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/* Data and Control Flow Analysis for Trees.

   Copyright (C) 2001, 2003, 2004, 2005 Free Software Foundation, Inc.

   Contributed by Diego Novillo <dnovillo@redhat.com>

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 _TREE_FLOW_H

#define _TREE_FLOW_H 1

#include "bitmap.h"

#include "hard-reg-set.h"

#include "basic-block.h"

#include "hashtab.h"

#include "tree-gimple.h"

#include "tree-ssa-operands.h"

#include "cgraph.h"

#include "ipa-reference.h"

/* Forward declare structures for the garbage collector GTY markers.  */

#ifndef GCC_BASIC_BLOCK_H

struct edge_def;

typedef struct edge_def *edge;

struct basic_block_def;

typedef struct basic_block_def *basic_block;

#endif

/* True if the code is in ssa form.  */

extern bool in_ssa_p;

typedef struct

{

  htab_t htab;

  PTR *slot;

  PTR *limit;

} htab_iterator;

/* Iterate through the elements of hashtable HTAB, using htab_iterator ITER,

   storing each element in RESULT, which is of type TYPE.  */

#define FOR_EACH_HTAB_ELEMENT(HTAB, RESULT, TYPE, ITER) \

  for (RESULT = (TYPE) first_htab_element (&(ITER), (HTAB)); \

        !end_htab_p (&(ITER)); \

        RESULT = (TYPE) next_htab_element (&(ITER)))

/*---------------------------------------------------------------------------

                      Attributes for SSA_NAMEs.

  NOTE: These structures are stored in struct tree_ssa_name

  but are only used by the tree optimizers, so it makes better sense

  to declare them here to avoid recompiling unrelated files when

  making changes.

---------------------------------------------------------------------------*/

/* Aliasing information for SSA_NAMEs representing pointer variables.  */

struct ptr_info_def GTY(())

{

  /* Nonzero if points-to analysis couldn't determine where this pointer

     is pointing to.  */

  unsigned int pt_anything : 1;

  /* Nonzero if the value of this pointer escapes the current function.  */

  unsigned int value_escapes_p : 1;

  /* Nonzero if this pointer is dereferenced.  */

  unsigned int is_dereferenced : 1;

  /* Nonzero if this pointer points to a global variable.  */

  unsigned int pt_global_mem : 1;

  /* Nonzero if this pointer points to NULL.  */

  unsigned int pt_null : 1;

  /* Set of variables that this pointer may point to.  */

  bitmap pt_vars;

  /* If this pointer has been dereferenced, and points-to information is

     more precise than type-based aliasing, indirect references to this

     pointer will be represented by this memory tag, instead of the type

     tag computed by TBAA.  */

  tree name_mem_tag;

};

/*---------------------------------------------------------------------------

                   Tree annotations stored in tree_common.ann

---------------------------------------------------------------------------*/

enum tree_ann_type { TREE_ANN_COMMON, VAR_ANN, STMT_ANN };

struct tree_ann_common_d GTY(())

{

  /* Annotation type.  */

  enum tree_ann_type type;

 /* Auxiliary info specific to a pass.  At all times, this

    should either point to valid data or be NULL.  */

  PTR GTY ((skip (""))) aux;

  /* The value handle for this expression.  Used by GVN-PRE.  */

  tree GTY((skip)) value_handle;

};

/* It is advantageous to avoid things like life analysis for variables which

   do not need PHI nodes.  This enum describes whether or not a particular

   variable may need a PHI node.  */

enum need_phi_state {

  /* This is the default.  If we are still in this state after finding

     all the definition and use sites, then we will assume the variable

     needs PHI nodes.  This is probably an overly conservative assumption.  */

  NEED_PHI_STATE_UNKNOWN,

  /* This state indicates that we have seen one or more sets of the

     variable in a single basic block and that the sets dominate all

     uses seen so far.  If after finding all definition and use sites

     we are still in this state, then the variable does not need any

     PHI nodes.  */

  NEED_PHI_STATE_NO,

  /* This state indicates that we have either seen multiple definitions of

     the variable in multiple blocks, or that we encountered a use in a

     block that was not dominated by the block containing the set(s) of

     this variable.  This variable is assumed to need PHI nodes.  */

  NEED_PHI_STATE_MAYBE

};

