To use the gcc package from sunfreeware.com you MUST install all of the SUNW developer packages that come on Sun's Solaris CDs.
The software used to create gcc 3.4.6 (the steps are very similar for earlier versions of gcc) was all from packages on sunfreeware.com. These include the gcc-3.3.2, bison-1.875d, flex-2.5.31, texinfo-4.2, autoconf-2.59, make-3.80, and automake-1.9 packages. It may also be important to install the libiconv-1.8 package to use some of the languages in gcc 3.4.6. See also a comment below about the libgcc package.
gunzip gcc-3.4.6.tar.gz tar xvf gcc-3.4.6.tar (this creates a directory gcc-3.4.6) cd gcc-3.4.6 mkdir objdir cd objdir ../configure --with-as=/usr/ccs/bin/as --with-ld=/usr/ccs/bin/ld --enable-shared --enable-languages-c,c++,f77 (I choose to use the as and ld that come with Solaris and are usually in the /usr/ccs/bin directory. These files are only there if the SUNW developer packages from the Solaris have been installed. The default installation directory is /usr/local.) make make install (this puts a lot of files in /usr/local subdirectories) and the gcc and other executables in /usr/local/bin.
In particular, gcc-3.4.6 offers support for the creation of 64-bit executables when the source code permits it. Programs like top, lsof, ipfilter, and others support, and may need, such compiles to work properly when running the 64-bit versions of Solaris 7, 8, and 9 on SPARC platforms. In some cases, simply using the -m64 flag for gcc during compiles (which may require either editing the Makefiles to add -m64 to CFLAGS or just doing gcc -m64 on command lines) works.
When you compile something with any of these compilers, the executable may end up depending on one or more of the libraries in /usr/local/lib such as libgcc_s.so. An end user may need these libraries, but not want the entire gcc file set. I have provided a package called libgcc (right now this is for gcc-3.3.x but a version for 3.4.x is being created) for each level of Solaris. This contains all the files from /usr/local/lib generated by a gcc package installation. An end user can install this or a subset. You can determine if one of these libraries is needed by running ldd on an executable to see the library dependencies.
I am happy to hear about better ways to create gcc or problems that may be specific to my packages. Detailed problems with gcc can be asked in the gnu.gcc.help newsgroup or related places.