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