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Re: [patch] tuning gcc for Intel Core2


On Tue, Nov 14, 2006 at 07:49:56AM -0800, H. J. Lu wrote:
> 
> Can you turn on x86_rep_movl_optimal for -mtune=generic to see what
> it does for SPEC CPU 2K on both 32bit and 64bit?
> 

Here are the 64bit SPEC CPU 2K results of -O2 + x86_rep_movl_optimal
vs. -O2.  There are little changes in SPEC CPU 2K FP.  For SPEC CPU 2K
INT:

On Core 2 Duo
			-O2 + x86_rep_movl_optimal vs -O2
164.gzip                         -0.0724113%
175.vpr                          -0.175234%
176.gcc                          14.6647%
181.mcf                          -0.475687%
186.crafty                       0.0384911%
197.parser                       0.322841%
252.eon                          0.039604%
253.perlbmk                      1.15354%
254.gap                          0.319781%
255.vortex                       0.0425532%
256.bzip2                        -0.14918%
300.twolf                        -0.0391543%
Est. SPECint_base2000            1.23335%

On Nocona

164.gzip                         0.0954198%
175.vpr                          -0.286533%
176.gcc                          10.2731%
181.mcf                          0.871731%
186.crafty                       -0.519818%
197.parser                       -0.205761%
252.eon                          -0.285225%
253.perlbmk                      0.306185%
254.gap                          -0.119474%
255.vortex                       0.406977%
256.bzip2                        -0.541377%
300.twolf                        -3.44411%
Est. SPECint_base2000            0.519673%

On Core 2 Duo

			-O2 + x86_rep_movl_optimal vs -O2 -mtune=core2
164.gzip                         0.729927%
175.vpr                          -1.09954%
176.gcc                          -0.174292%
181.mcf                          -0.94687%
186.crafty                       0.932039%
197.parser                       0.566343%
252.eon                          1.1209%
253.perlbmk                      -0.625244%
254.gap                          -0.27248%
255.vortex                       1.42364%
256.bzip2                        0.500501%
300.twolf                        0%
Est. SPECint_base2000            0.146413%

So for 64bit, -O2 + x86_rep_movl_optimal is better than -O2 and
-O2 -mtune=core2 on Core 2 Duo and Nocona. I suspect that we will
see similar trend on Opteron.

Jan, given what we have now, should we turn on x86_rep_movl_optimal
for m_GENERIC64 if it will also improve Opteron? We can always turn it
off when your memory optimization is in.


H.J.


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