[Bug tree-optimization/122577] New: (int)bool is not handled by the vectorizer

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122577

            Bug ID: 122577
           Summary: (int)bool is not handled by the vectorizer
           Product: gcc
           Version: 16.0
            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 count_true(const bool *values, int len) {
    int count = 0;
    for (int i = 0; i < len; i++) {
        if (values[i]) {
            count++;
        }
    }
    return count;
}
int count_true1(const bool *values, int len) {
    int count = 0;
    for (int i = 0; i < len; i++) {
        if (values[i]) {
            count+=2;
        }
    }
    return count;
}
```

count_true1 is vectorized but count_true is not.


In count_true case we have:
```
  # count_15 = PHI <_13(6), 0(5)>
...
  _3 = *_2;
  _12 = (int) _3;
  _13 = _12 + count_15;
```

While in count_true1 we have:
```
  # count_16 = PHI <_14(6), 0(5)>
...
  _3 = *_2;
  _12 = (int) _3;
  _13 = _12 * 2;
  _14 = _13 + count_16;
```


count_true dump:
```
/app/example.cpp:3:23: missed:   type conversion to/from bit-precision
unsupported.
/app/example.cpp:3:23: note:   vect_is_simple_use: operand *_2, type of def:
internal
/app/example.cpp:3:23: note:   vect_is_simple_use: operand *_2, type of def:
internal
/app/example.cpp:4:12: missed:   not vectorized: relevant stmt not supported:
_12 = (int) _3;
/app/example.cpp:3:23: note:   unsupported SLP instance starting from: _13 =
_12 + count_15;
/app/example.cpp:3:23: missed:  unsupported SLP instances
```


count_true1 dump:
```
/app/example.cpp:12:23: note:   op template: patt_23 = patt_27 w* 2;
/app/example.cpp:12:23: note:           stmt 0 patt_23 = patt_27 w* 2;
```

We recognize it as a widening multiply by 2.