[thirdparty/gcc.git] / gcc / cfgloop.h

/* Natural loop functions
   Copyright (C) 1987, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004
   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;
};

/* 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;

  /* Basic block of loop preheader or NULL if it does not exist.  */
  basic_block pre_header;

  /* 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;

  /* Array of edges along the preheader extended basic block trace.
     The source of the first edge is the root node of preheader
     extended basic block, if it exists.  */
  edge *pre_header_edges;

  /* Number of edges along the pre_header extended basic block trace.  */
  int num_pre_header_edges;

  /* 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;

  /* Bitmap of blocks contained within the loop.  */
  sbitmap nodes;

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

  /* Array of edges that enter the loop.  */
  edge *entry_edges;

  /* Number of edges that enter the loop.  */
  int num_entries;

  /* Array of edges that exit the loop.  */
  edge *exit_edges;

  /* Number of edges that exit the loop.  */
  int num_exits;

  /* Bitmap of blocks that dominate all exits of the loop.  */
  sbitmap exits_doms;

  /* 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 as loop.c is converted to use the CFG.  */

  /* Nonzero if the loop has a NOTE_INSN_LOOP_VTOP.  */
  rtx vtop;

  /* Nonzero if the loop has a NOTE_INSN_LOOP_CONT.
     A continue statement will generate a branch to NEXT_INSN (cont).  */
  rtx cont;

  /* The dominator of cont.  */
  rtx cont_dominator;

  /* 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;

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

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

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

  /* Maximum nested loop level in the function.  */
  unsigned levels;

  /* 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.  */
  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;
};

/* Flags for loop discovery.  */

#define LOOP_TREE		1	/* Build loop hierarchy tree.  */
#define LOOP_PRE_HEADER		2	/* Analyze loop preheader.  */
#define LOOP_ENTRY_EDGES	4	/* Find entry edges.  */
#define LOOP_EXIT_EDGES		8	/* Find exit edges.  */
#define LOOP_EDGES		(LOOP_ENTRY_EDGES | LOOP_EXIT_EDGES)
#define LOOP_ALL	       15	/* All of the above  */

/* Loop recognition.  */
extern int flow_loops_find (struct loops *, int flags);
extern int flow_loops_update (struct loops *, int flags);
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 int flow_loop_scan (struct loop *, int);
extern void flow_loop_free (struct loop *);
void mark_irreducible_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 int num_loop_insns (struct loop *);
extern int average_num_loop_insns (struct loop *);
extern unsigned get_loop_level (const struct loop *);

/* 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 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 int 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);
extern void unloop (struct loops *, struct loop *);
extern bool remove_path (struct loops *, edge);
extern edge split_loop_bb (basic_block, rtx);

/* 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 = NIL, 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 NIL).  */
  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 void find_simple_exit (struct loop *, struct niter_desc *);
extern void iv_number_of_iterations (struct loop *, rtx, rtx,
				     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;
}

/* 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 *);

