Help catching floating point exceptions

[Rowan Hughes]

In <SDL.91May29181249 at adagio.austin.ibm.com> sdl at adagio.austin.ibm.com (sdl) writes:
>In article <91149.150333AER7101 at TECHNION.BITNET> AER7101 at TECHNION.BITNET (Zvika Bar-Deroma) writes:
>Zvika> I've been told by my IBM rep.  that as IEEE didn't require that division
>Zvika> by zero  be trapped and  signalled, then (some/many/most)  RISC machines
>Zvika> don't, and he thinks, that unless  there's such a requirement from IEEE,
>Zvika> they won't also in the forseeable future.
>Your rep. is correct.  From IEEE 854-1987:  "There are five types of
>exceptions that shall be signaled when detected.  The signal entails
>setting a status flag, taking a trap, or possibly doing both".
>Moreover, IEEE requires that if you implement IEEE trapping, that
>"A trap handler should have the capabilities of a subroutine that can

DEC have released their new f77v3.0 compiler for the DECStations
(=R3000) and it traps all floating exceptions; the job aborts
with a core dump. I've done some benchmarking between the new and old
compilers (with and without fpe) and the performance has dropped by
less than 1/2%.  Fpe is enabled ALL the time, irrelevent of
compiler options. There is an option for the job to continue after
a fault, and the user is notified at the end of execution.
Integer overflow can be trapped also.

It can be done easily on RISC, with no loss in performance.


-- 
Rowan Hughes                                James Cook University
Marine Modelling Unit                       Townsville, Australia.
Dept. Civil and Systems Engineering         csrdh at marlin.jcu.edu.au