[Bug rtl-optimization/94795] New: Failure to use fast sbb method on x86 for spreading any set bit to all bits

[gabravier at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94795

            Bug ID: 94795
           Summary: Failure to use fast sbb method on x86 for spreading
                    any set bit to all bits
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gabravier at gmail dot com
  Target Milestone: ---

int isNonzero(int x)
{
    if (x == 0)
        return 0x00000000;
    else
        return 0xFFFFFFFF;
}

On x86, this can be simplified to a `neg`+`sbb`. LLVM does this transformation,
but GCC doesn't

Comparison here : https://godbolt.org/z/QFz9to