[Bug c/109393] Very trivial address calculation does not fold

["rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109393

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|tree-optimization           |c
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2023-04-11
     Ever confirmed|0                           |1

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
It's probably a mismatch of GENERIC/GIMPLE folding.  In this case it's
pointer_int_sum prematurely distributing the multiplication:

/* Return a tree for the sum or difference (RESULTCODE says which)
   of pointer PTROP and integer INTOP.  */

tree  
pointer_int_sum (location_t loc, enum tree_code resultcode,
                 tree ptrop, tree intop, bool complain)
{     
...
  /* If what we are about to multiply by the size of the elements
     contains a constant term, apply distributive law
     and multiply that constant term separately.
     This helps produce common subexpressions.  */

but this kind of stuff shouldn't be done by the frontends these days.

Gating this fixes the issue.  I think this piece of code should be axed
(after careful evaluation of its effect)