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Re: [patch] fold-const.c: Don't transform X & C into (X >> C') & 1in fold_binary.

From: Jeffrey A Law <law at redhat dot com>
To: Richard Henderson <rth at redhat dot com>
Cc: Kazu Hirata <kazu at cs dot umass dot edu>, rsandifo at redhat dot com, gcc-patches at gcc dot gnu dot org, roger at eyesopen dot com
Date: Wed, 20 Apr 2005 17:51:15 -0600
Subject: Re: [patch] fold-const.c: Don't transform X & C into (X >> C') & 1in fold_binary.
Organization: Red Hat, Inc
References: <20050420.172552.50360813.kazu@cs.umass.edu> <87r7h5jf6g.fsf@firetop.home> <20050420.180456.127201770.kazu@cs.umass.edu> <20050420224648.GC5549@redhat.com>
Reply-to: law at redhat dot com

On Wed, 2005-04-20 at 15:46 -0700, Richard Henderson wrote:
> On Wed, Apr 20, 2005 at 06:04:56PM -0400, Kazu Hirata wrote:
> > If you like, I'd be happy to teach fold_binary to transform
> > (a >> 2) & 1 != 0 back to a & 4 != 0 for you
> 
> Having a canonical representation wouldn't be a bad thing.
That's probably the single biggest thing I'd like to see out
of this work -- a canonical form for expressing bit tests
and hopefully some simplifications of the expanders and
maybe RTL optimizers as a result.

Jeff

References:
- [patch] fold-const.c: Don't transform X & C into (X >> C') & 1 infold_binary.
  - From: Kazu Hirata
- Re: [patch] fold-const.c: Don't transform X & C into (X >> C') & 1in fold_binary.
  - From: Richard Sandiford
- Re: [patch] fold-const.c: Don't transform X & C into (X >> C') & 1in fold_binary.
  - From: Kazu Hirata
- Re: [patch] fold-const.c: Don't transform X & C into (X >> C') & 1 in fold_binary.
  - From: Richard Henderson

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