[Bug tree-optimization/69297] [6 Regression] Performance regression after r230020

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69297

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
With a fix:

t.c:76:10: note: Cost model analysis:
  Vector inside of basic block cost: 376
  Vector prologue cost: 0
  Vector epilogue cost: 0
  Scalar cost of basic block: 96
t.c:76:10: note: not vectorized: vectorization is not profitable.

Note the reduction loop is still vectorized:

t.c:74:5: note: Cost model analysis:
  Vector inside of loop cost: 3
  Vector prologue cost: 1
  Vector epilogue cost: 7
  Scalar iteration cost: 3
  Scalar outside cost: 0
  Vector outside cost: 8
  prologue iterations: 0
  epilogue iterations: 0
  Calculated minimum iters for profitability: 4

but likely this isn't profitable either?