[Bug rtl-optimization/68212] Loop unroller breaks basic block frequencies

[pthaugen at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68212

Pat Haugen <pthaugen at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                 CC|                            |wschmidt at gcc dot gnu.org

--- Comment #3 from Pat Haugen <pthaugen at gcc dot gnu.org> ---
Patch to fix frequencies/counts of switch block code and peeled loop copies
posted here https://gcc.gnu.org/ml/gcc-patches/2016-09/msg01363.html.

I still see a couple issues that need to get worked:

1) Freq of unrolled loop block is still wrong, doesn't match sum of incoming
edges.

2) Probably a separate issue, but general issue of unrolling reducing frequency
too much such that loop no longer looks hotter than surrounding code. Since
guessed frequency is relative (capped at 10000), I don't think it's a simple
matter of orig_freq/unroll factor to get freq of unrolled loop block.