[gcc.git] / gcc / cfgloop.h

/* Natural loop functions
   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
version.

GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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, 59 Temple Place - Suite 330, Boston, MA
02111-1307, USA.  */

#ifndef GCC_CFGLOOP_H
#define GCC_CFGLOOP_H

#include "basic-block.h"
/* For rtx_code.  */
#include "rtl.h"

/* Structure to hold decision about unrolling/peeling.  */
enum lpt_dec
{
  LPT_NONE,
  LPT_PEEL_COMPLETELY,
  LPT_PEEL_SIMPLE,
  LPT_UNROLL_CONSTANT,
  LPT_UNROLL_RUNTIME,
  LPT_UNROLL_STUPID
};

struct lpt_decision
{
  enum lpt_dec decision;
  unsigned times;
};

/* The structure describing a bound on number of iterations of a loop.  */

struct nb_iter_bound
{
  tree bound;		/* The expression whose value is an upper bound on the
			   number of executions of anything after ...  */
  tree at_stmt;		/* ... this statement during one execution of loop.  */
  tree additional;	/* A conjunction of conditions the operands of BOUND
			   satisfy.  The additional information about the value
			   of the bound may be derived from it.  */
  struct nb_iter_bound *next;
			/* The next bound in a list.  */
};

/* Structure to hold information for each natural loop.  */
struct loop
{
  /* Index into loops array.  */
  int num;

  /* Basic block of loop header.  */
  basic_block header;

  /* Basic block of loop latch.  */
  basic_block latch;

  /* For loop unrolling/peeling decision.  */
  struct lpt_decision lpt_decision;

  /* Number of loop insns.  */
  unsigned ninsns;

  /* Average number of executed insns per iteration.  */
  unsigned av_ninsns;

  /* The first block in the loop.  This is not necessarily the same as
     the loop header.  */
  basic_block first;

  /* The last block in the loop.  This is not necessarily the same as
     the loop latch.  */
  basic_block last;

  /* Number of blocks contained within the loop.  */
  unsigned num_nodes;

  /* The loop nesting depth.  */
  int depth;

  /* Superloops of the loop.  */
  struct loop **pred;

  /* The height of the loop (enclosed loop levels) within the loop
     hierarchy tree.  */
  int level;

  /* The outer (parent) loop or NULL if outermost loop.  */
  struct loop *outer;

  /* The first inner (child) loop or NULL if innermost loop.  */
  struct loop *inner;

  /* Link to the next (sibling) loop.  */
  struct loop *next;

  /* Loop that is copy of this loop.  */
  struct loop *copy;

  /* Nonzero if the loop is invalid (e.g., contains setjmp.).  */
  int invalid;

  /* Auxiliary info specific to a pass.  */
  void *aux;

  /* The following are currently used by loop.c but they are likely to
     disappear when loop.c is replaced and removed.  */

  /* The NOTE_INSN_LOOP_BEG.  */
  rtx start;

  /* The NOTE_INSN_LOOP_END.  */
  rtx end;

  /* For a rotated loop that is entered near the bottom,
     this is the label at the top.  Otherwise it is zero.  */
  rtx top;

  /* Place in the loop where control enters.  */
  rtx scan_start;

  /* The position where to sink insns out of the loop.  */
  rtx sink;

  /* List of all LABEL_REFs which refer to code labels outside the
     loop.  Used by routines that need to know all loop exits, such as
     final_biv_value and final_giv_value.

     This does not include loop exits due to return instructions.
     This is because all bivs and givs are pseudos, and hence must be
     dead after a return, so the presence of a return does not affect
     any of the optimizations that use this info.  It is simpler to
     just not include return instructions on this list.  */
  rtx exit_labels;

  /* The number of LABEL_REFs on exit_labels for this loop and all
     loops nested inside it.  */
  int exit_count;

  /* The probable number of times the loop is executed at runtime.
     This is an INTEGER_CST or an expression containing symbolic
     names.  Don't access this field directly:
     number_of_iterations_in_loop computes and caches the computed
     information in this field.  */
  tree nb_iterations;

  /* An INTEGER_CST estimation of the number of iterations.  NULL_TREE
     if there is no estimation.  */
  tree estimated_nb_iterations;

  /* Upper bound on number of iterations of a loop.  */
  struct nb_iter_bound *bounds;

