+ *
+ * After this pass the following should hold:
+ * - The only inputs with mode_b are for the Cond node or the
+ * Sel input of a Mux node.
+ * - The only nodes producing mode_b are: Proj(Cmp) and ConvB(X) (where X
+ * is some mode that can be converted to the lowered mode).
+ * ConvB will usually be implemented by a comparison with 0 producing some
+ * flags in the backends.
+ * All other former uses should be converted to manipulations with an integer
+ * mode that was specified in the pass configuration.