[Bug middle-end/47048] misc vect.exp failures with -fgraphite-identity enabled at -O2.

[spop at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47048

Sebastian Pop <spop at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2011.02.01 21:15:06
         AssignedTo|unassigned at gcc dot       |spop at gcc dot gnu.org
                   |gnu.org                     |
     Ever Confirmed|0                           |1

--- Comment #2 from Sebastian Pop <spop at gcc dot gnu.org> 2011-02-01 21:15:06 UTC ---
Looks like the classic data dependence test can be improved:
A[0] does not overlap with A[1], and so there is no dependence:

Data ref a:
#(Data Ref: 
#  bb: 6 
#  stmt: points[D.2720_36][0] = start$0_8(D);
#  ref: points[D.2720_36][0];
#  base_object: points
#  Access function 0: 0
#  Access function 1: (int) {0, +, 1}_2;
#)
Data ref b:
#(Data Ref: 
#  bb: 6 
#  stmt: points[D.2720_36][1] = D.2723_40;
#  ref: points[D.2720_36][1];
#  base_object: points
#  Access function 0: 1
#  Access function 1: (int) {0, +, 1}_2;
#)
affine dependence test not usable: access function not affine or constant.
(dependence classified: scev_not_known)
)

/home/seb/gcc/trunk/gcc/testsuite/gcc.dg/vect/pr33866.c:13: note: not
vectorized: data ref analysis failed points[D.2720_36][0] = start$0_8(D);