  /* If not NULL, loop has just single exit edge stored here (edges to the
     EXIT_BLOCK_PTR do not count.  */
  edge single_exit;

  /* True when the loop does not carry data dependences, and
     consequently the iterations can be executed in any order.  False
     when the loop carries data dependences, or when the property is
     not decidable.  */
  bool parallel_p;
};

/* Flags for state of loop structure.  */
enum
{
  LOOPS_HAVE_PREHEADERS = 1,
  LOOPS_HAVE_SIMPLE_LATCHES = 2,
  LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS = 4,
  LOOPS_HAVE_MARKED_SINGLE_EXITS = 8
};

/* Structure to hold CFG information about natural loops within a function.  */
struct loops
{
  /* Number of natural loops in the function.  */
  unsigned num;

  /* Array of natural loop descriptors (scanning this array in reverse order
     will find the inner loops before their enclosing outer loops).  */
  struct loop *array;

  /* The above array is unused in new loop infrastructure and is kept only for
     purposes of the old loop optimizer.  Instead we store just pointers to
     loops here.  
     Note that a loop in this array may actually be NULL, if the loop
     has been removed and the entire loops structure has not been
     recomputed since that time.  */
  struct loop **parray;

  /* Pointer to root of loop hierarchy tree.  */
  struct loop *tree_root;

  /* Information derived from the CFG.  */
  struct cfg
  {
    /* The ordering of the basic blocks in a depth first search.  */
    int *dfs_order;

    /* The reverse completion ordering of the basic blocks found in a
       depth first search.  */
    int *rc_order;
  } cfg;

  /* Headers shared by multiple loops that should be merged.  */
  sbitmap shared_headers;

  /* State of loops.  */
  int state;
};

/* The loop tree currently optimized.  */

extern struct loops *current_loops;

/* Loop recognition.  */
extern int flow_loops_find (struct loops *);
extern void flow_loops_free (struct loops *);
extern void flow_loops_dump (const struct loops *, FILE *,
			     void (*)(const struct loop *, FILE *, int), int);
extern void flow_loop_dump (const struct loop *, FILE *,
			    void (*)(const struct loop *, FILE *, int), int);
extern void flow_loop_free (struct loop *);
int flow_loop_nodes_find (basic_block, struct loop *);
void fix_loop_structure (struct loops *, bitmap changed_bbs);
void mark_irreducible_loops (struct loops *);
void mark_single_exit_loops (struct loops *);
extern void create_loop_notes (void);

/* Loop data structure manipulation/querying.  */
extern void flow_loop_tree_node_add (struct loop *, struct loop *);
extern void flow_loop_tree_node_remove (struct loop *);
extern bool flow_loop_outside_edge_p (const struct loop *, edge);
extern bool flow_loop_nested_p	(const struct loop *, const struct loop *);
extern bool flow_bb_inside_loop_p (const struct loop *, const basic_block);
extern struct loop * find_common_loop (struct loop *, struct loop *);
struct loop *superloop_at_depth (struct loop *, unsigned);
extern unsigned tree_num_loop_insns (struct loop *);
extern int num_loop_insns (struct loop *);
extern int average_num_loop_insns (struct loop *);
extern unsigned get_loop_level (const struct loop *);
extern bool loop_exit_edge_p (const struct loop *, edge);
extern void mark_loop_exit_edges (struct loops *);

/* Loops & cfg manipulation.  */
extern basic_block *get_loop_body (const struct loop *);
extern basic_block *get_loop_body_in_dom_order (const struct loop *);
extern basic_block *get_loop_body_in_bfs_order (const struct loop *);
extern edge *get_loop_exit_edges (const struct loop *, unsigned *);
extern unsigned num_loop_branches (const struct loop *);

extern edge loop_preheader_edge (const struct loop *);
extern edge loop_latch_edge (const struct loop *);

extern void add_bb_to_loop (basic_block, struct loop *);
extern void remove_bb_from_loops (basic_block);

extern void cancel_loop (struct loops *, struct loop *);
extern void cancel_loop_tree (struct loops *, struct loop *);

extern basic_block loop_split_edge_with (edge, rtx);
extern int fix_loop_placement (struct loop *);

enum
{
  CP_SIMPLE_PREHEADERS = 1
};

extern void create_preheaders (struct loops *, int);
extern void force_single_succ_latches (struct loops *);

extern void verify_loop_structure (struct loops *);

