[Bug target/17959] New: -mpowerpc64 can cause worse code than without it

["pinskia at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

unsigned long long div16(unsigned long long n) { return n / 16; }

Without -mpowerpc64:
_div16:
        slwi r0,r3,28
        srwi r4,r4,4
        or r4,r0,r4
        srwi r3,r3,4
        blr

With:
_div16:
        li r0,0
        rldimi r0,r3,32,0
        rldimi r0,r4,0,32
        srdi r4,r0,4
        srdi r3,r0,36
        blr

-- 
           Summary: -mpowerpc64 can cause worse code than without it
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: enhancement
          Priority: P2
         Component: target
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: pinskia at gcc dot gnu dot org
                CC: gcc-bugs at gcc dot gnu dot org
GCC target triplet: powerpc-darwin


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17959