Re: [Bug-gnubg] Re: Bug? Pruning On/Pruning Off gives significantly different results at 4ply

[Christian Anthon]

On my single core athlon the results are perfectly normal. I assume
that we are seeing another compiler bug. The one we found recently
couldn't be reproduced on this machine either.

Linux anthon-desktop 2.6.29.6-217.2.16.fc11.i686.PAE #1 SMP Mon Aug 24
17:16:21 EDT 2009 i686 athlon i386 GNU/Linux

gcc (GCC) 4.4.1 20090725 (Red Hat 4.4.1-2)

Multiple threads supported.
SSE/SSE2 supported.


    1. Cubeful 4-ply    10/6 5/2                     Eq.:  +0.558
       0.810 0.002 0.000 - 0.190 0.000 0.000
        4-ply cubeful prune
    2. Cubeful 4-ply    10/3                         Eq.:  +0.555 ( -0.003)
       0.809 0.002 0.000 - 0.191 0.000 0.000
        4-ply cubeful prune
    3. Cubeful 4-ply    10/6 4/1                     Eq.:  +0.551 ( -0.007)
       0.807 0.002 0.000 - 0.193 0.000 0.000
        4-ply cubeful prune
    4. Cubeful 4-ply    9/6 9/5                      Eq.:  +0.542 ( -0.017)
       0.801 0.009 0.000 - 0.199 0.002 0.000
        4-ply cubeful prune


    1. Cubeful 4-ply    10/6 5/2                     Eq.:  +0.560
       0.810 0.002 0.000 - 0.190 0.000 0.000
        4-ply cubeful
    2. Cubeful 4-ply    10/3                         Eq.:  +0.558 ( -0.002)
       0.810 0.002 0.000 - 0.190 0.000 0.000
        4-ply cubeful
    3. Cubeful 4-ply    10/6 4/1                     Eq.:  +0.552 ( -0.008)
       0.807 0.002 0.000 - 0.193 0.000 0.000
        4-ply cubeful
    4. Cubeful 4-ply    9/6 9/5                      Eq.:  +0.540 ( -0.019)
       0.800 0.009 0.000 - 0.200 0.002 0.000
        4-ply cubeful


2009/8/31 Michael Petch <address@hidden>:
>
> On 31/08/09 3:33 PM, "Øystein Johansen" <address@hidden> wrote:
>
> * /Should/ means that it should give the same answer. I have tested a lot of
> inputs and got the desired output, however..... there can be surprises.
>
> Unless there is a bug or there is a precision change there is a difference
> between the outputs pre-patch and post patch versions. I am not the only one
> to have seen it. Now what I haven’t ruled out is that an unintended side
> effect of something else (optimizations, sse2 compiler bug etc).
>
> I am running some eval tests today., When finished I will take out the
> latest CVS, and make 2 builds. No Multithreading with SSE only, and No
> Multithreading with SSE2 only (both builds with no compiler optimizations so
> no –O2 or -O3), I have a few thousand matches and I’ll analyze a random
> subset of the files on both versions (At 0 ply) and see if I can find any
> differences.
>
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