/* Loop analysis.  */
extern bool just_once_each_iteration_p (struct loop *, basic_block);
extern unsigned expected_loop_iterations (const struct loop *);

/* Loop manipulation.  */
extern bool can_duplicate_loop_p (struct loop *loop);

#define DLTHE_FLAG_UPDATE_FREQ	1	/* Update frequencies in
					   duplicate_loop_to_header_edge.  */

extern struct loop * duplicate_loop (struct loops *, struct loop *,
				     struct loop *);
extern bool duplicate_loop_to_header_edge (struct loop *, edge, struct loops *,
					   unsigned, sbitmap, edge, edge *,
					   unsigned *, int);
extern struct loop *loopify (struct loops *, edge, edge,
			     basic_block, edge, edge, bool);
struct loop * loop_version (struct loops *, struct loop *, void *,
			    basic_block *);			     
extern bool remove_path (struct loops *, edge);
extern edge split_loop_bb (basic_block, void *);

/* Induction variable analysis.  */

/* The description of induction variable.  The things are a bit complicated
   due to need to handle subregs and extends.  The value of the object described
   by it can be obtained as follows (all computations are done in extend_mode):

   Value in i-th iteration is
     delta + mult * extend_{extend_mode} (subreg_{mode} (base + i * step)).

   If first_special is true, the value in the first iteration is
     delta + mult * base
     
   If extend = UNKNOWN, first_special must be false, delta 0, mult 1 and value is
     subreg_{mode} (base + i * step)

   The get_iv_value function can be used to obtain these expressions.

   ??? Add a third mode field that would specify the mode in that inner
   computation is done, which would enable it to be different from the
   outer one?  */

struct rtx_iv
{
  /* Its base and step (mode of base and step is supposed to be extend_mode,
     see the description above).  */
  rtx base, step;

  /* The type of extend applied to it (SIGN_EXTEND, ZERO_EXTEND or UNKNOWN).  */
  enum rtx_code extend;

  /* Operations applied in the extended mode.  */
  rtx delta, mult;

  /* The mode it is extended to.  */
  enum machine_mode extend_mode;

  /* The mode the variable iterates in.  */
  enum machine_mode mode;

  /* Whether we have already filled the remaining fields.  */
  unsigned analysed : 1;

  /* Whether the first iteration needs to be handled specially.  */
  unsigned first_special : 1;
};

/* The description of an exit from the loop and of the number of iterations
   till we take the exit.  */

struct niter_desc
{
  /* The edge out of the loop.  */
  edge out_edge;

  /* The other edge leading from the condition.  */
  edge in_edge;

  /* True if we are able to say anything about number of iterations of the
     loop.  */
  bool simple_p;

  /* True if the loop iterates the constant number of times.  */
  bool const_iter;

  /* Number of iterations if constant.  */
  unsigned HOST_WIDEST_INT niter;

  /* Upper bound on the number of iterations.  */
  unsigned HOST_WIDEST_INT niter_max;

  /* Assumptions under that the rest of the information is valid.  */
  rtx assumptions;

  /* Assumptions under that the loop ends before reaching the latch,
     even if value of niter_expr says otherwise.  */
  rtx noloop_assumptions;

  /* Condition under that the loop is infinite.  */
  rtx infinite;

  /* Whether the comparison is signed.  */
  bool signed_p;

  /* The mode in that niter_expr should be computed.  */
  enum machine_mode mode;

  /* The number of iterations of the loop.  */
  rtx niter_expr;
};

extern void iv_analysis_loop_init (struct loop *);
extern rtx iv_get_reaching_def (rtx, rtx);
extern bool iv_analyze (rtx, rtx, struct rtx_iv *);
extern rtx get_iv_value (struct rtx_iv *, rtx);
extern bool biv_p (rtx, rtx);
extern void find_simple_exit (struct loop *, struct niter_desc *);
extern void iv_analysis_done (void);

extern struct niter_desc *get_simple_loop_desc (struct loop *loop);
extern void free_simple_loop_desc (struct loop *loop);

static inline struct niter_desc *
simple_loop_desc (struct loop *loop)
{
  return loop->aux;
}

