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From: Niklas Holsti <niklas.holsti@tidorum.invalid>
Newsgroups: comp.lang.ada
Subject: Re: How to get Ada to ?cross the chasm??
Date: Fri, 11 May 2018 23:39:19 +0300
Organization: Tidorum Ltd
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Xref: reader02.eternal-september.org comp.lang.ada:52289
Date: 2018-05-11T23:39:19+03:00
List-Id: <comp.lang.ada>

On 18-05-11 22:50 , Paul Rubin wrote:
> Niklas Holsti <niklas.holsti@tidorum.invalid> writes:

>> If one uses specific array index types, as good Ada style requires, an
>> Ada compiler can trivially omit many array bounds checks for which a
>> bounds-checking C compiler would have to use a global data-flow
>
> If you mean the index is in an int range type, then the Ada compiler
> should have to make a range check every time you modify the index,
> unless it can statically prove that the new value is in range.

Yes, but often the compiler can do that.

> So you've just moved the check from one place to another.

Sometimes that is so. But sometimes the value is used in many places, or 
frequently, and modified in one place, or rarely, so the number of 
checks is reduced, in the static and/or dynamic measure.

-- 
Niklas Holsti
Tidorum Ltd
niklas holsti tidorum fi
       .      @       .