[Bug target/71800] New: GCC generates invalid instruction (stxsiwx) with -mcpu=power7

[pthaugen at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71800

            Bug ID: 71800
           Summary: GCC generates invalid instruction (stxsiwx) with
                    -mcpu=power7
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pthaugen at gcc dot gnu.org
                CC: dje at gcc dot gnu.org, meissner at gcc dot gnu.org,
                    wschmidt at gcc dot gnu.org
  Target Milestone: ---
              Host: powerpc64*-unknown-linux-gnu
            Target: powerpc64*-unknown-linux-gnu
             Build: powerpc64*-unknown-linux-gnu

Created attachment 38856
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=38856&action=edit
reduced testcase

Noticed that GCC was generating a Power8 insn, stxsiwx, when -mcpu=power7 was
specified. First noticed in 177.mesa from cpu2000, but 435.gromacs and
454.calculix from cpu2006 have same issue.

Compile options : -O2 -mcpu=power7