/* The properties of the target.  */

extern unsigned target_avail_regs;	/* Number of available registers.  */
extern unsigned target_res_regs;	/* Number of reserved registers.  */
extern unsigned target_small_cost;	/* The cost for register when there
					   is a free one.  */
extern unsigned target_pres_cost;	/* The cost for register when there are
					   not too many free ones.  */
extern unsigned target_spill_cost;	/* The cost for register when we need
					   to spill.  */

/* Register pressure estimation for induction variable optimizations & loop
   invariant motion.  */
extern unsigned global_cost_for_size (unsigned, unsigned, unsigned);
extern void init_set_costs (void);

/* Loop optimizer initialization.  */
extern struct loops *loop_optimizer_init (FILE *);
extern void loop_optimizer_finalize (struct loops *, FILE *);

/* Optimization passes.  */
extern void unswitch_loops (struct loops *);

enum
{
  UAP_PEEL = 1,		/* Enables loop peeling.  */
  UAP_UNROLL = 2,	/* Enables peeling of loops if it seems profitable.  */
  UAP_UNROLL_ALL = 4	/* Enables peeling of all loops.  */
};

extern void unroll_and_peel_loops (struct loops *, int);
extern void doloop_optimize_loops (struct loops *);
extern void move_loop_invariants (struct loops *);
extern void record_estimate (struct loop *, tree, tree, tree);

/* Old loop optimizer interface.  */

/* Flags passed to loop_optimize.  */
#define LOOP_PREFETCH 1

extern void loop_optimize (rtx, FILE *, int);

