-msim-mmul=none-mmul=g13-mmul=rl78none, which uses software multiplication functions. The g13 option is for the hardware multiply/divide peripheral only on the RL78/G13 targets. The rl78 option is for the standard hardware multiplication defined in the RL78 software manual.
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Licensed under the GNU Free Documentation License, Version 1.3.
https://gcc.gnu.org/onlinedocs/gcc-4.9.3/gcc/RL78-Options.html