[Bug tree-optimization/77848] Gimple if-conversion results in redundant comparisons

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77848

--- Comment #17 from Richard Biener <rguenth at gcc dot gnu.org> ---
Nono, you misunderstood -- I meant for the if-converter to produce

 if (LOOP_VECTORIZED)
  {
    for (;;) // outer loop
      for (;;)
        // if-converted inner loop
  }
 else
  {
    for (;;) // outer loop
      for (;;) // inner loop
  }

if (and only if) the outer loop CFG shape matches what the vectorizer will
later eventually handle.

You still need adjustments to the vectorizer but only in its handling of
eliminating the LOOP_VECTORIZED conditional.