[Bug tree-optimization/66997] outer loop reduction fails to parallelize with graphite

[vries at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66997

--- Comment #1 from vries at gcc dot gnu.org ---
loop nest at parloops:
...
parloop (int N)
{
  _Bool Cross_BB_scalar_dependence.11_I_lsm.23;
  unsigned int Cross_BB_scalar_dependence.11_I_lsm.22;
  _Bool Cross_BB_scalar_dependence.13_I_lsm.21;
  unsigned int Cross_BB_scalar_dependence.13_I_lsm.20;
  _Bool Commutative_Associative_Reduction.19;
  unsigned int Commutative_Associative_Reduction.18;
  _Bool Close_Phi.10_I_lsm.17;
  unsigned int Close_Phi.10_I_lsm.16;
  signed long graphite_IV.15;
  signed long graphite_IV.14;
  unsigned int Cross_BB_scalar_dependence.13[1];
  unsigned int D.1890;
  unsigned int Cross_BB_scalar_dependence.12[1];
  unsigned int D.1888;
  unsigned int D.1887;
  unsigned int D.1886;
  unsigned int D.1885;
  unsigned int D.1884;
  unsigned int Cross_BB_scalar_dependence.11[1];
  unsigned int D.1882;
  unsigned int D.1881;
  unsigned int Close_Phi.10[1];
  unsigned int Commutative_Associative_Reduction.9[1];
  _Bool y_I_lsm.8;
  unsigned int y_I_lsm.7;
  unsigned int sum;
  int j;
  int i;
  _Bool _38;
  signed long _39;
  signed long _40;
  _Bool _47;
  signed long _48;
  signed long _49;
  unsigned int _52;
  int _53;
  int _54;
  int _62;
  unsigned int _67;

  <bb 2>:
  if (N_8(D) > 0)
    goto <bb 3>;
  else
    goto <bb 13>;

  <bb 3>:
  Commutative_Associative_Reduction.9[0] = 0;
  _38 = N_8(D) > 0;
  if (_38 != 0)
    goto <bb 4>;
  else
    goto <bb 12>;

  <bb 4>:
  _39 = (signed long) N_8(D);
  _40 = _39 + -1;
  Commutative_Associative_Reduction.18_34 =
Commutative_Associative_Reduction.9[0];
  Close_Phi.10_I_lsm.16_10 = Close_Phi.10[0];

  <bb 5>:
  # graphite_IV.14_41 = PHI <0(4), graphite_IV.14_42(10)>
  # Close_Phi.10_I_lsm.16_55 = PHI <Close_Phi.10_I_lsm.16_10(4),
Close_Phi.10_I_lsm.16_37(10)>
  # Close_Phi.10_I_lsm.17_22 = PHI <0(4), Close_Phi.10_I_lsm.17_6(10)>
  # Commutative_Associative_Reduction.18_24 = PHI
<Commutative_Associative_Reduction.18_34(4), sum_65(10)>
  _47 = N_8(D) > 0;
  if (_47 != 0)
    goto <bb 6>;
  else
    goto <bb 9>;

  <bb 6>:
  _48 = (signed long) N_8(D);
  _49 = _48 + -1;

  <bb 7>:
  # graphite_IV.15_50 = PHI <0(6), graphite_IV.15_51(8)>
  _53 = (int) graphite_IV.14_41;
  _54 = (int) graphite_IV.15_50;
  _52 = x[_53][_54];
  graphite_IV.15_51 = graphite_IV.15_50 + 1;
  if (graphite_IV.15_50 < _49)
    goto <bb 8>;
  else
    goto <bb 9>;

  <bb 8>:
  goto <bb 7>;

  <bb 9>:
  # Close_Phi.10_I_lsm.16_37 = PHI <_52(7), Close_Phi.10_I_lsm.16_55(5)>
  # Close_Phi.10_I_lsm.17_6 = PHI <1(7), Close_Phi.10_I_lsm.17_22(5)>
  _62 = (int) graphite_IV.14_41;
  y[_62] = Close_Phi.10_I_lsm.16_37;
  sum_65 = Commutative_Associative_Reduction.18_24 + Close_Phi.10_I_lsm.16_37;
  graphite_IV.14_42 = graphite_IV.14_41 + 1;
  if (graphite_IV.14_41 < _40)
    goto <bb 10>;
  else
    goto <bb 11>;

  <bb 10>:
  goto <bb 5>;

  <bb 11>:
  # Close_Phi.10_I_lsm.17_74 = PHI <Close_Phi.10_I_lsm.17_6(9)>
  # Commutative_Associative_Reduction.18_77 = PHI <sum_65(9)>
  Commutative_Associative_Reduction.9[0] =
Commutative_Associative_Reduction.18_77;

  <bb 12>:
  _67 = Commutative_Associative_Reduction.9[0];
  Cross_BB_scalar_dependence.12[0] = _67;
  sum_31 = Cross_BB_scalar_dependence.12[0];

  <bb 13>:
  # sum_25 = PHI <sum_31(12), 0(2)>
  g_sum = sum_25;
  return;

}
...