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Re: 3.0 vs 3.0.1 on oopack's Max


Hi and thank you very much for your feedback!

--- Richard Henderson <rth@redhat.com> wrote:
> You didn't mention how the compiler was configured, 
> or what options you gave for compilation.

Well, I did mention that the options were:

  -O2 -finline-limit=600

The compilers were built with a trivial:

  --prefix=... --enable-languages=c,c++,f77

> The performance regression is caused by
> 
> 3.0:
> >  8048912: 31 d2                 xor    %edx,%edx
> >  8048919: 0f 97 c2              seta   %dl
> >  804891c: 85 d2                 test   %edx,%edx
> 
> 3.0.1:
> >  8048917: 0f 97 c0              seta   %al
> >  804891a: 83 e0 01              and    $0x1,%eax
> 
> The 3.0.1 version has a partial register stall on
> %al.

Thanks for your analysis! I'm really puzzled by the
fact that (of course!) only very safe patches went in
in the branch between 3.0.0 and 3.0.1.

Is there something else I can do for you, RTL dumps or
whatever?!?

Cheers,
Paolo.


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