/* When computing aliasing information, we represent the memory pointed-to

   by pointers with artificial variables called "memory tags" (MT).  There

   are two kinds of tags: type and name.  Type tags (TMT) are used in

   type-based alias analysis, they represent all the pointed-to locations

   and variables of the same alias set class.  Name tags (NMT) are used in

   flow-sensitive points-to alias analysis, they represent the variables

   and memory locations pointed-to by a specific SSA_NAME pointer.  */

enum mem_tag_kind {

  /* This variable is not a memory tag.  */

  NOT_A_TAG,

  /* This variable is a type memory tag (TMT).  */

  TYPE_TAG,

  /* This variable is a name memory tag (NMT).  */

  NAME_TAG,

  /* This variable represents a structure field.  */

  STRUCT_FIELD

};

struct subvar;

typedef struct subvar *subvar_t;

/* This structure represents a fake sub-variable for a structure field.  */

struct subvar GTY(())

{

  /* Fake variable.  */

  tree var;

  /* Offset inside structure.  */

  unsigned HOST_WIDE_INT offset;

  /* Size of the field.  */

  unsigned HOST_WIDE_INT size;

  /* Next subvar for this structure.  */

  subvar_t next;

};

struct var_ann_d GTY(())

{

  struct tree_ann_common_d common;

  /* Used by the out of SSA pass to determine whether this variable has

     been seen yet or not.  */

  unsigned out_of_ssa_tag : 1;

  /* Used when building root_var structures in tree_ssa_live.[ch].  */

  unsigned root_var_processed : 1;

  /* If nonzero, this variable is a memory tag.  */

  ENUM_BITFIELD (mem_tag_kind) mem_tag_kind : 2;

  /* Nonzero if this variable is an alias tag that represents references to

     other variables (i.e., this variable appears in the MAY_ALIASES array

     of other variables).  */

  unsigned is_alias_tag : 1;

  /* Nonzero if this variable was used after SSA optimizations were

     applied.  We set this when translating out of SSA form.  */

  unsigned used : 1;

  /* This field indicates whether or not the variable may need PHI nodes.

     See the enum's definition for more detailed information about the

     states.  */

  ENUM_BITFIELD (need_phi_state) need_phi_state : 2;

  /* Used during operand processing to determine if this variable is already

     in the vuse list.  */

  unsigned in_vuse_list : 1;

  /* Used during operand processing to determine if this variable is already

     in the v_may_def list.  */

  unsigned in_v_may_def_list : 1;

  /* An artificial variable representing the memory location pointed-to by

     all the pointers that TBAA (type-based alias analysis) considers

     to be aliased.  If the variable is not a pointer or if it is never

     dereferenced, this must be NULL.  */

  tree type_mem_tag;

  /* Variables that may alias this variable.  */

  varray_type may_aliases;

  /* Used when going out of SSA form to indicate which partition this

     variable represents storage for.  */

  unsigned partition;

  /* Used by the root-var object in tree-ssa-live.[ch].  */

  unsigned root_index;

  /* Default definition for this symbol.  If this field is not NULL, it

     means that the first reference to this variable in the function is a

     USE or a VUSE.  In those cases, the SSA renamer creates an SSA name

     for this variable with an empty defining statement.  */

  tree default_def;

  /* During into-ssa and the dominator optimizer, this field holds the

     current version of this variable (an SSA_NAME).  */

  tree current_def;

  /* Pointer to the structure that contains the sets of global

     variables modified by function calls.  This field is only used

     for FUNCTION_DECLs.  */

  ipa_reference_vars_info_t GTY ((skip)) reference_vars_info;

  /* If this variable is a structure, this fields holds a list of

     symbols representing each of the fields of the structure.  */

  subvar_t subvars;

};

typedef struct immediate_use_iterator_d

{

  ssa_use_operand_t *imm_use;

  ssa_use_operand_t *end_p;

  ssa_use_operand_t iter_node;

} imm_use_iterator;

/* Use this iterator when simply looking at stmts.  Adding, deleting or

   modifying stmts will cause this iterator to malfunction.  */

#define FOR_EACH_IMM_USE_FAST(DEST, ITER, SSAVAR)                       \

  for ((DEST) = first_readonly_imm_use (&(ITER), (SSAVAR));     \

       !end_readonly_imm_use_p (&(ITER));                       \

       (DEST) = next_readonly_imm_use (&(ITER)))

