From: "Coline Lelong-Pantel" <coline.lelong-pantel@laposte.net>
To: "tprince" <tprince@myrealbox.com>
Cc: "gcc-help" <gcc-help@gcc.gnu.org>
Subject: Re: question about gcc assembly
Date: Tue, 27 Jun 2006 14:21:00 -0000 [thread overview]
Message-ID: <J1IVV9$E9E29DE1EC4D81668447541A33E8D5DD@laposte.net> (raw)
> Both gcc versions you quote are fairly old; if efficiency
interests you,
> you might try a current version. Were you able to show a
significant
> difference in performance on a CPU which is important to you?
I have not checked that, my goal is to produce, if it is
possible, the same assembly code.
I would
> guess the most important reason for avoiding use of eax here
would be to
> keep that register available for other use. The
optimization could be
> affected by compiler switches (-Os, -O2) or by selection of
-march
> option, and many other possibilities.
If I try using optimisation flags or -march, i get a
completely different code.
> Newer CPUs have hardware merging of operations, as well as
stalls on
> certain immediate data operations, so it is impossible to
know the
> performance implications from what you have presented.
What do you mean by "hardware merging of operations" ?
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next reply other threads:[~2006-06-27 14:21 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-06-27 14:21 Coline Lelong-Pantel [this message]
-- strict thread matches above, loose matches on Subject: below --
2006-06-27 8:04 Coline Lelong-Pantel
2006-06-27 13:57 ` Tim Prince
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