gcc/vr-values.h

   1 /* Support routines for Value Range Propagation (VRP).
   2    Copyright (C) 2016-2020 Free Software Foundation, Inc.
   3
   4 This file is part of GCC.
   5
   6 GCC is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 3, or (at your option)
   9 any later version.
  10
  11 GCC is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 GNU General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GCC; see the file COPYING3.  If not see
  18 <http://www.gnu.org/licenses/>.  */
  19
  20 #ifndef GCC_VR_VALUES_H
  21 #define GCC_VR_VALUES_H
  22
  23 #include "value-range-equiv.h"
  24
  25 // Abstract class to return a range for a given SSA.
  26
  27 class range_query
  28 {
  29 public:
  30   virtual const value_range_equiv *get_value_range (const_tree,
  31                                                     gimple * = NULL) = 0;
  32   virtual ~range_query () { }
  33 };
  34
  35 // Class to simplify a statement using range information.
  36 //
  37 // The constructor takes a full vr_values, but all it needs is
  38 // get_value_range() from it.  This class could be made to work with
  39 // any range repository.
  40
  41 class simplify_using_ranges : public range_query
  42 {
  43 public:
  44   simplify_using_ranges (class range_query *);
  45   ~simplify_using_ranges ();
  46   bool simplify (gimple_stmt_iterator *);
  47
  48   // ?? These should be cleaned, merged, and made private.
  49   tree vrp_evaluate_conditional (tree_code, tree, tree, gimple *);
  50   void vrp_visit_cond_stmt (gcond *, edge *);
  51   tree vrp_evaluate_conditional_warnv_with_ops (gimple *stmt, enum tree_code,
  52                                                 tree, tree, bool,
  53                                                 bool *, bool *);
  54
  55 private:
  56   const value_range_equiv *get_value_range (const_tree op,
  57                                             gimple *stmt = NULL) OVERRIDE;
  58   bool simplify_truth_ops_using_ranges (gimple_stmt_iterator *, gimple *);
  59   bool simplify_div_or_mod_using_ranges (gimple_stmt_iterator *, gimple *);
  60   bool simplify_abs_using_ranges (gimple_stmt_iterator *, gimple *);
  61   bool simplify_bit_ops_using_ranges (gimple_stmt_iterator *, gimple *);
  62   bool simplify_min_or_max_using_ranges (gimple_stmt_iterator *, gimple *);
  63   bool simplify_cond_using_ranges_1 (gcond *);
  64   bool fold_cond (gcond *);
  65   bool simplify_switch_using_ranges (gswitch *);
  66   bool simplify_float_conversion_using_ranges (gimple_stmt_iterator *,
  67                                                gimple *);
  68   bool simplify_internal_call_using_ranges (gimple_stmt_iterator *, gimple *);
  69
  70   bool two_valued_val_range_p (tree, tree *, tree *);
  71   bool op_with_boolean_value_range_p (tree);
  72   tree compare_name_with_value (enum tree_code, tree, tree, bool *, bool);
  73   tree compare_names (enum tree_code, tree, tree, bool *);
  74   const value_range_equiv *get_vr_for_comparison (int, value_range_equiv *);
  75   tree vrp_evaluate_conditional_warnv_with_ops_using_ranges (enum tree_code,
  76                                                              tree, tree,
  77                                                              bool *);
  78   void cleanup_edges_and_switches (void);
  79
  80   /* Vectors of edges that need removing and switch statements that
  81      need updating.  It is expected that a pass using the simplification
  82      routines will, at the end of the pass, clean up the edges and
  83      switch statements.  The class dtor will try to detect cases
  84      that do not follow that expectation.  */
  85   struct switch_update {
  86     gswitch *stmt;
  87     tree vec;
  88   };
  89
  90   vec<edge> to_remove_edges;
  91   vec<switch_update> to_update_switch_stmts;
  92   class range_query *store;
  93 };
  94
  95 /* The VR_VALUES class holds the current view of range information
  96    for all the SSA_NAMEs in the IL.
  97
  98    It can be used to hold context sensitive range information during
  99    a dominator walk or it may be used to hold range information in the
 100    standard VRP pass as ranges are propagated through the lattice to a
 101    steady state.