#endif /* GCC_CFGLOOP_H */
Commit	Line	Data
3d436d2a	1	/* Natural loop functions
613c5cd0	2	Copyright (C) 1987, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
3d436d2a ZD	3	Free Software Foundation, Inc.
	4
	5	This file is part of GCC.
	6
	7	GCC is free software; you can redistribute it and/or modify it under
	8	the terms of the GNU General Public License as published by the Free
	9	Software Foundation; either version 2, or (at your option) any later
	10	version.
	11
	12	GCC is distributed in the hope that it will be useful, but WITHOUT ANY
	13	WARRANTY; without even the implied warranty of MERCHANTABILITY or
	14	FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	15	for more details.
	16
	17	You should have received a copy of the GNU General Public License
	18	along with GCC; see the file COPYING. If not, write to the Free
	19	Software Foundation, 59 Temple Place - Suite 330, Boston, MA
	20	02111-1307, USA. */
	21
59587b18 JQ	22	#ifndef GCC_CFGLOOP_H
	23	#define GCC_CFGLOOP_H
	24
	25	#include "basic-block.h"
	26	/* For rtx_code. */
	27	#include "rtl.h"
	28
3d436d2a ZD	29	/* Structure to hold decision about unrolling/peeling. */
	30	enum lpt_dec
	31	{
	32	LPT_NONE,
	33	LPT_PEEL_COMPLETELY,
	34	LPT_PEEL_SIMPLE,
	35	LPT_UNROLL_CONSTANT,
	36	LPT_UNROLL_RUNTIME,
	37	LPT_UNROLL_STUPID
	38	};
	39
	40	struct lpt_decision
	41	{
	42	enum lpt_dec decision;
	43	unsigned times;
	44	};
	45
86df10e3 SP	46	/* The structure describing a bound on number of iterations of a loop. */
	47
	48	struct nb_iter_bound
	49	{
	50	tree bound; /* The expression whose value is an upper bound on the
	51	number of executions of anything after ... */
	52	tree at_stmt; /* ... this statement during one execution of loop. */
	53	tree additional; /* A conjunction of conditions the operands of BOUND
	54	satisfy. The additional information about the value
	55	of the bound may be derived from it. */
	56	struct nb_iter_bound *next;
	57	/* The next bound in a list. */
	58	};
	59
3d436d2a ZD	60	/* Structure to hold information for each natural loop. */
	61	struct loop
	62	{
	63	/* Index into loops array. */
	64	int num;
	65
	66	/* Basic block of loop header. */
	67	basic_block header;
	68
	69	/* Basic block of loop latch. */
	70	basic_block latch;
	71
3d436d2a ZD	72	/* For loop unrolling/peeling decision. */
	73	struct lpt_decision lpt_decision;
	74
3d436d2a ZD	75	/* Number of loop insns. */
	76	unsigned ninsns;
	77
	78	/* Average number of executed insns per iteration. */
	79	unsigned av_ninsns;
	80
3d436d2a ZD	81	/* The first block in the loop. This is not necessarily the same as
	82	the loop header. */
	83	basic_block first;
	84
	85	/* The last block in the loop. This is not necessarily the same as
	86	the loop latch. */
	87	basic_block last;
	88
3d436d2a ZD	89	/* Number of blocks contained within the loop. */
	90	unsigned num_nodes;
	91
3d436d2a ZD	92	/* The loop nesting depth. */
	93	int depth;
	94
	95	/* Superloops of the loop. */
	96	struct loop **pred;
	97
	98	/* The height of the loop (enclosed loop levels) within the loop
	99	hierarchy tree. */
	100	int level;
	101
	102	/* The outer (parent) loop or NULL if outermost loop. */
	103	struct loop *outer;
	104
	105	/* The first inner (child) loop or NULL if innermost loop. */
	106	struct loop *inner;
	107
	108	/* Link to the next (sibling) loop. */
	109	struct loop *next;
	110
	111	/* Loop that is copy of this loop. */
	112	struct loop *copy;
	113
6356f892	114	/* Nonzero if the loop is invalid (e.g., contains setjmp.). */
3d436d2a ZD	115	int invalid;
	116
	117	/* Auxiliary info specific to a pass. */
	118	void *aux;
	119
	120	/* The following are currently used by loop.c but they are likely to
75473b02	121	disappear when loop.c is replaced and removed. */
3d436d2a	122
3d436d2a ZD	123	/* The NOTE_INSN_LOOP_BEG. */
	124	rtx start;
	125
	126	/* The NOTE_INSN_LOOP_END. */
	127	rtx end;
	128
	129	/* For a rotated loop that is entered near the bottom,
	130	this is the label at the top. Otherwise it is zero. */
	131	rtx top;
	132
	133	/* Place in the loop where control enters. */
	134	rtx scan_start;
	135
	136	/* The position where to sink insns out of the loop. */
	137	rtx sink;
	138
	139	/* List of all LABEL_REFs which refer to code labels outside the
	140	loop. Used by routines that need to know all loop exits, such as
