[Bug tree-optimization/125399] New: Missed optimization of __builtin_bitreverse*() when comparing to 0

[kaelfandrew at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125399

            Bug ID: 125399
           Summary: Missed optimization of __builtin_bitreverse*() when
                    comparing to 0
           Product: gcc
           Version: 17.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: kaelfandrew at gmail dot com
  Target Milestone: ---

https://godbolt.org/z/Knoq64bTT
GCC trunk with -O3 does not optimized src () to tgt () from this simple
EQ_EXPR/NE_EXPR 0 while Clang 19+ does:

C code
```
unsigned char src(unsigned char x) {
    unsigned char y = __builtin_bitreverse8 (x);
    if (y == 0)
        return 0;
    return 1;
}

unsigned char tgt(unsigned char x) {
    if (x == 0)
        return 0;
    return 1;
}
```