[Bug tree-optimization/107413] Perf loss ~14% on 519.lbm_r SPEC cpu2017 benchmark with r8-7132-gb5b33e113434be

[rvmallad at amazon dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107413

--- Comment #9 from Rama Malladi <rvmallad at amazon dot com> ---
(In reply to Rama Malladi from comment #8)
> (In reply to Wilco from comment #7)
> > The revert results in about 0.5% loss on Neoverse N1, so it looks like the
> > reassociation pass is still splitting FMAs into separate MUL and ADD (which
> > is bad for narrow cores).
> 
> Thank you for checking on N1. Did you happen to check on V1 too to reproduce
> the perf results I had? Any other experiments/ tests I can do to help on
> this filing? Thanks again for the debug/ fix.

I ran SPEC cpu2017 fprate 1-copy benchmark built with the patch reverted and
using option 'neoverse-n1' on the Graviton 3 processor (which has support for
SVE). The performance was up by 0.4%, primary contributor being 519.lbm_r which
was up 13%.