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Re: [PATCH] PR rtl-optimization/14851: Move three-linked combinepass before two-linked

From: Bernd Schmidt <bernds_cb1 at t-online dot de>
To: Uros Bizjak <uros at kss-loka dot si>
Cc: gcc-patches at gcc dot gnu dot org, Roger Sayle <roger at eyesopen dot com>
Date: Mon, 14 Mar 2005 10:59:37 +0100
Subject: Re: [PATCH] PR rtl-optimization/14851: Move three-linked combinepass before two-linked
References: <4235320D.601@kss-loka.si>

Uros Bizjak wrote:

I would like to resend a combiner patch that moves three-linked combine pass before two-linked pass. A long explanation with a benchmark result can be found in http://gcc.gnu.org/ml/gcc-patches/2004-09/msg02193.html.

This patch was considered too risky for 4.0 stage3 and thus queued for 4.1 via PR 17652.

Patch, diffed against current mainline is attached to this message. Patch is bootstrapped on i386-pc-linux-gnu, regtested c,c++.

2005-03-14 Uros Bizjak <uros@kss-loka.si>
   PR rtl-optimization/14851
   PR target/19150
   * combine.c (combine_instructions): Move 'three linked insns'
   pass before 'two linked insns' pass.

This may or may not be a good idea, but the problem you describe sounds more like an issue with the machine description - it shouldn't be sensitive to such implementation details in combine.

Bernd

Follow-Ups:
- Re: [PATCH] PR rtl-optimization/14851: Move three-linked combinepass before two-linked
  - From: Uros Bizjak

References:
- [PATCH] PR rtl-optimization/14851: Move three-linked combine passbefore two-linked
  - From: Uros Bizjak

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