#endif /* GCC_CFGLOOP_H */
Commit	Line	Data
3d436d2a	1	/* Natural loop functions
aa335b76	2	Copyright (C) 1987, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004
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
3d436d2a ZD	46	/* Structure to hold information for each natural loop. */
	47	struct loop
	48	{
	49	/* Index into loops array. */
	50	int num;
	51
	52	/* Basic block of loop header. */
	53	basic_block header;
	54
	55	/* Basic block of loop latch. */
	56	basic_block latch;
	57
	58	/* Basic block of loop preheader or NULL if it does not exist. */
	59	basic_block pre_header;
	60
	61	/* For loop unrolling/peeling decision. */
	62	struct lpt_decision lpt_decision;
	63
3d436d2a ZD	64	/* Number of loop insns. */
	65	unsigned ninsns;
	66
	67	/* Average number of executed insns per iteration. */
	68	unsigned av_ninsns;
	69
	70	/* Array of edges along the preheader extended basic block trace.
	71	The source of the first edge is the root node of preheader
	72	extended basic block, if it exists. */
	73	edge *pre_header_edges;
	74
	75	/* Number of edges along the pre_header extended basic block trace. */
	76	int num_pre_header_edges;
	77
	78	/* The first block in the loop. This is not necessarily the same as
	79	the loop header. */
	80	basic_block first;
	81
	82	/* The last block in the loop. This is not necessarily the same as
	83	the loop latch. */
	84	basic_block last;
	85
	86	/* Bitmap of blocks contained within the loop. */
	87	sbitmap nodes;
	88
	89	/* Number of blocks contained within the loop. */
	90	unsigned num_nodes;
	91
	92	/* Array of edges that enter the loop. */
	93	edge *entry_edges;
	94
	95	/* Number of edges that enter the loop. */
	96	int num_entries;
	97
	98	/* Array of edges that exit the loop. */
	99	edge *exit_edges;
	100
	101	/* Number of edges that exit the loop. */
	102	int num_exits;
	103
	104	/* Bitmap of blocks that dominate all exits of the loop. */
	105	sbitmap exits_doms;
	106
	107	/* The loop nesting depth. */
	108	int depth;
	109
	110	/* Superloops of the loop. */
	111	struct loop **pred;
	112
	113	/* The height of the loop (enclosed loop levels) within the loop
	114	hierarchy tree. */
	115	int level;
	116
	117	/* The outer (parent) loop or NULL if outermost loop. */
	118	struct loop *outer;
	119
	120	/* The first inner (child) loop or NULL if innermost loop. */
	121	struct loop *inner;
	122
	123	/* Link to the next (sibling) loop. */
	124	struct loop *next;
	125
	126	/* Loop that is copy of this loop. */
	127	struct loop *copy;
128
6356f892	129	/* Nonzero if the loop is invalid (e.g., contains setjmp.). */
3d436d2a ZD	130	int invalid;
	131
	132	/* Auxiliary info specific to a pass. */
	133	void *aux;
	134
	135	/* The following are currently used by loop.c but they are likely to
	136	disappear as loop.c is converted to use the CFG. */
	137
6356f892	138	/* Nonzero if the loop has a NOTE_INSN_LOOP_VTOP. */
3d436d2a ZD	139	rtx vtop;
3d436d2a ZD	140
6356f892	141	/* Nonzero if the loop has a NOTE_INSN_LOOP_CONT.
3d436d2a ZD	142	A continue statement will generate a branch to NEXT_INSN (cont). */
	143	rtx cont;
	144
	145	/* The dominator of cont. */
	146	rtx cont_dominator;
	147
	148	/* The NOTE_INSN_LOOP_BEG. */
	149	rtx start;
	150
	151	/* The NOTE_INSN_LOOP_END. */
	152	rtx end;
	153
	154	/* For a rotated loop that is entered near the bottom,
	155	this is the label at the top. Otherwise it is zero. */
	156	rtx top;
	157
	158	/* Place in the loop where control enters. */
	159	rtx scan_start;
	160
	161	/* The position where to sink insns out of the loop. */
	162	rtx sink;
	163
	164	/* List of all LABEL_REFs which refer to code labels outside the
	165	loop. Used by routines that need to know all loop exits, such as
	166	final_biv_value and final_giv_value.
	167
	168	This does not include loop exits due to return instructions.
	169	This is because all bivs and givs are pseudos, and hence must be
	170	dead after a return, so the presence of a return does not affect
	171	any of the optimizations that use this info. It is simpler to
	172	just not include return instructions on this list. */
	173	rtx exit_labels;
	174
	175	/* The number of LABEL_REFs on exit_labels for this loop and all
	176	loops nested inside it. */
	177	int exit_count;
e9eb809d ZD	178
	179	/* Upper bound on number of iterations of a loop. */
	180	struct nb_iter_bound *bounds;
3d436d2a ZD	181	};
	182
	183	/* Flags for state of loop structure. */
	184	enum
	185	{
	186	LOOPS_HAVE_PREHEADERS = 1,
	187	LOOPS_HAVE_SIMPLE_LATCHES = 2,
	188	LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS = 4
	189	};
	190
	191	/* Structure to hold CFG information about natural loops within a function. */
	192	struct loops
	193	{
	194	/* Number of natural loops in the function. */
