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/* Data structures and function declarations for the SSA value propagation

   engine.

   Copyright (C) 2004, 2005, 2007 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 3, 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 COPYING3.  If not see

<http://www.gnu.org/licenses/>.  */

#ifndef _TREE_SSA_PROPAGATE_H

#define _TREE_SSA_PROPAGATE_H 1

/* Use the TREE_VISITED bitflag to mark statements and PHI nodes that

   have been deemed varying and should not be simulated again.  */

#define DONT_SIMULATE_AGAIN(T)  TREE_VISITED (T)

/* Lattice values used for propagation purposes.  Specific instances

   of a propagation engine must return these values from the statement

   and PHI visit functions to direct the engine.  */

enum ssa_prop_result {

    /* The statement produces nothing of interest.  No edges will be

       added to the work lists.  */

    SSA_PROP_NOT_INTERESTING,

    /* The statement produces an interesting value.  The set SSA_NAMEs

       returned by SSA_PROP_VISIT_STMT should be added to

       INTERESTING_SSA_EDGES.  If the statement being visited is a

       conditional jump, SSA_PROP_VISIT_STMT should indicate which edge

       out of the basic block should be marked executable.  */

    SSA_PROP_INTERESTING,

    /* The statement produces a varying (i.e., useless) value and

       should not be simulated again.  If the statement being visited

       is a conditional jump, all the edges coming out of the block

       will be considered executable.  */

    SSA_PROP_VARYING

};

struct prop_value_d {

    /* Lattice value.  Each propagator is free to define its own

       lattice and this field is only meaningful while propagating.

       It will not be used by substitute_and_fold.  */

    unsigned lattice_val;

    /* Propagated value.  */

    tree value;

    /* If this value is held in an SSA name for a non-register

       variable, this field holds the actual memory reference

       associated with this value.  This field is taken from

       the LHS of the assignment that generated the associated SSA

       name.  However, in the case of PHI nodes, this field is copied

       from the PHI arguments (assuming that all the arguments have

       the same memory reference).  See replace_vuses_in for a more

       detailed description.  */

    tree mem_ref;

};

typedef struct prop_value_d prop_value_t;

/* Type of value ranges.  See value_range_d for a description of these

   types.  */

enum value_range_type { VR_UNDEFINED, VR_RANGE, VR_ANTI_RANGE, VR_VARYING };

/* Range of values that can be associated with an SSA_NAME after VRP

   has executed.  */

struct value_range_d

{

  /* Lattice value represented by this range.  */

  enum value_range_type type;

  /* Minimum and maximum values represented by this range.  These

     values should be interpreted as follows:

        - If TYPE is VR_UNDEFINED or VR_VARYING then MIN and MAX must

          be NULL.

        - If TYPE == VR_RANGE then MIN holds the minimum value and

          MAX holds the maximum value of the range [MIN, MAX].

        - If TYPE == ANTI_RANGE the variable is known to NOT

          take any values in the range [MIN, MAX].  */

  tree min;

  tree max;

  /* Set of SSA names whose value ranges are equivalent to this one.

     This set is only valid when TYPE is VR_RANGE or VR_ANTI_RANGE.  */

  bitmap equiv;

};

typedef struct value_range_d value_range_t;

/* Call-back functions used by the value propagation engine.  */

typedef enum ssa_prop_result (*ssa_prop_visit_stmt_fn) (tree, edge *, tree *);

typedef enum ssa_prop_result (*ssa_prop_visit_phi_fn) (tree);

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

void ssa_propagate (ssa_prop_visit_stmt_fn, ssa_prop_visit_phi_fn);

tree get_rhs (tree);

bool set_rhs (tree *, tree);

tree first_vdef (tree);

bool stmt_makes_single_load (tree);

bool stmt_makes_single_store (tree);

prop_value_t *get_value_loaded_by (tree, prop_value_t *);

bool replace_uses_in (tree, bool *, prop_value_t *);

void substitute_and_fold (prop_value_t *, bool);

#endif /* _TREE_SSA_PROPAGATE_H  */