of interest. 97 98Second, you create I<GDB-DISASSEMBLY-FILE> by running B<gdb>, with my patch 99to print out hex bytes in the B<disassemble> command output, on 100B<lli>. Set a breakpoint in C<Emitter::finishFunction()> and wait until 101the function you want is compiled. Then use the B<disassemble> command 102to 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.) 104It's easiest to save this output by using B<script>. 105 106Finally, you run B<codegen-diff>, as indicated in the Synopsis section of 107this manpage. It will print out a two-line stanza for each mismatched 108instruction, 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 116Don't show instructions where the bytes are different but they 117disassemble to the same thing. This puts a lot of trust in the 118disassembler, but it might help you highlight the more egregious cases 119of misassembly. 120 121=back 122 123=head1 AUTHOR 124 125B<codegen-diff> was written by Brian Gaeke. 126 127=head1 SEE ALSO 128 129L<gdb(1)>, L<objdump(1)>, L<script(1)>. 130 131You will need my B<gdb> patch: 132 133 http://llvm.cs.uiuc.edu/~gaeke/gdb-disassembly-print-bytes.patch 134 135=cut 136