[Bug target/80834] New: PowerPC gcc -mcpu=power9 seems to turn off vectorization that -mcpu=power8 enables

[meissner at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80834

            Bug ID: 80834
           Summary: PowerPC gcc -mcpu=power9 seems to turn off
                    vectorization that -mcpu=power8 enables
           Product: gcc
           Version: 8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: meissner at gcc dot gnu.org
  Target Milestone: ---

Created attachment 41391
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=41391&action=edit
File from spec 2006 milc, compile with -O3 -ffast-math -mcpu=power9

I was working on PR 80718 (which is on ISA 2.07/power8, vec_splat of DFmode
sometimes generates a load to a GPR, direct move, and then a permute, instead
of loading directly to the vector registers).

I was curious to see what code ISA 3.0/power9 generated.  And it looked like
power9 turns off vectorization in this code.