I am trying to compile my C code to use soft multiplication in MIPS I as my hardware does not have a hard multiplier.
From this document (page 10): http://www.sm.luth.se/csee/courses/smd/137/doc/gcc.pdf indicates that "-mno-mul" option can be used to inform the compiler to not generate integer multiply/divide instructions and instead insert calls to multiply/divide subroutines.
However, when I feed in the "-mno-mul" option to my compiler, the error message returned is: unrecognized command line option "-mno-mul"
I tried googling for more information on "-mno-mul", but there is very limited search results returned. The option is not even listed here: https://gcc.gnu.org/onlinedocs/gcc/Option-Summary.html
My question is: Has the mno-mul option become obsolete? If so, is there a workaround for the compiler to generate code for soft multiplication?
This option is obsolete, since all MIPS architecture specifications since MIPS1 require an integer multiplier.
You might still be able to track down a copy of GCC 2.96 and compile using that. Or you could write a handler for the illegal instruction trap that implements soft multiplication.