[Gm2] Div Ceil overflow/underflow checking implemented

[Gaius Mulley]

Hi,

I've just git pushed (to trunk) some completed code which implements div
ceil checking for whole numbers.  Only div_floor remains unimplemented.
This code is used when -fiso -fsoft-check-all is employed.  Dejagnu
regression tests have also been committed.

I've run some limited benchmarks with -O2 with and without
-fsoft-check-all and see binaries increase by about 28% for an integer
maze application.  I'm wondering whether it might be beneficial to
introduce some finer grained check options?  On the positive side when
this is fully complete the compiler should be able to go beyond line
level reporting and determine which arithmetic token will cause an
overflow (sometimes at compile time)


regards,
Gaius