Re: [gentoo-amd64] First Impressions

[Daniel Iliev]

Dice R. Random wrote:
>
> It is not necessary to tell gcc to use special instruction sets for
> your processor.  When you specify -march gcc automatically knows
> exactly what instructions your processor is capable of utilizing most
> effectively.
I'm not sure about this. Tonight I'll make a test: I'll compile a
package with and without these flags and watch the output and the outcome.

>
> I am not familiar with PIC, but if portage gives a big red warning
> about explicitly enabling it in your CFLAGS I'm sure that there have
> been problems with it.  If a package requires the flag then it should
> enable it in its own local CFLAGS.
>
Already answered about Position Independent Code and why I use it.
Shortly: http://www.gentoo.org/doc/en/prelink-howto.xml
> A 3dnow instruction path isn't always the best optimization for every
> user and every package.  Also, AMD's Athlon and Opteron processors are
> not the only ones supported under the amd64 arch, there are also
> Intel's x86-64 processors to consider.  While I imagine that Intel
> processors can execute 3dnow instructions I also imagine that SSE
> would be faster.
I'm really not sure here. I cant tell which is better -3dnow(ext)  or
sse{1..3}, but isn't it best if one enables all kinds of optimizations
supported by the CPU?

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