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From: Ludovic Brenta <ludovic@ludovic-brenta.org>
Newsgroups: comp.lang.ada
Subject: Re: 64 bit codes
Date: Tue, 27 Sep 2011 07:50:31 -0700 (PDT)
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Date: 2011-09-27T07:50:31-07:00
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Mok-Kong Shen wrote on comp.lang.ada:
> For on 64-bit hardware a native 64-bit arithmetic
> operation shouldn't last very much longer than a corresponding 32-bit
> opeartion, I would think.

Only a benchmark can tell.  It is true that individual 64-bit machine
instructions are usually just as fast as their 32-bit counterparts but
64-bit words use up twice as much memory and, especially, cache memory
as 32-bit words.  The 64-bit ISA has 16 extra registers that may or
may not compensate for the increased cache pressure and decreased code
locality in your particular case.

--
Ludovic Brenta.