https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111432
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Assignee|unassigned at gcc dot gnu.org |pinskia at gcc dot
gnu.org
Last reconfirmed| |2023-10-10
Ever confirmed|0 |1
Status|UNCONFIRMED |ASSIGNED
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
The reason why this is correct is:
a & (x | CST) -> (a & x) | (a & CST) -> // due to `a & CST -> a`
(a & x) | a -> a
So:
```
/* `a & (x | CST)` -> a if we know that (a & ~CST) == 0 */
(simplify
(bit_and:c SSA_NAME@0 (bit_ior @1 INTEGER_CST@2))
(if (INTEGRAL_TYPE_P (TREE_TYPE (@0))
&& wi::bit_and_not (get_nonzero_bits (@0), wi::to_wide (@2)) == 0)
@0))
```
// a | (x & CST) simplifies down to `(a | x) & CST` but I don't see if that is
an improvement here as we still have 2 operations.
