basic-block.h   [plain text]

/* Define control and data flow tables, and regsets.
   Copyright (C) 1987, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
   Free Software Foundation, Inc.

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 2, or (at your option) any later

GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
for more details.

You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING.  If not, write to the Free
Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301, USA.  */


#include "bitmap.h"
#include "sbitmap.h"
#include "varray.h"
#include "partition.h"
#include "hard-reg-set.h"
#include "predict.h"
#include "vec.h"
#include "function.h"

/* Head of register set linked list.  */
typedef bitmap_head regset_head;

/* A pointer to a regset_head.  */
typedef bitmap regset;

/* Allocate a register set with oballoc.  */

/* Do any cleanup needed on a regset when it is no longer used.  */

/* Initialize a new regset.  */
#define INIT_REG_SET(HEAD) bitmap_initialize (HEAD, &reg_obstack)

/* Clear a register set by freeing up the linked list.  */
#define CLEAR_REG_SET(HEAD) bitmap_clear (HEAD)

/* Copy a register set to another register set.  */
#define COPY_REG_SET(TO, FROM) bitmap_copy (TO, FROM)

/* Compare two register sets.  */
#define REG_SET_EQUAL_P(A, B) bitmap_equal_p (A, B)

/* `and' a register set with a second register set.  */
#define AND_REG_SET(TO, FROM) bitmap_and_into (TO, FROM)

/* `and' the complement of a register set with a register set.  */
#define AND_COMPL_REG_SET(TO, FROM) bitmap_and_compl_into (TO, FROM)

/* Inclusive or a register set with a second register set.  */
#define IOR_REG_SET(TO, FROM) bitmap_ior_into (TO, FROM)

/* Exclusive or a register set with a second register set.  */
#define XOR_REG_SET(TO, FROM) bitmap_xor_into (TO, FROM)

/* Or into TO the register set FROM1 `and'ed with the complement of FROM2.  */
  bitmap_ior_and_compl_into (TO, FROM1, FROM2)

/* Clear a single register in a register set.  */
#define CLEAR_REGNO_REG_SET(HEAD, REG) bitmap_clear_bit (HEAD, REG)

/* Set a single register in a register set.  */
#define SET_REGNO_REG_SET(HEAD, REG) bitmap_set_bit (HEAD, REG)

/* Return true if a register is set in a register set.  */
#define REGNO_REG_SET_P(TO, REG) bitmap_bit_p (TO, REG)

/* Copy the hard registers in a register set to the hard register set.  */
extern void reg_set_to_hard_reg_set (HARD_REG_SET *, bitmap);
do {									\
  reg_set_to_hard_reg_set (&TO, FROM);					\
} while (0)

typedef bitmap_iterator reg_set_iterator;

/* Loop over all registers in REGSET, starting with MIN, setting REGNUM to the
   register number and executing CODE for all registers that are set.  */

/* Loop over all registers in REGSET1 and REGSET2, starting with MIN, setting
   REGNUM to the register number and executing CODE for all registers that are
   set in the first regset and not set in the second.  */

/* Loop over all registers in REGSET1 and REGSET2, starting with MIN, setting
   REGNUM to the register number and executing CODE for all registers that are
   set in both regsets.  */

/* Type we use to hold basic block counters.  Should be at least
   64bit.  Although a counter cannot be negative, we use a signed
   type, because erroneous negative counts can be generated when the
   flow graph is manipulated by various optimizations.  A signed type
   makes those easy to detect.  */
typedef HOST_WIDEST_INT gcov_type;

/* Control flow edge information.  */
struct edge_def GTY(())
  /* The two blocks at the ends of the edge.  */
  struct basic_block_def *src;
  struct basic_block_def *dest;

  /* Instructions queued on the edge.  */
  union edge_def_insns {
    rtx GTY ((tag ("0"))) r;
    tree GTY ((tag ("1"))) t;
  } GTY ((desc ("ir_type ()"))) insns;

  /* Auxiliary info specific to a pass.  */
  PTR GTY ((skip (""))) aux;

  /* Location of any goto implicit in the edge, during tree-ssa.  */
  source_locus goto_locus;

  int flags;			/* see EDGE_* below  */
  int probability;		/* biased by REG_BR_PROB_BASE */
  gcov_type count;		/* Expected number of executions calculated
				   in profile.c  */

  /* The index number corresponding to this edge in the edge vector
     dest->preds.  */
  unsigned int dest_idx;

typedef struct edge_def *edge;