#define FOR_EACH_IMM_USE_SAFE(DEST, ITER, SSAVAR)               \

  for ((DEST) = first_safe_imm_use (&(ITER), (SSAVAR));         \

       !end_safe_imm_use_p (&(ITER));                           \

       (DEST) = next_safe_imm_use (&(ITER)))

#define BREAK_FROM_SAFE_IMM_USE(ITER)                           \

   {                                                            \

     end_safe_imm_use_traverse (&(ITER));                       \

     break;                                                     \

   }

struct stmt_ann_d GTY(())

{

  struct tree_ann_common_d common;

  /* Nonzero if the statement has been modified (meaning that the operands

     need to be scanned again).  */

  unsigned modified : 1;

  /* Nonzero if the statement makes aliased loads.  */

  unsigned makes_aliased_loads : 1;

  /* Nonzero if the statement makes aliased stores.  */

  unsigned makes_aliased_stores : 1;

  /* Nonzero if the statement makes references to volatile storage.  */

  unsigned has_volatile_ops : 1;

  /* Nonzero if the statement makes a function call that may clobber global

     and local addressable variables.  */

  unsigned makes_clobbering_call : 1;

  /* Basic block that contains this statement.  */

  basic_block bb;

  /* Operand cache for stmt.  */

  struct stmt_operands_d GTY ((skip (""))) operands;

  /* Set of variables that have had their address taken in the statement.  */

  bitmap addresses_taken;

  /* Unique identifier for this statement.  These ID's are to be created

     by each pass on an as-needed basis in any order convenient for the

     pass which needs statement UIDs.  */

  unsigned int uid;

  /* Linked list of histograms for value-based profiling.  This is really a

     struct histogram_value*.  We use void* to avoid having to export that

     everywhere, and to avoid having to put it in GC memory.  */

  void * GTY ((skip (""))) histograms;

};

union tree_ann_d GTY((desc ("ann_type ((tree_ann_t)&%h)")))

{

  struct tree_ann_common_d GTY((tag ("TREE_ANN_COMMON"))) common;

  struct var_ann_d GTY((tag ("VAR_ANN"))) decl;

  struct stmt_ann_d GTY((tag ("STMT_ANN"))) stmt;

};

extern GTY(()) VEC(tree,gc) *modified_noreturn_calls;

typedef union tree_ann_d *tree_ann_t;

typedef struct var_ann_d *var_ann_t;

typedef struct stmt_ann_d *stmt_ann_t;

static inline tree_ann_t tree_ann (tree);

static inline tree_ann_t get_tree_ann (tree);

static inline var_ann_t var_ann (tree);

static inline var_ann_t get_var_ann (tree);

static inline stmt_ann_t stmt_ann (tree);

static inline stmt_ann_t get_stmt_ann (tree);

static inline enum tree_ann_type ann_type (tree_ann_t);

static inline basic_block bb_for_stmt (tree);

extern void set_bb_for_stmt (tree, basic_block);

static inline bool noreturn_call_p (tree);

static inline void update_stmt (tree);

static inline bool stmt_modified_p (tree);

static inline varray_type may_aliases (tree);

static inline int get_lineno (tree);

static inline const char *get_filename (tree);

static inline bool is_exec_stmt (tree);

static inline bool is_label_stmt (tree);

static inline bitmap addresses_taken (tree);

static inline void set_default_def (tree, tree);

static inline tree default_def (tree);

/*---------------------------------------------------------------------------

                  Structure representing predictions in tree level.

---------------------------------------------------------------------------*/

struct edge_prediction GTY((chain_next ("%h.next")))

{

  struct edge_prediction *next;

  edge edge;

  enum br_predictor predictor;

  int probability;

};

/* Accessors for basic block annotations.  */

static inline tree phi_nodes (basic_block);

static inline void set_phi_nodes (basic_block, tree);

/*---------------------------------------------------------------------------

                              Global declarations

---------------------------------------------------------------------------*/

struct int_tree_map GTY(())

{

  unsigned int uid;

  tree to;

};

extern unsigned int int_tree_map_hash (const void *);

extern int int_tree_map_eq (const void *, const void *);

typedef struct

{

  htab_iterator hti;

} referenced_var_iterator;

