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From: Martin <martin.dowie@btopenworld.com>
Newsgroups: comp.lang.ada
Subject: Re: Interesting performance quirk.
Date: Wed, 29 Oct 2008 03:19:53 -0700 (PDT)
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Date: 2008-10-29T03:19:53-07:00
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On Oct 29, 9:59=A0am, "Peter C. Chapin" <pcc482...@gmail.com> wrote:
> In any event I don't want to "resort" to assembly language or to
> removing the Ada mandated checks (at least not in the final version).

With a bit of care a lot of checks can be avoided or removed by the
compiler. A fairly common example of this wrt loops is:

   type Array_Index_Type is range ...;
   type Array_Type is array (Array_Index_Type) of ...;

   procedure Example (A : Array_Type) is
   begin
      for I in Array_Index_Type loop
         -- Do something with array I - a check is often included
      end loop;
   end Example;

is better written as:

   procedure Example (A : Array_Type) is
   begin
      for I in A'Range loop
         -- Do something with array I - no need for a check
      end loop;
   end Example;

I'm not a language lawyer, so I can't tell if that's compiler
inefficiencies or what the language requires but this was certainly
the behaviour of several compilers I've used***.

Cheers
-- Martin

*** I haven't checked this recently!!! :-)