[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.  */

/* 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;
};

/* 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 *);

/* 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 *);
extern int num_loop_insns (struct loop *);
extern int average_num_loop_insns (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;
}

/* 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);
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
	22	/* Structure to hold decision about unrolling/peeling. */
	23	enum lpt_dec
	24	{
	25	LPT_NONE,
	26	LPT_PEEL_COMPLETELY,
	27	LPT_PEEL_SIMPLE,
	28	LPT_UNROLL_CONSTANT,
	29	LPT_UNROLL_RUNTIME,
	30	LPT_UNROLL_STUPID
	31	};
	32
	33	struct lpt_decision
	34	{
	35	enum lpt_dec decision;
	36	unsigned times;
	37	};
	38
3d436d2a ZD	39	/* Structure to hold information for each natural loop. */
	40	struct loop
	41	{
	42	/* Index into loops array. */
	43	int num;
	44
	45	/* Basic block of loop header. */
	46	basic_block header;
	47
	48	/* Basic block of loop latch. */
	49	basic_block latch;
	50
	51	/* Basic block of loop preheader or NULL if it does not exist. */
	52	basic_block pre_header;
	53
	54	/* For loop unrolling/peeling decision. */
	55	struct lpt_decision lpt_decision;
	56
3d436d2a ZD	57	/* Number of loop insns. */
	58	unsigned ninsns;
	59
	60	/* Average number of executed insns per iteration. */
	61	unsigned av_ninsns;
	62
	63	/* Array of edges along the preheader extended basic block trace.
	64	The source of the first edge is the root node of preheader
	65	extended basic block, if it exists. */
	66	edge *pre_header_edges;
	67
	68	/* Number of edges along the pre_header extended basic block trace. */
	69	int num_pre_header_edges;
	70
	71	/* The first block in the loop. This is not necessarily the same as
	72	the loop header. */
	73	basic_block first;
	74
	75	/* The last block in the loop. This is not necessarily the same as
	76	the loop latch. */
	77	basic_block last;
	78
	79	/* Bitmap of blocks contained within the loop. */
	80	sbitmap nodes;
	81
	82	/* Number of blocks contained within the loop. */
	83	unsigned num_nodes;
	84
	85	/* Array of edges that enter the loop. */
	86	edge *entry_edges;
	87
	88	/* Number of edges that enter the loop. */
	89	int num_entries;
	90
	91	/* Array of edges that exit the loop. */
	92	edge *exit_edges;
	93
	94	/* Number of edges that exit the loop. */
	95	int num_exits;
	96
	97	/* Bitmap of blocks that dominate all exits of the loop. */
	98	sbitmap exits_doms;
	99
	100	/* The loop nesting depth. */
	101	int depth;
	102
	103	/* Superloops of the loop. */
	104	struct loop **pred;
	105
	106	/* The height of the loop (enclosed loop levels) within the loop
	107	hierarchy tree. */
	108	int level;
	109
	110	/* The outer (parent) loop or NULL if outermost loop. */
	111	struct loop *outer;
	112
	113	/* The first inner (child) loop or NULL if innermost loop. */
	114	struct loop *inner;
	115
	116	/* Link to the next (sibling) loop. */
	117	struct loop *next;
	118
	119	/* Loop that is copy of this loop. */
	120	struct loop *copy;
121
6356f892	122	/* Nonzero if the loop is invalid (e.g., contains setjmp.). */
3d436d2a ZD	123	int invalid;
	124
	125	/* Auxiliary info specific to a pass. */
	126	void *aux;
	127
	128	/* The following are currently used by loop.c but they are likely to
	129	disappear as loop.c is converted to use the CFG. */
	130
6356f892	131	/* Nonzero if the loop has a NOTE_INSN_LOOP_VTOP. */
3d436d2a ZD	132	rtx vtop;
3d436d2a ZD	133
6356f892	134	/* Nonzero if the loop has a NOTE_INSN_LOOP_CONT.
