Fw: [PATCH] Change bb-reorder.c to use succ block frequency

[Pat Haugen <pthaugen at us dot ibm dot com>]

Forwarding to mailing list since I didn't trim gcc-patches-owner and got
rejected...


Pat Haugen <pthaugen@us.ibm.com> wrote on 06/14/2005 09:29:29 AM:
> better_edge_p() first compares edge probabilities to see which is the
> better edge, if probabilities are equivalent then it proceeds to the
> frequency test. It makes no sense to compare edge frequencies as a
> tie-breaker when probabilities are equivalent because edge frequencies
are
> also going to be equivalent. The algorithm is trying to find the succ
block
> with the greatest affinity to the current block. The succ block with the
> smallest frequency would be that block since the block with the larger
> frequency is obtaining that larger frequency from a different predecessor
> and therfore possibly has a better affinity to that predecessor.
>
> -Pat
>

Would it be more acceptable if my patch only affected the call to
better_edge_p()?  I could see where the other two places where freq is
tested against the threshhold could be better off using edge frequency for
the same reason stated above (i.e. we don't want to include the block if
its frequency is large enough only because some other predecessor is
pushing it over the limit).

-Pat