[Bug tree-optimization/53571] [4.6/4.7/4.8 regression] ICE with -O{2,3} -floop-parallelize-all in cloog_domain_stride()

["burnus at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53571

Tobias Burnus <burnus at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                 CC|                            |burnus at gcc dot gnu.org

--- Comment #4 from Tobias Burnus <burnus at gcc dot gnu.org> 2012-06-05 21:03:03 UTC ---
(In reply to comment #1)
> Please specify the cloog/ppl versions you are using.  What target is this on?

I can reproduce it with the current GCC trunk on openSUSE Factory (x86-64)
[package libcloog0-debuginfo-0.15.10+ppl-9.8].

Program received signal SIGSEGV, Segmentation fault.

#0  0x00002aaaaace1656 in cloog_domain_stride (domain=<optimized out>,
strided_level=<optimized out>, 
    nb_par=<optimized out>, stride=0x7fffffffd5e0, offset=0x7fffffffd5d0) at
source/ppl/domain.c:2813
#1  0x00002aaaaacd7b21 in cloog_loop_stride_1 (nb_par=2, level=1,
loop=0x15a8c20) at source/loop.c:1077
#2  cloog_loop_generate_general (loop=0x0, level=1, scalar=1,
scaldims=0x158b000, nb_scattdims=3, 
    nb_par=<optimized out>, options=0x1596780) at source/loop.c:1371
#3  0x00002aaaaacd71f3 in cloog_loop_generate_scalar (options=0x1596780,
nb_par=2, nb_scattdims=3, 
    scaldims=0x158b000, scalar=0, level=1, loop=0x159c930) at
source/loop.c:1489
#4  cloog_loop_generate (loop=<optimized out>, context=0x0, level=1, scalar=0,
scaldims=0x158b000, 
    nb_scattdims=3, nb_par=2, options=0x1596780) at source/loop.c:1573
#5  0x00002aaaaace834b in cloog_program_generate (program=0x1595d00,
options=0x1596780) at source/program.c:687
#6  0x0000000000cd34b5 in scop_to_clast (scop=0x158e890)
    at /home/tob/projects/gcc-git/gcc/gcc/graphite-clast-to-gimple.c:1551
#7  0x0000000000cd36d5 in gloog (scop=0x158e890, bb_pbb_mapping=0x158e4f0)
    at /home/tob/projects/gcc-git/gcc/gcc/graphite-clast-to-gimple.c:1632
#8  0x0000000000cd078e in graphite_transform_loops () at
/home/tob/projects/gcc-git/gcc/gcc/graphite.c:276
#9  0x00000000009e2c87 in graphite_transforms () at
/home/tob/projects/gcc-git/gcc/gcc/tree-ssa-loop.c:254

The failing line is:
      cloog_vector_gcd (U->p[0], U->NbColumns, stride);
The problem is that U->p == NULL.

And U is initialized via cloog_solve_diophantine,
  cloog_matrix_hermite (temp, &hermi, &unimod);
  rank = cloog_dio_get_first_diagonal_zero (hermi);
  nbc = temp->NbColumns;
...
  *u = cloog_dio_init_U (unimodinv, hermi->NbColumns, rank);

In the latter, one has:
  if (rank == n)
    return cloog_matrix_alloc (0, 0);

And according to gdb rank==2 (the other arguments are optimized out). Well, and
for a 0 argument, cloog_matrix_alloc sets u->p to NULL.