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 // Class to simplify a statement using range information.
  26 //
  27 // The constructor takes a full vr_values, but all it needs is
  28 // get_value_range() from it.  This class could be made to work with
  29 // any range repository.
  30
  31 class simplify_using_ranges
  32 {
  33 public:
  34   simplify_using_ranges (class vr_values *);
  35   ~simplify_using_ranges ();
  36   bool simplify (gimple_stmt_iterator *);
  37
  38   // ?? These should be cleaned, merged, and made private.
  39   tree vrp_evaluate_conditional (tree_code, tree, tree, gimple *);
  40   void vrp_visit_cond_stmt (gcond *, edge *);
  41   tree vrp_evaluate_conditional_warnv_with_ops (enum tree_code,
  42                                                 tree, tree, bool,
  43                                                 bool *, bool *);
  44
  45 private:
  46   const value_range_equiv *get_value_range (const_tree op);
  47   bool simplify_truth_ops_using_ranges (gimple_stmt_iterator *, gimple *);
  48   bool simplify_div_or_mod_using_ranges (gimple_stmt_iterator *, gimple *);
  49   bool simplify_abs_using_ranges (gimple_stmt_iterator *, gimple *);
  50   bool simplify_bit_ops_using_ranges (gimple_stmt_iterator *, gimple *);
  51   bool simplify_min_or_max_using_ranges (gimple_stmt_iterator *, gimple *);
  52   bool simplify_cond_using_ranges_1 (gcond *);
  53   bool fold_cond (gcond *);
  54   bool simplify_switch_using_ranges (gswitch *);
  55   bool simplify_float_conversion_using_ranges (gimple_stmt_iterator *,
  56                                                gimple *);
  57   bool simplify_internal_call_using_ranges (gimple_stmt_iterator *, gimple *);
  58
  59   bool two_valued_val_range_p (tree, tree *, tree *);
  60   bool op_with_boolean_value_range_p (tree);
  61   tree compare_name_with_value (enum tree_code, tree, tree, bool *, bool);
  62   tree compare_names (enum tree_code, tree, tree, bool *);
  63   const value_range_equiv *get_vr_for_comparison (int, value_range_equiv *);
  64   tree vrp_evaluate_conditional_warnv_with_ops_using_ranges (enum tree_code,
  65                                                              tree, tree,
  66                                                              bool *);
  67   void cleanup_edges_and_switches (void);
  68
  69   /* Vectors of edges that need removing and switch statements that
  70      need updating.  It is expected that a pass using the simplification
  71      routines will, at the end of the pass, clean up the edges and
  72      switch statements.  The class dtor will try to detect cases
  73      that do not follow that expectation.  */
  74   struct switch_update {
  75     gswitch *stmt;
  76     tree vec;
  77   };
  78
  79   vec<edge> to_remove_edges;
  80   vec<switch_update> to_update_switch_stmts;
  81   class vr_values *store;
  82 };
  83
  84 /* The VR_VALUES class holds the current view of range information
  85    for all the SSA_NAMEs in the IL.
  86
  87    It can be used to hold context sensitive range information during
  88    a dominator walk or it may be used to hold range information in the
  89    standard VRP pass as ranges are propagated through the lattice to a
  90    steady state.
  91
  92    This information is independent of the range information that gets
  93    attached to SSA_NAMEs.  A pass such as VRP may choose to transfer
  94    the global information it produces into global range information that
  95    gets attached to an SSA_NAME.  It's unclear how useful that global
  96    information will be in a world where we can compute context sensitive
  97    range information fast or perform on-demand queries.  */
  98 class vr_values
  99 {
 100  public:
 101   vr_values (void);
 102   ~vr_values (void);
 103
 104   const value_range_equiv *get_value_range (const_tree);
 105   void set_vr_value (tree, value_range_equiv *);
 106   value_range_equiv *swap_vr_value (tree, value_range_equiv *);
 107
 108   void set_def_to_varying (const_tree);
 109   void set_defs_to_varying (gimple *);
 110   bool update_value_range (const_tree, value_range_equiv *);
 111   tree op_with_constant_singleton_value_range (tree);
 112   void adjust_range_with_scev (value_range_equiv *, class loop *,
 113                                gimple *, tree);
 114   void dump_all_value_ranges (FILE *);
 115
 116   void extract_range_for_var_from_comparison_expr (tree, enum tree_code,
 117                                                    tree, tree,
 118                                                    value_range_equiv *);
 119   void extract_range_from_phi_node (gphi *, value_range_equiv *);
 120   void extract_range_basic (value_range_equiv *, gimple *);
 121   void extract_range_from_stmt (gimple *, edge *, tree *, value_range_equiv *);
 122
 123   /* Indicate that propagation through the lattice is complete.  */
 124   void set_lattice_propagation_complete (void) { values_propagated = true; }
 125
 126   /* Allocate a new value_range object.  */
 127   value_range_equiv *allocate_value_range_equiv (void)
 128     { return vrp_value_range_pool.allocate (); }
 129   void free_value_range (value_range_equiv *vr)
 130     { vrp_value_range_pool.remove (vr); }
 131
 132  private:
 133   value_range_equiv *get_lattice_entry (const_tree);
 134   bool vrp_stmt_computes_nonzero (gimple *);
 135   void extract_range_from_assignment (value_range_equiv *, gassign *);
 136   void extract_range_from_assert (value_range_equiv *, tree);
 137   void extract_range_from_ssa_name (value_range_equiv *, tree);
 138   void extract_range_from_binary_expr (value_range_equiv *, enum tree_code,
 139                                        tree, tree, tree);
 140   void extract_range_from_unary_expr (value_range_equiv *, enum tree_code,
 141                                       tree, tree);
 142   void extract_range_from_cond_expr (value_range_equiv *, gassign *);
 143   void extract_range_from_comparison (value_range_equiv *, enum tree_code,
 144                                       tree, tree, tree);
 145   void vrp_visit_assignment_or_call (gimple*, tree *, value_range_equiv *);
 146   void vrp_visit_switch_stmt (gswitch *, edge *);
 147
 148   /* Allocation pools for value_range objects.  */
 149   object_allocator<value_range_equiv> vrp_value_range_pool;
 150
 151   /* This probably belongs in the lattice rather than in here.  */
 152   bool values_propagated;
 153
 154   /* Allocations for equivalences all come from this obstack.  */
 155   bitmap_obstack vrp_equiv_obstack;
 156
 157   /* Value range array.  After propagation, VR_VALUE[I] holds the range
 158      of values that SSA name N_I may take.  */
 159   unsigned int num_vr_values;
 160   value_range_equiv **vr_value;
 161
 162   /* For a PHI node which sets SSA name N_I, VR_COUNTS[I] holds the
 163      number of executable edges we saw the last time we visited the
 164      node.  */
 165   int *vr_phi_edge_counts;
 166   simplify_using_ranges simplifier;
 167 };
 168
 169 inline const value_range_equiv *
 170 simplify_using_ranges::get_value_range (const_tree op)
 171 {
 172   return store->get_value_range (op);
 173 }
 174
 175 extern tree get_output_for_vrp (gimple *);
 176
 177 // FIXME: Move this to tree-vrp.c.
 178 void simplify_cond_using_ranges_2 (class vr_values *, gcond *);
 179
 180 #endif /* GCC_VR_VALUES_H */