Backport AVX256 load/store split patches to gcc 4.6 for performance boost on latest AMD/Intel hardware.

Fang, Changpeng Changpeng.Fang@amd.com
Mon Jun 27 23:10:00 GMT 2011


Hi,

Attached are the patches we propose to backport to gcc 4.6 branch which are related to avx256 unaligned load/store splitting.
As we mentioned before,  The combined effect of these patches are positive on both AMD and Intel CPUs on cpu2006 and
polyhedron 2005.

0001-Split-32-byte-AVX-unaligned-load-store.patch
Initial patch that implements unaligned load/store splitting

0001-Don-t-assert-unaligned-256bit-load-store.patch
Remove the assert.

0001-Fix-a-typo-in-mavx256-split-unaligned-store.patch
Fix a typo.

0002-pr49089-enable-avx256-splitting-unaligned-load-store.patch
Disable unaligned load splitting for bdver1.

All these patches are in 4.7 trunk.

Bootstrap and tests are on-going in gcc 4.6 branch.

Is It OK to commit to 4.6 branch as long as the tests pass?

Thanks,

Changpeng 



________________________________________
From: Jagasia, Harsha
Sent: Monday, June 20, 2011 12:03 PM
To: 'H.J. Lu'
Cc: 'gcc-patches@gcc.gnu.org'; 'hubicka@ucw.cz'; 'ubizjak@gmail.com'; 'hongjiu.lu@intel.com'; Fang, Changpeng
Subject: RE: Backport AVX256 load/store split patches to gcc 4.6 for performance boost on latest AMD/Intel hardware.

> On Mon, Jun 20, 2011 at 9:58 AM,  <harsha.jagasia@amd.com> wrote:
> > Is it ok to backport patches, with Changelogs below, already in trunk
> to gcc
> > 4.6? These patches are for AVX-256bit load store splitting. These
> patches
> > make significant performance difference >=3% to several CPU2006 and
> > Polyhedron benchmarks on latest AMD and Intel hardware. If ok, I will
> post
> > backported patches for commit approval.
> >
> > AMD plans to submit additional patches on AVX-256 load/store
> splitting to
> > trunk. We will send additional backport requests for those later once
> they
> > are accepted/comitted to trunk.
> >
>
> Since we will make some changes on trunk, I would prefer to to do
> the backport after trunk change is finished.

Ok, thanks. Adding Changpeng who is working on the trunk changes.

Harsha

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