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

From: James E Wilson <wilson at specifixinc dot com>
To: Richard Earnshaw <rearnsha at gcc dot gnu dot org>
Cc: gcc-patches <gcc-patches at gcc dot gnu dot org>
Date: Wed, 27 Apr 2005 15:08:41 -0700
Subject: Re: [patch] fold-const.c: Don't transform X & C into (X >> C') &1 in fold_binary.
References: <87r7h5jf6g.fsf@firetop.home> <20050420.180456.127201770.kazu@cs.umass.edu> <87br88eim3.fsf@firetop.home> <20050421.105441.20504321.kazu@cs.umass.edu> <1114406229.8780.59.camel@localhost.localdomain> <20050425145733.GA13119@nevyn.them.org> <1114606388.2729.29.camel@pc960.cambridge.arm.com>

Richard Earnshaw wrote:

  i = i - 1;
  if (i != -000000001) goto <L0>; else goto <L2>;

This is done by ivopts. There was just a thread about this on the gcc list, where we got the same complaint reported as an x86 regression. http://gcc.gnu.org/ml/gcc/2005-04/msg01242.html I suggested creating a bug report to document it. I don't think there is one yet. -- Jim Wilson, GNU Tools Support, http://www.SpecifixInc.com

References:
- 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') & 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') & 1in fold_binary.
  - From: Jeffrey A Law
- Re: [patch] fold-const.c: Don't transform X & C into (X >> C') & 1 in fold_binary.
  - From: Daniel Jacobowitz
- Re: [patch] fold-const.c: Don't transform X & C into (X >> C') & 1in fold_binary.
  - From: Richard Earnshaw

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