Re: Bug in 'gnatmake' (Was: Range check for type 'Integer')

[Shark8 <onewingedshark@gmail.com>]

On Monday, June 17, 2013 1:15:26 PM UTC-6, Peter Brooks wrote:
> On Jun 17, 6:50 pm, Robert A Duff <bobd...@shell01.TheWorld.com>
> 
> wrote:
> >
> > You usually want -g (debugging info).  And the debugger works
> > better if you turn off optimizations (-O0).
> >
> 
> Since you mention it, I'm interested to know if there are many Ada
> benchmarks.
> 
> Leaving on range, and other, checking must slow things down a tad, but
> turning the optimiser on must speed them up. It'll only really matter
> in CPU intensive stuff, but do you have any idea what the effects are?

I'm not sure about that -- one user here did some testing (C++ vs Ada [w/ checks and w/o; IIRC, all optimized]) and found that the difference in C++ and checked Ada was basically measurement-error. [Again, IIRC.]

Also to note is that Ada compilers are generally good about removing unneeded checks FOR INDEX IN THE_ARRAY'RANGE LOOP, for example doesn't need any checks precisely *because* the checks are implicit in setting the ranges of the for-loop -- and that is the oversimple case.

> 
> I know I could just take my code and try it, but it'd be interesting
> to have a bigger picture of the performance question.

IMO this is somewhat akin to some people trying to optimize the number of tasks based on their CPU core-count -- that's the stupid way to go, use TASKs to split your program logically and let the run-time handle managing things. If there's more tasks than Cores, great the cores will all be active -- if not then another core can do more meaningful work from somewhere else, great! (IE no need to optimize so prematurely.)