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[RFC] [PATCH, i386] Adjust unroll factor for bdver3 and bdver4

From: "Gopalasubramanian, Ganesh" <Ganesh dot Gopalasubramanian at amd dot com>
To: "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>
Cc: "Uros Bizjak (ubizjak at gmail dot com)" <ubizjak at gmail dot com>, "Richard Guenther <richard dot guenther at gmail dot com> (richard dot guenther at gmail dot com)" <richard dot guenther at gmail dot com>, "borntraeger at de dot ibm dot com" <borntraeger at de dot ibm dot com>, "H.J. Lu (hjl dot tools at gmail dot com)" <hjl dot tools at gmail dot com>, "Jakub Jelinek (jakub at redhat dot com)" <jakub at redhat dot com>
Date: Wed, 20 Nov 2013 18:26:11 +0000
Subject: [RFC] [PATCH, i386] Adjust unroll factor for bdver3 and bdver4
Authentication-results: sourceware.org; auth=none

Hi,

Steamroller processors contain a loop predictor and a loop buffer, which may make unrolling small loops less important.
When unrolling small loops for steamroller, making the unrolled loop fit in the loop buffer should be a priority.

This patch uses a heuristic approach (number of memory references) to decide the unrolling factor for small loops.
This patch has some noise in SPEC 2006 results. 

Bootstrapping passes.

I would like to know your comments before committing.

Regards
Ganesh

Attachment: loop_unroll_bdver3.patch
Description: loop_unroll_bdver3.patch

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