Source tarball generation:

1. check out source from svn repository
   svn co svn://svn.gna.org/svn/ghdl/trunk ghdl
2. cd to the script directory
   cd ghdl/translate/gcc/dist.sh
3. create a tarball ghdl-VERSION.tar.bz2
   ./dist.sh sources

Please refer to README in the svn source tree for details.