info gcc

These ‘-m’ options are defined for the H8/300 implementations:

@gcctabopt -mrelax: Shorten some address references at link time, when possible; uses the linker option ‘-relax’. See (ld)H8/300 section `ld and the H8/300' in Using ld, for a fuller description.
@gcctabopt -mh: Generate code for the H8/300H.
@gcctabopt -ms: Generate code for the H8S.
@gcctabopt -mn: Generate code for the H8S and H8/300H in the normal mode. This switch must be used either with ‘-mh’ or ‘-ms’.
@gcctabopt -ms2600: Generate code for the H8S/2600. This switch must be used with ‘-ms’.
@gcctabopt -mint32: Make int data 32 bits by default.
@gcctabopt -malign-300: On the H8/300H and H8S, use the same alignment rules as for the H8/300. The default for the H8/300H and H8S is to align longs and floats on 4 byte boundaries. ‘-malign-300’ causes them to be aligned on 2 byte boundaries. This option has no effect on the H8/300.