message: Don't cause undefined behavior in the first place
diff: @@ -21,11 +21,6 @@ namespace detail
  inline unsigned clz(unsigned val)
  {
  - if (val == 0)
  - {
  - return unsigned(-1);
  - }
  -
  #if defined(__CUDA_ARCH__) && __CUDA_ARCH__ >= 200
  return __clz(val);
  #elif defined(_WIN32)
  @@ -84,7 +79,7 @@ struct lbvh_builder
  if (next < last)
  {
  unsigned code = prim_refs[next].morton_code;
  - if (clz(code_first ^ code) > common_prefix)
  + if (code_first == code || clz(code_first ^ code) > common_prefix)
  {
  result = next;
  }
  