#define EDGE_FALLTHRU		1	/* 'Straight line' flow */
#define EDGE_ABNORMAL		2	/* Strange flow, like computed
					   label, or eh */
#define EDGE_ABNORMAL_CALL	4	/* Call with abnormal exit
					   like an exception, or sibcall */
#define EDGE_EH			8	/* Exception throw */
#define EDGE_FAKE		16	/* Not a real edge (profile.c) */
#define EDGE_DFS_BACK		32	/* A backwards edge */
#define EDGE_CAN_FALLTHRU	64	/* Candidate for straight line
					   flow.  */
#define EDGE_IRREDUCIBLE_LOOP	128	/* Part of irreducible loop.  */
#define EDGE_SIBCALL		256	/* Edge from sibcall to exit.  */
#define EDGE_LOOP_EXIT		512	/* Exit of a loop.  */
#define EDGE_TRUE_VALUE		1024	/* Edge taken when controlling
					   predicate is nonzero.  */
#define EDGE_FALSE_VALUE	2048	/* Edge taken when controlling
					   predicate is zero.  */
#define EDGE_EXECUTABLE		4096	/* Edge is executable.  Only
					   valid during SSA-CCP.  */
#define EDGE_CROSSING		8192    /* Edge crosses between hot
					   and cold sections, when we
					   do partitioning.  */
#define EDGE_ALL_FLAGS	       16383


/* Counter summary from the last set of coverage counts read by
   profile.c.  */
extern const struct gcov_ctr_summary *profile_info;

/* Declared in cfgloop.h.  */
struct loop;
struct loops;

/* Declared in tree-flow.h.  */
struct edge_prediction;
struct rtl_bb_info;

/* A basic block is a sequence of instructions with only entry and
   only one exit.  If any one of the instructions are executed, they
   will all be executed, and in sequence from first to last.

   There may be COND_EXEC instructions in the basic block.  The
   COND_EXEC *instructions* will be executed -- but if the condition
   is false the conditionally executed *expressions* will of course
   not be executed.  We don't consider the conditionally executed
   expression (which might have side-effects) to be in a separate
   basic block because the program counter will always be at the same
   location after the COND_EXEC instruction, regardless of whether the
   condition is true or not.

   Basic blocks need not start with a label nor end with a jump insn.
   For example, a previous basic block may just "conditionally fall"
   into the succeeding basic block, and the last basic block need not
   end with a jump insn.  Block 0 is a descendant of the entry block.

   A basic block beginning with two labels cannot have notes between
   the labels.

   Data for jump tables are stored in jump_insns that occur in no
   basic block even though these insns can follow or precede insns in
   basic blocks.  */

/* Basic block information indexed by block number.  */
struct basic_block_def GTY((chain_next ("%h.next_bb"), chain_prev ("%h.prev_bb")))
  /* Pointers to the first and last trees of the block.  */
  tree stmt_list;

  /* The edges into and out of the block.  */
  VEC(edge,gc) *preds;
  VEC(edge,gc) *succs;

  /* Auxiliary info specific to a pass.  */
  PTR GTY ((skip (""))) aux;

  /* Innermost loop containing the block.  */
  struct loop * GTY ((skip (""))) loop_father;

  /* The dominance and postdominance information node.  */
  struct et_node * GTY ((skip (""))) dom[2];

  /* Previous and next blocks in the chain.  */
  struct basic_block_def *prev_bb;
  struct basic_block_def *next_bb;

  union basic_block_il_dependent {
      struct rtl_bb_info * GTY ((tag ("1"))) rtl;
    } GTY ((desc ("((%1.flags & BB_RTL) != 0)"))) il;

  /* Chain of PHI nodes for this block.  */
  tree phi_nodes;

  /* A list of predictions.  */
  struct edge_prediction *predictions;

  /* Expected number of executions: calculated in profile.c.  */
  gcov_type count;

  /* The index of this block.  */
  int index;

  /* The loop depth of this block.  */
  int loop_depth;

  /* Expected frequency.  Normalized to be in range 0 to BB_FREQ_MAX.  */
  int frequency;

  /* Various flags.  See BB_* below.  */
  int flags;

struct rtl_bb_info GTY(())
  /* The first and last insns of the block.  */
  rtx head_;
  rtx end_;

  /* The registers that are live on entry to this block.  */
  bitmap GTY ((skip (""))) global_live_at_start;

  /* The registers that are live on exit from this block.  */
  bitmap GTY ((skip (""))) global_live_at_end;

  /* In CFGlayout mode points to insn notes/jumptables to be placed just before
     and after the block.   */
  rtx header;
  rtx footer;

  /* This field is used by the bb-reorder and tracer passes.  */
  int visited;

typedef struct basic_block_def *basic_block;


#define BB_FREQ_MAX 10000

/* Masks for basic_block.flags.

   BB_HOT_PARTITION and BB_COLD_PARTITION should be preserved throughout
   the compilation, so they are never cleared.

