[Bug middle-end/43182] GCC does not pull out a[0] from loop that changes a[i] for i:[1,n]

[pinskia at gcc dot gnu dot org]

------- Comment #2 from pinskia at gcc dot gnu dot org  2010-02-25 23:50 -------
So currently inside LIM (which does load motion in general):
  D.2724_7 = a_6(D) + D.2723_5;
  D.2725_8 = *a_6(D);
  *D.2724_7 = D.2725_8;

But LIM/alias oracle does not know that D.2723_5 has a range of [4, n_3*4]
which means D.2724_7 can never equal a_6 so we don't pull out the load from
a_6.


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2010-02-25 23:50:10
               date|                            |
            Summary|gcc could not vectorize this|GCC does not pull out a[0]
                   |simple loop (un-handled     |from loop that changes a[i]
                   |data-ref)                   |for i:[1,n]


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43182