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

[meissner at gcc dot gnu.org]

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

            Bug ID: 86448
           Summary: GCC 9 compiler generates slower code for spec 2006
                    milc on a power9 using -mcpu=power9 than using
                    -mcpu=power8
           Product: gcc
           Version: 9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: meissner at gcc dot gnu.org
  Target Milestone: ---

I built spec 2006 on a DD2.2 power9 and ran it.  I noticed that the milc
benchmark was 2% slower using either the trunk or the GCC 8 branch (subversion
id 262483) if I compiled the code using -mcpu=power9 compared to -mcpu=power8.