   All other flags may be cleared by clear_bb_flags().  It is generally
   a bad idea to rely on any flags being up-to-date.  */

enum bb_flags

  /* Set if insns in BB have are modified.  Used for updating liveness info.  */
  BB_DIRTY = 1,

  /* Only set on blocks that have just been created by create_bb.  */
  BB_NEW = 2,

  /* Set by find_unreachable_blocks.  Do not rely on this being set in any
     pass.  */

  /* Set for blocks in an irreducible loop by loop analysis.  */

  /* Set on blocks that may actually not be single-entry single-exit block.  */

  /* Set on basic blocks that the scheduler should not touch.  This is used
     by SMS to prevent other schedulers from messing with the loop schedule.  */

  /* Set on blocks that should be put in a hot section.  */

  /* Set on blocks that should be put in a cold section.  */

  /* Set on block that was duplicated.  */

  /* Set on blocks that are in RTL format.  */
  BB_RTL = 1024,

  /* Set on blocks that are forwarder blocks.
     Only used in cfgcleanup.c.  */

  /* Set on blocks that cannot be threaded through.
     Only used in cfgcleanup.c.  */

/* Dummy flag for convenience in the hot/cold partitioning code.  */

/* Partitions, to be used when partitioning hot and cold basic blocks into
   separate sections.  */
#define BB_SET_PARTITION(bb, part) do {					\
  basic_block bb_ = (bb);						\
  bb_->flags = ((bb_->flags & ~(BB_HOT_PARTITION|BB_COLD_PARTITION))	\
		| (part));						\
} while (0)

#define BB_COPY_PARTITION(dstbb, srcbb) \

/* A structure to group all the per-function control flow graph data.
   The x_* prefixing is necessary because otherwise references to the
   fields of this struct are interpreted as the defines for backward
   source compatibility following the definition of this struct.  */
struct control_flow_graph GTY(())
  /* Block pointers for the exit and entry of a function.
     These are always the head and tail of the basic block list.  */
  basic_block x_entry_block_ptr;
  basic_block x_exit_block_ptr;

  /* Index by basic block number, get basic block struct info.  */
  VEC(basic_block,gc) *x_basic_block_info;

  /* Number of basic blocks in this flow graph.  */
  int x_n_basic_blocks;

  /* Number of edges in this flow graph.  */
  int x_n_edges;

  /* The first free basic block number.  */
  int x_last_basic_block;

  /* Mapping of labels to their associated blocks.  At present
     only used for the tree CFG.  */
  VEC(basic_block,gc) *x_label_to_block_map;

  enum profile_status {
  } x_profile_status;

/* Defines for accessing the fields of the CFG structure for function FN.  */
#define ENTRY_BLOCK_PTR_FOR_FUNCTION(FN)     ((FN)->cfg->x_entry_block_ptr)
#define EXIT_BLOCK_PTR_FOR_FUNCTION(FN)	     ((FN)->cfg->x_exit_block_ptr)
#define basic_block_info_for_function(FN)    ((FN)->cfg->x_basic_block_info)
#define n_basic_blocks_for_function(FN)	     ((FN)->cfg->x_n_basic_blocks)
#define n_edges_for_function(FN)	     ((FN)->cfg->x_n_edges)
#define last_basic_block_for_function(FN)    ((FN)->cfg->x_last_basic_block)
#define label_to_block_map_for_function(FN)  ((FN)->cfg->x_label_to_block_map)

  (VEC_index (basic_block, basic_block_info_for_function(FN), (N)))

/* Defines for textual backward source compatibility.  */
#define ENTRY_BLOCK_PTR		(cfun->cfg->x_entry_block_ptr)
#define EXIT_BLOCK_PTR		(cfun->cfg->x_exit_block_ptr)
#define basic_block_info	(cfun->cfg->x_basic_block_info)
#define n_basic_blocks		(cfun->cfg->x_n_basic_blocks)
#define n_edges			(cfun->cfg->x_n_edges)
#define last_basic_block	(cfun->cfg->x_last_basic_block)
#define label_to_block_map	(cfun->cfg->x_label_to_block_map)
#define profile_status		(cfun->cfg->x_profile_status)

#define BASIC_BLOCK(N)		(VEC_index (basic_block, basic_block_info, (N)))
#define SET_BASIC_BLOCK(N,BB)	(VEC_replace (basic_block, basic_block_info, (N), (BB)))

/* For iterating over basic blocks.  */
  for (BB = FROM; BB != TO; BB = BB->DIR)

#define FOR_EACH_BB_FN(BB, FN) \
  FOR_BB_BETWEEN (BB, (FN)->cfg->x_entry_block_ptr->next_bb, (FN)->cfg->x_exit_block_ptr, next_bb)

#define FOR_EACH_BB(BB) FOR_EACH_BB_FN (BB, cfun)

  FOR_BB_BETWEEN (BB, (FN)->cfg->x_exit_block_ptr->prev_bb, (FN)->cfg->x_entry_block_ptr, prev_bb)


/* For iterating over insns in basic block.  */
#define FOR_BB_INSNS(BB, INSN)			\
  for ((INSN) = BB_HEAD (BB);			\
       (INSN) && (INSN) != NEXT_INSN (BB_END (BB));	\
       (INSN) = NEXT_INSN (INSN))

  for ((INSN) = BB_END (BB);			\
       (INSN) && (INSN) != PREV_INSN (BB_HEAD (BB));	\
       (INSN) = PREV_INSN (INSN))

