[Bug tree-optimization/91459] Tail-Call Optimization is not performed when return value is assumed.

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91459

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|2019-08-16 00:00:00         |2021-12-26

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
So when DOM3 changes:

  result_5 = function_returns_only_1_or_doesnt_return (a_2(D), b_3(D));
  if (result_5 == 1)
    goto <bb 3>; [100.00%]
  else
    goto <bb 4>; [0.00%]

  <bb 3> [local count: 1073741824]:
  return 1;

  <bb 4> [count: 0]:
  __builtin_unreachable ();

To

  result_5 = function_returns_only_1_or_doesnt_return (a_2(D), b_3(D));
  return 1;

I wonder if it could change 1 back into result_5 because it comes from a
function call.