[Bug tree-optimization/69675] New: [6 Regression] [graphite] ICE: verify_ssa failed (definition in block 42 does not dominate use in block 34)

[asolokha at gmx dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69675

            Bug ID: 69675
           Summary: [6 Regression] [graphite] ICE: verify_ssa failed
                    (definition in block 42 does not dominate use in block
                    34)
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: asolokha at gmx dot com
  Target Milestone: ---

gcc-6.0.0-alpha20160131 ICEs when compiling the following snippet w/ -O2
-floop-nest-optimize:

static int b2[4] = { 0 };
int uv[4];
int hh, aq;

void
rp(void)
{
  while (aq < 1) {
    for (hh = 0; hh < 4; ++hh)
      uv[hh] = b2[hh];
    ++aq;
  }
}

udrkapws.c: In function 'rp':
udrkapws.c:6:1: error: definition in block 42 does not dominate use in block 34
 rp(void)
 ^~
for SSA_NAME: pretmp_39 in statement:
prephitmp_26 = PHI <0(35), pretmp_39(34)>
PHI argument
pretmp_39
for PHI node
prephitmp_26 = PHI <0(35), pretmp_39(34)>
udrkapws.c:6:1: internal compiler error: verify_ssa failed

This ICE is similar to one from PR69341, except that the snippet from that PR
doesn't make the latest gcc 6 snapshot fail any more.