[Bug target/108346] gather/scatter loops optimized too often for znver4 (and other zens)

[hubicka at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108346

--- Comment #2 from Jan Hubicka  ---
Sadly the win/loss cases does not seem to suggest a simple cost scheme.
We currently compute gather/scatter costs as static startup cost + cost per
lane and they are set to approximately match actual latencies.  I am not sure
how much better we can do.

[Bug target/108346] gather/scatter loops optimized too often for znver4 (and other zens)

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108346

Andrew Pinski  changed:

   What|Removed |Added

  Component|middle-end  |target
 Blocks||53947
 Target||x86_64-linux-gnu
   Keywords||missed-optimization

--- Comment #1 from Andrew Pinski  ---
This is a cost issue, either not having a decent way of expressing the cost or
the backend cost model needs to be improved (or both).


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53947
[Bug 53947] [meta-bug] vectorizer missed-optimizations