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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/113134] gcc does not version loops with early
 break conditions that don't have side-effects
Date: Wed, 31 Jan 2024 12:04:06 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D113134

--- Comment #20 from Richard Biener <rguenth at gcc dot gnu.org> ---
I think we want split_loop () handle this case.  That means extending it to
handle loops with multiple exits.  OTOH after loop rotation to

  if (i_21 =3D=3D 1001)
    goto <bb 5>; [1.00%]
  else
    goto <bb 4>; [99.00%]

  <bb 4> [local count: 1004539166]:
  i_18 =3D i_21 + 1;
  if (N_13(D) > i_18)
    goto <bb 3>; [94.50%]
  else
    goto <bb 5>; [5.50%]

it could be also IVCANONs job to rewrite the exit test so the bound is
loop invariant and it becomes a single exit.

There's another recent PR where an exit condition like i < N && i < M
should become i < MIN(N,M).=