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

[Jeffrey Carter <spam.jrcarter.not@spam.not.acm.org>]

On 06/17/2013 12:15 PM, Peter Brooks wrote:
 >
 > 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?
 > More or less.

IMO, leaving on checks speeds things up a bit, if you're interested in correct 
code; code without buffer-overflow and integer-overflow vulnerabilities and the 
like. An Ada compiler can optimize away many index checks, for example, which 
doesn't happen to checks manually inserted in a language without automatic 
checks. So it should be the case that correct code in Ada is faster than 
equivalent code in a language without automatic checks.

Of course, if correctness isn't an issue, then things might work otherwise. But 
if correctness isn't an issue, the null program should be an acceptable solution 
to any problem, and that should be just as fast in Ada as in any other language.

 > 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.

There's always the Ada (83) beats assembler paper:

http://www.seas.gwu.edu/~adagroup/sigada-website/lawlis.html

-- 
Jeff Carter
"Pray that there's intelligent life somewhere up in
space, 'cause there's bugger all down here on earth."
Monty Python's Meaning of Life
61