5.9. GCC-4.7.2 - Pass 2

5.9.1. Installation of GCC

Our first build of GCC has installed a couple of internal system headers. Normally one of them, limits.h will in turn include the corresponding system limits.h header, in this case, /tools/include/limits.h. However, at the time of the first build of gcc /tools/include/limits.h did not exist, so the internal header that GCC installed is a partial, self-contained file and does not include the extended features of the system header. This was adequate for building the temporary libc, but this build of GCC now requires the full internal header. Create a full version of the internal header using a command that is identical to what the GCC build system does in normal circumstances:

cat gcc/limitx.h gcc/glimits.h gcc/limity.h > \
  `dirname $($LFS_TGT-gcc -print-libgcc-file-name)`/include-fixed/limits.h

For x86 machines, a bootstrap build of GCC uses the -fomit-frame-pointer compiler flag. Non-bootstrap builds omit this flag by default, and the goal should be to produce a compiler that is exactly the same as if it were bootstrapped. Apply the following sed command to force the build to use the flag:

cp -v gcc/Makefile.in{,.tmp}
sed 's/^T_CFLAGS =$/& -fomit-frame-pointer/' gcc/Makefile.in.tmp \
  > gcc/Makefile.in

Once again, change the location of GCC's default dynamic linker to use the one installed in /tools.

for file in \
 $(find gcc/config -name linux64.h -o -name linux.h -o -name sysv4.h)
do
  cp -uv $file{,.orig}
  sed -e 's@/lib\(64\)\?\(32\)\?/ld@/tools&@g' \
  -e 's@/usr@/tools@g' $file.orig > $file
  echo '
#undef STANDARD_STARTFILE_PREFIX_1
#undef STANDARD_STARTFILE_PREFIX_2
#define STANDARD_STARTFILE_PREFIX_1 "/tools/lib/"
#define STANDARD_STARTFILE_PREFIX_2 ""' >> $file
  touch $file.orig
done

As in the first build of GCC it requires the GMP, MPFR and MPC packages. Unpack the tarballs and move them into the required directory names:

tar -Jxf ../mpfr-3.1.1.tar.xz
mv -v mpfr-3.1.1 mpfr
tar -Jxf ../gmp-5.1.1.tar.xz
mv -v gmp-5.1.1 gmp
tar -zxf ../mpc-1.0.1.tar.gz
mv -v mpc-1.0.1 mpc

Again, do not build the .info files. They are not needed here and are broken with the current version of makeinfo.

sed -i 's/BUILD_INFO=info/BUILD_INFO=/' gcc/configure

Create a separate build directory again:

mkdir -v ../gcc-build
cd ../gcc-build

Before starting to build GCC, remember to unset any environment variables that override the default optimization flags.

Now prepare GCC for compilation:

CC=$LFS_TGT-gcc \
AR=$LFS_TGT-ar                  \
RANLIB=$LFS_TGT-ranlib          \
../gcc-4.7.2/configure          \
    --prefix=/tools             \
    --with-local-prefix=/tools  \
    --with-native-system-header-dir=/tools/include \
    --enable-clocale=gnu        \
    --enable-shared             \
    --enable-threads=posix      \
    --enable-__cxa_atexit       \
    --enable-languages=c,c++    \
    --disable-libstdcxx-pch     \
    --disable-multilib          \
    --disable-bootstrap         \
    --disable-libgomp           \
    --with-mpfr-include=$(pwd)/../gcc-4.7.2/mpfr/src \
    --with-mpfr-lib=$(pwd)/mpfr/src/.libs

Compile the package:

make

Install the package:

make install

As a finishing touch, create a symlink. Many programs and scripts run cc instead of gcc, which is used to keep programs generic and therefore usable on all kinds of UNIX systems where the GNU C compiler is not always installed. Running cc leaves the system administrator free to decide which C compiler to install:

ln -sv gcc /tools/bin/cc