[Bug tree-optimization/121258] Missed optimization with 'while' loop that can be converted to 'do-while'

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121258

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
I noticed LLVM does it slightly different. They do it more like:
```
uint32_t func_c(uint32_t xs, uint32_t x) {
    uint32_t i = xs;
    bool t;
    do {
       t = cond(i);
        i++;
    }while (t);
//    asm("":"+r"(i));
    i--;
    return i;
}
```