gcc/vr-values.h

   1 /* Support routines for Value Range Propagation (VRP).
   2    Copyright (C) 2016-2021 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 (range_query *query = NULL,
  34                          int not_executable_flag = 0);
  35   ~simplify_using_ranges ();
  36   void set_range_query (class range_query *q, int not_executable_flag = 0)
  37       { query = q; m_not_executable_flag = not_executable_flag; }
  38
  39   bool simplify (gimple_stmt_iterator *);
  40
  41   // ?? These should be cleaned, merged, and made private.
  42   tree vrp_evaluate_conditional (tree_code, tree, tree, gimple *);
  43   void vrp_visit_cond_stmt (gcond *, edge *);
  44   tree vrp_evaluate_conditional_warnv_with_ops (gimple *stmt, enum tree_code,
  45                                                 tree, tree, bool,
  46                                                 bool *, bool *);
  47   bool simplify_casted_cond (gcond *);
  48
  49 private:
  50   bool simplify_truth_ops_using_ranges (gimple_stmt_iterator *, gimple *);
  51   bool simplify_div_or_mod_using_ranges (gimple_stmt_iterator *, gimple *);
  52   bool simplify_abs_using_ranges (gimple_stmt_iterator *, gimple *);
  53   bool simplify_bit_ops_using_ranges (gimple_stmt_iterator *, gimple *);
  54   bool simplify_min_or_max_using_ranges (gimple_stmt_iterator *, gimple *);
  55   bool simplify_cond_using_ranges_1 (gcond *);
  56   bool fold_cond (gcond *);
  57   bool simplify_switch_using_ranges (gswitch *);
  58   bool simplify_float_conversion_using_ranges (gimple_stmt_iterator *,
  59                                                gimple *);
  60   bool simplify_internal_call_using_ranges (gimple_stmt_iterator *, gimple *);
  61
  62   bool two_valued_val_range_p (tree, tree *, tree *, gimple *);
  63   bool op_with_boolean_value_range_p (tree, gimple *);
  64   tree compare_name_with_value (enum tree_code, tree, tree, bool *, bool,
  65                                 gimple *);
  66   tree compare_names (enum tree_code, tree, tree, bool *, gimple *s);
  67   const value_range_equiv *get_vr_for_comparison (int, value_range_equiv *,
  68                                                   gimple *s);
  69   tree vrp_evaluate_conditional_warnv_with_ops_using_ranges (enum tree_code,
  70                                                              tree, tree,
  71                                                              bool *, gimple *s);
  72   void set_and_propagate_unexecutable (edge e);
  73   void cleanup_edges_and_switches (void);
  74
  75   /* Vectors of edges that need removing and switch statements that
  76      need updating.  It is expected that a pass using the simplification
  77      routines will, at the end of the pass, clean up the edges and
  78      switch statements.  The class dtor will try to detect cases
  79      that do not follow that expectation.  */
  80   struct switch_update {
  81     gswitch *stmt;
  82     tree vec;
  83   };
  84
  85   vec<edge> to_remove_edges;
  86   vec<switch_update> to_update_switch_stmts;
  87   class range_query *query;
  88   int m_not_executable_flag;   // Non zero if not_executable flag exists.
  89   vec<edge> m_flag_set_edges;  // List of edges with flag to be cleared.
  90 };
  91
  92 /* The VR_VALUES class holds the current view of range information
  93    for all the SSA_NAMEs in the IL.
  94
  95    It can be used to hold context sensitive range information during
  96    a dominator walk or it may be used to hold range information in the
  97    standard VRP pass as ranges are propagated through the lattice to a
  98    steady state.
  99
 100    This information is independent of the range information that gets
 101    attached to SSA_NAMEs.  A pass such as VRP may choose to transfer
 102    the global information it produces into global range information that
 103    gets attached to an SSA_NAME.  It's unclear how useful that global
 104    information will be in a world where we can compute context sensitive
 105    range information fast or perform on-demand queries.  */
 106 class vr_values : public range_query
 107 {
 108  public:
 109   vr_values (void);
 110   ~vr_values (void);
 111
 112   virtual bool range_of_expr (irange &r, tree expr, gimple *stmt) OVERRIDE;
 113   virtual tree value_of_expr (tree, gimple * = NULL) OVERRIDE;
 114   virtual tree value_on_edge (edge, tree) OVERRIDE;
 115   virtual tree value_of_stmt (gimple *, tree = NULL_TREE) OVERRIDE;
 116   virtual const value_range_equiv *get_value_range (const_tree,
 117                                                     gimple * = NULL) OVERRIDE;
 118   void set_vr_value (tree, value_range_equiv *);
 119   value_range_equiv *swap_vr_value (tree, value_range_equiv *);
 120
 121   void set_def_to_varying (const_tree);
 122   void set_defs_to_varying (gimple *);
 123   bool update_value_range (const_tree, value_range_equiv *);
 124   tree op_with_constant_singleton_value_range (tree);
 125   void adjust_range_with_scev (value_range_equiv *, class loop *,
 126                                gimple *, tree);
 127   virtual void dump (FILE *) OVERRIDE;
 128
 129   void extract_range_for_var_from_comparison_expr (tree, enum tree_code,
 130                                                    tree, tree,
 131                                                    value_range_equiv *);
 132   void extract_range_from_phi_node (gphi *, value_range_equiv *);
 133   void extract_range_basic (value_range_equiv *, gimple *);
 134   void extract_range_from_stmt (gimple *, edge *, tree *, value_range_equiv *);
 135
 136   /* Indicate that propagation through the lattice is complete.  */
 137   void set_lattice_propagation_complete (void) { values_propagated = true; }
 138
 139   /* Allocate a new value_range object.  */
 140   value_range_equiv *allocate_value_range_equiv (void)
 141     { return range_query::allocate_value_range_equiv (); }
 142   void free_value_range (value_range_equiv *vr)
 143     { free_value_range_equiv (vr); }
 144
 145  private:
 146   value_range_equiv *get_lattice_entry (const_tree);
 147   bool vrp_stmt_computes_nonzero (gimple *);
 148   void extract_range_from_assignment (value_range_equiv *, gassign *);
 149   void extract_range_from_assert (value_range_equiv *, tree);
 150   void extract_range_from_ssa_name (value_range_equiv *, tree);
 151   void extract_range_from_binary_expr (value_range_equiv *, enum tree_code,
 152                                        tree, tree, tree);
 153   void extract_range_from_unary_expr (value_range_equiv *, enum tree_code,
 154                                       tree, tree);
 155   void extract_range_from_cond_expr (value_range_equiv *, gassign *);
 156   void extract_range_from_comparison (value_range_equiv *, gimple *);
 157   void vrp_visit_assignment_or_call (gimple*, tree *, value_range_equiv *);
 158   void vrp_visit_switch_stmt (gswitch *, edge *);
 159   bool extract_range_from_ubsan_builtin (value_range_equiv *, gimple *);
 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 extern tree get_output_for_vrp (gimple *);
 180
 181 extern bool range_fits_type_p (const value_range *vr,
 182                                unsigned dest_precision, signop dest_sgn);
 183 extern bool bounds_of_var_in_loop (tree *min, tree *max, range_query *,
 184                                    class loop *loop, gimple *stmt, tree var);
 185
 186 #endif /* GCC_VR_VALUES_H */