[Bug tree-optimization/116702] New: `MIN_EXPR , 0>` can be optimized to `a >> (BITSIZE-1)` for signed types

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116702

            Bug ID: 116702
           Summary: `MIN_EXPR <MAX_EXPR<a, -1> , 0>` can be optimized to
                    `a >> (BITSIZE-1)` for signed types
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: enhancement
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pinskia at gcc dot gnu.org
  Target Milestone: ---

While looking into something phiopt related I accidently noticed that:
```
int f(int a, int b, int c)
{
  int t = (c > -1 ? c : -1);
  int t2 = (t < 0) ? t : 0;
  return t2;
}

int f2(int a, int b, int c)
{
  int t = (c > -1 ? c : -1);
  if (c < 0) return t;
  return 0;
}
```

these 2 could be optimized to just:
`return a >> (BITSIZE-1);`


At -O2, we are able to optimize f2 to that.
But at -O1 we fail both.