[Bug tree-optimization/127223] New: (int)unsigned0+(int)unsigned1 -> (int)(unsigned0+unsigned1) if unsigned0+unsigned1 does not overflow

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127223

            Bug ID: 127223
           Summary: (int)unsigned0+(int)unsigned1 ->
                    (int)(unsigned0+unsigned1) if unsigned0+unsigned1 does
                    not overflow
           Product: gcc
           Version: 17.0
            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: ---

Take:
```
unsigned ff2(unsigned f, unsigned m)
{
  unsigned char af = f;
  unsigned char am = m;
  int t = af+am;
  return t;
}
```

Right now this produces this mess:
```
  int t;
  int _1;
  int _2;
  unsigned int _6;
  unsigned int _8;
  unsigned int _9;

  _8 = f_3(D) & 255;
  _1 = (int) _8;
  _9 = m_4(D) & 255;
  _2 = (int) _9;
  t_5 = _1 + _2;
  _6 = (unsigned int) t_5;
  return _6;
```

But _1+_2 should be done in unsigned without losing any information.  as _8+_9
will not overflow.