Default mtune/mcpu setting for i386
This should be changed. Sorry I didn't catch it earlier...
++ ix86_cpu_string = cpu_names [TARGET_CPU_DEFAULT_pentium];
For unknown (to me) reasons, scheduling is very different on the
original Pentium (586) and the Pentium Pro (686).
Perhaps surprisingly, the 686 scheduling runs better on 486s than the
586 scheduling.
Less surprisingly, the 686 scheduling runs better than the 586
scheduling on all newer chips (Pentium II/III/IV and all derivatives,
plus most of the other manufacturers' chips of the same vintage).
(The choice apparently doesn't make much difference on 386.)
We should optimize tuning for the most common machines, which means the
686 tuning is the best choice anyway. This isn't a large difference,
but one might as well get it right, no?
So this should be, in all three places:
++ ix86_cpu_string = cpu_names [TARGET_CPU_DEFAULT_pentiumpro];
And the comments in the various patches should be updated accordingly.
--
Nathanael Nerode <neroden at gcc.gnu.org>
http://home.twcny.rr.com/nerode/neroden/fdl.html
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