[Bug target/86448] GCC 9 compiler generates slower code for spec 2006 milc on a power9 using -mcpu=power9 than using -mcpu=power8

[kelvin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86448

--- Comment #6 from kelvin at gcc dot gnu.org ---
I should also clarify regarding all of the above comments that the numbers I
have been reporting are the spec ratios.  I had misunderstood that these ratios
were encoded such that smaller values represented better performance.  So some
of my "interpretation remarks" are incorrect.  Still, my measurements do not
show the 2% difference that Michael observed, so there remains a question of
whether there is enough of a performance change to merit further exploration.