	141	final_biv_value and final_giv_value.
	142
	143	This does not include loop exits due to return instructions.
	144	This is because all bivs and givs are pseudos, and hence must be
	145	dead after a return, so the presence of a return does not affect
	146	any of the optimizations that use this info. It is simpler to
	147	just not include return instructions on this list. */
	148	rtx exit_labels;
	149
	150	/* The number of LABEL_REFs on exit_labels for this loop and all
	151	loops nested inside it. */
	152	int exit_count;
e9eb809d	153
9baba81b SP	154	/* The probable number of times the loop is executed at runtime.
	155	This is an INTEGER_CST or an expression containing symbolic
	156	names. Don't access this field directly:
	157	number_of_iterations_in_loop computes and caches the computed
	158	information in this field. */
	159	tree nb_iterations;
	160
86df10e3 SP	161	/* An INTEGER_CST estimation of the number of iterations. NULL_TREE
	162	if there is no estimation. */
	163	tree estimated_nb_iterations;
	164
e9eb809d ZD	165	/* Upper bound on number of iterations of a loop. */
e9eb809d ZD	166	struct nb_iter_bound *bounds;
82b85a85 ZD	167
	168	/* If not NULL, loop has just single exit edge stored here (edges to the
	169	EXIT_BLOCK_PTR do not count. */
	170	edge single_exit;
86df10e3 SP	171
	172	/* True when the loop does not carry data dependences, and
	173	consequently the iterations can be executed in any order. False
	174	when the loop carries data dependences, or when the property is
	175	not decidable. */
	176	bool parallel_p;
3d436d2a ZD	177	};
	178
	179	/* Flags for state of loop structure. */
	180	enum
	181	{
	182	LOOPS_HAVE_PREHEADERS = 1,
	183	LOOPS_HAVE_SIMPLE_LATCHES = 2,
82b85a85 ZD	184	LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS = 4,
82b85a85 ZD	185	LOOPS_HAVE_MARKED_SINGLE_EXITS = 8
3d436d2a ZD	186	};
	187
	188	/* Structure to hold CFG information about natural loops within a function. */
	189	struct loops
	190	{
	191	/* Number of natural loops in the function. */
	192	unsigned num;
	193
3d436d2a ZD	194	/* Array of natural loop descriptors (scanning this array in reverse order
	195	will find the inner loops before their enclosing outer loops). */
	196	struct loop *array;
	197
	198	/* The above array is unused in new loop infrastructure and is kept only for
	199	purposes of the old loop optimizer. Instead we store just pointers to
43a613f7 DB	200	loops here.
	201	Note that a loop in this array may actually be NULL, if the loop
	202	has been removed and the entire loops structure has not been
	203	recomputed since that time. */
3d436d2a ZD	204	struct loop **parray;
	205
	206	/* Pointer to root of loop hierarchy tree. */
	207	struct loop *tree_root;
	208
	209	/* Information derived from the CFG. */
	210	struct cfg
	211	{
3d436d2a ZD	212	/* The ordering of the basic blocks in a depth first search. */
	213	int *dfs_order;
	214
	215	/* The reverse completion ordering of the basic blocks found in a
	216	depth first search. */
	217	int *rc_order;
	218	} cfg;
	219
	220	/* Headers shared by multiple loops that should be merged. */
	221	sbitmap shared_headers;
	222
	223	/* State of loops. */
	224	int state;
	225	};
	226
9baba81b SP	227	/* The loop tree currently optimized. */
	228
	229	extern struct loops *current_loops;
	230
3d436d2a	231	/* Loop recognition. */
70388d94	232	extern int flow_loops_find (struct loops *);
d329e058 AJ	233	extern void flow_loops_free (struct loops *);
	234	extern void flow_loops_dump (const struct loops , FILE ,
	235	void ()(const struct loop , FILE *, int), int);
	236	extern void flow_loop_dump (const struct loop , FILE ,
	237	void ()(const struct loop , FILE *, int), int);
d329e058	238	extern void flow_loop_free (struct loop *);
2b271002 ZD	239	int flow_loop_nodes_find (basic_block, struct loop *);
2b271002 ZD	240	void fix_loop_structure (struct loops *, bitmap changed_bbs);
d329e058	241	void mark_irreducible_loops (struct loops *);
82b85a85	242	void mark_single_exit_loops (struct loops *);
6de9cd9a	243	extern void create_loop_notes (void);
3d436d2a	244
4d6922ee	245	/* Loop data structure manipulation/querying. */
d329e058 AJ	246	extern void flow_loop_tree_node_add (struct loop , struct loop );
	247	extern void flow_loop_tree_node_remove (struct loop *);
	248	extern bool flow_loop_outside_edge_p (const struct loop *, edge);
