[Bug middle-end/77608] missing protection on trivially detectable runtime buffer overflow

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77608

Martin Sebor <msebor at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2016-09-16
           Assignee|unassigned at gcc dot gnu.org      |msebor at gcc dot gnu.org
     Ever confirmed|0                           |1

--- Comment #1 from Martin Sebor <msebor at gcc dot gnu.org> ---
Created attachment 39627
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=39627&action=edit
Lightly tested patch.

The attached patch extends __builtin_object_size to handle non-constant offsets
in POINTER_PLUS expressions.  It also adds handling of ranges although to
benefit from those the VRP pass needs to run before the object size pass.  (It
doesn't handle the test case in comment #0 because of the volatile qualifier.)