message: Optimize `SbTag::eq`
  The code before generated really bad code with a branch.
  This nudges LLVM towards being smarter and simply comparing
  the integers.
diff: @@ -27,12 +27,27 @@ pub type CallId = NonZeroU64;
  pub type AllocExtra = Stacks;
  /// Tracking pointer provenance
  -#[derive(Copy, Clone, Hash, PartialEq, Eq)]
  +#[derive(Copy, Clone, Hash, Eq)]
  pub enum SbTag {
  Tagged(PtrId),
  Untagged,
  }
  +impl SbTag {
  + fn as_u64(self) -> u64 {
  + match self {
  + SbTag::Tagged(id) => id.get(),
  + SbTag::Untagged => 0,
  + }
  + }
  +}
  +
  +impl PartialEq for SbTag {
  + fn eq(&self, other: &Self) -> bool {
  + self.as_u64() == other.as_u64()
  + }
  +}
  +
  impl fmt::Debug for SbTag {
  fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  match self {
  