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gcc/gcc/cfgloop.h

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/* Natural loop functions
Copyright (C) 1987, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004,
2005, 2006, 2007Free 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, 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301, USA. */
#ifndef GCC_CFGLOOP_H
#define GCC_CFGLOOP_H
#include "basic-block.h"
/* For rtx_code. */
#include "rtl.h"
#include "vecprim.h"
#include "double-int.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 GTY (())
{
enum lpt_dec decision;
unsigned times;
};
/* The structure describing a bound on number of iterations of a loop. */
struct nb_iter_bound GTY ((chain_next ("%h.next")))
{
/* The statement STMT is executed at most ... */
tree stmt;
/* ... BOUND + 1 times (BOUND must be an unsigned constant).
The + 1 is added for the following reasons:
a) 0 would otherwise be unused, while we would need to care more about
overflows (as MAX + 1 is sometimes produced as the estimate on number
of executions of STMT).
b) it is consistent with the result of number_of_iterations_exit. */
double_int bound;
/* True if the statement will cause the loop to be leaved the (at most)
BOUND + 1-st time it is executed, that is, all the statements after it
are executed at most BOUND times. */
bool is_exit;
/* The next bound in the list. */
struct nb_iter_bound *next;
};
/* Description of the loop exit. */
struct loop_exit GTY (())
{
/* The exit edge. */
struct edge_def *e;
/* Previous and next exit in the list of the exits of the loop. */
struct loop_exit *prev;
struct loop_exit *next;
/* Next element in the list of loops from that E exits. */
struct loop_exit *next_e;
};
typedef struct loop *loop_p;
DEF_VEC_P (loop_p);
DEF_VEC_ALLOC_P (loop_p, heap);
DEF_VEC_ALLOC_P (loop_p, gc);
/* An integer estimation of the number of iterations. Estimate_state
describes what is the state of the estimation. */
enum loop_estimation
{
/* Estimate was not computed yet. */
EST_NOT_COMPUTED,
/* Estimate is ready. */
EST_AVAILABLE
};
/* Structure to hold information for each natural loop. */
struct loop GTY ((chain_next ("%h.next")))
{
/* Index into loops array. */
int num;
/* Basic block of loop header. */
struct basic_block_def *header;
/* Basic block of loop latch. */
struct basic_block_def *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;
/* Number of blocks contained within the loop. */
unsigned num_nodes;
/* Superloops of the loop, starting with the outermost loop. */
VEC (loop_p, gc) *superloops;
/* The first inner (child) loop or NULL if innermost loop. */
struct loop *inner;
/* Link to the next (sibling) loop. */
struct loop *next;
/* Auxiliary info specific to a pass. */
PTR GTY ((skip (""))) aux;
/* The number of times the latch of the loop is executed.
This is an INTEGER_CST or an expression containing symbolic
names. Don't access this field directly:
number_of_latch_executions computes and caches the computed
information in this field. */
tree nb_iterations;
/* An integer estimation of the number of iterations. Estimate_state
describes what is the state of the estimation. */
enum loop_estimation estimate_state;
/* An integer guaranteed to bound the number of iterations of the loop
from above. */
bool any_upper_bound;
double_int nb_iterations_upper_bound;
/* An integer giving the expected number of iterations of the loop. */
bool any_estimate;
double_int nb_iterations_estimate;
/* Upper bound on number of iterations of a loop. */
struct nb_iter_bound *bounds;
/* Head of the cyclic list of the exits of the loop. */
struct loop_exit *exits;
};
/* Flags for state of loop structure. */
enum
{
LOOPS_HAVE_PREHEADERS = 1,
LOOPS_HAVE_SIMPLE_LATCHES = 2,
LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS = 4,
LOOPS_HAVE_RECORDED_EXITS = 8,
LOOPS_MAY_HAVE_MULTIPLE_LATCHES = 16,
LOOP_CLOSED_SSA = 32
};
#define LOOPS_NORMAL (LOOPS_HAVE_PREHEADERS | LOOPS_HAVE_SIMPLE_LATCHES \
| LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS)
