[Bug target/69252] [4.9/5/6 Regression] gcc.dg/vect/vect-iv-9.c FAILs with -Os -fmodulo-sched -fmodulo-sched-allow-regmoves -fsched-pressure

["msebor at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69252

Martin Sebor <msebor at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Target|powerpc64-unknown-linux-gnu |powerpc64*-unknown-linux-gn
                   |                            |u
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2016-01-13
                 CC|                            |msebor at gcc dot gnu.org
               Host|x86_64-pc-linux-gnu         |
     Ever confirmed|0                           |1

--- Comment #1 from Martin Sebor <msebor at gcc dot gnu.org> ---
Confirmed with today's top of trunk (6.0.0 20160113) also on powerpc764le with
-O1 and -Os.  

Using a slightly simplified test case

  int a[N] = { 0, 2, 4, 8 };

  __attribute__ ((noinline, noclone)) int main1 (void)
  {
    int s = 0;
    int i;
    for (i = 0; i != sizeof a / sizeof *a; i++)
      s += i + a[i];
    return s;
  }

and looking at the tree dumps, the first one that looks suspicious (with -O1)
is:

$ cat t.c.152t.ivopts

;; Function main1 (main1, funcdef_no=0, decl_uid=2350, cgraph_uid=0,
symbol_order=1)

__attribute__((noclone, noinline))
main1 ()
{
  unsigned long ivtmp.10;
  int i;
  int s;
  int _4;
  int _5;
  int * _14;
  void * _15;

  <bb 2>:
  _14 = &a + 18446744073709551612;
  ivtmp.10_13 = (unsigned long) _14;

  <bb 3>:
  # s_10 = PHI <s_6(4), 0(2)>
  # i_12 = PHI <i_7(4), 0(2)>
  # ivtmp.10_9 = PHI <ivtmp.10_8(4), ivtmp.10_13(2)>
  ivtmp.10_8 = ivtmp.10_9 + 4;
  _15 = (void *) ivtmp.10_8;
  _4 = MEM[base: _15, offset: 0B];
  _5 = _4 + i_12;
  s_6 = _5 + s_10;
  i_7 = i_12 + 1;
  if (i_7 != 4)
    goto <bb 4>;
  else
    goto <bb 5>;

  <bb 4>:
  goto <bb 3>;

  <bb 5>:
  # s_11 = PHI <s_6(3)>
  return s_11;
}