	195	unsigned num;
	196
	197	/* Maximum nested loop level in the function. */
	198	unsigned levels;
	199
	200	/* Array of natural loop descriptors (scanning this array in reverse order
	201	will find the inner loops before their enclosing outer loops). */
	202	struct loop *array;
	203
	204	/* The above array is unused in new loop infrastructure and is kept only for
	205	purposes of the old loop optimizer. Instead we store just pointers to
	206	loops here. */
	207	struct loop **parray;
	208
	209	/* Pointer to root of loop hierarchy tree. */
	210	struct loop *tree_root;
	211
	212	/* Information derived from the CFG. */
	213	struct cfg
	214	{
3d436d2a ZD	215	/* The ordering of the basic blocks in a depth first search. */
	216	int *dfs_order;
	217
	218	/* The reverse completion ordering of the basic blocks found in a
	219	depth first search. */
	220	int *rc_order;
	221	} cfg;
	222
	223	/* Headers shared by multiple loops that should be merged. */
	224	sbitmap shared_headers;
	225
	226	/* State of loops. */
	227	int state;
	228	};
	229
	230	/* Flags for loop discovery. */
	231
	232	#define LOOP_TREE 1 /* Build loop hierarchy tree. */
	233	#define LOOP_PRE_HEADER 2 /* Analyze loop preheader. */
	234	#define LOOP_ENTRY_EDGES 4 /* Find entry edges. */
	235	#define LOOP_EXIT_EDGES 8 /* Find exit edges. */
	236	#define LOOP_EDGES (LOOP_ENTRY_EDGES \| LOOP_EXIT_EDGES)
	237	#define LOOP_ALL 15 /* All of the above */
	238
	239	/* Loop recognition. */
d329e058 AJ	240	extern int flow_loops_find (struct loops *, int flags);
	241	extern int flow_loops_update (struct loops *, int flags);
	242	extern void flow_loops_free (struct loops *);
	243	extern void flow_loops_dump (const struct loops , FILE ,
	244	void ()(const struct loop , FILE *, int), int);
	245	extern void flow_loop_dump (const struct loop , FILE ,
	246	void ()(const struct loop , FILE *, int), int);
d47cc544	247	extern int flow_loop_scan (struct loop *, int);
d329e058 AJ	248	extern void flow_loop_free (struct loop *);
d329e058 AJ	249	void mark_irreducible_loops (struct loops *);
6de9cd9a	250	extern void create_loop_notes (void);
3d436d2a	251
4d6922ee	252	/* Loop data structure manipulation/querying. */
d329e058 AJ	253	extern void flow_loop_tree_node_add (struct loop , struct loop );
	254	extern void flow_loop_tree_node_remove (struct loop *);
	255	extern bool flow_loop_outside_edge_p (const struct loop *, edge);
	256	extern bool flow_loop_nested_p (const struct loop , const struct loop );
	257	extern bool flow_bb_inside_loop_p (const struct loop *, const basic_block);
	258	extern struct loop * find_common_loop (struct loop , struct loop );
a7e5372d	259	struct loop superloop_at_depth (struct loop , unsigned);
d329e058 AJ	260	extern int num_loop_insns (struct loop *);
d329e058 AJ	261	extern int average_num_loop_insns (struct loop *);
689ba89d	262	extern unsigned get_loop_level (const struct loop *);
3d436d2a ZD	263
3d436d2a ZD	264	/* Loops & cfg manipulation. */
d329e058	265	extern basic_block get_loop_body (const struct loop );
50654f6c	266	extern basic_block get_loop_body_in_dom_order (const struct loop );
d329e058	267	extern edge get_loop_exit_edges (const struct loop , unsigned *);
50654f6c	268	extern unsigned num_loop_branches (const struct loop *);
3d436d2a	269
d329e058 AJ	270	extern edge loop_preheader_edge (const struct loop *);
d329e058 AJ	271	extern edge loop_latch_edge (const struct loop *);
3d436d2a	272
d329e058 AJ	273	extern void add_bb_to_loop (basic_block, struct loop *);
d329e058 AJ	274	extern void remove_bb_from_loops (basic_block);
3d436d2a	275
d329e058 AJ	276	extern void cancel_loop (struct loops , struct loop );
d329e058 AJ	277	extern void cancel_loop_tree (struct loops , struct loop );
3d436d2a	278
d47cc544	279	extern basic_block loop_split_edge_with (edge, rtx);
d329e058	280	extern int fix_loop_placement (struct loop *);
3d436d2a ZD	281
	282	enum
	283	{
bc35512f	284	CP_SIMPLE_PREHEADERS = 1
3d436d2a ZD	285	};
3d436d2a ZD	286
d329e058 AJ	287	extern void create_preheaders (struct loops *, int);
d329e058 AJ	288	extern void force_single_succ_latches (struct loops *);
3d436d2a	289
d329e058	290	extern void verify_loop_structure (struct loops *);
3d436d2a ZD	291
3d436d2a ZD	292	/* Loop analysis. */
d47cc544	293	extern bool just_once_each_iteration_p (struct loop *, basic_block);
d329e058	294	extern unsigned expected_loop_iterations (const struct loop *);
617b465c ZD	295
617b465c ZD	296	/* Loop manipulation. */
d329e058	297	extern bool can_duplicate_loop_p (struct loop *loop);
617b465c ZD	298
	299	#define DLTHE_FLAG_UPDATE_FREQ 1 /* Update frequencies in
	300	duplicate_loop_to_header_edge. */
	301
d329e058 AJ	302	extern int duplicate_loop_to_header_edge (struct loop , edge, struct loops ,