 102
 103    This information is independent of the range information that gets
 104    attached to SSA_NAMEs.  A pass such as VRP may choose to transfer
 105    the global information it produces into global range information that
 106    gets attached to an SSA_NAME.  It's unclear how useful that global
 107    information will be in a world where we can compute context sensitive
 108    range information fast or perform on-demand queries.  */
 109 class vr_values : public range_query
 110 {
 111  public:
 112   vr_values (void);
 113   ~vr_values (void);
 114
 115   const value_range_equiv *get_value_range (const_tree, gimple * = NULL);
 116   void set_vr_value (tree, value_range_equiv *);
 117   value_range_equiv *swap_vr_value (tree, value_range_equiv *);
 118
 119   void set_def_to_varying (const_tree);
 120   void set_defs_to_varying (gimple *);
 121   bool update_value_range (const_tree, value_range_equiv *);
 122   tree op_with_constant_singleton_value_range (tree);
 123   void adjust_range_with_scev (value_range_equiv *, class loop *,
 124                                gimple *, tree);
 125   void dump_all_value_ranges (FILE *);
 126
 127   void extract_range_for_var_from_comparison_expr (tree, enum tree_code,
 128                                                    tree, tree,
 129                                                    value_range_equiv *);
 130   void extract_range_from_phi_node (gphi *, value_range_equiv *);
 131   void extract_range_basic (value_range_equiv *, gimple *);
 132   void extract_range_from_stmt (gimple *, edge *, tree *, value_range_equiv *);
 133
 134   /* Indicate that propagation through the lattice is complete.  */
 135   void set_lattice_propagation_complete (void) { values_propagated = true; }
 136
 137   /* Allocate a new value_range object.  */
 138   value_range_equiv *allocate_value_range_equiv (void)
 139     { return vrp_value_range_pool.allocate (); }
 140   void free_value_range (value_range_equiv *vr)
 141     { vrp_value_range_pool.remove (vr); }
 142
 143  private:
 144   value_range_equiv *get_lattice_entry (const_tree);
 145   bool vrp_stmt_computes_nonzero (gimple *);
 146   void extract_range_from_assignment (value_range_equiv *, gassign *);
 147   void extract_range_from_assert (value_range_equiv *, tree);
 148   void extract_range_from_ssa_name (value_range_equiv *, tree);
 149   void extract_range_from_binary_expr (value_range_equiv *, enum tree_code,
 150                                        tree, tree, tree);
 151   void extract_range_from_unary_expr (value_range_equiv *, enum tree_code,
 152                                       tree, tree);
 153   void extract_range_from_cond_expr (value_range_equiv *, gassign *);
 154   void extract_range_from_comparison (value_range_equiv *, gimple *);
 155   void vrp_visit_assignment_or_call (gimple*, tree *, value_range_equiv *);
 156   void vrp_visit_switch_stmt (gswitch *, edge *);
 157
 158   /* Allocation pools for value_range objects.  */
 159   object_allocator<value_range_equiv> vrp_value_range_pool;
 160
 161   /* This probably belongs in the lattice rather than in here.  */
 162   bool values_propagated;
 163
 164   /* Allocations for equivalences all come from this obstack.  */
 165   bitmap_obstack vrp_equiv_obstack;
 166
 167   /* Value range array.  After propagation, VR_VALUE[I] holds the range
 168      of values that SSA name N_I may take.  */
 169   unsigned int num_vr_values;
 170   value_range_equiv **vr_value;
 171
 172   /* For a PHI node which sets SSA name N_I, VR_COUNTS[I] holds the
 173      number of executable edges we saw the last time we visited the
 174      node.  */
 175   int *vr_phi_edge_counts;
 176   simplify_using_ranges simplifier;
 177 };
 178
 179 inline const value_range_equiv *
 180 simplify_using_ranges::get_value_range (const_tree op, gimple *stmt)
 181 {
 182   return store->get_value_range (op, stmt);
 183 }
 184
 185 extern tree get_output_for_vrp (gimple *);
 186
 187 // FIXME: Move this to tree-vrp.c.
 188 void simplify_cond_using_ranges_2 (class vr_values *, gcond *);
 189
 190 extern bool bounds_of_var_in_loop (tree *min, tree *max, range_query *,
 191                                    class loop *loop, gimple *stmt, tree var);
 192
 193 #endif /* GCC_VR_VALUES_H */