https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111773
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |UNCONFIRMED
Ever confirmed|1 |0
Assignee|rguenth at gcc dot gnu.org |unassigned at gcc dot
gnu.org
--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
So the second example is fixed, but it's quite a corner-case so probably not
worth backporting. Given we have a single bugreport for two issues back to
UNCONFIRMED for the first issue.
I agree with Andrew _that_ issue behaves within the constraints of the
standard.
ISTR it says that 'operator new' has to return a pointer that nothing else
points to which means it acts as if it were restrict qualified. That allows
GCC to conclude x != 0 because it rewrites x == 0 as a - p == 0 and
a == p. The difference operation cannot be constant folded based on this
but during IPA optimization we inline 'new' which exposes p == a and thus
a - p == 0.
