[Bug tree-optimization/126743] If a != b, then (a | b) (==,!=) 0 -> (false, true)

"pinskia at gcc dot gnu.org via Gcc-bugs" <[email protected]> Sun, 09 Aug 2026 00:36:10 +0000

Newsgroups	gmane.comp.gcc.bugs
Message-ID	<[email protected]/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126743

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2026-08-09
             Status|UNCONFIRMED                 |NEW
           Severity|normal                      |enhancement
             Blocks|                            |85316
     Ever confirmed|0                           |1

--- Comment #1 from Drea Pinski <pinskia at gcc dot gnu.org> ---
Confirmed.

That is the range of `a|b` when `a != b` is non-zero. (For integer and
pointers).

Yes this should an easy thing to do I think.

Add an operator_bitwise_or::op1_op2_relation_effect which does that for
rel==VREL_NE.

See operator_bitwise_xor::op1_op2_relation_effect also for a quick example.


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85316
[Bug 85316] [meta-bug] VRP range propagation missed cases