[Bug tree-optimization/118662] [14/15 regression] -ftree-slp-vectorize causes incorrect math

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118662

--- Comment #2 from Sam James <sjames at gcc dot gnu.org> ---
```
int addup(char *num) {
  int val = num[0] + num[1] + num[2] + num[3];
  if (num[3] >= 0)
    val++;
  return val;
}

int main(int, char *[]) {
  char num[4] = {1, 1, 1, -1};
  if (addup(num) != 2)
    __builtin_abort();
  return 0;
}
```