3d436d2a ZD	135	A continue statement will generate a branch to NEXT_INSN (cont). */
	136	rtx cont;
	137
	138	/* The dominator of cont. */
	139	rtx cont_dominator;
	140
	141	/* The NOTE_INSN_LOOP_BEG. */
	142	rtx start;
	143
	144	/* The NOTE_INSN_LOOP_END. */
	145	rtx end;
	146
	147	/* For a rotated loop that is entered near the bottom,
	148	this is the label at the top. Otherwise it is zero. */
	149	rtx top;
	150
	151	/* Place in the loop where control enters. */
	152	rtx scan_start;
	153
	154	/* The position where to sink insns out of the loop. */
	155	rtx sink;
	156
	157	/* List of all LABEL_REFs which refer to code labels outside the
	158	loop. Used by routines that need to know all loop exits, such as
	159	final_biv_value and final_giv_value.
	160
	161	This does not include loop exits due to return instructions.
	162	This is because all bivs and givs are pseudos, and hence must be
	163	dead after a return, so the presence of a return does not affect
	164	any of the optimizations that use this info. It is simpler to
	165	just not include return instructions on this list. */
	166	rtx exit_labels;
	167
	168	/* The number of LABEL_REFs on exit_labels for this loop and all
	169	loops nested inside it. */
	170	int exit_count;
	171	};
	172
	173	/* Flags for state of loop structure. */
	174	enum
	175	{
	176	LOOPS_HAVE_PREHEADERS = 1,
	177	LOOPS_HAVE_SIMPLE_LATCHES = 2,
	178	LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS = 4
	179	};
	180
	181	/* Structure to hold CFG information about natural loops within a function. */
	182	struct loops
	183	{
	184	/* Number of natural loops in the function. */
	185	unsigned num;
	186
	187	/* Maximum nested loop level in the function. */
	188	unsigned levels;
	189
	190	/* Array of natural loop descriptors (scanning this array in reverse order
	191	will find the inner loops before their enclosing outer loops). */
	192	struct loop *array;
	193
	194	/* The above array is unused in new loop infrastructure and is kept only for
	195	purposes of the old loop optimizer. Instead we store just pointers to
	196	loops here. */
	197	struct loop **parray;
	198
199	/* Pointer to root of loop hierarchy tree. */
200	struct loop *tree_root;
201
202	/* Information derived from the CFG. */
203	struct cfg
204	{
3d436d2a ZD	205	/* The ordering of the basic blocks in a depth first search. */
	206	int *dfs_order;
	207
	208	/* The reverse completion ordering of the basic blocks found in a
	209	depth first search. */
	210	int *rc_order;
	211	} cfg;
	212
	213	/* Headers shared by multiple loops that should be merged. */
	214	sbitmap shared_headers;
	215
	216	/* State of loops. */
	217	int state;
	218	};
	219
	220	/* Flags for loop discovery. */
	221
	222	#define LOOP_TREE 1 /* Build loop hierarchy tree. */
	223	#define LOOP_PRE_HEADER 2 /* Analyze loop preheader. */
	224	#define LOOP_ENTRY_EDGES 4 /* Find entry edges. */
	225	#define LOOP_EXIT_EDGES 8 /* Find exit edges. */
	226	#define LOOP_EDGES (LOOP_ENTRY_EDGES \| LOOP_EXIT_EDGES)
	227	#define LOOP_ALL 15 /* All of the above */
	228
	229	/* Loop recognition. */
d329e058 AJ	230	extern int flow_loops_find (struct loops *, int flags);
	231	extern int flow_loops_update (struct loops *, int flags);
	232	extern void flow_loops_free (struct loops *);
	233	extern void flow_loops_dump (const struct loops , FILE ,
	234	void ()(const struct loop , FILE *, int), int);
	235	extern void flow_loop_dump (const struct loop , FILE ,
