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From: Segher Boessenkool <segher@kernel.crashing.org>
To: David Edelsohn <dje@watson.ibm.com>
Cc: Andrew Pinski <pinskia@gmail.com>,
	gcc@gcc.gnu.org,         Zack Weinberg <zack@codesourcery.com>
Subject: Re: RFC: Simplify rules for ctz/clz patterns and RTL
Date: Wed, 15 Aug 2007 20:33:00 -0000	[thread overview]
Message-ID: <e97702b184cbfb3f295b74dd5204a192@kernel.crashing.org> (raw)
In-Reply-To: <200708151955.l7FJtvOf031002@makai.watson.ibm.com>

> 	I think the cost would be something like:

> +    case POPCOUNT:
> +      *total = COSTS_N_INSNS (3);
> +      return false;

Is that the cost when using popcountb?  It is a lot more
expensive when that instruction isn't available (like on
most current machines).

The rest (i.e. CLZ, CTZ) looks good to me.


Segher

  reply	other threads:[~2007-08-15 20:05 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
2007-08-15 19:53         ` David Edelsohn
2007-08-15 20:04         ` David Edelsohn
2007-08-15 20:33           ` Segher Boessenkool [this message]
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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