[Bug tree-optimization/118483] New: Missed optimization due to cast being used more than once

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118483

            Bug ID: 118483
           Summary: Missed optimization due to cast being used more than
                    once
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pinskia at gcc dot gnu.org
  Target Milestone: ---

Take:
```
int d;
int f(int b)
{
  int e = b == 0;
  d = e;
  int l = b != 0;
  if (l == e)
    __builtin_abort ();
}
```

The call to abort should be eliminated but currently is not.

I accidently noticed this while fixing PR 102705.  I was (manually) replacing
`b >= 2 ? 0 : 1 >> b` with `(b == 0)` since those 2 expressions are the same
(with taking into account the undefined behavior for `b >= sizeof(int)` cases).

It just happens simplifying `1 >> b` into `(type)b == 0` in the case of PR
102705 works because of an extra cast to char in there ...