Re: PowerPC 64 x 32 bits performance

[Andrew Pinski <pinskia at physics dot uc dot edu>]

On Mar 4, 2005, at 6:57 PM, David Edelsohn wrote:

> > > > > > Edmar Wienskoski writes:
>
> Edmar> I checked with several gcc versions. Some of the spec2k
> Edmar> benchmarks has a considerable performance loss when
> Edmar> the benchmark is compiled with a 64 bits tool.
>
> Edmar> I looked into the assembler code generated for try_route 
> (route.c)
> Edmar> (compiled with: gcc -S -DSPEC_CPU2000 -O3 -m64 route.c)
> Edmar> and notice a considerable number of load instructions in the 64 
> bits one.
>
> Edmar> Does anyone have an insight on why this is happening ?
>
> 	GCC 4.0 is a more useful comparison.

It might also just be instruction alignment as vpr is known to be
very alignment dependent.

-- Pinski