#define AVOID_CFG_MODIFICATIONS (LOOPS_MAY_HAVE_MULTIPLE_LATCHES)
/* Structure to hold CFG information about natural loops within a function. */
struct loops GTY (())
{
/* State of loops. */
int state;
/* Array of the loops. */
VEC (loop_p, gc) *larray;
/* Maps edges to the list of their descriptions as loop exits. Edges
whose sources or destinations have loop_father == NULL (which may
happen during the cfg manipulations) should not appear in EXITS. */
htab_t GTY((param_is (struct loop_exit))) exits;
/* Pointer to root of loop hierarchy tree. */
struct loop *tree_root;
};
/* Loop recognition. */
extern int flow_loops_find (struct loops *);
extern void disambiguate_loops_with_multiple_latches (void);
extern void flow_loops_free (struct loops *);
extern void flow_loops_dump (FILE *,
void (*)(const struct loop *, FILE *, int), int);
extern void flow_loop_dump (const struct loop *, FILE *,
void (*)(const struct loop *, FILE *, int), int);
struct loop *alloc_loop (void);
extern void flow_loop_free (struct loop *);
int flow_loop_nodes_find (basic_block, struct loop *);
void fix_loop_structure (bitmap changed_bbs);
void mark_irreducible_loops (void);
void release_recorded_exits (void);
void record_loop_exits (void);
void rescan_loop_exit (edge, bool, bool);
/* 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 void add_loop (struct loop *, struct loop *);
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);
struct eni_weights_d;
extern unsigned tree_num_loop_insns (struct loop *, struct eni_weights_d *);
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 (void);
/* Loops & cfg manipulation. */
extern basic_block *get_loop_body (const struct loop *);
extern unsigned get_loop_body_with_size (const struct loop *, basic_block *,
unsigned);
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 VEC (edge, heap) *get_loop_exit_edges (const struct loop *);
edge single_exit (const struct loop *);
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_tree (struct loop *);
extern void delete_loop (struct loop *);
enum
{
CP_SIMPLE_PREHEADERS = 1
};
basic_block create_preheader (struct loop *, int);
extern void create_preheaders (int);
extern void force_single_succ_latches (void);
extern void verify_loop_structure (void);
/* Loop analysis. */
extern bool just_once_each_iteration_p (const struct loop *, basic_block);
gcov_type expected_loop_iterations_unbounded (const struct loop *);
extern unsigned expected_loop_iterations (const struct loop *);
extern rtx doloop_condition_get (rtx);
void estimate_numbers_of_iterations_loop (struct loop *);
HOST_WIDE_INT estimated_loop_iterations_int (struct loop *, bool);
bool estimated_loop_iterations (struct loop *, bool, double_int *);
/* 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. */
#define DLTHE_RECORD_COPY_NUMBER 2 /* Record copy number in the aux
field of newly create BB. */
#define DLTHE_FLAG_COMPLETTE_PEEL 4 /* Update frequencies expecting
a complete peeling. */
extern struct loop * duplicate_loop (struct loop *, struct loop *);
extern bool duplicate_loop_to_header_edge (struct loop *, edge,
unsigned, sbitmap, edge,
VEC (edge, heap) **, int);
extern struct loop *loopify (edge, edge,
basic_block, edge, edge, bool,
unsigned, unsigned);
struct loop * loop_version (struct loop *, void *,
basic_block *, unsigned, unsigned, unsigned, bool);
extern bool remove_path (edge);
void scale_loop_frequencies (struct loop *, int, int);
/* 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 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 bool iv_analyze (rtx, rtx, struct rtx_iv *);
extern bool iv_analyze_result (rtx, rtx, struct rtx_iv *);
extern bool iv_analyze_expr (rtx, rtx, enum machine_mode, 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 (struct niter_desc *) loop->aux;
}
/* Accessors for the loop structures. */
/* Returns the loop with index NUM from current_loops. */
static inline struct loop *
get_loop (unsigned num)
{
return VEC_index (loop_p, current_loops->larray, num);
}
/* Returns the number of superloops of LOOP. */
