These ‘-m’ options are defined for the VMS implementations:
-mvms-return-codesmain. The default is to return POSIX-style condition (e.g. error) codes. -mdebug-main=prefix
-mmalloc64-mpointer-size=size
32’ or ‘short’ for 32 bit pointers, ‘64’ or ‘long’ for 64 bit pointers, and ‘no’ for supporting only 32 bit pointers. The later option disables pragma pointer_size.
© Free Software Foundation
Licensed under the GNU Free Documentation License, Version 1.3.
https://gcc.gnu.org/onlinedocs/gcc-6.3.0/gcc/VMS-Options.html