pentium/ppro optimization settings

Marc Lehmann (mlehmann@hildesheim.sgh-net.de)
Sun, 22 Dec 1996 11:29:15 +0100 (MET)


Hi.. here is MY opinion on the Cyrix is 486/586/686 issue
(and another thing):

The latest available gcc does not include any pentium/ppro
specific optimizations. The only difference in the makefile
(in arch/i386) is the smaller alignment on pentium/ppro processors.

I guess, since EVERY cpu (except the pentium) from intel actually
NEEDS 16 byte alignments to get real performance, the 486
setting (which uses this large alignments) is best suited for
every intel cpu, and it *might* be a good guess for the cyrix one,
too. The bigger alignment doesn't harm too much, too.

On the other hand, the alignments for the pentium are pretty high,
I think a zero or one alignment would suffice.

And I don't understand why the ppro setting, too, uses only 4 byte
alignment? The ppro (as the i486) gets a BIG performance boost of
these alignments, they are NOT don't cares, as on the pentium.

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