[lno] copy header and vectorization

[Devang Patel <dpatel at apple dot com>]

Current lno-branch sources are not able to auto-vectorize simple loops.
I need to disable copy header phase on lno-branch to fix this.

-----------------
#define N 16

void foo (int n)
{
  int a[N+1];
  int i,j;

  /* Vectorizable.  */
  for (i = 0; i < N; i++){
    a[i] = i;
  }
}
-----------------

After copy header phase, scev determines the initial condition for this
loop is i=1 and that causes vectorizer to reject this loop. I am 
including
debug dump after copy header at the end of email.

Is it a known issue ?
--
Devang


;; Function foo (foo)

;; 3 loops found, 2 levels
;;
;; Loop 0:
;;  header -1, latch -2, pre-header -1
;;  depth 0, level 2, outer -1
;;  nodes: -1 0 1 5 2 4 6 3 -2
;;
;; Loop 1:
;;  header 1, latch 5, pre-header -1
;;  depth 1, level 1, outer 0
;;  nodes: 1 5
;;
;; Loop 2:
;;  header 4, latch 6, pre-header -1
;;  depth 1, level 1, outer 0
;;  nodes: 4 6
;; 0 succs { 1 }
;; 1 succs { 2 5 }
;; 5 succs { 1 }
;; 2 succs { 4 }
;; 4 succs { 3 6 }
;; 6 succs { 4 }
;; 3 succs { -2 }
Removing basic block 5
Removing basic block 2
Removing basic block 6
Merging blocks 0 and 8
foo (n)
{
  int j;
  int i;
  int a[17];
  int T.1;

<bb 0>:
  i_2 = 0;
  a[i_2] = i_2;
  i_15 = i_2 + 1;
  if (i_15 <= 15) goto <L0>; else goto <L9>;

  # i_1 = PHI <i_15(0), i_18(1)>;
<L0>:;
  a[i_1] = i_1;
  i_18 = i_1 + 1;
  if (i_18 <= 15) goto <L0>; else goto <L9>;

<L9>:;
  i_16 = 0;

  # i_14 = PHI <i_16(2), i_17(3)>;
<L6>:;
  T.1_5 = a[i_14];
  printf ("%d\n", T.1_5);
  i_17 = i_14 + 1;
  if (i_17 <= 15) goto <L6>; else goto <L5>;

<L5>:;
  return;

}



;; Function main (main)

main ()
{
<bb 0>:
  foo (16);
  return;

}