[Bug middle-end/23412] New: [data deps] Overflow problem in Omega

[Bug middle-end/23412] New: [data deps] Overflow problem in Omega

[sebastian dot pop at cri dot ensmp dot fr]

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=23412

[Bug middle-end/23412] [data deps] Overflow problem in Omega

[sebastian dot pop at cri dot ensmp dot fr]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
OtherBugsDependingO|                            |23409
              nThis|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23412

[Bug middle-end/23412] [data deps] Overflow problem in Omega

[sebastian dot pop at cri dot ensmp dot fr]

------- Additional Comments From sebastian dot pop at cri dot ensmp dot fr  2005-08-15 23:16 -------
This one is also probably an overflow in Omega,
but the dependence problem looks pretty simple...
This occurs in gcc/gcc/omega.c on amd64-linux.

Dist vectors from the first dependence analyzer:
   1    1    0 
Omega dist vectors are not the same:
   0 10922 10922 
Data dependence relation is:
(Data Dep: 
  access_fn_A: {1, +, 1}_7
  access_fn_B: {1, +, 1}_7

 (subscript 
  iterations_that_access_an_element_twice_in_A: 0
  last_conflict: scev_not_known;
  iterations_that_access_an_element_twice_in_B: 0
  last_conflict: scev_not_known;
  (Subscript distance: 0
  )
 )
  distance_vect:      0 10922 10922 
  direction_vect:     =    +    +
)



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23412

[Bug middle-end/23412] [data deps] Overflow problem in Omega

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-08-17 12:23 -------
Confirmed.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|                            |1
   Last reconfirmed|0000-00-00 00:00:00         |2005-08-17 12:23:44
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23412

[Bug middle-end/23412] [data deps] Overflow problem in Omega

[sebastian dot pop at cri dot ensmp dot fr]

------- Comment #3 from sebastian dot pop at cri dot ensmp dot fr  2006-03-29 20:40 -------
Fixed on autovect.


-- 

sebastian dot pop at cri dot ensmp dot fr changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23412