From: "J. Mayer" <l_indien@magic.fr>
To: qemu-devel@nongnu.org
Cc: Blue Swirl <blauwirbel@gmail.com>,
Christian Eddie Dost <ecd@brainaid.de>
Subject: Re: [Qemu-devel] Mips 64 emulation not compiling
Date: Sat, 27 Oct 2007 16:12:50 +0200 [thread overview]
Message-ID: <1193494370.16781.308.camel@rapid> (raw)
In-Reply-To: <47233CA5.3070509@brainaid.de>
On Sat, 2007-10-27 at 15:27 +0200, Christian "Eddie" Dost wrote:
> The sparc64 popc works in O(lg(n))
No, it has a fix cost, whatever the operand is.
It has another advantage: it does not need any intermediate variable,
which is great when running on CISC host in the Qemu execution
environmnent.
> , the "optimized" code below work in
> O(n).
Yes. But it's false.... It shoudl be val &= val - 1
instead of val ^= val - 1...
[...]
I did tests on my PC, which will imho close the debate: the Sparc
implementation is at least 50 % faster. I did generate 2 ^ 29 random
numbers to achieve this test (and checked that the repartition was OK).
--
J. Mayer <l_indien@magic.fr>
Never organized
next prev parent reply other threads:[~2007-10-27 14:14 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-10-24 10:41 [Qemu-devel] Mips 64 emulation not compiling J. Mayer
2007-10-27 11:19 ` Thiemo Seufer
2007-10-27 12:24 ` J. Mayer
2007-10-27 13:01 ` Blue Swirl
2007-10-27 13:22 ` J. Mayer
2007-10-27 13:27 ` Christian "Eddie" Dost
2007-10-27 14:12 ` J. Mayer [this message]
2007-10-27 13:08 ` Thiemo Seufer
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