[Bug tree-optimization/86605] Suboptimal code for pointer arithmetic with 'this'

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86605

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|c++                         |tree-optimization
   Last reconfirmed|2018-07-20 00:00:00         |2021-7-22
           Severity|normal                      |enhancement

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
So on the trunk we get:
  if (&test != 4B)
    goto <bb 4>; [70.00%]
  else
    goto <bb 3>; [30.00%]

  <bb 3> [local count: 322122544]:

  <bb 4> [local count: 1073741824]:
  # iftmp.0_3 = PHI <10(2), 20(3)>

I know we fold &v != 0B but it seems like if the constant is within a few bytes
of 0, we should fold it similar.  Shouldn't we?