[Bug rtl-optimization/33737] [4.3 Regression] verify_flow_info failed: Wrong probability of edge 94->1 -6651

[ebotcazou at gcc dot gnu dot org]

------- Comment #8 from ebotcazou at gcc dot gnu dot org  2007-11-05 22:44 -------
> Re. comment #5, yes the code is right to add the frequencies together.
> After cross jumping, the tail-merged block is traversed with the combined
> frequencies of the new incoming edges, so adding the frequencies is correct.

That's not clear in my opinion.  In any case, there is something wrong:

  redirect_to->frequency += src1->frequency;

is performed before the weighted mean

      if (!redirect_to->frequency && !src1->frequency)
        s->probability = (s->probability + s2->probability) / 2;
      else
        s->probability
          = ((s->probability * redirect_to->frequency +
              s2->probability * src1->frequency)
             / (redirect_to->frequency + src1->frequency));

so the weights are screwed.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33737