	249	extern bool flow_loop_nested_p (const struct loop , const struct loop );
	250	extern bool flow_bb_inside_loop_p (const struct loop *, const basic_block);
	251	extern struct loop * find_common_loop (struct loop , struct loop );
a7e5372d	252	struct loop superloop_at_depth (struct loop , unsigned);
82b85a85	253	extern unsigned tree_num_loop_insns (struct loop *);
d329e058 AJ	254	extern int num_loop_insns (struct loop *);
d329e058 AJ	255	extern int average_num_loop_insns (struct loop *);
689ba89d	256	extern unsigned get_loop_level (const struct loop *);
70388d94 ZD	257	extern bool loop_exit_edge_p (const struct loop *, edge);
70388d94 ZD	258	extern void mark_loop_exit_edges (struct loops *);
3d436d2a ZD	259
3d436d2a ZD	260	/* Loops & cfg manipulation. */
d329e058	261	extern basic_block get_loop_body (const struct loop );
50654f6c	262	extern basic_block get_loop_body_in_dom_order (const struct loop );
40923b20	263	extern basic_block get_loop_body_in_bfs_order (const struct loop );
d329e058	264	extern edge get_loop_exit_edges (const struct loop , unsigned *);
50654f6c	265	extern unsigned num_loop_branches (const struct loop *);
3d436d2a	266
d329e058 AJ	267	extern edge loop_preheader_edge (const struct loop *);
d329e058 AJ	268	extern edge loop_latch_edge (const struct loop *);
3d436d2a	269
d329e058 AJ	270	extern void add_bb_to_loop (basic_block, struct loop *);
d329e058 AJ	271	extern void remove_bb_from_loops (basic_block);
3d436d2a	272
d329e058 AJ	273	extern void cancel_loop (struct loops , struct loop );
d329e058 AJ	274	extern void cancel_loop_tree (struct loops , struct loop );
3d436d2a	275
d47cc544	276	extern basic_block loop_split_edge_with (edge, rtx);
d329e058	277	extern int fix_loop_placement (struct loop *);
3d436d2a ZD	278
	279	enum
	280	{
bc35512f	281	CP_SIMPLE_PREHEADERS = 1
3d436d2a ZD	282	};
3d436d2a ZD	283
d329e058 AJ	284	extern void create_preheaders (struct loops *, int);
d329e058 AJ	285	extern void force_single_succ_latches (struct loops *);
3d436d2a	286
d329e058	287	extern void verify_loop_structure (struct loops *);
3d436d2a ZD	288
3d436d2a ZD	289	/* Loop analysis. */
d47cc544	290	extern bool just_once_each_iteration_p (struct loop *, basic_block);
d329e058	291	extern unsigned expected_loop_iterations (const struct loop *);
617b465c ZD	292
617b465c ZD	293	/* Loop manipulation. */
d329e058	294	extern bool can_duplicate_loop_p (struct loop *loop);
617b465c ZD	295
	296	#define DLTHE_FLAG_UPDATE_FREQ 1 /* Update frequencies in
	297	duplicate_loop_to_header_edge. */
	298
f67d92e9 DB	299	extern struct loop * duplicate_loop (struct loops , struct loop ,
f67d92e9 DB	300	struct loop *);
1cb7dfc3 MH	301	extern bool duplicate_loop_to_header_edge (struct loop , edge, struct loops ,
	302	unsigned, sbitmap, edge, edge *,
	303	unsigned *, int);
5132abc2 KH	304	extern struct loop loopify (struct loops , edge, edge,
5132abc2 KH	305	basic_block, edge, edge, bool);
1cb7dfc3 MH	306	struct loop * loop_version (struct loops , struct loop , void *,
1cb7dfc3 MH	307	basic_block *);
d329e058	308	extern bool remove_path (struct loops *, edge);
92fc4a2f	309	extern edge split_loop_bb (basic_block, void *);
617b465c	310
50654f6c ZD	311	/* Induction variable analysis. */
	312
	313	/* The description of induction variable. The things are a bit complicated
	314	due to need to handle subregs and extends. The value of the object described
	315	by it can be obtained as follows (all computations are done in extend_mode):
	316
	317	Value in i-th iteration is
	318	delta + mult * extend_{extend_mode} (subreg_{mode} (base + i * step)).
	319
	320	If first_special is true, the value in the first iteration is
	321	delta + mult * base
	322
f822d252	323	If extend = UNKNOWN, first_special must be false, delta 0, mult 1 and value is
50654f6c ZD	324	subreg_{mode} (base + i * step)
	325
	326	The get_iv_value function can be used to obtain these expressions.
	327
	328	??? Add a third mode field that would specify the mode in that inner
	329	computation is done, which would enable it to be different from the
	330	outer one? */
	331
	332	struct rtx_iv
	333	{
	334	/* Its base and step (mode of base and step is supposed to be extend_mode,
	335	see the description above). */
	336	rtx base, step;
	337
f822d252	338	/* The type of extend applied to it (SIGN_EXTEND, ZERO_EXTEND or UNKNOWN). */