/* Cycles through _all_ basic blocks, even the fake ones (entry and
   exit block).  */

#define FOR_ALL_BB(BB) \
  for (BB = ENTRY_BLOCK_PTR; BB; BB = BB->next_bb)

#define FOR_ALL_BB_FN(BB, FN) \
  for (BB = ENTRY_BLOCK_PTR_FOR_FUNCTION (FN); BB; BB = BB->next_bb)

extern bitmap_obstack reg_obstack;

/* Indexed by n, gives number of basic block that  (REG n) is used in.
   If the value is REG_BLOCK_GLOBAL (-2),
   it means (REG n) is used in more than one basic block.
   REG_BLOCK_UNKNOWN (-1) means it hasn't been seen yet so we don't know.
   This information remains valid for the rest of the compilation
   of the current function; it is used to control register allocation.  */


#define REG_BASIC_BLOCK(N)				\
  (VEC_index (reg_info_p, reg_n_info, N)->basic_block)
/* Stuff for recording basic block info.  */

#define BB_HEAD(B)      (B)->il.rtl->head_
#define BB_END(B)       (B)->il.rtl->end_

/* Special block numbers [markers] for entry and exit.  */
#define ENTRY_BLOCK (0)
#define EXIT_BLOCK (1)

/* The two blocks that are always in the cfg.  */
#define NUM_FIXED_BLOCKS (2)

#define BLOCK_NUM(INSN)	      (BLOCK_FOR_INSN (INSN)->index + 0)
#define set_block_for_insn(INSN, BB)  (BLOCK_FOR_INSN (INSN) = BB)

extern void compute_bb_for_insn (void);
extern unsigned int free_bb_for_insn (void);
extern void update_bb_for_insn (basic_block);

extern void free_basic_block_vars (void);

extern void insert_insn_on_edge (rtx, edge);

extern void commit_edge_insertions (void);
extern void commit_edge_insertions_watch_calls (void);

extern void remove_fake_edges (void);
extern void remove_fake_exit_edges (void);
extern void add_noreturn_fake_exit_edges (void);
extern void connect_infinite_loops_to_exit (void);
extern edge unchecked_make_edge (basic_block, basic_block, int);
extern edge cached_make_edge (sbitmap, basic_block, basic_block, int);
extern edge make_edge (basic_block, basic_block, int);
extern edge make_single_succ_edge (basic_block, basic_block, int);
extern void remove_edge (edge);
extern void redirect_edge_succ (edge, basic_block);
extern edge redirect_edge_succ_nodup (edge, basic_block);
extern void redirect_edge_pred (edge, basic_block);
extern basic_block create_basic_block_structure (rtx, rtx, rtx, basic_block);
extern void clear_bb_flags (void);
extern int post_order_compute (int *, bool);
extern int pre_and_rev_post_order_compute (int *, int *, bool);
extern int dfs_enumerate_from (basic_block, int,
			       bool (*)(basic_block, void *),
			       basic_block *, int, void *);
extern void compute_dominance_frontiers (bitmap *);
extern void dump_bb_info (basic_block, bool, bool, int, const char *, FILE *);
extern void dump_edge_info (FILE *, edge, int);
extern void brief_dump_cfg (FILE *);
extern void clear_edges (void);
extern rtx first_insn_after_basic_block_note (basic_block);
extern void scale_bbs_frequencies_int (basic_block *, int, int, int);
extern void scale_bbs_frequencies_gcov_type (basic_block *, int, gcov_type,

/* Structure to group all of the information to process IF-THEN and
   IF-THEN-ELSE blocks for the conditional execution support.  This
   needs to be in a public file in case the IFCVT macros call
   functions passing the ce_if_block data structure.  */

typedef struct ce_if_block
  basic_block test_bb;			/* First test block.  */
  basic_block then_bb;			/* THEN block.  */
  basic_block else_bb;			/* ELSE block or NULL.  */
  basic_block join_bb;			/* Join THEN/ELSE blocks.  */
  basic_block last_test_bb;		/* Last bb to hold && or || tests.  */
  int num_multiple_test_blocks;		/* # of && and || basic blocks.  */
  int num_and_and_blocks;		/* # of && blocks.  */
  int num_or_or_blocks;			/* # of || blocks.  */
  int num_multiple_test_insns;		/* # of insns in && and || blocks.  */
  int and_and_p;			/* Complex test is &&.  */
  int num_then_insns;			/* # of insns in THEN block.  */
  int num_else_insns;			/* # of insns in ELSE block.  */
  int pass;				/* Pass number.  */

  IFCVT_EXTRA_FIELDS			/* Any machine dependent fields.  */

} ce_if_block_t;

/* This structure maintains an edge list vector.  */
struct edge_list
  int num_blocks;
  int num_edges;
  edge *index_to_edge;

/* The base value for branch probability notes and edge probabilities.  */
#define REG_BR_PROB_BASE  10000