static inline unsigned
loop_depth (const struct loop *loop)
{
return VEC_length (loop_p, loop->superloops);
}
/* Returns the immediate superloop of LOOP, or NULL if LOOP is the outermost
loop. */
static inline struct loop *
loop_outer (const struct loop *loop)
{
unsigned n = VEC_length (loop_p, loop->superloops);
if (n == 0)
return NULL;
return VEC_index (loop_p, loop->superloops, n - 1);
}
/* Returns the list of loops in current_loops. */
static inline VEC (loop_p, gc) *
get_loops (void)
{
if (!current_loops)
return NULL;
return current_loops->larray;
}
/* Returns the number of loops in current_loops (including the removed
ones and the fake loop that forms the root of the loop tree). */
static inline unsigned
number_of_loops (void)
{
if (!current_loops)
return 0;
return VEC_length (loop_p, current_loops->larray);
}
/* Loop iterators. */
/* Flags for loop iteration. */
enum li_flags
{
LI_INCLUDE_ROOT = 1, /* Include the fake root of the loop tree. */
LI_FROM_INNERMOST = 2, /* Iterate over the loops in the reverse order,
starting from innermost ones. */
LI_ONLY_INNERMOST = 4 /* Iterate only over innermost loops. */
};
/* The iterator for loops. */
typedef struct
{
/* The list of loops to visit. */
VEC(int,heap) *to_visit;
/* The index of the actual loop. */
unsigned idx;
} loop_iterator;
static inline void
fel_next (loop_iterator *li, loop_p *loop)
{
int anum;
while (VEC_iterate (int, li->to_visit, li->idx, anum))
{
li->idx++;
*loop = get_loop (anum);
if (*loop)
return;
}
VEC_free (int, heap, li->to_visit);
*loop = NULL;
}
static inline void
fel_init (loop_iterator *li, loop_p *loop, unsigned flags)
{
struct loop *aloop;
unsigned i;
int mn;
li->idx = 0;
if (!current_loops)
{
li->to_visit = NULL;
*loop = NULL;
return;
}
li->to_visit = VEC_alloc (int, heap, number_of_loops ());
mn = (flags & LI_INCLUDE_ROOT) ? 0 : 1;
if (flags & LI_ONLY_INNERMOST)
{
for (i = 0; VEC_iterate (loop_p, current_loops->larray, i, aloop); i++)
if (aloop != NULL
&& aloop->inner == NULL
&& aloop->num >= mn)
VEC_quick_push (int, li->to_visit, aloop->num);
}
else if (flags & LI_FROM_INNERMOST)
{
/* Push the loops to LI->TO_VISIT in postorder. */
for (aloop = current_loops->tree_root;
aloop->inner != NULL;
aloop = aloop->inner)
continue;
while (1)
{
if (aloop->num >= mn)
VEC_quick_push (int, li->to_visit, aloop->num);
if (aloop->next)
{
for (aloop = aloop->next;
aloop->inner != NULL;
aloop = aloop->inner)
continue;
}
else if (!loop_outer (aloop))
break;
else
aloop = loop_outer (aloop);
}
}
else
{
/* Push the loops to LI->TO_VISIT in preorder. */
aloop = current_loops->tree_root;
while (1)
{
if (aloop->num >= mn)
VEC_quick_push (int, li->to_visit, aloop->num);
if (aloop->inner != NULL)
aloop = aloop->inner;
else
{
while (aloop != NULL && aloop->next == NULL)
aloop = loop_outer (aloop);
if (aloop == NULL)
break;
aloop = aloop->next;
}
}
}
fel_next (li, loop);
}
#define FOR_EACH_LOOP(LI, LOOP, FLAGS) \
for (fel_init (&(LI), &(LOOP), FLAGS); \
(LOOP); \
fel_next (&(LI), &(LOOP)))
#define FOR_EACH_LOOP_BREAK(LI) \
{ \
VEC_free (int, heap, (LI)->to_visit); \
break; \
}
/* The properties of the target. */
extern unsigned target_avail_regs;
extern unsigned target_res_regs;
extern unsigned target_reg_cost;
extern unsigned target_spill_cost;
/* Register pressure estimation for induction variable optimizations & loop
invariant motion. */
extern unsigned estimate_reg_pressure_cost (unsigned, unsigned);
extern void init_set_costs (void);
/* Loop optimizer initialization. */
extern void loop_optimizer_init (unsigned);
extern void loop_optimizer_finalize (void);
/* Optimization passes. */
extern void unswitch_loops (void);
enum
{
UAP_PEEL = 1, /* Enables loop peeling. */
UAP_UNROLL = 2, /* Enables unrolling of loops if it seems profitable. */
UAP_UNROLL_ALL = 4 /* Enables unrolling of all loops. */
};
extern void unroll_and_peel_loops (int);
extern void doloop_optimize_loops (void);
extern void move_loop_invariants (void);
#endif /* GCC_CFGLOOP_H */
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