[Bug tree-optimization/79483] [7 Regression] [graphite] ICE: verify_ssa failed (error: definition in block 31 does not dominate use in block 28)

[asolokha at gmx dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79483

--- Comment #1 from Arseny Solokha <asolokha at gmx dot com> ---
int tc, ag;

int
yv (void)
{
  int bt[2];
  int cu;

  bt[0] = 0;
  for (tc = 0; tc < 2; ++tc)
  {
    cu = bt[tc];
    for (ag = 0; ag < 2; ++ag)
      bt[ag] = 0;
  }

  return cu;
}

% gcc-7.0.0-alpha20170212 -O2 -floop-nest-optimize -c xggwz5dp.c                
xggwz5dp.c: In function 'yv':
xggwz5dp.c:4:1: error: definition in block 31 does not dominate use in block 28
 yv (void)
 ^~
for SSA_NAME: pretmp_27 in statement:
prephitmp_25 = PHI <0(17), pretmp_27(28)>
PHI argument
pretmp_27
for PHI node
prephitmp_25 = PHI <0(17), pretmp_27(28)>
xggwz5dp.c:4:1: internal compiler error: verify_ssa failed

It looks similar to PR69675 but also reproduces w/ isl 0.18.