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Re: RFC: Simplify rules for ctz/clz patterns and RTL

From: Jan Hubicka <hubicka at ucw dot cz>
To: Zack Weinberg <zack at codesourcery dot com>
Cc: Segher Boessenkool <segher at kernel dot crashing dot org>, gcc at gcc dot gnu dot org
Date: Wed, 15 Aug 2007 21:34:28 +0200
Subject: Re: RFC: Simplify rules for ctz/clz patterns and RTL
References: <46BD5B17.9080009@codesourcery.com> <62defd1ecb56eda092535c7147d5d3c6@kernel.crashing.org> <46C34786.3@codesourcery.com>

> 
> Is popcount really slow on PowerPC?  (Compared to clz?)  Ideally one 
> would choose between the two expansions based on RTL costs, but the only 
>  architectures it matters for are i386 and powerpc, and neither of them 
> define the cost of either clz or popcount.

Of course adding a popcount/clz cost into i386 cost tables is easy and
probably most correct thing to do :)

Honza
> 
> zw

References:
- RFC: Simplify rules for ctz/clz patterns and RTL
  - From: Zack Weinberg
- Re: RFC: Simplify rules for ctz/clz patterns and RTL
  - From: Segher Boessenkool
- Re: RFC: Simplify rules for ctz/clz patterns and RTL
  - From: Zack Weinberg

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