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From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
Subject: Re: Ada 2012 Constraints (WRT an Ada IR)
Date: Wed, 30 Nov 2016 16:17:50 -0600
Organization: JSA Research & Innovation
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Xref: news.eternal-september.org comp.lang.ada:32536
Date: 2016-11-30T16:17:50-06:00
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"Shark8" <onewingedshark@gmail.com> wrote in message 
news:8b3ea401-822b-4b51-be48-133861ef2e0b@googlegroups.com...
>On Tuesday, November 29, 2016 at 4:52:20 PM UTC-7, Randy Brukardt wrote:
>>
>> P0 and P1 are more likely to be optimized by a compiler (just because of 
>> the
>> many years of history). Perhaps P3 will catch up, but I wouldn't hold my
>> breath on that.
>
>Oh, BTW, *THIS* is exactly the motivation for having a uniform IR -- when 
>put into a
>common form then all optimizations on that object/construct are applicable. 
>This is to
>say that when P3 and P1 share a representation, every optimization of P1 is 
>possible
>for P3. (Despite syntax differences; again, assuming they're truly 
>equivalent in the same
>way that "Integer > 0" and "Integer in 1..Integer'Last" are.)

We don't do any optimizations in the high-level IR (that would be expression 
trees); that's all done in the conversion to the low-level IR (the stack 
based machine) or on that IR directly. There's few Ada constructs in the 
low-level IR.

In any case, the semantic description of the two constructs is different, 
although as far as I know the effect is the same. My experience in Ada is 
that whenever you think you can collapse Ada constructs, you eventually will 
be proved wrong, either by a new ACATS test, a customer bug report, or by 
some future change in the language (either a bug fix or new revision). I 
would generally reecommend avoiding that as much as possible.

                                     Randy.