you said "installing compiler" which i assume you are not building it from source.
my recommendation would be to build from source:
download gcc source tarball from a gnu.gcc.org mirror site. You will download something like
gcc-4.9.4.tar.bz2. Get all the versions you need...
Important: if for example your IRIX 6.5 has gcc-3.2.3, then get and start with gcc-3.4.6 which is the last version of gcc-3. And once built then use that to build the last gcc-4.x.x version; then use that to build the last version of gcc-5.x.x and so on.
The big 3 dependencies GCC uses is
build gmp first since everything else is dependent on that, then build mpfr-3.1.6; then mpc-1.0.3 which is the one you are missing. Don' get mpfr-4.x you won't need it on IRIX, it's too new and will likely give you problems.
for any, do
./configure --help to see a list of build options, prior to doing
- ./make check
- ./make install
tar -xf gmp-6.1.2.tar.bz2
tar -xf mpfr-3.1.6.tar.gz
./configure --prefix=/opt/mpfr-3.1.6 --with-gmp=/opt/gmp-6.1.2
tar -xf mpc-1.1.0.tar.gz
./configure --prefix=/opt/mpc-1.1.0 --with-gmp=/opt/gmp-6.1.2 --with-mpfr=/opt/mpfr-3.1.6
for each gcc-#.x.x do the same process, using
./configure --prefix=/opt/gcc-#.x.x --with-gmp=/opt/gmp-6.1.2 --with-mpfr=/opt/mpfr-3.1.6 --with-mpc=/opt/mpc-1.1.0
then be sure to set
before building the next version of gcc.
https://gcc.gnu.org/mirrors.html or https://www.gnu.org/prep/ftp.html then choose closest then look under releases for the gcc tarball.
mpc might be more linux than irix, which is why you don't have it.