[Bug middle-end/122047] New: Incorrect handling of access attribute in uninit pass

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122047

            Bug ID: 122047
           Summary: Incorrect handling of access attribute in uninit pass
           Product: gcc
           Version: 16.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jakub at gcc dot gnu.org
  Target Milestone: ---

I think we should warn in foo because we are reading from what the argument
points to and with write_only attribute it might be uninitialized.
But I think we shouldn't warn in the bar case, while p is still a function
argument, its value has been changed to something unrelated.

__attribute__((access (write_only, 1)))
int
foo (int *p)
{
  return *p;
}

int *q, *r;

__attribute__((access (write_only, 1)))
int
bar (int *p, int x)
{
  if (x == 42)
    p = q;
  else
    p = r;
  return *p;
}