/* This is the value which indicates no edge is present.  */

/* EDGE_INDEX returns an integer index for an edge, or EDGE_INDEX_NO_EDGE
   if there is no edge between the 2 basic blocks.  */
#define EDGE_INDEX(el, pred, succ) (find_edge_index ((el), (pred), (succ)))

/* INDEX_EDGE_PRED_BB and INDEX_EDGE_SUCC_BB return a pointer to the basic
   block which is either the pred or succ end of the indexed edge.  */
#define INDEX_EDGE_PRED_BB(el, index)	((el)->index_to_edge[(index)]->src)
#define INDEX_EDGE_SUCC_BB(el, index)	((el)->index_to_edge[(index)]->dest)

/* INDEX_EDGE returns a pointer to the edge.  */
#define INDEX_EDGE(el, index)           ((el)->index_to_edge[(index)])

/* Number of edges in the compressed edge list.  */
#define NUM_EDGES(el)			((el)->num_edges)

/* BB is assumed to contain conditional jump.  Return the fallthru edge.  */
#define FALLTHRU_EDGE(bb)		(EDGE_SUCC ((bb), 0)->flags & EDGE_FALLTHRU \
					 ? EDGE_SUCC ((bb), 0) : EDGE_SUCC ((bb), 1))

/* BB is assumed to contain conditional jump.  Return the branch edge.  */
#define BRANCH_EDGE(bb)			(EDGE_SUCC ((bb), 0)->flags & EDGE_FALLTHRU \
					 ? EDGE_SUCC ((bb), 1) : EDGE_SUCC ((bb), 0))

/* Return expected execution frequency of the edge E.  */
#define EDGE_FREQUENCY(e)		(((e)->src->frequency \
					  * (e)->probability \
					  + REG_BR_PROB_BASE / 2) \

/* Return nonzero if edge is critical.  */
#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))

/* Returns true if BB has precisely one successor.  */

static inline bool
single_succ_p (basic_block bb)
  return EDGE_COUNT (bb->succs) == 1;

/* Returns true if BB has precisely one predecessor.  */

static inline bool
single_pred_p (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 (basic_block bb)
  gcc_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 (basic_block bb)
  gcc_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 (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 (basic_block bb)
  return single_pred_edge (bb)->src;

/* Iterator object for edges.  */

typedef struct {
  unsigned index;
  VEC(edge,gc) **container;
} edge_iterator;

static inline VEC(edge,gc) *
ei_container (edge_iterator i)
  gcc_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,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,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_assert (i->index < EDGE_COUNT (ei_container (*i)));

/* Move the iterator to the previous element.  */
static inline void
ei_prev (edge_iterator *i)
  gcc_assert (i->index > 0);

/* 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;
      *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);
	  ei_next (&ei);

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

struct edge_list * create_edge_list (void);
void free_edge_list (struct edge_list *);
void print_edge_list (FILE *, struct edge_list *);
void verify_edge_list (FILE *, struct edge_list *);
int find_edge_index (struct edge_list *, basic_block, basic_block);
edge find_edge (basic_block, basic_block);

enum update_life_extent

/* Flags for life_analysis and update_life_info.  */

#define PROP_DEATH_NOTES	1	/* Create DEAD and UNUSED notes.  */
#define PROP_LOG_LINKS		2	/* Create LOG_LINKS.  */
#define PROP_REG_INFO		4	/* Update regs_ever_live et al.  */
#define PROP_KILL_DEAD_CODE	8	/* Remove dead code.  */
#define PROP_SCAN_DEAD_CODE	16	/* Scan for dead code.  */
#define PROP_ALLOW_CFG_CHANGES	32	/* Allow the CFG to be changed
					   by dead code removal.  */
#define PROP_AUTOINC		64	/* Create autoinc mem references.  */
#define PROP_SCAN_DEAD_STORES	128	/* Scan for dead code.  */
#define PROP_ASM_SCAN		256	/* Internal flag used within flow.c
					   to flag analysis of asms.  */
#define PROP_DEAD_INSN		1024	/* Internal flag used within flow.c
					   to flag analysis of dead insn.  */
#define PROP_POST_REGSTACK	2048	/* We run after reg-stack and need
					   to preserve REG_DEAD notes for
					   stack regs.  */

#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_UPDATE_LIFE	8	/* Keep life information up to date.  */
#define CLEANUP_THREADING	16	/* Do jump threading.  */
#define CLEANUP_NO_INSN_DEL	32	/* Do not try to delete trivially dead
					   insns.  */
#define CLEANUP_CFGLAYOUT	64	/* Do cleanup in cfglayout mode.  */
#define CLEANUP_LOG_LINKS	128	/* Update log links.  */

