Bounds Checking Patches for GCC 4.0.4
-------------------------------------

Version: 1.03

12May07

I copied the gcc-4.0.2 bounds checking patches from
http://sourceforge.net/projects/boundschecking/
This distribution is all patches made by the script makediffs.sh which runs
  gdiff -ruN egcs-yyyymmdd/gcc begcs-yyyymmdd/gcc
where egcs-yyyymmdd is an unmodified built version of gcc and
begcs-yyyymmdd is a built version with the bounds checking patches.
(For gcc versions, replace "egcs-yyyymmdd" with "gcc-#.#.#".)
I have moved the PostScript of Richard Jones's papers from
gcc/bounds/report to a separate archive "bounds-checking-reports.tar.bz2"
to reduce the size of the patches.
I used CentOS Linux 4.4 with a 2.6.9-42.0.10.ELsmp kernel.
I needed about 1030 MB to build bgcc-3.3 under RH 8.0 on an ext3 file system:
187 MB for the unpacked source and 843 MB for the generated objects
(168 MB for the bgcc-3.1 generated objects with --enable-languages=c).
The bounds checking patches should work any system that can build a normal gcc.

OS-specific build notes:
Most ELF platforms:
  gcc 3.1: gcc 3.1 writes DWARF 2 debugging information and requires
    gdb 5.1 or higher and binutils 2.10 or higher.
    See INSTALL/specific.html for GCC Host/Target specific installation notes.
RedHat Linux 8.0 / RedHat's gcc 3.2 20020903
  bgcc 3.2: RedHat's libc is newer than gcc-3.2 expects and ctype is different.
RedHat Linux 7.1 / RedHat's gcc 2.96 20000731
  bgcc 3.1: When loading executables built with bounds checking,
    RedHat's gdb 5.0rh-5 gets
    "Dwarf Error: Cannot handle DW_FORM_strp in DWARF reader".
    gdb-5.2 built from source works OK.
RedHat Linux 6.0 / RedHat's egcs-2.91.66 19990314
  bgcc 3.1: gcc 3.1 requires updating binutils and gdb.
    I built binutils 2.12.1 and gdb 5.2 from source and forced the build
    to use them with
    --with-as=<path-to-GNU-as> --with-gnu-as --with-ld=<path-to-GNU-ld> --with-gnu-ld
SCO OpenServer 5.0.5 / SCO cc
  bgcc 4.0.1: The bgcc 4.0.1 patches include a fix for config.gcc
    for the gcc "machmode.def: undefined symbol: BITS_PER_UNIT" error.
    See http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=7623
  The bgcc 4.0.1 build needs 428 MB (132 MB for source + 296 MB for objects).
Solaris 2.6 / gcc 2.7.2.3 + binutils 2.9.1 from http://www.sunfreeware.com
  bgcc 3.1: If you get an error about "libgcc.map: file format not recognized",
    use make.sh with "-with-gnu" to force a ./configure with
    --with-as=<path-to-GNU-as> --with-gnu-as --with-ld=<path-to-GNU-ld> --with-gnu-ld
  The sunfreeware bison-1.50 fails on c-parse.y.  bison-1.28 is OK.
  The Solaris 5.8 /usr/ccs/bin/m4 fails on c-parse.in.  gnu m4-1.4 is OK.
  The bgcc 4.0.1 build needs 484 MB (140 MB for source + 343 MB for the objects).

To build a bounds checking gcc:
  cd /u/gnu					# go to a work area
  tar xzf egcs-yyyymmdd.tar.gz			# unpack gcc
  mv egcs-yyyymmdd begcs-yyyymmdd		# rename the egcs directory
  cd begcs-yyyymmdd				# go to the begcs directory
  patch -p1 -T < egcs-yyyymmdd-begcs-yyyymmdd.pat	# apply the patches
  touch gcc/c-parse.in				# force a rebuild of .y and .c
  mkdir objdir					# make an object file area
  cd objdir					# enter the area
  /u/gnu/begcs-yyyymmdd/configure		# initialize the build
  make bootstrap				# do the build

The patches change c-parse.in but do not include the generated .y or .c files.
You must "touch" gcc/c-parse.in after applying the patches, and you will need
yacc or bison.  gcc snapshots use bison-1.28.  The bison-1.25 on SuSE 6.2
generates different tables than bison-1.28 and might cause problems.

Many versions of gcc fail to bootstrap unless you set CFLAGS=-O0 to disable
optimization.  This reflects gcc problems.  The bounds checking patches have
no effect on the generated code unless you compile with "-fbounds-checking".

The script gcc/bounds/make.sh does the touch command, configures with an
object directory and does a make bootstrap.  You can run this script from
the top level directory immediately after applying the patches.

Building a C-only version of gcc takes less time and uses less disk space.
Also, some gcc snapshots have problems with languages other than C.
Since the bounds checker mainly does C, you can use
  /u/gnu/begcs-yyyymmdd/configure --enable-languages=c
or
  ./gcc/bounds/make.sh -langc

You can run your new begcs without installing it through the script
  /u/gnu/begcs-yyyymmdd/gcc/bounds/bgcc
If you build in a different area or copy the script, you will need
to edit the initial sequence that locates the root directory.

You can test the bounds checker with
  cd /u/gnu/begcs-yyyymmdd/gcc/bounds/tests
  chmod +x ../bgcc
  make CC=../bgcc
All tests should return OK.

If you want to experiment with changes, you can recompile your changes with
  cd objdir
  make bootstrap3

I started with Herman van Brugge's bounds checking patches at
http://sourceforge.net/projects/boundschecking/
In addition to updating Richard Jones's work for gcc-2.7, he added some lookup
optimizations and support for threads.  Herman updates the patches only for
gcc releases.  If the latest gcc release works for you, you should use his
patches instead of mine since gcc releases are more stable than snapshots.

As I have time, I will put patches into
http://williambader.com/bounds/example.html#download

You may freely mix objects compiled with and without bounds checking.
I find this convenient because I must link programs to third-party object
libraries.

These patches are unrelated to the fat pointer bounds checking patches by Greg
McGary gkm@eng.ascend.com which change the size of pointers and require building
modified versions of libc and every other library that your program calls.
I have heard that Greg's patches will eventually be incorporated into gcc.
If you can use Greg's fat pointer bounds checker, it has the advantage of
better run-time performance and support for languages other than C.

William Bader
email: williambader@hotmail.com
www:   http://williambader.com