These -m options are defined for the VAX:
Do not output certain jump instructions (
aobleq and so on) that the Unix assembler for the VAX cannot handle across long ranges.
Do output those jump instructions, on the assumption that the GNU assembler is being used.
Output code for G-format floating-point numbers instead of D-format.
Enable Local Register Allocation. This is still experimental for the VAX, so by default the compiler uses standard reload.