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Date: Tue, 12 May 2009 13:07:25 +0200
From: Georg Bauhaus <rm.dash-bauhaus@futureapps.de>
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Subject: Re: Use aggregates (Was: Allocation question)
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Date: 2009-05-12T13:07:25+02:00
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Brian Drummond schrieb:

> If anything gives Ada the reputation for inefficiency and bloat, it's that sort
> of missed opportunity, and not the language itself.

(Did you try this with C99's variable length arrays?)

> There is no fundamental reason why the compiler can't do as good a job as I can
> at unrolling that into loops. And unfortunately, you have thrown away half the
> point of using Ada, if you have to write C in Ada to match the performance of C.

GNAT does seem to emit loop instructions for the following
input.  I get a REPZ in the assembly listing.  What do you get?

package A is

   pragma Pure;

   subtype Intensity is Natural range 0 .. 255;
   type Index is range 1 .. 100;
   type List is array(Index) of Intensity;

   Zero: constant List := List'(others => 0);

   function Is_Zero(Item: List) return Boolean;

end A;

package body A is

   function Is_Zero(Item: List) return Boolean is
   begin
      return Item = Zero;
   end Is_Zero;

end A;