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Re: Optimization for PII
On Mon, Sep 13, 1999 at 11:34:45AM +0300, Rainer Dorsch <rainer@rainer.informatik.uni-stuttgart.de> wrote:
>
> The egcs documentation says
>
> `-march=CPU TYPE'
> Generate instructions for the machine type CPU TYPE. The choices
> for CPU TYPE are: `i386', `i486', `pentium', and `pentiumpro'.
> Specifying `-march=CPU TYPE' implies `-mcpu=CPU TYPE'.
>
> It does not mention PII and PIII. Does pentiumpro run on PII and PIII or is
> there another undocumented option (I am using gcc-2.95.1)?
i386 == i486 == pentium == k6 < pentiumpro == pii == piii
(e.g. i386 code runs on pii, but pii code not on i386)
This is the view the compiler currently has. The pii and piii additional
instructions are not yet used, as isn't mmx.
It is unclear (to me) wether this will change, as there is no real strong
hierarchy anymore (chip can have mmx but not fcomi, or vice versa), or
wether additional switches (-mmx, -m3dnow) will be introduced.
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