https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105937
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Assignee|unassigned at gcc dot gnu.org |rguenth at gcc dot
gnu.org
Ever confirmed|0 |1
Status|UNCONFIRMED |ASSIGNED
Last reconfirmed| |2022-08-19
--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
The predicate analysis has difficulties in handling this case, its like
void foo (int val)
{
int uninit;
for (;;)
{
if (..)
{
.. = val; (*)
val = uninit;
}
# val = PHI <..>
}
}
and we diagnose (*), figuring the loop PHI of 'val' eventually leads to
the PHI that post-dominates the use we want to diagnose. One issue with
this is that the predicates provided are from a different iteration than
those used so we won't have a chance to compare things meanigfully here.
I think the best thing is to avoid diagnosing possibly uninitialized
uses in the next iteration of a loop because we have no chance to
prove the path is unreachable and thus we'll always warn.
At least I think so.
I do have a patch.
