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On Friday, September 21, 2001, at 12:13 PM, Daniel Egger wrote: > On Fre, 2001-09-21 at 21:03, Dale Johannesen wrote: > >> That's true. Well, how about doing it this way then: >> >> (define_function_unit "iu" 1 0 >> (and (eq_attr "type" "compare,delayed_compare") >> (eq_attr "cpu" "ppc750,ppc7400")) >> 1 1 [(eq_attr "type" "!branch")]) >> >> (define_function_unit "iu" 1 0 >> (and (eq_attr "type" "compare,delayed_compare") >> (eq_attr "cpu" "ppc750,ppc7400")) >> 3 1 [(eq_attr "type" "branch")]) > >> I'll try that and see how it works. > > I think this matter is too new for me to grok all the effects > of this change in one go. What are you trying to achieve with > the additional restrictions? This means: if the compare/delayed_compare is followed by a dependent branch, assume a 3-cycle issue delay; if followed by anything else, assume a 1-cycle issue delay. It seems to be a slight improvement (over 3 1 throughout) in practice, although the differences are small.
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