[Bug tree-optimization/114331] New: Missed optimization: indicate knownbits from dominating condition switch(trunc(a))

[xxs_chy at outlook dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114331

            Bug ID: 114331
           Summary: Missed optimization: indicate knownbits from
                    dominating condition switch(trunc(a))
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: xxs_chy at outlook dot com
  Target Milestone: ---

Godbolt link: https://godbolt.org/z/dso53ndTo
For code like:

int src(int num) {
    switch((short)num){
        case 111:
          return num & 0xfffe;
        case 267:
        case 204:
        case 263:
          return 0;
        default:
          dummy();
          return 0;
    }
}

"num & 0xfffe" can be folded to "110". But both LLVM and GCC fail to fold it.