/* The following are ORed in on top of the CLEANUP* flags in calls to
   struct_equiv_block_eq.  */
#define STRUCT_EQUIV_START	256	 /* Initializes the search range.  */
#define STRUCT_EQUIV_RERUN	512	/* Rerun to find register use in
					   found equivalence.  */
#define STRUCT_EQUIV_FINAL	1024	/* Make any changes necessary to get
					   actual equivalence.  */
#define STRUCT_EQUIV_NEED_FULL_BLOCK 2048 /* struct_equiv_block_eq is required
					     to match only full blocks  */
#define STRUCT_EQUIV_MATCH_JUMPS 4096	/* Also include the jumps at the end of the block in the comparison.  */

extern void life_analysis (int);
extern int update_life_info (sbitmap, enum update_life_extent, int);
extern int update_life_info_in_dirty_blocks (enum update_life_extent, int);
extern int count_or_remove_death_notes (sbitmap, int);
extern int propagate_block (basic_block, regset, regset, regset, int);

struct propagate_block_info;
extern rtx propagate_one_insn (struct propagate_block_info *, rtx);
extern struct propagate_block_info *init_propagate_block_info
 (basic_block, regset, regset, regset, int);
extern void free_propagate_block_info (struct propagate_block_info *);

/* In lcm.c */
extern struct edge_list *pre_edge_lcm (int, sbitmap *, sbitmap *,
				       sbitmap *, sbitmap *, sbitmap **,
				       sbitmap **);
extern struct edge_list *pre_edge_rev_lcm (int, sbitmap *,
					   sbitmap *, sbitmap *,
					   sbitmap *, sbitmap **,
					   sbitmap **);
extern void compute_available (sbitmap *, sbitmap *, sbitmap *, sbitmap *);

/* In predict.c */
extern void expected_value_to_br_prob (void);
extern bool maybe_hot_bb_p (basic_block);
extern bool probably_cold_bb_p (basic_block);
extern bool probably_never_executed_bb_p (basic_block);
extern bool tree_predicted_by_p (basic_block, enum br_predictor);
extern bool rtl_predicted_by_p (basic_block, enum br_predictor);
extern void tree_predict_edge (edge, enum br_predictor, int);
extern void rtl_predict_edge (edge, enum br_predictor, int);
extern void predict_edge_def (edge, enum br_predictor, enum prediction);
extern void guess_outgoing_edge_probabilities (basic_block);
extern void remove_predictions_associated_with_edge (edge);
extern bool edge_probability_reliable_p (edge);
extern bool br_prob_note_reliable_p (rtx);

/* In flow.c */
extern void init_flow (void);
extern void debug_bb (basic_block);
extern basic_block debug_bb_n (int);
extern void dump_regset (regset, FILE *);
extern void debug_regset (regset);
extern void allocate_reg_life_data (void);
extern void expunge_block (basic_block);
extern void link_block (basic_block, basic_block);
extern void unlink_block (basic_block);
extern void compact_blocks (void);
extern basic_block alloc_block (void);
extern void find_unreachable_blocks (void);
extern int delete_noop_moves (void);
extern basic_block force_nonfallthru (edge);
extern rtx block_label (basic_block);
extern bool forwarder_block_p (basic_block);
extern bool purge_all_dead_edges (void);
extern bool purge_dead_edges (basic_block);
extern void find_many_sub_basic_blocks (sbitmap);
extern void rtl_make_eh_edge (sbitmap, basic_block, rtx);
extern bool can_fallthru (basic_block, basic_block);
extern bool could_fall_through (basic_block, basic_block);
extern void flow_nodes_print (const char *, const sbitmap, FILE *);
extern void flow_edge_list_print (const char *, const edge *, int, FILE *);
extern void alloc_aux_for_block (basic_block, int);
extern void alloc_aux_for_blocks (int);
extern void clear_aux_for_blocks (void);
extern void free_aux_for_blocks (void);
extern void alloc_aux_for_edge (edge, int);
extern void alloc_aux_for_edges (int);
extern void clear_aux_for_edges (void);
extern void free_aux_for_edges (void);
extern void find_basic_blocks (rtx);
extern bool cleanup_cfg (int);
extern bool delete_unreachable_blocks (void);
extern bool merge_seq_blocks (void);

typedef struct conflict_graph_def *conflict_graph;

/* Callback function when enumerating conflicts.  The arguments are
   the smaller and larger regno in the conflict.  Returns zero if
   enumeration is to continue, nonzero to halt enumeration.  */
typedef int (*conflict_graph_enum_fn) (int, int, void *);

/* Prototypes of operations on conflict graphs.  */

extern conflict_graph conflict_graph_new
extern void conflict_graph_delete (conflict_graph);
extern int conflict_graph_add (conflict_graph, int, int);
extern int conflict_graph_conflict_p (conflict_graph, int, int);
extern void conflict_graph_enum (conflict_graph, int, conflict_graph_enum_fn,
				 void *);
extern void conflict_graph_merge_regs (conflict_graph, int, int);
extern void conflict_graph_print (conflict_graph, FILE*);
extern bool mark_dfs_back_edges (void);
extern void set_edge_can_fallthru_flag (void);
extern void update_br_prob_note (basic_block);
extern void fixup_abnormal_edges (void);
extern bool inside_basic_block_p (rtx);
extern bool control_flow_insn_p (rtx);
extern rtx get_last_bb_insn (basic_block);

