[Bug middle-end/47341] unnecessary versioning in the vectorizer.

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47341

Richard Guenther <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2011.01.18 11:21:06
     Ever Confirmed|0                           |1

--- Comment #1 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-01-18 
11:21:06 UTC ---
t.f90:7: note: versioning for alias required: can't determine dependence
between *c_18(D)[D.1552_17] and *c_18(D)[D.1603_128]

  pretmp.22_273 = (integer(kind=8)) j_2;

  pretmp.22_274 = pretmp.22_273 * 4;

  pretmp.30_287 = pretmp.22_273 + 1;
  pretmp.30_288 = pretmp.30_287 * 4;

  D.1548_13 = (integer(kind=8)) i_1;
  D.1551_16 = D.1548_13 + pretmp.22_274;
  D.1552_17 = D.1551_16 + -5;

  D.1602_127 = D.1548_13 + pretmp.30_288;
  D.1603_128 = D.1602_127 + -5;

thus we can't determine the dependence between

  *(c_18(D) + (integer(kind=8)) i_1 + ((integer(kind=8)) j_2) * 4)

vs

  *(c_18(D) + (integer(kind=8)) i_1 + (((integer(kind=8)) j_2) + 1) * 4)


(compute_affine_dependence
  (stmt_a = 
D.1553_19 = *c_18(D)[D.1552_17];
)       
  (stmt_b = 
D.1604_129 = *c_18(D)[D.1603_128];
)
(subscript_dependence_tester
(analyze_overlapping_iterations 
  (chrec_a = {pretmp.22_274 + -4, +, 1}_2)
  (chrec_b = {pretmp.30_288 + -4, +, 1}_2)
(analyze_siv_subscript 
siv test failed: unimplemented.
)

the SCEVs cannot be expanded properly because of the casts.