[Bug middle-end/23413] New: [data deps] Overflow problem in Omega

["sebastian dot pop at cri dot ensmp dot fr" <gcc-bugzilla at gcc dot gnu dot org>]

This pattern shows something strange in the results of Omega.
Looking at the step of array accesses it seems like Omega has 
just no mechanism to handle -1 evolutions i.e. 0ffffffff in 
unsigned with modulo arithmetics.  This occurs in 
gcc/gcc/real.c during bootstrap on amd64-linux.

Dist vectors from the first dependence analyzer:
   1    1 
Omega dist vectors are not the same:
  -1    0 
Data dependence relation is:
(Data Dep: 
  access_fn_A: {1, +, 4294967295}_5
  access_fn_B: {2, +, 4294967295}_5

 (subscript 
  iterations_that_access_an_element_twice_in_A: {0, +, 1}_1
  last_conflict: 1
  iterations_that_access_an_element_twice_in_B: {1, +, 1}_1
  last_conflict: 1
  (Subscript distance: 1
  )
 )
  distance_vect:     -1    0 
  direction_vect:     -    =
)

-- 
           Summary: [data deps] Overflow problem in Omega
           Product: gcc
           Version: 4.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: middle-end
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: sebastian dot pop at cri dot ensmp dot fr
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23413