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From: "Jeffrey R. Carter" <spam.jrcarter.not@spam.not.acm.org>
Newsgroups: comp.lang.ada
Subject: Re: GNAT can't vectorize Real_Matrix multiplication from
 Ada.Numerics.Real_Arrays. What a surprise!
Date: Sun, 18 Feb 2018 14:31:15 +0100
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On 02/18/2018 01:05 PM, Bojan Bozovic wrote:
> Thanks very much for clarification! It's always good to learn something new, I suppose.

The real optimization in your example seems to be that the compiler optimizes 
away the 10E6 loop around the in-line code, but not around the call to "*". 
Removing both loops gives similar times for both multiplications. The call to 
"*" will never be as fast because it copies its result into your variable. 
Replacing Ada.Numerics.Real_Arrays with an instantiation of 
Ada.Numerics.Generic_Real_Arrays gives an additional factor of 2 reduction.

-- 
Jeff Carter
Just as Khan was hindered by two-dimensional thinking in a
three-dimensional situation, so many developers are hindered
by sequential thinking in concurrent situations.
118