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Re: new sign/zero extension elimination pass

From: Paolo Bonzini <bonzini at gnu dot org>
To: Eric Botcazou <ebotcazou at adacore dot com>
Cc: Tom de Vries <tom at codesourcery dot com>, gcc-patches at gcc dot gnu dot org, Bernd Schmidt <bernds at codesourcery dot com>
Date: Thu, 28 Oct 2010 23:14:13 +0200
Subject: Re: new sign/zero extension elimination pass
Newsgroups: gmane.comp.gcc.patches
References: <4CBC698B.3080204@codesourcery.com> <201010221030.30363.ebotcazou@adacore.com>

On 10/22/2010 10:30 AM, Eric Botcazou wrote:

If not, why does it not use
the DF framework instead of recomputing DU chains manually?

Rather than on DU chains (which are a very expensive problem just because of its asymptotic complexity, so it's better to use it only on small regions such as loops), I'd be picky about usage of note_uses, which can be very simply replaced by a loop over the DF_INSN_USES vector.

Paolo

References:
- new sign/zero extension elimination pass
  - From: Tom de Vries
- Re: new sign/zero extension elimination pass
  - From: Eric Botcazou

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