	236	void ()(const struct loop , FILE *, int), int);
d47cc544	237	extern int flow_loop_scan (struct loop *, int);
d329e058 AJ	238	extern void flow_loop_free (struct loop *);
d329e058 AJ	239	void mark_irreducible_loops (struct loops *);
3d436d2a	240
4d6922ee	241	/* Loop data structure manipulation/querying. */
d329e058 AJ	242	extern void flow_loop_tree_node_add (struct loop , struct loop );
	243	extern void flow_loop_tree_node_remove (struct loop *);
	244	extern bool flow_loop_outside_edge_p (const struct loop *, edge);
	245	extern bool flow_loop_nested_p (const struct loop , const struct loop );
	246	extern bool flow_bb_inside_loop_p (const struct loop *, const basic_block);
	247	extern struct loop * find_common_loop (struct loop , struct loop );
	248	extern int num_loop_insns (struct loop *);
	249	extern int average_num_loop_insns (struct loop *);
3d436d2a ZD	250
3d436d2a ZD	251	/* Loops & cfg manipulation. */
d329e058	252	extern basic_block get_loop_body (const struct loop );
50654f6c	253	extern basic_block get_loop_body_in_dom_order (const struct loop );
d329e058	254	extern edge get_loop_exit_edges (const struct loop , unsigned *);
50654f6c	255	extern unsigned num_loop_branches (const struct loop *);
3d436d2a	256
d329e058 AJ	257	extern edge loop_preheader_edge (const struct loop *);
d329e058 AJ	258	extern edge loop_latch_edge (const struct loop *);
3d436d2a	259
d329e058 AJ	260	extern void add_bb_to_loop (basic_block, struct loop *);
d329e058 AJ	261	extern void remove_bb_from_loops (basic_block);
3d436d2a	262
d329e058 AJ	263	extern void cancel_loop (struct loops , struct loop );
d329e058 AJ	264	extern void cancel_loop_tree (struct loops , struct loop );
3d436d2a	265
d47cc544	266	extern basic_block loop_split_edge_with (edge, rtx);
d329e058	267	extern int fix_loop_placement (struct loop *);
3d436d2a ZD	268
	269	enum
	270	{
bc35512f	271	CP_SIMPLE_PREHEADERS = 1
3d436d2a ZD	272	};
3d436d2a ZD	273
d329e058 AJ	274	extern void create_preheaders (struct loops *, int);
d329e058 AJ	275	extern void force_single_succ_latches (struct loops *);
3d436d2a	276
d329e058	277	extern void verify_loop_structure (struct loops *);
3d436d2a ZD	278
3d436d2a ZD	279	/* Loop analysis. */
d47cc544	280	extern bool just_once_each_iteration_p (struct loop *, basic_block);
d329e058	281	extern unsigned expected_loop_iterations (const struct loop *);
617b465c ZD	282
617b465c ZD	283	/* Loop manipulation. */
d329e058	284	extern bool can_duplicate_loop_p (struct loop *loop);
617b465c ZD	285
	286	#define DLTHE_FLAG_UPDATE_FREQ 1 /* Update frequencies in
	287	duplicate_loop_to_header_edge. */
	288
d329e058 AJ	289	extern int duplicate_loop_to_header_edge (struct loop , edge, struct loops ,
	290	unsigned, sbitmap, edge, edge *,
	291	unsigned *, int);
	292	extern struct loop loopify (struct loops , edge, edge, basic_block);
	293	extern void unloop (struct loops , struct loop );
	294	extern bool remove_path (struct loops *, edge);
d47cc544	295	extern edge split_loop_bb (basic_block, rtx);
617b465c	296
50654f6c ZD	297	/* Induction variable analysis. */
	298
	299	/* The description of induction variable. The things are a bit complicated
	300	due to need to handle subregs and extends. The value of the object described
	301	by it can be obtained as follows (all computations are done in extend_mode):
	302
	303	Value in i-th iteration is
	304	delta + mult * extend_{extend_mode} (subreg_{mode} (base + i * step)).
