gcc/tree-ssa-propagate.h

   1 /* Data structures and function declarations for the SSA value propagation
   2    engine.
   3    Copyright (C) 2004, 2005 Free Software Foundation, Inc.
   4    Contributed by Diego Novillo <dnovillo@redhat.com>
   5
   6 This file is part of GCC.
   7
   8 GCC is free software; you can redistribute it and/or modify
   9 it under the terms of the GNU General Public License as published by
  10 the Free Software Foundation; either version 2, or (at your option)
  11 any later version.
  12
  13 GCC is distributed in the hope that it will be useful,
  14 but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 GNU General Public License for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with GCC; see the file COPYING.  If not, write to
  20 the Free Software Foundation, 51 Franklin Street, Fifth Floor,
  21 Boston, MA 02110-1301, USA.  */
  22
  23 #ifndef _TREE_SSA_PROPAGATE_H
  24 #define _TREE_SSA_PROPAGATE_H 1
  25
  26 /* Use the TREE_VISITED bitflag to mark statements and PHI nodes that
  27    have been deemed varying and should not be simulated again.  */
  28 #define DONT_SIMULATE_AGAIN(T)  TREE_VISITED (T)
  29
  30 /* Lattice values used for propagation purposes.  Specific instances
  31    of a propagation engine must return these values from the statement
  32    and PHI visit functions to direct the engine.  */
  33 enum ssa_prop_result {
  34     /* The statement produces nothing of interest.  No edges will be
  35        added to the work lists.  */
  36     SSA_PROP_NOT_INTERESTING,
  37
  38     /* The statement produces an interesting value.  The set SSA_NAMEs
  39        returned by SSA_PROP_VISIT_STMT should be added to
  40        INTERESTING_SSA_EDGES.  If the statement being visited is a
  41        conditional jump, SSA_PROP_VISIT_STMT should indicate which edge
  42        out of the basic block should be marked executable.  */
  43     SSA_PROP_INTERESTING,
  44
  45     /* The statement produces a varying (i.e., useless) value and
  46        should not be simulated again.  If the statement being visited
  47        is a conditional jump, all the edges coming out of the block
  48        will be considered executable.  */
  49     SSA_PROP_VARYING
  50 };
  51
  52
  53 struct prop_value_d {
  54     /* Lattice value.  Each propagator is free to define its own
  55        lattice and this field is only meaningful while propagating.
  56        It will not be used by substitute_and_fold.  */
  57     unsigned lattice_val;
  58
  59     /* Propagated value.  */
  60     tree value;
  61
  62     /* If this value is held in an SSA name for a non-register
  63        variable, this field holds the actual memory reference
  64        associated with this value.  This field is taken from
  65        the LHS of the assignment that generated the associated SSA
  66        name.  However, in the case of PHI nodes, this field is copied
  67        from the PHI arguments (assuming that all the arguments have
  68        the same memory reference).  See replace_vuses_in for a more
  69        detailed description.  */
  70     tree mem_ref;
  71 };
  72
  73 typedef struct prop_value_d prop_value_t;
  74
  75
  76 /* Type of value ranges.  See value_range_d for a description of these
  77    types.  */
  78 enum value_range_type { VR_UNDEFINED, VR_RANGE, VR_ANTI_RANGE, VR_VARYING };
  79
  80 /* Range of values that can be associated with an SSA_NAME after VRP
  81    has executed.  */
  82 struct value_range_d
  83 {
  84   /* Lattice value represented by this range.  */
  85   enum value_range_type type;
  86
  87   /* Minimum and maximum values represented by this range.  These
  88      values should be interpreted as follows:
  89
  90         - If TYPE is VR_UNDEFINED or VR_VARYING then MIN and MAX must
  91           be NULL.
  92
  93         - If TYPE == VR_RANGE then MIN holds the minimum value and
  94           MAX holds the maximum value of the range [MIN, MAX].
  95
  96         - If TYPE == ANTI_RANGE the variable is known to NOT
  97           take any values in the range [MIN, MAX].  */
  98   tree min;
  99   tree max;
 100
 101   /* Set of SSA names whose value ranges are equivalent to this one.
 102      This set is only valid when TYPE is VR_RANGE or VR_ANTI_RANGE.  */
 103   bitmap equiv;
 104 };
 105
 106 typedef struct value_range_d value_range_t;
 107
 108
 109 /* Call-back functions used by the value propagation engine.  */
 110 typedef enum ssa_prop_result (*ssa_prop_visit_stmt_fn) (tree, edge *, tree *);
 111 typedef enum ssa_prop_result (*ssa_prop_visit_phi_fn) (tree);
 112
 113
 114 /* In tree-ssa-propagate.c  */
 115 void ssa_propagate (ssa_prop_visit_stmt_fn, ssa_prop_visit_phi_fn);
 116 tree get_rhs (tree);
 117 bool set_rhs (tree *, tree);
 118 tree first_vdef (tree);
 119 bool stmt_makes_single_load (tree);
 120 bool stmt_makes_single_store (tree);
 121 prop_value_t *get_value_loaded_by (tree, prop_value_t *);
 122 bool replace_uses_in (tree, bool *, prop_value_t *);
 123 bool substitute_and_fold (prop_value_t *, bool);
 124
 125 #endif /* _TREE_SSA_PROPAGATE_H  */