From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: 
X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00
	autolearn=unavailable autolearn_force=no version=3.4.4
Path: 
 eternal-september.org!reader01.eternal-september.org!reader02.eternal-september.org!news.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From: "Jeffrey R. Carter" <spam.jrcarter.not@spam.not.acm.org>
Newsgroups: comp.lang.ada
Subject: Re: Profiling Ada binaries
Date: Mon, 1 Aug 2016 16:36:41 -0700
Organization: Also freenews.netfront.net; news.tornevall.net;
 news.eternal-september.org
Message-ID: <nnome9$iac$1@dont-email.me>
References: <nmt6qe$3d6$1@gioia.aioe.org> <nmtcbq$6fh$1@dont-email.me>
 <nmtcns$81a$1@dont-email.me> <nn4dfh$1cog$1@gioia.aioe.org>
 <a9f6bc88-81e3-480f-9e2d-91060e1dbdb5@googlegroups.com>
 <04e12bd0-2c9d-f90d-2497-bf58593addfd@spam.spam>
 <845e12db-9e2c-4d0f-a3b0-19ac50f14d24@googlegroups.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 8bit
Injection-Date: Mon, 1 Aug 2016 23:36:44 -0000 (UTC)
Injection-Info: mx02.eternal-september.org;
 posting-host="d7c030f56102b58a2c16dea977db88bb";
	logging-data="18764"; mail-complaints-to="abuse@eternal-september.org";
	posting-account="U2FsdGVkX1+xhdVPMiBwCbkZ3Tg3fLA+Cdai7l3EP3c="
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101
 Thunderbird/45.2.0
In-Reply-To: <845e12db-9e2c-4d0f-a3b0-19ac50f14d24@googlegroups.com>
Cancel-Lock: sha1:bojgbuQSj1uQy8/ccipnjhtgi7U=
Xref: news.eternal-september.org comp.lang.ada:31245
Date: 2016-08-01T16:36:41-07:00
List-Id: <comp.lang.ada>

On 08/01/2016 03:40 PM, rieachus@comcast.net wrote:
> On Tuesday, July 26, 2016 at 4:37:31 AM UTC-4, Markus Schöpflin wrote:
>  
> 
>> Even using the non-generic versions I have not been able to get the hardware 
>> built-ins. The best I can achieve for a call to e.g. cos(X) is: 
> 
>>         call    ada__numerics__long_elementary_functions__cos
> 
> Again GNAT docs to the rescue: 15.1 Machine code insertions:

I think the OP would benefit from knowing why this is necessary.

If you look at the body of Ada.Numerics.Long_Elementary_Functions.Cos, you'll
probably find a call to {something that calls} the built-in function.

If you look at the requirements for the Cos function in Annex A and Annex G (if
implemented, which it is for GNAT), you'll find a number of requirements for
accuracy and special cases. If you look at the definition of the built-in
function, you'll likely find that it doesn't meet all of those requirements. Any
call to Cos has to involve wrapping a call to the built-in function in code to
ensure those requirements are met, so you won't find a call to the built-in
function in the generated code.

Even if the built-in function met all the requirements, the desire for the
compiler to be portable will result in the call to the built-in being squirreled
away, not produced by the code generator.

The general rule, "If you need specific machine code, use a machine-code
insertion," applies here. Of course, the result is non-portable code, while the
call to the language-defined library function is portable.

-- 
Jeff Carter
"Hello! Smelly English K...niggets."
Monty Python & the Holy Grail
08