docs: private void newValueOnTOS() {
          IsNullValueFrame frame = getFrame();
          if (frame.getStackDepth() < 1) {
              return;
          }
          int tosSlot = frame.getNumSlots() - 1;
          IsNullValue tos = frame.getValue(tosSlot);
          if (tos.isDefinitelyNull()) {
              slotContainingNewNullValue = tosSlot;
          }
          if (trackValueNumbers) {
              try {
                  ValueNumberFrame vnaFrameAfter = vnaDataflow.getFactAfterLocation(getLocation());
                  if (vnaFrameAfter.isValid()) {
                      ValueNumber tosVN = vnaFrameAfter.getTopValue();
                      getFrame().setKnownValue(tosVN, tos);
                  }
              } catch (DataflowAnalysisException e) {
                  AnalysisContext.logError("error", e);
              }
          }
      }