(const_basic_block bb)
{
  return EDGE_COUNT (bb->preds) == 1;
}

/* Returns the single successor edge of basic block BB.  Aborts if
   BB does not have exactly one successor.  */

static inline edge
single_succ_edge (const_basic_block bb)
{
  gcc_checking_assert (single_succ_p (bb));
  return EDGE_SUCC (bb, 0);
}

/* Returns the single predecessor edge of basic block BB.  Aborts
   if BB does not have exactly one predecessor.  */

static inline edge
single_pred_edge (const_basic_block bb)
{
  gcc_checking_assert (single_pred_p (bb));
  return EDGE_PRED (bb, 0);
}

/* Returns the single successor block of basic block BB.  Aborts
   if BB does not have exactly one successor.  */

static inline basic_block
single_succ (const_basic_block bb)
{
  return single_succ_edge (bb)->dest;
}

/* Returns the single predecessor block of basic block BB.  Aborts
   if BB does not have exactly one predecessor.*/

static inline basic_block
single_pred (const_basic_block bb)
{
  return single_pred_edge (bb)->src;
}

/* Iterator object for edges.  */

struct edge_iterator {
  unsigned index;
  vec<edge, va_gc> **container;
};

static inline vec<edge, va_gc> *
ei_container (edge_iterator i)
{
  gcc_checking_assert (i.container);
  return *i.container;
}

#define ei_start(iter) ei_start_1 (&(iter))
#define ei_last(iter) ei_last_1 (&(iter))

/* Return an iterator pointing to the start of an edge vector.  */
static inline edge_iterator
ei_start_1 (vec<edge, va_gc> **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_1 (vec<edge, va_gc> **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 (ei_container (i)));
}

/* 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 (ei_container (i)));
}

/* Advance the iterator to the next element.  */
static inline void
ei_next (edge_iterator *i)
{
  gcc_checking_assert (i->index < EDGE_COUNT (ei_container (*i)));
  i->index++;
}

/* Move the iterator to the previous element.  */
static inline void
ei_prev (edge_iterator *i)
{
  gcc_checking_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 (ei_container (i), 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;
}

/* Return 1 if we should continue to iterate.  Return 0 otherwise.
   *Edge P is set to the next edge if we are to continue to iterate
   and NULL otherwise.  */

static inline bool
ei_cond (edge_iterator ei, edge *p)
{
  if (!ei_end_p (ei))
    {
      *p = ei_edge (ei);
      return 1;
    }
  else
    {
      *p = NULL;
      return 0;
    }
}

/* 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)
	  remove_edge (e);
	ELSE
	  ei_next (&ei);
     }
*/

#define FOR_EACH_EDGE(EDGE,ITER,EDGE_VEC)	\
  for ((ITER) = ei_start ((EDGE_VEC));		\
       ei_cond ((ITER), &(EDGE));		\
       ei_next (&(ITER)))

#define CLEANUP_EXPENSIVE	1	/* Do relatively expensive optimizations
					   except for edge forwarding */
#define CLEANUP_CROSSJUMP	2	/* Do crossjumping.  */
#define CLEANUP_POST_REGSTACK	4	/* We run after reg-stack and need
					   to care REG_DEAD notes.  */
#define CLEANUP_THREADING	8	/* Do jump threading.  */
#define CLEANUP_NO_INSN_DEL	16	/* Do not try to delete trivially dead
					   insns.  */
#define CLEANUP_CFGLAYOUT	32	/* Do cleanup in cfglayout mode.  */
#define CLEANUP_CFG_CHANGED	64      /* The caller changed the CFG.  */

/* Return true if BB is in a transaction.  */

static inline bool
bb_in_transaction (basic_block bb)
{
  return bb->flags & BB_IN_TRANSACTION;
}

/* Return true when one of the predecessor edges of BB is marked with EDGE_EH.  */
static inline bool
bb_has_eh_pred (basic_block bb)
{
  edge e;
  edge_iterator ei;

  FOR_EACH_EDGE (e, ei, bb->preds)
    {
      if (e->flags & EDGE_EH)
	return true;
    }
  return false;
}

/* Return true when one of the predecessor edges of BB is marked with EDGE_ABNORMAL.  */
static inline bool
bb_has_abnormal_pred (basic_block bb)
{
  edge e;
  edge_iterator ei;

  FOR_EACH_EDGE (e, ei, bb->preds)
    {
      if (e->flags & EDGE_ABNORMAL)
	return true;
    }
  return false;
}

/* Return the fallthru edge in EDGES if it exists, NULL otherwise.  */
static inline edge
find_fallthru_edge (vec<edge, va_gc> *edges)
{
  edge e;
  edge_iterator ei;

  FOR_EACH_EDGE (e, ei, edges)
    if (e->flags & EDGE_FALLTHRU)
      break;

  return e;
}

/* Check tha probability is sane.  */

static inline void
check_probability (int prob)
{
  gcc_checking_assert (prob >= 0 && prob <= REG_BR_PROB_BASE);
}

/* Given PROB1 and PROB2, return PROB1*PROB2/REG_BR_PROB_BASE. 
   Used to combine BB probabilities.  */

static inline int
combine_probabilities (int prob1, int prob2)
{
  check_probability (prob1);
  check_probability (prob2);
  return RDIV (prob1 * prob2, REG_BR_PROB_BASE);
}

/* Apply scale factor SCALE on frequency or count FREQ. Use this
   interface when potentially scaling up, so that SCALE is not
   constrained to be < REG_BR_PROB_BASE.  */

static inline gcov_type
apply_scale (gcov_type freq, gcov_type scale)
{
  return RDIV (freq * scale, REG_BR_PROB_BASE);
}

/* Apply probability PROB on frequency or count FREQ.  */

static inline gcov_type
apply_probability (gcov_type freq, int prob)
{
  check_probability (prob);
  return apply_scale (freq, prob);
}

/* Return inverse probability for PROB.  */

static inline int
inverse_probability (int prob1)
{
  check_probability (prob1);
  return REG_BR_PROB_BASE - prob1;
}

/* Return true if BB has at least one abnormal outgoing edge.  */

static inline bool
has_abnormal_or_eh_outgoing_edge_p (basic_block bb)
{
  edge e;
  edge_iterator ei;

  FOR_EACH_EDGE (e, ei, bb->succs)
    if (e->flags & (EDGE_ABNORMAL | EDGE_EH))
      return true;

  return false;
}

/* Return true when one of the predecessor edges of BB is marked with
   EDGE_ABNORMAL_CALL or EDGE_EH.  */

static inline bool
has_abnormal_call_or_eh_pred_edge_p (basic_block bb)
{
  edge e;
  edge_iterator ei;

  FOR_EACH_EDGE (e, ei, bb->preds)
    if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
      return true;

  return false;
}

#endif /* GCC_BASIC_BLOCK_H */