/* In bb-reorder.c */
extern void reorder_basic_blocks (unsigned int);

/* In dominance.c */

enum cdi_direction

enum dom_state
  DOM_NONE,		/* Not computed at all.  */
  DOM_NO_FAST_QUERY,	/* The data is OK, but the fast query data are not usable.  */
  DOM_OK		/* Everything is ok.  */

extern enum dom_state dom_computed[2];

extern bool dom_info_available_p (enum cdi_direction);
extern void calculate_dominance_info (enum cdi_direction);
extern void free_dominance_info (enum cdi_direction);
extern basic_block nearest_common_dominator (enum cdi_direction,
					     basic_block, basic_block);
extern basic_block nearest_common_dominator_for_set (enum cdi_direction,
extern void set_immediate_dominator (enum cdi_direction, basic_block,
extern basic_block get_immediate_dominator (enum cdi_direction, basic_block);
extern bool dominated_by_p (enum cdi_direction, basic_block, basic_block);
extern int get_dominated_by (enum cdi_direction, basic_block, basic_block **);
extern unsigned get_dominated_by_region (enum cdi_direction, basic_block *,
					 unsigned, basic_block *);
extern void add_to_dominance_info (enum cdi_direction, basic_block);
extern void delete_from_dominance_info (enum cdi_direction, basic_block);
basic_block recount_dominator (enum cdi_direction, basic_block);
extern void redirect_immediate_dominators (enum cdi_direction, basic_block,
extern void iterate_fix_dominators (enum cdi_direction, basic_block *, int);
extern void verify_dominators (enum cdi_direction);
extern basic_block first_dom_son (enum cdi_direction, basic_block);
extern basic_block next_dom_son (enum cdi_direction, basic_block);
unsigned bb_dom_dfs_in (enum cdi_direction, basic_block);
unsigned bb_dom_dfs_out (enum cdi_direction, basic_block);

extern edge try_redirect_by_replacing_jump (edge, basic_block, bool);
extern void break_superblocks (void);
extern void check_bb_profile (basic_block, FILE *);
extern void update_bb_profile_for_threading (basic_block, int, gcov_type, edge);
extern void init_rtl_bb_info (basic_block);

extern void initialize_original_copy_tables (void);
extern void free_original_copy_tables (void);
extern void set_bb_original (basic_block, basic_block);
extern basic_block get_bb_original (basic_block);
extern void set_bb_copy (basic_block, basic_block);
extern basic_block get_bb_copy (basic_block);

extern rtx insert_insn_end_bb_new (rtx, basic_block);

#include "cfghooks.h"

/* In struct-equiv.c */

/* Constants used to size arrays in struct equiv_info (currently only one).
   When these limits are exceeded, struct_equiv returns zero.
   The maximum number of pseudo registers that are different in the two blocks,
   but appear in equivalent places and are dead at the end (or where one of
   a pair is dead at the end).  */
/* The maximum number of references to an input register that struct_equiv
   can handle.  */

/* Structure used to track state during struct_equiv that can be rolled
   back when we find we can't match an insn, or if we want to match part
   of it in a different way.
   This information pertains to the pair of partial blocks that has been
   matched so far.  Since this pair is structurally equivalent, this is
   conceptually just one partial block expressed in two potentially
   different ways.  */
struct struct_equiv_checkpoint
  int ninsns;       /* Insns are matched so far.  */
  int local_count;  /* Number of block-local registers.  */
  int input_count;  /* Number of inputs to the block.  */

  /* X_START and Y_START are the first insns (in insn stream order)
     of the partial blocks that have been considered for matching so far.
     Since we are scanning backwards, they are also the instructions that
     are currently considered - or the last ones that have been considered -
     for matching (Unless we tracked back to these because a preceding
     instruction failed to match).  */
  rtx x_start, y_start;

  /*  INPUT_VALID indicates if we have actually set up X_INPUT / Y_INPUT
      during the current pass; we keep X_INPUT / Y_INPUT around between passes
      so that we can match REG_EQUAL / REG_EQUIV notes referring to these.  */
  bool input_valid;

  /* Some information would be expensive to exactly checkpoint, so we
     merely increment VERSION any time information about local
     registers, inputs and/or register liveness changes.  When backtracking,
     it is decremented for changes that can be undone, and if a discrepancy
     remains, NEED_RERUN in the relevant struct equiv_info is set to indicate
     that a new pass should be made over the entire block match to get
     accurate register information.  */
  int version;

/* A struct equiv_info is used to pass information to struct_equiv and
   to gather state while two basic blocks are checked for structural
   equivalence.  */

struct equiv_info
  /* Fields set up by the caller to struct_equiv_block_eq */

  basic_block x_block, y_block;  /* The two blocks being matched.  */

  /* MODE carries the mode bits from cleanup_cfg if we are called from
     try_crossjump_to_edge, and additionally it carries the
     STRUCT_EQUIV_* bits described above.  */
  int mode;

