+#define EDGE_CRITICAL_P(e) (EDGE_COUNT ((e)->src->succs) >= 2 \
+ && EDGE_COUNT ((e)->dest->preds) >= 2)
+
+#define EDGE_COUNT(ev) VEC_length (edge, (ev))
+#define EDGE_I(ev,i) VEC_index (edge, (ev), (i))
+#define EDGE_PRED(bb,i) VEC_index (edge, (bb)->preds, (i))
+#define EDGE_SUCC(bb,i) VEC_index (edge, (bb)->succs, (i))
+
+/* Iterator object for edges. */
+
+typedef struct {
+ unsigned index;
+ VEC(edge) *container;
+} edge_iterator;
+
+/* Return an iterator pointing to the start of an edge vector. */
+static inline edge_iterator
+ei_start (VEC(edge) *ev)
+{
+ edge_iterator i;
+
+ i.index = 0;
+ i.container = ev;
+
+ return i;
+}
+
+/* Return an iterator pointing to the last element of an edge
+ vector. */
+static inline edge_iterator
+ei_last (VEC(edge) *ev)
+{
+ edge_iterator i;
+
+ i.index = EDGE_COUNT (ev) - 1;
+ i.container = ev;
+
+ return i;
+}
+
+/* Is the iterator `i' at the end of the sequence? */
+static inline bool
+ei_end_p (edge_iterator i)
+{
+ return (i.index == EDGE_COUNT (i.container));
+}
+
+/* Is the iterator `i' at one position before the end of the
+ sequence? */
+static inline bool
+ei_one_before_end_p (edge_iterator i)
+{
+ return (i.index + 1 == EDGE_COUNT (i.container));
+}
+
+/* Advance the iterator to the next element. */
+static inline void
+ei_next (edge_iterator *i)
+{
+ gcc_assert (i->index < EDGE_COUNT (i->container));
+ i->index++;
+}
+
+/* Move the iterator to the previous element. */
+static inline void
+ei_prev (edge_iterator *i)
+{
+ gcc_assert (i->index > 0);
+ i->index--;
+}
+
+/* Return the edge pointed to by the iterator `i'. */
+static inline edge
+ei_edge (edge_iterator i)
+{
+ return EDGE_I (i.container, i.index);
+}
+
+/* Return an edge pointed to by the iterator. Do it safely so that
+ NULL is returned when the iterator is pointing at the end of the
+ sequence. */
+static inline edge
+ei_safe_edge (edge_iterator i)
+{
+ return !ei_end_p (i) ? ei_edge (i) : NULL;
+}
+
+/* This macro serves as a convenient way to iterate each edge in a
+ vector of predecessor or successor edges. It must not be used when
+ an element might be removed during the traversal, otherwise
+ elements will be missed. Instead, use a for-loop like that shown
+ in the following pseudo-code:
+
+ FOR (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
+ {
+ IF (e != taken_edge)
+ ssa_remove_edge (e);
+ ELSE
+ ei_next (&ei);
+ }
+*/
+
+#define FOR_EACH_EDGE(EDGE,ITER,EDGE_VEC) \
+ for ((EDGE) = NULL, (ITER) = ei_start ((EDGE_VEC)); \
+ ((EDGE) = ei_safe_edge ((ITER))); \
+ ei_next (&(ITER)))