[Bug c/31245] New: SSE2 generation bug with 4.1.2 and -O3

["prakash at punnoor dot de" <gcc-bugzilla at gcc dot gnu dot org>]

This is my simple test proggie.

test1 is always ok, but test2 fails with -O3 (produces output 1 0 0 0 for 
test2), but -O2 makes it behave.


I ?am on x86_64. -m32 has interesting effects:

-O3 -Wall -m32 -msse2 -march=i486 is ok (output 1 0 3 0, as expected)
-O3 -Wall -m32 -msse2 -march=i586 is broken (output 0 2 3 4)
-O3 -Wall -m32 -msse2 -march=athlon is broken (output 1 0 0 0)

Is this the aliasing issues I read about with 4.1 compiler? Is there an easy 
work-around? In fact I need to pass data as aligned buffer, so I need test2 
to behave correctly. :-(

Do you need anything else?


-- 
           Summary: SSE2 generation bug with 4.1.2 and -O3
           Product: gcc
           Version: 4.1.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: prakash at punnoor dot de
 GCC build triplet: x86_64-pc-linux-gnu
  GCC host triplet: x86_64-pc-linux-gnu
GCC target triplet: x86_64-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31245