/* 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, 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" /* 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 { /* 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 { /* The exit edge. */ edge 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; }; /* 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; /* Number of blocks contained within the loop. */ unsigned num_nodes; /* The loop nesting depth. */ int depth; /* Superloops of the loop. */ struct loop **pred; /* 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; /* Auxiliary info specific to a pass. */ void *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 { /* Estimate was not computed yet. */ EST_NOT_COMPUTED, /* Estimate is ready. */ EST_AVAILABLE } 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) typedef struct loop *loop_p; DEF_VEC_P (loop_p); DEF_VEC_ALLOC_P (loop_p, heap); /* Structure to hold CFG information about natural loops within a function. */ struct loops { /* State of loops. */ int state; /* Array of the loops. */ VEC (loop_p, heap) *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 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 }; 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 df *iv_current_loop_df (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 list of loops in current_loops. */ static inline VEC (loop_p, heap) * 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 (!aloop->outer) break; else aloop = aloop->outer; } } 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 = aloop->outer; 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 */