This is the GCC used for compiling illumos.

The il-* branches contain the the patches used for building illumos, which are rebased versions of those used for Solaris/OpenSolaris, and then additional changes. The versions actually in use are tagged with il-VERSION-ilN where N version the illumos changes over the GCC version in question.

The wip/* branches are works in progress and should never be used

The codesourcery/* and sun/* branches contain the original GCCs as patched by CodeSourcery and Sun Microsystems for use compiling Solaris and OpenSolaris as was, and the GCCFSS patches of Sun's

When building the compilers for illumos use the flags generally used are:

i386

../../configure --prefix=/opt/gcc/$VER --with-as=/usr/sfw/bin/gas --with-gnu-as \
   --with-ld=/usr/bin/ld --without-gnu-ld --enable-languages="c,c++,objc" \
   --enable-shared  --with-mpfr-include=/usr/include/mpfr \
   --with-gmp-include=/usr/include/gmp \
   --with-pkgversion="Illumos $(git describe --all)" \
   --with-bugurl="http://github.com/richlowe/gcc/issues"

sparc

../../configure --prefix=/opt/gcc/$VER --without-gnu-as --with-as=/usr/ccs/bin/as" \
   --with-ld=/usr/bin/ld --without-gnu-ld --enable-languages="c,c++,objc" \
   --enable-shared  --with-mpfr-include=/usr/include/mpfr \
   --with-gmp-include=/usr/include/gmp \
   --with-pkgversion="Illumos $(git describe --all)" \
   --with-bugurl="http://github.com/richlowe/gcc/issues"

Please use the correct --with-bugurl and --with-pkgversion flags as appropriate for any modifications you make, but please also be sure that they accurately describe what is in use (ie, are not left at the defaults) either.