[Bug c/52897] New: gcc 4.7.0 generates worse code than gcc 3.4.6 for m68000

[fdarkangel at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52897

             Bug #: 52897
           Summary: gcc 4.7.0 generates worse code than gcc 3.4.6 for
                    m68000
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: fdarkangel@gmail.com


cube_flat demo included with SGDK (http://code.google.com/p/sgdk) performed
very differently when compiled with gcc 3.4.6 and gcc 4.7.0. Attached code was
the core of the problem; you can find the assembly codes generated by -O2,
although the problem appears at -O3 as well.

I also noticed that turning off gsce adds a pointless "move.l #12582912,%a1"
instruction (.L3 of bmp-gcc4-O2-no-gcse.s), which doesn't appear in gcc3.