From: Zack Weinberg <zack@codesourcery.com>
To: Andrew Pinski <pinskia@gmail.com>
Cc: Segher Boessenkool <segher@kernel.crashing.org>, gcc@gcc.gnu.org
Subject: Re: RFC: Simplify rules for ctz/clz patterns and RTL
Date: Wed, 15 Aug 2007 19:03:00 -0000 [thread overview]
Message-ID: <46C34C3D.3070707@codesourcery.com> (raw)
In-Reply-To: <de8d50360708151144o15f8ea21obd1d1bab21ffc581@mail.gmail.com>
Andrew Pinski wrote:
> On 8/15/07, Zack Weinberg <zack@codesourcery.com> wrote:
>> Is popcount really slow on PowerPC? (Compared to clz?)
> popcount is really popcount in bytes and then you do a multiple to get
> the real popcount. This is why it is slower than count leading zeros.
> Also popcount does not exist in most powerpc's while count leading
> zeros exist in all.
Makes sense. I don't suppose I could persuade you to teach rs6000
RTX_COSTS about clz and popcount...?
zw
next prev parent reply other threads:[~2007-08-15 18:56 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-08-11 6:45 Zack Weinberg
2007-08-11 10:54 ` Richard Kenner
2007-08-11 18:02 ` Zack Weinberg
2007-08-12 14:00 ` Segher Boessenkool
2007-08-13 0:13 ` Segher Boessenkool
2007-08-15 18:44 ` Zack Weinberg
2007-08-15 18:56 ` Andrew Pinski
2007-08-15 19:03 ` Zack Weinberg [this message]
2007-08-15 19:53 ` David Edelsohn
2007-08-15 20:04 ` David Edelsohn
2007-08-15 20:33 ` Segher Boessenkool
2007-08-15 21:09 ` David Edelsohn
2007-08-15 21:24 ` Segher Boessenkool
2007-08-15 21:54 ` David Edelsohn
2007-08-15 19:37 ` Jan Hubicka
2007-08-15 19:56 ` Segher Boessenkool
2007-08-13 17:11 Joern Rennecke
[not found] ` <46C34C06.3000103@codesourcery.com>
2007-08-15 22:53 ` Joern Rennecke
2007-08-15 19:27 Zack Weinberg
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