`-m*': platform-specific flags

Some flags only make sense for particular target platforms.

`-mlong-calls':

(HPPA machines) Means to pass the like-named option to GCC. Required for Very Big modules, maybe. (Probably means you're in trouble...)

`-monly-[432]-regs':

(iX86 machines) GHC tries to "steal" five registers from GCC, for performance reasons; it almost always works. However, when GCC is compiling some modules with five stolen registers, it will crash, probably saying:

Foo.hc:533: fixed or forbidden register was spilled.
This may be due to a compiler bug or to impossible asm
statements or clauses.

Just give some registers back with `-monly-N-regs'. Try `4' first, then `3', then `2'. If `2' doesn't work, please report the bug to us.