[Bug tree-optimization/93131] ((a&8) == 8) && ((a&2) == 2) is not optimized to (a&(8|2)) == (8|2)

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93131

--- Comment #7 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #6)
> Note the generic version of this is:
> ((A & N) == CST1) & ((A & M) == CST2)
> 
> if (N&M)&CST1 == (N&M)&CST2, then
>    (A&(N|M)) == (CST1|CST2)
> else
>   false

And now for the !=/| case:

((A & N) != CST1) | ((A & M) != CST2)

if (N&M)&CST1 == (N&M)&CST2, then
   (A&(N|M)) != (CST1|CST2)
else
  true

so something like:
(for bitop (bit_and bit_ior)
     cmp   (eq      ne)
 (simplify
  (bitop
   (cmp (bit_and @0 INTEGER_CST@mask1) INTEGER_CST@CST1)
   (cmp (bit_and @0 INTEGER_CST@mask2) INTEGER_CST@CST2))
  (with
   {
     tree type1 = TREE_TYPE (@0);
     wide_int mask = wi::to_wide(@mask1) | wi::to_wide(@mask2);
     wide_int cst1 = wi::to_wide(@cst1);
     wide_int cst2 = wi::to_wide(@cst2);
   }
   (if (wi::eq(mask & cst1,mask & cst2))
    (cmp (bit_and @0 {wide_int_to_tree (type1, mask); } ) { wide_int_to_tree
(cst1|cst2, mask); } )
    { constant_boolean_node (cmp == EQ_EXPR, type); }))))