/* This macro loops over all the referenced vars, one at a time, putting the

   current var in VAR.  Note:  You are not allowed to add referenced variables

   to the hashtable while using this macro.  Doing so may cause it to behave

   erratically.  */

#define FOR_EACH_REFERENCED_VAR(VAR, ITER) \

  for ((VAR) = first_referenced_var (&(ITER)); \

       !end_referenced_vars_p (&(ITER)); \

       (VAR) = next_referenced_var (&(ITER)))

typedef struct

{

  int i;

} safe_referenced_var_iterator;

/* This macro loops over all the referenced vars, one at a time, putting the

   current var in VAR.  You are allowed to add referenced variables during the

   execution of this macro, however, the macro will not iterate over them.  It

   requires a temporary vector of trees, VEC, whose lifetime is controlled by

   the caller.  The purpose of the vector is to temporarily store the

   referenced_variables hashtable so that adding referenced variables does not

   affect the hashtable.  */

#define FOR_EACH_REFERENCED_VAR_SAFE(VAR, VEC, ITER) \

  for ((ITER).i = 0, fill_referenced_var_vec (&(VEC)); \

       VEC_iterate (tree, (VEC), (ITER).i, (VAR)); \

       (ITER).i++)

/* Array of all variables referenced in the function.  */

extern GTY((param_is (struct int_tree_map))) htab_t referenced_vars;

extern tree referenced_var_lookup (unsigned int);

extern tree referenced_var_lookup_if_exists (unsigned int);

#define num_referenced_vars htab_elements (referenced_vars)

#define referenced_var(i) referenced_var_lookup (i)

/* Array of all SSA_NAMEs used in the function.  */

extern GTY(()) VEC(tree,gc) *ssa_names;

#define num_ssa_names (VEC_length (tree, ssa_names))

#define ssa_name(i) (VEC_index (tree, ssa_names, (i)))

/* Artificial variable used to model the effects of function calls.  */

extern GTY(()) tree global_var;

/* Call clobbered variables in the function.  If bit I is set, then

   REFERENCED_VARS (I) is call-clobbered.  */

extern bitmap call_clobbered_vars;

/* Addressable variables in the function.  If bit I is set, then

   REFERENCED_VARS (I) has had its address taken.  */

extern bitmap addressable_vars;

/* 'true' after aliases have been computed (see compute_may_aliases).  */

extern bool aliases_computed_p;

/* Macros for showing usage statistics.  */

#define SCALE(x) ((unsigned long) ((x) < 1024*10        \

                  ? (x)                                 \

                  : ((x) < 1024*1024*10                 \

                     ? (x) / 1024                       \

                     : (x) / (1024*1024))))

#define LABEL(x) ((x) < 1024*10 ? 'b' : ((x) < 1024*1024*10 ? 'k' : 'M'))

#define PERCENT(x,y) ((float)(x) * 100.0 / (float)(y))

/*---------------------------------------------------------------------------

                              Block iterators

---------------------------------------------------------------------------*/

typedef struct {

  tree_stmt_iterator tsi;

  basic_block bb;

} block_stmt_iterator;

static inline block_stmt_iterator bsi_start (basic_block);

static inline block_stmt_iterator bsi_last (basic_block);

static inline block_stmt_iterator bsi_after_labels (basic_block);

block_stmt_iterator bsi_for_stmt (tree);

static inline bool bsi_end_p (block_stmt_iterator);

static inline void bsi_next (block_stmt_iterator *);

static inline void bsi_prev (block_stmt_iterator *);

static inline tree bsi_stmt (block_stmt_iterator);

static inline tree * bsi_stmt_ptr (block_stmt_iterator);

extern void bsi_remove (block_stmt_iterator *);

extern void bsi_move_before (block_stmt_iterator *, block_stmt_iterator *);

extern void bsi_move_after (block_stmt_iterator *, block_stmt_iterator *);

extern void bsi_move_to_bb_end (block_stmt_iterator *, basic_block);

enum bsi_iterator_update

{

  /* Note that these are intentionally in the same order as TSI_FOO.  They

     mean exactly the same as their TSI_* counterparts.  */

  BSI_NEW_STMT,

  BSI_SAME_STMT,

  BSI_CHAIN_START,

  BSI_CHAIN_END,

  BSI_CONTINUE_LINKING

};

extern void bsi_insert_before (block_stmt_iterator *, tree,

                               enum bsi_iterator_update);

extern void bsi_insert_after (block_stmt_iterator *, tree,

                              enum bsi_iterator_update);

extern void bsi_replace (const block_stmt_iterator *, tree, bool);

