[Cbe-oss-dev] Cell and new CPU feature bits

Segher Boessenkool segher at kernel.crashing.org
Fri May 19 17:49:18 EST 2006

>> I'm assuming you mean the instructions described under "AltiVec  
>> Memory
>> Bandwidth Management" in secion 5.2 of the Altivec PEM -- dst, dstt,
>> dstst, dss and dssall?
> They are nops on the Cell though.

And that is a compliant implementation.  I don't see a need
or real use for a feature bit here, esp. if we do get one for
the extended dcbt insns (which often are used as a replacement
for the data streaming insns).

> They are also microcoded on the 970.

No, they are cracked, instead.  Much lower hit.  They are completion
serialized though, so the only insn in an issue group, etc.


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