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 21:24:00 -0000 [thread overview]
Message-ID: <7b48fcc425d0d180e04c73f4c789be68@kernel.crashing.org> (raw)
In-Reply-To: <200708152032.l7FKWtVY030118@makai.watson.ibm.com>
>>> I think the cost would be something like:
>>> + case POPCOUNT:
>>> + *total = COSTS_N_INSNS (3);
>>> + return false;
>
> Segher> Is that the cost when using popcountb? It is a lot more
> Segher> expensive when that instruction isn't available (like on
> Segher> most current machines).
>
> Yes, but do we even create POPCOUNT rtx if the insn isn't
> supported? Wouldn't we expand or create libcall early?
I don't know, there's only one way to find out... :-)
Segher
next prev parent reply other threads:[~2007-08-15 21:09 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
2007-08-15 21:09 ` David Edelsohn
2007-08-15 21:24 ` Segher Boessenkool [this message]
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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