$ mips64-linux-gcc --version mips64-linux-gcc (GCC) 4.5.0 20091201 (experimental) [trunk revision 154864]
The fine GCC documentation says: -mmad -mno-mad Enable (disable) use of the mad, madu and mul instructions, as provided by the R4650 ISA. I get: $ mips64-linux-gcc -march=r5000 -mmad -S hello.c cc1: error: unrecognized command line option "-mmad" $ mips64-linux-gcc -march=r5000 -mno-mad -S hello.c cc1: error: unrecognized command line option "-mno-mad" But these undocumented options are accpeted: $ mips64-linux-gcc -march=r5000 -mad -S hello.c $ mips64-linux-gcc -march=r5000 -mno-ad -S hello.c -- Summary: Documented -mmad option not accepted. Product: gcc Version: 4.5.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: target AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: daney at gcc dot gnu dot org GCC build triplet: mips64-unknown-linux GCC host triplet: mips64-unknown-linux GCC target triplet: mips64-unknown-linux http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42661