[Bug tree-optimization/49771] [4.7 Regression] wrong code with -ftree-vectorize

[irar at il dot ibm.com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49771

--- Comment #5 from Ira Rosen <irar at il dot ibm.com> 2011-07-18 20:01:24 UTC ---
Right, the dependence analysis fails here:

(compute_affine_dependence
  (stmt_a =
D.2713_5 = a[i_20];
)
  (stmt_b =
a[j_19] = D.2714_6;
)
(subscript_dependence_tester
(analyze_overlapping_iterations
  (chrec_a = i_20)
  (chrec_b = {0, +, 1}_2)
  (overlap_iterations_a = not known
)
  (overlap_iterations_b = not known
)
)
(dependence classified: scev_not_known)
)
)

I think it would be better to open a separate missed-optimization pr for that.

Meanwhile, I tested the patch on powerpc64-suse-linux. I'll commit it tomorrow
if there are no objections.

Ira