[Bug target/19046] New: [4.0 Regression] MOVE_RATIO should be tweaked

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

Take the following C++ code:
class StringMap {
  const char empty_str[8];
public:
  StringMap() : empty_str() {}
};

StringMap f()
{
 StringMap a;
 return a;
}

For 3.3.2, we produced (at -O3):
__Z1fv:
LFB6:
        li r4,0
        stw r4,0(r3)
        stw r4,4(r3)
        blr

on the mainline we get:
__Z1fv:
LFB5:
        mflr r0
LCFI0:
        bcl 20,31,"L00000000001$pb"
"L00000000001$pb":
        stw r31,-4(r1)
LCFI1:
        mflr r31
        stw r0,8(r1)
LCFI2:
        addis r2,r31,ha16(__ZZN9StringMapC1EvE3C.0-"L00000000001$pb")
        la r9,lo16(__ZZN9StringMapC1EvE3C.0-"L00000000001$pb")(r2)
        lwz r10,4(r9)
        lwz r9,0(r9)
        stw r10,4(r3)
        lwz r0,8(r1)
        lwz r31,-4(r1)
        mtlr r0
        stw r9,0(r3)
        blr

-- 
           Summary: [4.0 Regression] MOVE_RATIO should be tweaked
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: normal
          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=19046