[Bug tree-optimization/41577] Broken code with -O -ftree-vrp

[rguenth at gcc dot gnu dot org]

------- Comment #6 from rguenth at gcc dot gnu dot org  2009-10-05 12:02 -------
Actually the testcase is invalid.

        uint32 res = ((uint16)(cpu->gprs[12]  >> 16) * (uint16)(cpu->gprs[16]
>> 16));

performs a signed multiplication which invokes undefined behavior if it
overflows.  Thus the compiler rightfully can assume that the result can
be converted to a positive signed value.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |INVALID


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41577