~PredicateFactory() {
    DCHECK_EQ(stack_depth_, 0) << "Unnested IncrementStackDepth?";
  }

 private:
  Predicate* MakeNotPredicateImpl(Predicate* pred) {
    IncrementStackDepth stack_frame(this);
    if (!stack_frame.HasOverflowed()) {
      if (Predicate* simplified = SimplifyUsingDeMorgan(pred)) {
        return simplified;
      }

      // ~~A => A

		}
		state.varParts[topSlot.N] = append(state.varParts[topSlot.N], SlotID(i))
	}

	// Recreate the LocalSlot for each stack-only variable.
	// This would probably be better as an output from stackframe.
	for _, b := range f.Blocks {
		for _, v := range b.Values {
			if v.Op == OpVarDef {
				n := v.Aux.(*ir.Name)
				if ir.IsSynthetic(n) {
					continue
				}