I've been considering doing some work with the Saturn after I'm done with the Sega CD, but alas, I have no idea what version of gcc SGL uses. I'm wondering if it's an old MinGW, or Cygwin, or exeGCC, or what.
SGL used the Hitachi SH-2C compiler, which would now be the Renesas SH C compiler. At least in the early days. SGL itself, incedentally, was mostly written in GAS. SNASMSH2 was the assembler used (ASMSH with the Psy-Q). Use the COFF version of GNUSH for compatability with the libraries. I'd recommend giving the DTS documents a read for more information.
Well, I found my compilers on some old DTS cds, upped them to the downloads section too. I guess lock/trash this staffers