[Bug tree-optimization/119399] Overlap check in vectorized code may invoke UB

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119399

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2025-03-21
           Keywords|                            |wrong-code
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW
                 CC|                            |rguenth at gcc dot gnu.org,
                   |                            |rsandifo at gcc dot gnu.org

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Confirmed.  We'd have to do q < p || (unsigned)(q+4) - (unsigned)p > 8 or sth
like this I think.

Possibly not relevant on 64bit virtual address space targets, but also
obviously OS dependent (and possibly dependent on whether we deal with user or
kernel address space or a freestanding env.)

Alternatively we can document additional restrictions on object placement,
though I think there was 32bit x86 kernel support with more than half of
the virtual address space available to userland.