  /* INPUT_COST is the cost that adding an extra input to the matched blocks
     is supposed to have, and is taken into account when considering if the
     matched sequence should be extended backwards.  input_cost < 0 means
     don't accept any inputs at all.  */
  int input_cost;

  /* Fields to track state inside of struct_equiv_block_eq.  Some of these
     are also outputs.  */

  /* X_INPUT and Y_INPUT are used by struct_equiv to record a register that
     is used as an input parameter, i.e. where different registers are used
     as sources.  This is only used for a register that is live at the end
     of the blocks, or in some identical code at the end of the blocks;
     Inputs that are dead at the end go into X_LOCAL / Y_LOCAL.  */
  rtx x_input, y_input;
  /* When a previous pass has identified a valid input, INPUT_REG is set
     by struct_equiv_block_eq, and it is henceforth replaced in X_BLOCK
     for the input.  */
  rtx input_reg;

  /* COMMON_LIVE keeps track of the registers which are currently live
     (as we scan backwards from the end) and have the same numbers in both
     blocks.  N.B. a register that is in common_live is unsuitable to become
     a local reg.  */
  regset common_live;
  /* Likewise, X_LOCAL_LIVE / Y_LOCAL_LIVE keep track of registers that are
     local to one of the blocks; these registers must not be accepted as
     identical when encountered in both blocks.  */
  regset x_local_live, y_local_live;

  /* EQUIV_USED indicates for which insns a REG_EQUAL or REG_EQUIV note is
     being used, to avoid having to backtrack in the next pass, so that we
     get accurate life info for this insn then.  For each such insn,
     the bit with the number corresponding to the CUR.NINSNS value at the
     time of scanning is set.  */
  bitmap equiv_used;

  /* Current state that can be saved & restored easily.  */
  struct struct_equiv_checkpoint cur;
  /* BEST_MATCH is used to store the best match so far, weighing the
     cost of matched insns COSTS_N_INSNS (CUR.NINSNS) against the cost
     CUR.INPUT_COUNT * INPUT_COST of setting up the inputs.  */
  struct struct_equiv_checkpoint best_match;
  /* If a checkpoint restore failed, or an input conflict newly arises,
     NEED_RERUN is set.  This has to be tested by the caller to re-run
     the comparison if the match appears otherwise sound.  The state kept in
     x_start, y_start, equiv_used and check_input_conflict ensures that
     we won't loop indefinitely.  */
  bool need_rerun;
  /* If there is indication of an input conflict at the end,
     CHECK_INPUT_CONFLICT is set so that we'll check for input conflicts
     for each insn in the next pass.  This is needed so that we won't discard
     a partial match if there is a longer match that has to be abandoned due
     to an input conflict.  */
  bool check_input_conflict;
  /* HAD_INPUT_CONFLICT is set if CHECK_INPUT_CONFLICT was already set and we
     have passed a point where there were multiple dying inputs.  This helps
     us decide if we should set check_input_conflict for the next pass.  */
  bool had_input_conflict;

  /* LIVE_UPDATE controls if we want to change any life info at all.  We
     set it to false during REG_EQUAL / REG_EUQIV note comparison of the final
     pass so that we don't introduce new registers just for the note; if we
     can't match the notes without the current register information, we drop
     them.  */
  bool live_update;

  /* X_LOCAL and Y_LOCAL are used to gather register numbers of register pairs
     that are local to X_BLOCK and Y_BLOCK, with CUR.LOCAL_COUNT being the index
     to the next free entry.  */
  /* LOCAL_RVALUE is nonzero if the corresponding X_LOCAL / Y_LOCAL entry
     was a source operand (including STRICT_LOW_PART) for the last invocation
     of struct_equiv mentioning it, zero if it was a destination-only operand.
     Since we are scanning backwards, this means the register is input/local
     for the (partial) block scanned so far.  */
  bool local_rvalue[STRUCT_EQUIV_MAX_LOCAL];

  /* Additional fields that are computed for the convenience of the caller.  */

  /* DYING_INPUTS is set to the number of local registers that turn out
     to be inputs to the (possibly partial) block.  */
  int dying_inputs;
  /* X_END and Y_END are the last insns in X_BLOCK and Y_BLOCK, respectively,
     that are being compared.  A final jump insn will not be included.  */
  rtx x_end, y_end;

  /* If we are matching tablejumps, X_LABEL in X_BLOCK corresponds to
     Y_LABEL in Y_BLOCK.  */
  rtx x_label, y_label;


extern bool insns_match_p (rtx, rtx, struct equiv_info *);
extern int struct_equiv_block_eq (int, struct equiv_info *);
extern bool struct_equiv_init (int, struct equiv_info *);
extern bool rtx_equiv_p (rtx *, rtx, int, struct equiv_info *);

/* In cfgrtl.c */
extern bool condjump_equiv_p (struct equiv_info *, bool);

/* 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;

#endif /* GCC_BASIC_BLOCK_H */