/*---------------------------------------------------------------------------

                              Function prototypes

---------------------------------------------------------------------------*/

/* In tree-cfg.c  */

/* Location to track pending stmt for edge insertion.  */

#define PENDING_STMT(e) ((e)->insns.t)

extern void delete_tree_cfg_annotations (void);

extern void disband_implicit_edges (void);

extern bool stmt_ends_bb_p (tree);

extern bool is_ctrl_stmt (tree);

extern bool is_ctrl_altering_stmt (tree);

extern bool computed_goto_p (tree);

extern bool simple_goto_p (tree);

extern basic_block single_noncomplex_succ (basic_block bb);

extern void tree_dump_bb (basic_block, FILE *, int);

extern void debug_tree_bb (basic_block);

extern basic_block debug_tree_bb_n (int);

extern void dump_tree_cfg (FILE *, int);

extern void debug_tree_cfg (int);

extern void dump_cfg_stats (FILE *);

extern void debug_cfg_stats (void);

extern void debug_loop_ir (void);

extern void print_loop_ir (FILE *);

extern void cleanup_dead_labels (void);

extern void group_case_labels (void);

extern tree first_stmt (basic_block);

extern tree last_stmt (basic_block);

extern tree *last_stmt_ptr (basic_block);

extern tree last_and_only_stmt (basic_block);

extern edge find_taken_edge (basic_block, tree);

extern basic_block label_to_block_fn (struct function *, tree);

#define label_to_block(t) (label_to_block_fn (cfun, t))

extern void bsi_insert_on_edge (edge, tree);

extern basic_block bsi_insert_on_edge_immediate (edge, tree);

extern void bsi_commit_one_edge_insert (edge, basic_block *);

extern void bsi_commit_edge_inserts (void);

extern void notice_special_calls (tree);

extern void clear_special_calls (void);

extern void verify_stmts (void);

extern tree tree_block_label (basic_block);

extern void extract_true_false_edges_from_block (basic_block, edge *, edge *);

extern bool tree_duplicate_sese_region (edge, edge, basic_block *, unsigned,

                                        basic_block *);

extern void add_phi_args_after_copy_bb (basic_block);

extern void add_phi_args_after_copy (basic_block *, unsigned);

extern bool tree_purge_dead_eh_edges (basic_block);

extern bool tree_purge_all_dead_eh_edges (bitmap);

extern tree gimplify_val (block_stmt_iterator *, tree, tree);

extern tree gimplify_build1 (block_stmt_iterator *, enum tree_code,

                             tree, tree);

extern tree gimplify_build2 (block_stmt_iterator *, enum tree_code,

                             tree, tree, tree);

extern tree gimplify_build3 (block_stmt_iterator *, enum tree_code,

                             tree, tree, tree, tree);

extern void init_empty_tree_cfg (void);

extern void fold_cond_expr_cond (void);

extern void replace_uses_by (tree, tree);

extern void start_recording_case_labels (void);

extern void end_recording_case_labels (void);

/* In tree-cfgcleanup.c  */

extern bool cleanup_tree_cfg (void);

extern void cleanup_tree_cfg_loop (void);

/* In tree-pretty-print.c.  */

extern void dump_generic_bb (FILE *, basic_block, int, int);

/* In tree-dfa.c  */

extern var_ann_t create_var_ann (tree);

extern stmt_ann_t create_stmt_ann (tree);

extern tree_ann_t create_tree_ann (tree);

extern void dump_dfa_stats (FILE *);

extern void debug_dfa_stats (void);

extern void debug_referenced_vars (void);

extern void dump_referenced_vars (FILE *);

extern void dump_variable (FILE *, tree);

extern void debug_variable (tree);

extern void dump_subvars_for (FILE *, tree);

extern void debug_subvars_for (tree);

extern tree get_virtual_var (tree);

extern void add_referenced_tmp_var (tree);

extern void mark_new_vars_to_rename (tree);

extern void find_new_referenced_vars (tree *);

extern tree make_rename_temp (tree, const char *);

/* In tree-phinodes.c  */

extern void reserve_phi_args_for_new_edge (basic_block);

extern tree create_phi_node (tree, basic_block);

extern void add_phi_arg (tree, tree, edge);

extern void remove_phi_args (edge);

extern void remove_phi_node (tree, tree);

extern tree phi_reverse (tree);

