[Bug c/122732] Add __builtin_assume_dereferenceable(a,N) which tells the compiler *a ... *(a+(N-1)/sizeof(*a)) is not trapping

[rguenth at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122732

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2025-11-18
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
It's related to pointer "range" info, a size range of the pointed-to object,
but conservative on the "small" side.  The simplest thing would be to add
a field to ptr_info_def recording the minimum pointed-to size so [0, size - 1]
are valid byte offsets to dereference.  PTA can populate that from
pointed-to-decls, the question is whether we want to exclude 'NULL', so
that 'size' is only valid if !pt.null, since non-NULL-ness is often available
context-sentitive via ranger (but points-to info is not).