From: fjh@mundook.cs.mu.OZ.AU (Fergus Henderson)
Subject: Re: C's register keyword
Date: 1997/09/09
Date: 1997-09-09T00:00:00+00:00 [thread overview]
Message-ID: <5v3v3o$np5@mulga.cs.mu.OZ.AU> (raw)
In-Reply-To: 5v1k1v$3mq6$1@prime.imagin.net
dweller@news.imagin.net (David Weller) writes:
>C version:
>
> for (int i = 0; i < 10000; i++)
> for (int j = 0; j < 10000; j++)
> /*some nontrivial statement*/
>
>Ada version:
>
> for i in 0..9999 loop
> for j in 0..9999 loop
> --some nontrivial statement
> end loop;
> end loop;
>
>Using gcc/GNAT, you find that the Ada executable yields faster
>performance (assuming same optimization levels and identical times for
>the "some nontrivial statement".
I find that very hard to believe.
Perhaps I have misunderstood some of your assumptions.
Certainly if `i' and `j' are local (auto) variables whose
address is not taken, then gcc will (at -O1 or higher) put
them in registers, so I don't see why the Ada version would
be faster than the C version.
--
Fergus Henderson <fjh@cs.mu.oz.au> | "I have always known that the pursuit
WWW: <http://www.cs.mu.oz.au/~fjh> | of excellence is a lethal habit"
PGP: finger fjh@128.250.37.3 | -- the last words of T. S. Garp.
next prev parent reply other threads:[~1997-09-09 0:00 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
1997-09-06 0:00 C's register keyword Tristan Ludowyk
1997-09-06 0:00 ` Tarjei T. Jensen
1997-09-10 0:00 ` Richard Kenner
1997-09-08 0:00 ` Tucker Taft
1997-09-08 0:00 ` David Weller
1997-09-09 0:00 ` Fergus Henderson [this message]
1997-09-11 0:00 ` Robert Dewar
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