/* In gimple-low.c  */

extern void record_vars (tree);

extern bool block_may_fallthru (tree block);

/* In tree-ssa-alias.c  */

extern void dump_may_aliases_for (FILE *, tree);

extern void debug_may_aliases_for (tree);

extern void dump_alias_info (FILE *);

extern void debug_alias_info (void);

extern void dump_points_to_info (FILE *);

extern void debug_points_to_info (void);

extern void dump_points_to_info_for (FILE *, tree);

extern void debug_points_to_info_for (tree);

extern bool may_be_aliased (tree);

extern bool is_aliased_with (tree, tree);

extern struct ptr_info_def *get_ptr_info (tree);

extern void add_type_alias (tree, tree);

extern void new_type_alias (tree, tree);

extern void count_uses_and_derefs (tree, tree, unsigned *, unsigned *, bool *);

static inline subvar_t get_subvars_for_var (tree);

static inline tree get_subvar_at (tree, unsigned HOST_WIDE_INT);

static inline bool ref_contains_array_ref (tree);

static inline bool array_ref_contains_indirect_ref (tree);

extern tree okay_component_ref_for_subvars (tree, unsigned HOST_WIDE_INT *,

                                            unsigned HOST_WIDE_INT *);

static inline bool var_can_have_subvars (tree);

static inline bool overlap_subvar (unsigned HOST_WIDE_INT,

                                   unsigned HOST_WIDE_INT,

                                   subvar_t, bool *);

/* Call-back function for walk_use_def_chains().  At each reaching

   definition, a function with this prototype is called.  */

typedef bool (*walk_use_def_chains_fn) (tree, tree, void *);

/* In tree-ssa.c  */

extern void init_tree_ssa (void);

extern edge ssa_redirect_edge (edge, basic_block);

extern void flush_pending_stmts (edge);

extern bool tree_ssa_useless_type_conversion (tree);

extern bool tree_ssa_useless_type_conversion_1 (tree, tree);

extern void verify_ssa (bool);

extern void delete_tree_ssa (void);

extern void register_new_def (tree, VEC(tree,heap) **);

extern void walk_use_def_chains (tree, walk_use_def_chains_fn, void *, bool);

extern bool stmt_references_memory_p (tree);

/* In tree-into-ssa.c  */

void update_ssa (unsigned);

void delete_update_ssa (void);

void register_new_name_mapping (tree, tree);

tree create_new_def_for (tree, tree, def_operand_p);

bool need_ssa_update_p (void);

bool name_registered_for_update_p (tree);

bitmap ssa_names_to_replace (void);

void release_ssa_name_after_update_ssa (tree name);

void compute_global_livein (bitmap, bitmap);

tree duplicate_ssa_name (tree, tree);

void mark_sym_for_renaming (tree);

void mark_set_for_renaming (bitmap);

tree get_current_def (tree);

void set_current_def (tree, tree);

/* In tree-ssa-ccp.c  */

bool fold_stmt (tree *);

bool fold_stmt_inplace (tree);

tree widen_bitfield (tree, tree, tree);

/* In tree-vrp.c  */

tree vrp_evaluate_conditional (tree, bool);

void simplify_stmt_using_ranges (tree);

/* In tree-ssa-dom.c  */

extern void dump_dominator_optimization_stats (FILE *);

extern void debug_dominator_optimization_stats (void);

int loop_depth_of_name (tree);

/* In tree-ssa-copy.c  */

extern void merge_alias_info (tree, tree);

extern void propagate_value (use_operand_p, tree);

extern void propagate_tree_value (tree *, tree);

extern void replace_exp (use_operand_p, tree);

extern bool may_propagate_copy (tree, tree);

extern bool may_propagate_copy_into_asm (tree);

/* Description of number of iterations of a loop.  All the expressions inside

   the structure can be evaluated at the end of the loop's preheader

   (and due to ssa form, also anywhere inside the body of the loop).  */

struct tree_niter_desc

{

  tree assumptions;     /* The boolean expression.  If this expression evaluates

                           to false, then the other fields in this structure

                           should not be used; there is no guarantee that they

                           will be correct.  */

  tree may_be_zero;     /* The boolean expression.  If it evaluates to true,

                           the loop will exit in the first iteration (i.e.

                           its latch will not be executed), even if the niter