	305
	306	If first_special is true, the value in the first iteration is
	307	delta + mult * base
	308
	309	If extend = NIL, first_special must be false, delta 0, mult 1 and value is
	310	subreg_{mode} (base + i * step)
	311
	312	The get_iv_value function can be used to obtain these expressions.
	313
	314	??? Add a third mode field that would specify the mode in that inner
	315	computation is done, which would enable it to be different from the
	316	outer one? */
	317
	318	struct rtx_iv
	319	{
	320	/* Its base and step (mode of base and step is supposed to be extend_mode,
	321	see the description above). */
	322	rtx base, step;
	323
	324	/* The type of extend applied to it (SIGN_EXTEND, ZERO_EXTEND or NIL). */
	325	enum rtx_code extend;
	326
	327	/* Operations applied in the extended mode. */
	328	rtx delta, mult;
	329
	330	/* The mode it is extended to. */
	331	enum machine_mode extend_mode;
	332
	333	/* The mode the variable iterates in. */
	334	enum machine_mode mode;
	335
	336	/* Whether we have already filled the remaining fields. */
	337	unsigned analysed : 1;
	338
	339	/* Whether the first iteration needs to be handled specially. */
	340	unsigned first_special : 1;
	341	};
	342
f2dca510 ZD	343	/* The description of an exit from the loop and of the number of iterations
f2dca510 ZD	344	till we take the exit. */
50654f6c ZD	345
	346	struct niter_desc
	347	{
	348	/* The edge out of the loop. */
	349	edge out_edge;
	350
	351	/* The other edge leading from the condition. */
	352	edge in_edge;
	353
	354	/* True if we are able to say anything about number of iterations of the
	355	loop. */
	356	bool simple_p;
	357
	358	/* True if the loop iterates the constant number of times. */
	359	bool const_iter;
	360
	361	/* Number of iterations if constant. */
	362	unsigned HOST_WIDEST_INT niter;
	363
	364	/* Upper bound on the number of iterations. */
	365	unsigned HOST_WIDEST_INT niter_max;
	366
	367	/* Assumptions under that the rest of the information is valid. */
	368	rtx assumptions;
	369
	370	/* Assumptions under that the loop ends before reaching the latch,
	371	even if value of niter_expr says otherwise. */
	372	rtx noloop_assumptions;
	373
	374	/* Condition under that the loop is infinite. */
	375	rtx infinite;
	376
	377	/* Whether the comparison is signed. */
	378	bool signed_p;
	379
	380	/* The mode in that niter_expr should be computed. */
	381	enum machine_mode mode;
	382
	383	/* The number of iterations of the loop. */
	384	rtx niter_expr;
	385	};
	386
	387	extern void iv_analysis_loop_init (struct loop *);
	388	extern rtx iv_get_reaching_def (rtx, rtx);
6d4e0ecc	389	extern bool iv_analyze (rtx, rtx, struct rtx_iv *);
50654f6c ZD	390	extern rtx get_iv_value (struct rtx_iv *, rtx);
	391	extern void find_simple_exit (struct loop , struct niter_desc );
	392	extern void iv_number_of_iterations (struct loop *, rtx, rtx,
	393	struct niter_desc *);
	394	extern void iv_analysis_done (void);
	395
	396	extern struct niter_desc get_simple_loop_desc (struct loop loop);
	397	extern void free_simple_loop_desc (struct loop *loop);
	398
	399	static inline struct niter_desc *
	400	simple_loop_desc (struct loop *loop)
	401	{
	402	return loop->aux;
	403	}
	404
617b465c	405	/* Loop optimizer initialization. */
d329e058 AJ	406	extern struct loops loop_optimizer_init (FILE );
d329e058 AJ	407	extern void loop_optimizer_finalize (struct loops , FILE );
617b465c ZD	408
617b465c ZD	409	/* Optimization passes. */
d329e058	410	extern void unswitch_loops (struct loops *);
617b465c	411
b17d5d7c ZD	412	enum
	413	{
	414	UAP_PEEL = 1, /* Enables loop peeling. */
	415	UAP_UNROLL = 2, /* Enables peeling of loops if it seems profitable. */
	416	UAP_UNROLL_ALL = 4 /* Enables peeling of all loops. */
	417	};
	418
d329e058	419	extern void unroll_and_peel_loops (struct loops *, int);