[Mingw-users] Rebuilding GCC 4.2.1

[Stephen L. <sld...@so...>]

Hi all,

Here are my working draft on rebuilding gcc-4.2.1-dw2.  If there is
enough interest I can clean it up and perhaps put it into the mingw wiki.

A few questions:
- I have only built C & C++.  What packages are needed for the other
  languages?
- Does hard links only work on NTFS?
- How do you create the binary packages (gcc-core-*, etc) from the
  install tree?
- How do you change the version string?
- Does it matter if you build with --prefix=/mingw but finally install
  it somewhere else?

Recompiling MinGW GCC

1. Setting up the environment
=============================

x. Decide where to build your packages.
You need a directory that is mounted "identically", that is, accessible
with the same path under Windows and cygwin/mingw.  We'll put the
source and build tree there.

Here I'll use the directory x:\develop.

x. Install MSYS/MinGW.
Only the base packages is needed here.  I did not install GCC here as
it defaults to the 3.x version. Here I assume you installed it under x:
\mingw.

Mount the build directory under MSYS by editing its /etc/fstab file.

x. Install gcc 4.x.
Download gcc-4.x from the MinGW release page and untar it to the mingw
installation directory. You'll need the core package (gcc), and g++
also to build pthreads.

I used the 4.2.1-dw2 version.

msys$ cd /mingw
msys$ tar zxvf gcc-core-4.2.1-dw2.tar.gz
msys$ tar zxvf gcc-g++-4.2.1-dw2.tar.gz

msys$ cd /mingw/bin
msys$ ln gcc-dw2.exe gcc.exe
msys$ ln g++-dw2.exe g++.exe
msys$ ln cpp-dw2.exe cpp.exe

/*
draft:
rm c++-dw2.exe mingw32-c++-dw2.exe mingw32-g++-dw2.exe
ln g++-dw2.exe c++-dw2.exe
ln g++-dw2.exe mingw32-c++-dw2.exe
ln g++-dw2.exe mingw32-g++-dw2.exe
ln g++-dw2.exe g++.exe
ln g++-dw2.exe c++.exe

rm gcc-dw2.exe mingw32-gcc-dw2.exe
ln mingw32-gcc-4.2.1-dw2.exe gcc-dw2.exe
ln mingw32-gcc-4.2.1-dw2.exe mingw32-gcc-dw2.exe
ln mingw32-gcc-4.2.1-dw2.exe gcc.exe

ln cpp-dw2.exe cpp.exe
ln gccbug-dw2 gccbug
ln gcov-dw2.exe gcov.exe
*/

x. Install a minimal cygwin <www.cygwin.com> environment.
It is possible to build under MinGW, however the release packages are
build under cygwin and I am trying to duplicate the setup used.

You'll only need the default install, plus the following packages.
Cygwin GCC is not needed.
- make (GNU make)
- diffutils (for cmp and patch)

Cygwin softlinks are unusable under native windows, so we need to disable
Cygwin's "ln" command and let gcc's build scripts use "cp" instead.

cygwin$ mv /usr/bin/ln /usr/bin/ln-bak

Mount the build and mingw directories under cygwin.

cygwin$ mkdir /develop
cygwin$ mkdir /mingw
cygwin$ mount "x:/develop" "/develop"
cygwin$ mount "x:/mingw" "/mingw"

x. Install pthreads-win32 <http://sourceware.org/pthreads-win32/>.
This is needed if you want to build libgomp.
Get the pthreads-win32 source from
ftp://sourceware.org/pub/pthreads-win32/.

I used pthreads-w32-2-8-0-release.tar.gz.

Build it under MSYS.  You need "-fkeep-inline-functions" otherwise it
won't build.

msys$ make clean GC
msys$ make clean GCE "GCE_CFLAGS += -fkeep-inline-functions"

Copy the relevent files to /mingw so libgomp build can find it.
(draft: if this doesn't work, use /mingw/mingw32 instead)

/mingw/bin:
pthreadGC2.dll  pthreadGCE2.dll

/mingw/include:
pthread.h  sched.h  semaphore.h

/mingw/lib:
libpthreadGC2.a  libpthreadGCE2.a

Create a link so gcc can find it:
msys$ ln /mingw/lib/libpthreadGCE2 /mingw/lib/libpthread

x. Installing ??? (for fortran)
x. Installing ??? (for ada)

2. Building GCC
===============

Basically, follow gcc-4.2.1-build-dw2-2.sh but use cygwin for the build.

Get the source.
I used gcc-4.2.1-2-src.tar.gz from MinGW.

Unpack it under the build directory.
msys$ cd /develop
msys$ tar zxvf gcc-4.2.1-2-src.tar.gz

Create a directory for building.
msys$ mkdir /develop/build

Patch libgomp/configure.
Replace all lines that read
fopen ("conftest.val", "w");
with
fopen ("conftest.val", "wb");

To build the -dw2 version: (from gcc-4.2.1-build-dw2-2.sh):
msys$ cd /develop/build
msys$ rm ../gcc-4.2.1-2-src/gcc/BASE-VER \
  ../gcc-4.2.1-2-src/gcc/config/i386/t-mingw32 \
  ../gcc-4.2.1-2-src/libstdc ++-v3/config/os/mingw32/x-mingw32
msys$ ln ../gcc-4.2.1-2-src/gcc/BASE-VER-dw2 \
  ../gcc-4.2.1-2-src/gcc/BASE-VER \
msys$ ln ../gcc-4.2.1-2-src/gcc/config/i386/t-mingw32dw2 \
  ../gcc-4.2.1-2-src/gcc/config/i386/t-mingw32
msys$ ln ../gcc-4.2.1-2-src/libstdc++-v3/config/os/mingw32/x-mingw32dw2 \
  ../gcc-4.2.1-2-src/libstdc++-v3/config/os/mingw32/x-mingw32

Switch to cygwin to build.  I only build C and C++ for the moment.
cygwin$ cd /develop/build
cygwin$ ../gcc-4.2.1-2-src/configure  --with-gcc  --enable-libgomp \
 --host=mingw32 --build=mingw32 --target=mingw32 --program-suffix=-dw2 \
 --with-arch=i486 --with-tune=generic --disable-werror --prefix=/mingw \
 --with-local-prefix=/mingw --enable-threads --disable-nls \
 --enable-languages=c,c++ --disable-win32-registry \
 --disable-sjlj-exceptions --enable-libstdcxx-debug \
 --enable-cxx-flags='-fno-function-sections -fno-data-sections' \
 --enable-version-specific-runtime-libs --disable-bootstrap
cygwin$ make BOOTCFLAGS="-O2 -D__USE_MINGW_ACCESS" \
 CFLAGS="-O2 -D__USE_MINGW_ACCESS" \
 CXXFLAGS="-mthreads -O2" \
 LDFLAGS="-s -Wl,--stack=0x2000000" 2>err.log 1>out.log

3. Packaging
============
cygwin$ DEST=/develop/install
cygwin$ mkdir ${DEST}
cygwin$ make prefix=${DEST} install
cygwin$ make prefix=${DEST} -C gcc  install-shared-libgcc
cygwin$ make prefix=${DEST} -C mingw32/libstdc++-v3/ install-shared-libstdc++

...

4. Cleanup
============
Restore "ln" under cygwin.
cygwin$ mv /usr/bin/ln-bak /usr/bin/ln

-- 
Stephen Lee <sld...@so...>