[Bug tree-optimization/105990] Dead code elimination failed at -O3

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105990

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |enhancement
   Last reconfirmed|                            |2022-06-21
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
I think the first and second cases are different issues.

In the first case (even if we remove the struct), we can't figure out that b
does not change from 0.
Because we only have a trivial pass which detects read-onlyness. That is it
only checks if b was read-only and not if b could have been written to if b was
read-only.

The second case I didn't analyzed.