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 #include "value-query.h"
  25
  26 // Abstract class to return a range for a given SSA.
  27
  28 // Class to simplify a statement using range information.
  29
  30 class simplify_using_ranges
  31 {
  32 public:
  33   simplify_using_ranges (class range_query *query = NULL);
  34   ~simplify_using_ranges ();
  35   void set_range_query (class range_query *q) { query = q; }
  36
  37   bool simplify (gimple_stmt_iterator *);
  38
  39   // ?? These should be cleaned, merged, and made private.
  40   tree vrp_evaluate_conditional (tree_code, tree, tree, gimple *);
  41   void vrp_visit_cond_stmt (gcond *, edge *);
  42   tree vrp_evaluate_conditional_warnv_with_ops (gimple *stmt, enum tree_code,
  43                                                 tree, tree, bool,
  44                                                 bool *, bool *);
  45
  46 private:
  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 range_query *query;
  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 : public range_query
  99 {
 100  public:
 101   vr_values (void);
 102   ~vr_values (void);
 103
 104   virtual bool range_of_expr (irange &r, tree expr, gimple *stmt) OVERRIDE;
 105   virtual tree value_of_expr (tree, gimple * = NULL) OVERRIDE;
 106   virtual tree value_on_edge (edge, tree) OVERRIDE;
 107   virtual tree value_of_stmt (gimple *, tree = NULL_TREE) OVERRIDE;
 108   virtual const value_range_equiv *get_value_range (const_tree,
 109                                                     gimple * = NULL) OVERRIDE;
 110   void set_vr_value (tree, value_range_equiv *);
 111   value_range_equiv *swap_vr_value (tree, value_range_equiv *);
 112
 113   void set_def_to_varying (const_tree);
 114   void set_defs_to_varying (gimple *);
 115   bool update_value_range (const_tree, value_range_equiv *);
 116   tree op_with_constant_singleton_value_range (tree);
 117   void adjust_range_with_scev (value_range_equiv *, class loop *,
 118                                gimple *, tree);
 119   void dump_all_value_ranges (FILE *);
 120
 121   void extract_range_for_var_from_comparison_expr (tree, enum tree_code,
 122                                                    tree, tree,
 123                                                    value_range_equiv *);
 124   void extract_range_from_phi_node (gphi *, value_range_equiv *);
 125   void extract_range_basic (value_range_equiv *, gimple *);
 126   void extract_range_from_stmt (gimple *, edge *, tree *, value_range_equiv *);
 127
 128   /* Indicate that propagation through the lattice is complete.  */
 129   void set_lattice_propagation_complete (void) { values_propagated = true; }
 130
 131   /* Allocate a new value_range object.  */
 132   value_range_equiv *allocate_value_range_equiv (void)
 133     { return range_query::allocate_value_range_equiv (); }
 134   void free_value_range (value_range_equiv *vr)
 135     { free_value_range_equiv (vr); }
 136
 137  private:
 138   value_range_equiv *get_lattice_entry (const_tree);
 139   bool vrp_stmt_computes_nonzero (gimple *);
 140   void extract_range_from_assignment (value_range_equiv *, gassign *);
 141   void extract_range_from_assert (value_range_equiv *, tree);
 142   void extract_range_from_ssa_name (value_range_equiv *, tree);
 143   void extract_range_from_binary_expr (value_range_equiv *, enum tree_code,
 144                                        tree, tree, tree);
 145   void extract_range_from_unary_expr (value_range_equiv *, enum tree_code,
 146                                       tree, tree);
 147   void extract_range_from_cond_expr (value_range_equiv *, gassign *);
 148   void extract_range_from_comparison (value_range_equiv *, gimple *);
 149   void vrp_visit_assignment_or_call (gimple*, tree *, value_range_equiv *);
 150   void vrp_visit_switch_stmt (gswitch *, edge *);
 151   bool extract_range_from_ubsan_builtin (value_range_equiv *, gimple *);
 152
 153   /* This probably belongs in the lattice rather than in here.  */
 154   bool values_propagated;
 155
 156   /* Allocations for equivalences all come from this obstack.  */
 157   bitmap_obstack vrp_equiv_obstack;
 158
 159   /* Value range array.  After propagation, VR_VALUE[I] holds the range
 160      of values that SSA name N_I may take.  */
 161   unsigned int num_vr_values;
 162   value_range_equiv **vr_value;
 163
 164   /* For a PHI node which sets SSA name N_I, VR_COUNTS[I] holds the
 165      number of executable edges we saw the last time we visited the
 166      node.  */
 167   int *vr_phi_edge_counts;
 168   simplify_using_ranges simplifier;
 169 };
 170
 171 extern tree get_output_for_vrp (gimple *);
 172
 173 extern bool range_fits_type_p (const value_range *vr,
 174                                unsigned dest_precision, signop dest_sgn);
 175 extern bool bounds_of_var_in_loop (tree *min, tree *max, range_query *,
 176                                    class loop *loop, gimple *stmt, tree var);
 177
 178 #endif /* GCC_VR_VALUES_H */