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Re: gcc loop unrolling problem ??

From: Robert Dewar <dewar at gnat dot com>
To: Matt Fago <fago at caltech dot edu>
Cc: Jan Hubicka <hubicka at ucw dot cz>, gcc at gcc dot gnu dot org
Date: Thu, 12 Feb 2004 11:13:27 -0500
Subject: Re: gcc loop unrolling problem ??
References: <402B9B84.70602@caltech.edu> <402B9E14.5050509@gnat.com> <402BA0FD.4070804@caltech.edu>

Matt Fago wrote:

My code contains quite a few simple loops with 9 iterations. While I'm surprised that gcc doesn't attempt to completely unroll these, I do agree that doing so will not necessarily improve performance.


What's important to realize is that unrolling such a loop fully may
well *degrade* performance by increasing I-cache pressure without
any compensating gain.

Follow-Ups:
- Re: gcc loop unrolling problem ??
  - From: Jan Hubicka

References:
- Re: gcc loop unrolling problem ??
  - From: Matt Fago
- Re: gcc loop unrolling problem ??
  - From: Robert Dewar
- Re: gcc loop unrolling problem ??
  - From: Matt Fago

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