	303	unsigned, sbitmap, edge, edge *,
	304	unsigned *, int);
	305	extern struct loop loopify (struct loops , edge, edge, basic_block);
	306	extern void unloop (struct loops , struct loop );
	307	extern bool remove_path (struct loops *, edge);
d47cc544	308	extern edge split_loop_bb (basic_block, rtx);
617b465c	309
50654f6c ZD	310	/* Induction variable analysis. */
	311
	312	/* The description of induction variable. The things are a bit complicated
	313	due to need to handle subregs and extends. The value of the object described
	314	by it can be obtained as follows (all computations are done in extend_mode):
	315
	316	Value in i-th iteration is
	317	delta + mult * extend_{extend_mode} (subreg_{mode} (base + i * step)).
	318
	319	If first_special is true, the value in the first iteration is
	320	delta + mult * base
	321
	322	If extend = NIL, first_special must be false, delta 0, mult 1 and value is
	323	subreg_{mode} (base + i * step)
	324
	325	The get_iv_value function can be used to obtain these expressions.
	326
	327	??? Add a third mode field that would specify the mode in that inner
	328	computation is done, which would enable it to be different from the
	329	outer one? */
	330
	331	struct rtx_iv
	332	{
	333	/* Its base and step (mode of base and step is supposed to be extend_mode,
	334	see the description above). */
	335	rtx base, step;
	336
	337	/* The type of extend applied to it (SIGN_EXTEND, ZERO_EXTEND or NIL). */
	338	enum rtx_code extend;
	339
	340	/* Operations applied in the extended mode. */
	341	rtx delta, mult;
	342
	343	/* The mode it is extended to. */
	344	enum machine_mode extend_mode;
	345
	346	/* The mode the variable iterates in. */
	347	enum machine_mode mode;
	348
	349	/* Whether we have already filled the remaining fields. */
	350	unsigned analysed : 1;
	351
	352	/* Whether the first iteration needs to be handled specially. */
	353	unsigned first_special : 1;
	354	};
	355
f2dca510 ZD	356	/* The description of an exit from the loop and of the number of iterations
f2dca510 ZD	357	till we take the exit. */
50654f6c ZD	358
	359	struct niter_desc
	360	{
	361	/* The edge out of the loop. */
	362	edge out_edge;
	363
	364	/* The other edge leading from the condition. */
	365	edge in_edge;
	366
	367	/* True if we are able to say anything about number of iterations of the
	368	loop. */
	369	bool simple_p;
	370
	371	/* True if the loop iterates the constant number of times. */
	372	bool const_iter;
	373
	374	/* Number of iterations if constant. */
	375	unsigned HOST_WIDEST_INT niter;
	376
	377	/* Upper bound on the number of iterations. */
	378	unsigned HOST_WIDEST_INT niter_max;
	379
	380	/* Assumptions under that the rest of the information is valid. */
	381	rtx assumptions;
	382
	383	/* Assumptions under that the loop ends before reaching the latch,
	384	even if value of niter_expr says otherwise. */
	385	rtx noloop_assumptions;
	386
	387	/* Condition under that the loop is infinite. */
	388	rtx infinite;
	389
	390	/* Whether the comparison is signed. */
	391	bool signed_p;
	392
	393	/* The mode in that niter_expr should be computed. */
	394	enum machine_mode mode;
	395
	396	/* The number of iterations of the loop. */
	397	rtx niter_expr;
	398	};
	399
	400	extern void iv_analysis_loop_init (struct loop *);
	401	extern rtx iv_get_reaching_def (rtx, rtx);
6d4e0ecc	402	extern bool iv_analyze (rtx, rtx, struct rtx_iv *);
50654f6c ZD	403	extern rtx get_iv_value (struct rtx_iv *, rtx);
	404	extern void find_simple_exit (struct loop , struct niter_desc );
	405	extern void iv_number_of_iterations (struct loop *, rtx, rtx,
	406	struct niter_desc *);
	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
5e962776 ZD	418	/* Register pressure estimation for induction variable optimizations & loop
	419	invariant motion. */
	420	extern unsigned global_cost_for_size (unsigned, unsigned, unsigned);
	421	extern void init_set_costs (void);
	422
617b465c	423	/* Loop optimizer initialization. */
d329e058 AJ	424	extern struct loops loop_optimizer_init (FILE );
d329e058 AJ	425	extern void loop_optimizer_finalize (struct loops , FILE );
617b465c ZD	426
617b465c ZD	427	/* Optimization passes. */
d329e058	428	extern void unswitch_loops (struct loops *);
617b465c	429
b17d5d7c ZD	430	enum
	431	{
	432	UAP_PEEL = 1, /* Enables loop peeling. */
	433	UAP_UNROLL = 2, /* Enables peeling of loops if it seems profitable. */
	434	UAP_UNROLL_ALL = 4 /* Enables peeling of all loops. */
	435	};
	436
d329e058	437	extern void unroll_and_peel_loops (struct loops *, int);
689ba89d	438	extern void doloop_optimize_loops (struct loops *);
5e962776	439	extern void move_loop_invariants (struct loops *);
59587b18 JQ	440
59587b18 JQ	441	#endif /* GCC_CFGLOOP_H */