Re: Overhead for type conversions?

["Robert I. Eachus" <rieachus@attbi.com>]

Bobby D. Bryant wrote:

> and given that run-time range checks are enabled, should I expect my
> compiler to execute range checking code for each f1*f2 multiplication,
> or will the compiler conclude from the definitions that the two types
> are always convertible without error regardless of the specific value,
> and thus not generate any code for a range check?
> 
> (In practice the compiler is GNAT.)

GNAT chooses IEEE representation for Float with non-signalling NaNs.  In 
other words there are operation which will generate +infinity or 
-infinity but no constraint checks.

Of course this means that if you really want to force a Constraint_Error 
you have to assign a Float to a variable with a constraint.  To 
reference a huge amount of sound and fury going on right now, something 
like:

   BH := Short_Integer(Some_Float_Value);

will do just fine. (But then you have to decide how the exception should 
be handled. ;-)

-- 

                                                        Robert I. Eachus

�In an ally, considerations of house, clan, planet, race are 
insignificant beside two prime questions, which are: 1. Can he shoot? 2. 
Will he aim at your enemy?� -- from the Laiden novels by Sharon Lee and 
Steve Miller.