contrib/compare-debug

#! /bin/sh

# Compare stripped copies of two given object files.

# Copyright (C) 2007-2025 Free Software Foundation, Inc.
# Originally by Alexandre Oliva <aoliva@redhat.com>

# This file is part of GCC.

# GCC is free software; you can redistribute it and/or modify it under
# the terms of the GNU General Public License as published by the Free
# Software Foundation; either version 3, or (at your option) any later
# version.

# GCC is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
# or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
# License for more details.

# You should have received a copy of the GNU General Public License
# along with GCC; see the file COPYING3.  If not see
# <http://www.gnu.org/licenses/>.

rm='rm -f'

case $1 in
-p | --preserve)
  rm='echo preserving'
  shift
  ;;
esac

if test $# != 2; then
  echo 'usage: compare-debug file1.o file2.o' >&2
  exit 1
fi

if test ! -f "$1"; then
  echo "$1" does not exist >&2
  exit 1
fi

if test ! -f "$2"; then
  echo "$2" does not exist >&2
  exit 1
fi

suf1=stripped
while test -f "$1.$suf1"; do
  suf1=$suf1.
done

suf2=stripped
while test -f "$2.$suf2"; do
  suf2=$suf2.
done

trap 'rm -f "$1.$suf1" "$2.$suf2"' 0 1 2 15

case `uname -s` in
Darwin)
  # The strip command on darwin does not remove all debug info.
  # Fortunately, we can use ld to do it instead.
  ld -S -r -no_uuid "$1" -o "$1.$suf1"
  ld -S -r -no_uuid "$2" -o "$2.$suf2"
  ;;
*)
  cp "$1" "$1.$suf1"
  strip "$1.$suf1"

  cp "$2" "$2.$suf2"
  strip "$2.$suf2"
  ;;
esac

remove_comment ()
{
  file=$1
  opts=
  for s in `objdump --section-headers "$file" | awk '{ print $2 }'`; do
    case "$s" in
    .comment*)
      opts="$opts --remove-section $s"
      ;;
    esac
  done
  [ -n "$opts" ] && objcopy $opts $file
}

if cmp "$1.$suf1" "$2.$suf2"; then
  status=0
else
  status=1

  # Remove any .comment sections.
  if (objcopy -v) 2>&1 | grep ' --remove-section' > /dev/null \
     && (objdump --help) 2>&1 | grep ' --\[*section-\]*headers' > /dev/null; then
    remove_comment "$1.$suf1"
    remove_comment "$2.$suf2"
    if cmp "$1.$suf1" "$2.$suf2"; then
      status=0
    fi
  fi

  # Assembler-generated CFI will add an .eh_frame section for -g not
  # present in -g0.  Try to cope with it by checking that an .eh_frame
  # section is present in either object file, and then stripping it
  # off before re-comparing.

  cmd=
  cmp1=
  cmp2=

  for t in objdump readelf eu-readelf; do
    if ($t --help) 2>&1 | grep ' --\[*section-\]*headers' > /dev/null; then
      cmd=$t

      $cmd --section-headers "$1.$suf1" | grep '\.eh_frame' > /dev/null
      cmp1=$?

      $cmd --section-headers "$2.$suf2" | grep '\.eh_frame' > /dev/null
      cmp2=$?

      break
    fi
  done

  # If we found .eh_frame in one but not the other, or if we could not
  # find a command to tell, or if there are LTO sections, try to strip
  # off the .eh_frame and LTO sections from both.
  if test "x$cmp1" != "x$cmp2" || test "x$cmd" = "x" ||
     $cmd --section-headers "$1.$suf1" | grep '.gnu.lto_' > /dev/null ||
     $cmd --section-headers "$2.$suf2" | grep '.gnu.lto_' > /dev/null ; then
    suf3=$suf1.
    while test -f "$1.$suf3"; do
      suf3=$suf3.
    done

    suf4=$suf2.
    while test -f "$2.$suf4"; do
      suf4=$suf4.
    done

    trap 'rm -f "$1.$suf1" "$2.$suf2" "$1.$suf3" "$2.$suf4"' 0 1 2 15

    echo stripping off .eh_frame and LTO sections, then retrying >&2

    seclist=".eh_frame .rel.eh_frame .rela.eh_frame"
    if test "x$cmd" != "x"; then
      seclist="$seclist "`{ $cmd --section-headers "$1.$suf1"; $cmd --section-headers "$2.$suf2"; } | sed -n 's,.* \(\.gnu\.lto_[^ 	]*\).*,\1,p' | sort -u`
    fi
    rsopts=`for sec in $seclist; do echo " --remove-section $sec"; done`

    if (objcopy -v) 2>&1 | grep ' --remove-section' > /dev/null; then
      objcopy $rsopts "$1.$suf1" "$1.$suf3"
      mv "$1.$suf3" "$1.$suf1"

      objcopy $rsopts "$2.$suf2" "$2.$suf4"
      mv "$2.$suf4" "$2.$suf2"
    elif (strip --help) 2>&1 | grep ' --remove-section' > /dev/null; then
      cp "$1.$suf1" "$1.$suf3"
      strip $rsopts "$1.$suf3"
      mv "$1.$suf3" "$1.$suf1"

      cp "$2.$suf2" "$2.$suf4"
      strip $rsopts "$2.$suf4"
      mv "$2.$suf4" "$2.$suf2"
    else
      echo failed to strip off .eh_frame >&2
    fi

    trap 'rm -f "$1.$suf1" "$2.$suf2"' 0 1 2 15

    if cmp "$1.$suf1" "$2.$suf2"; then
      status=0
    else
      status=1
    fi
  fi
fi

$rm "$1.$suf1" "$2.$suf2"

trap "exit $status; exit" 0 1 2 15

# Replace the suffix in $1 and $2 with .*.gkd, compare them if a
# single file is found by the globbing.
base1=`echo "$1" | sed '$s,\.[^.]*$,,'` gkd1=
for f in "$base1".*.gkd; do
  if test "x$gkd1" != x; then
    gkd1=
    break
  elif test -f "$f"; then
    gkd1=$f
  fi
done
base2=`echo "$2" | sed '$s,\.[^.]*$,,'` gkd2=
for f in "$base2".*.gkd; do
  if test "x$gkd2" != x; then
    gkd2=
    break
  elif test -f "$f"; then
    gkd2=$f
  fi
done
if test "x$gkd1" != x || test "x$gkd2" != x; then
  if cmp "${gkd1-/dev/null}" "${gkd2-/dev/null}"; then
    :
  else
    status=$?
  fi
fi

exit $status