llvm-project

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#!/usr/bin/env perl
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use Getopt::Std;
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$DEBUG = 0;
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sub parse_objdump_file {
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  my ($filename) = @_;
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  my @result;
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  open (INPUT, $filename) or die "$filename: $!\n";
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  print "opened objdump output file $filename\n" if $DEBUG;
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  while (<INPUT>) {
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    if (/\s*([0-9a-f]*):\t(([0-9a-f]{2} )+) *\t(.*)$/) {
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      my ($addr, $bytes, $instr) = ($1, $2, $4);
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      $addr = "0x" . $addr;
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      $bytes =~ s/\s*(.*\S)\s*/$1/; # trim any remaining whitespace
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      $instr =~ s/\s*(.*\S)\s*/$1/;
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      push (@result, {'addr' => $addr, 'bytes' => $bytes, 'instr' => $instr});
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      print "addr=$addr bytes='$bytes' instr='$instr'\n" if $DEBUG;
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    }
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  }
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  close INPUT;
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  return @result;
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}
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sub parse_gdb_file {
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  my ($filename) = @_;
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  my @result;
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  my $got_addr;
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  open (INPUT, $filename) or die "$filename: $!\n";
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  print "opened gdb output file $filename\n" if $DEBUG;
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  while (<INPUT>) {
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    if (/^(0x[0-9a-f]*):\t([^\t]*)\t[^:]*:\t((0x[0-9a-f]{2}\s*)+)\s*$/) {
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      my ($addr, $bytes, $instr) = ($1, $3, $2);
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      $bytes =~ s/0x//g;
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      $bytes =~ s/\s+/ /g;           # regularize whitespace
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      $bytes =~ s/\s*(.*\S)\s*/$1/;  # trim any remaining whitespace
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      $instr =~ s/\s*(.*\S)\s*/$1/;
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      push (@result, {'addr' => $addr, 'bytes' => $bytes, 'instr' => $instr});
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      print "addr=$addr bytes='$bytes' instr='$instr'\n" if $DEBUG;
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    } elsif (/^(0x[0-9a-f]*):\t$/) { # deal with gdb's line breaker
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      $got_addr = $1;
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    } elsif ($got_addr && /^    ([^\t]*)\t[^:]*:\t((0x[0-9a-f]{2}\s*)+)\s*$/) {
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      my ($addr, $bytes, $instr) = ($got_addr, $2, $1);
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      $bytes =~ s/0x//g;
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      $bytes =~ s/\s+/ /g;           # regularize whitespace
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      $bytes =~ s/\s*(.*\S)\s*/$1/;  # trim any remaining whitespace
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      $instr =~ s/\s*(.*\S)\s*/$1/;
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      push (@result, {'addr' => $addr, 'bytes' => $bytes, 'instr' => $instr});
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      print "addr=$addr bytes='$bytes' instr='$instr'\n" if $DEBUG;
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      undef $got_addr;
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    }
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  }
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  close INPUT;
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  return @result;
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}
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sub binary_diffs {
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  my ($objdump_file, $gdb_file) = @_;
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  my @file1 = parse_objdump_file ($objdump_file);
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  my @file2 = parse_gdb_file ($gdb_file);
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  my $lastrecord = ($#file1 >= $#file2) ? ($#file1) : ($#file2);
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  for (my $i = 0; $i <= $lastrecord; ++$i) {
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    my $d1 = $file1[$i];
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    my $d2 = $file2[$i];
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    if ($d1->{'bytes'} ne $d2->{'bytes'}) {
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      next if (($d1->{'instr'} eq $d2->{'instr'}) && $opt_d);
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      printf "0x%08x:\t%30s \t%s\n", 0+$d1->{'addr'}, $d1->{'bytes'}, $d1->{'instr'};
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      printf "0x%08x:\t%30s \t%s\n\n", 0+$d2->{'addr'}, $d2->{'bytes'}, $d2->{'instr'};
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    }
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  }
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}
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&getopts('d');
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$objdump_file = $ARGV[0];
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$gdb_file = $ARGV[1];
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binary_diffs ($objdump_file, $gdb_file);
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exit (0);
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__END__
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=pod
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=head1 NAME
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codegen-diff
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=head1 SYNOPSIS
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codegen-diff [-d] I<OBJDUMP-OUTPUT-FILE> I<GDB-DISASSEMBLY-FILE>
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=head1 DESCRIPTION
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B<codegen-diff> is a program that tries to show you the differences
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between the code that B<llc> generated and the code that B<lli> generated.
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The way you use it is as follows: first, you create I<OBJDUMP-OUTPUT-FILE>
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by running B<objdump> on the B<llc> compiled and linked binary. You need to
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trim down the result so it contains only the function of interest.
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Second, you create I<GDB-DISASSEMBLY-FILE> by running B<gdb>, with my patch
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to print out hex bytes in the B<disassemble> command output, on
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B<lli>.  Set a breakpoint in C<Emitter::finishFunction()> and wait until
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the function you want is compiled.  Then use the B<disassemble> command
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to print out the assembly dump of the function B<lli> just compiled.
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(Use C<lli -debug> to find out where the function starts and ends in memory.)
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It's easiest to save this output by using B<script>.
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Finally, you run B<codegen-diff>, as indicated in the Synopsis section of
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this manpage. It will print out a two-line stanza for each mismatched
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instruction, with the  B<llc> version first, and the  B<lli> version second.
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=head1 OPTIONS
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=over 4
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=item -d
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Don't show instructions where the bytes are different but they
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disassemble to the same thing. This puts a lot of trust in the
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disassembler, but it might help you highlight the more egregious cases
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of misassembly.
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=back
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=head1 AUTHOR
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B<codegen-diff> was written by Brian Gaeke.
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=head1 SEE ALSO
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L<gdb(1)>, L<objdump(1)>, L<script(1)>.
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You will need my B<gdb> patch:
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  http://llvm.cs.uiuc.edu/~gaeke/gdb-disassembly-print-bytes.patch
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=cut
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