50654f6c ZD	339	enum rtx_code extend;
	340
	341	/* Operations applied in the extended mode. */
	342	rtx delta, mult;
	343
	344	/* The mode it is extended to. */
	345	enum machine_mode extend_mode;
	346
	347	/* The mode the variable iterates in. */
	348	enum machine_mode mode;
	349
	350	/* Whether we have already filled the remaining fields. */
	351	unsigned analysed : 1;
	352
	353	/* Whether the first iteration needs to be handled specially. */
	354	unsigned first_special : 1;
	355	};
	356
f2dca510 ZD	357	/* The description of an exit from the loop and of the number of iterations
f2dca510 ZD	358	till we take the exit. */
50654f6c ZD	359
	360	struct niter_desc
	361	{
	362	/* The edge out of the loop. */
	363	edge out_edge;
	364
	365	/* The other edge leading from the condition. */
	366	edge in_edge;
	367
	368	/* True if we are able to say anything about number of iterations of the
	369	loop. */
	370	bool simple_p;
	371
	372	/* True if the loop iterates the constant number of times. */
	373	bool const_iter;
	374
	375	/* Number of iterations if constant. */
	376	unsigned HOST_WIDEST_INT niter;
	377
	378	/* Upper bound on the number of iterations. */
	379	unsigned HOST_WIDEST_INT niter_max;
	380
	381	/* Assumptions under that the rest of the information is valid. */
	382	rtx assumptions;
	383
	384	/* Assumptions under that the loop ends before reaching the latch,
	385	even if value of niter_expr says otherwise. */
	386	rtx noloop_assumptions;
	387
	388	/* Condition under that the loop is infinite. */
	389	rtx infinite;
	390
	391	/* Whether the comparison is signed. */
	392	bool signed_p;
	393
	394	/* The mode in that niter_expr should be computed. */
	395	enum machine_mode mode;
	396
	397	/* The number of iterations of the loop. */
	398	rtx niter_expr;
	399	};
	400
	401	extern void iv_analysis_loop_init (struct loop *);
	402	extern rtx iv_get_reaching_def (rtx, rtx);
6d4e0ecc	403	extern bool iv_analyze (rtx, rtx, struct rtx_iv *);
50654f6c	404	extern rtx get_iv_value (struct rtx_iv *, rtx);
113d659a	405	extern bool biv_p (rtx, rtx);
50654f6c	406	extern void find_simple_exit (struct loop , struct niter_desc );
50654f6c ZD	407	extern void iv_analysis_done (void);
	408
	409	extern struct niter_desc get_simple_loop_desc (struct loop loop);
	410	extern void free_simple_loop_desc (struct loop *loop);
	411
	412	static inline struct niter_desc *
	413	simple_loop_desc (struct loop *loop)
	414	{
	415	return loop->aux;
	416	}
	417
8b11a64c ZD	418	/* The properties of the target. */
	419
	420	extern unsigned target_avail_regs; /* Number of available registers. */
	421	extern unsigned target_res_regs; /* Number of reserved registers. */
	422	extern unsigned target_small_cost; /* The cost for register when there
	423	is a free one. */
	424	extern unsigned target_pres_cost; /* The cost for register when there are
	425	not too many free ones. */
	426	extern unsigned target_spill_cost; /* The cost for register when we need
	427	to spill. */
	428
5e962776 ZD	429	/* Register pressure estimation for induction variable optimizations & loop
	430	invariant motion. */
	431	extern unsigned global_cost_for_size (unsigned, unsigned, unsigned);
	432	extern void init_set_costs (void);
	433
617b465c	434	/* Loop optimizer initialization. */
d329e058 AJ	435	extern struct loops loop_optimizer_init (FILE );
d329e058 AJ	436	extern void loop_optimizer_finalize (struct loops , FILE );
617b465c ZD	437
617b465c ZD	438	/* Optimization passes. */
d329e058	439	extern void unswitch_loops (struct loops *);
617b465c	440
b17d5d7c ZD	441	enum
	442	{
	443	UAP_PEEL = 1, /* Enables loop peeling. */
	444	UAP_UNROLL = 2, /* Enables peeling of loops if it seems profitable. */
	445	UAP_UNROLL_ALL = 4 /* Enables peeling of all loops. */
	446	};
	447
d329e058	448	extern void unroll_and_peel_loops (struct loops *, int);
689ba89d	449	extern void doloop_optimize_loops (struct loops *);
5e962776	450	extern void move_loop_invariants (struct loops *);
86df10e3	451	extern void record_estimate (struct loop *, tree, tree, tree);
59587b18	452
c94583fe ZD	453	/* Old loop optimizer interface. */
	454
	455	/* Flags passed to loop_optimize. */
	456	#define LOOP_PREFETCH 1
	457
	458	extern void loop_optimize (rtx, FILE *, int);
	459
59587b18	460	#endif /* GCC_CFGLOOP_H */