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
  48 private:
  49   bool simplify_truth_ops_using_ranges (gimple_stmt_iterator *, gimple *);
  50   bool simplify_div_or_mod_using_ranges (gimple_stmt_iterator *, gimple *);
  51   bool simplify_abs_using_ranges (gimple_stmt_iterator *, gimple *);
  52   bool simplify_bit_ops_using_ranges (gimple_stmt_iterator *, gimple *);
  53   bool simplify_min_or_max_using_ranges (gimple_stmt_iterator *, gimple *);
  54   bool simplify_cond_using_ranges_1 (gcond *);
  55   bool fold_cond (gcond *);
  56   bool simplify_switch_using_ranges (gswitch *);
  57   bool simplify_float_conversion_using_ranges (gimple_stmt_iterator *,
  58                                                gimple *);
  59   bool simplify_internal_call_using_ranges (gimple_stmt_iterator *, gimple *);
  60
  61   bool two_valued_val_range_p (tree, tree *, tree *, gimple *);
  62   bool op_with_boolean_value_range_p (tree, gimple *);
  63   tree compare_name_with_value (enum tree_code, tree, tree, bool *, bool,
  64                                 gimple *);
  65   tree compare_names (enum tree_code, tree, tree, bool *, gimple *s);
  66   const value_range_equiv *get_vr_for_comparison (int, value_range_equiv *,
  67                                                   gimple *s);
  68   tree vrp_evaluate_conditional_warnv_with_ops_using_ranges (enum tree_code,
  69                                                              tree, tree,
  70                                                              bool *, gimple *s);
  71   void set_and_propagate_unexecutable (edge e);
  72   void cleanup_edges_and_switches (void);
  73
  74   /* Vectors of edges that need removing and switch statements that
  75      need updating.  It is expected that a pass using the simplification
  76      routines will, at the end of the pass, clean up the edges and
  77      switch statements.  The class dtor will try to detect cases
  78      that do not follow that expectation.  */
  79   struct switch_update {
  80     gswitch *stmt;
  81     tree vec;
  82   };
  83
  84   vec<edge> to_remove_edges;
  85   vec<switch_update> to_update_switch_stmts;
  86   class range_query *query;
  87   int m_not_executable_flag;   // Non zero if not_executable flag exists.
  88   vec<edge> m_flag_set_edges;  // List of edges with flag to be cleared.
  89 };
  90
  91 /* The VR_VALUES class holds the current view of range information
  92    for all the SSA_NAMEs in the IL.
  93
  94    It can be used to hold context sensitive range information during
  95    a dominator walk or it may be used to hold range information in the
  96    standard VRP pass as ranges are propagated through the lattice to a
  97    steady state.
  98
  99    This information is independent of the range information that gets
 100    attached to SSA_NAMEs.  A pass such as VRP may choose to transfer
 101    the global information it produces into global range information that
 102    gets attached to an SSA_NAME.  It's unclear how useful that global
 103    information will be in a world where we can compute context sensitive
 104    range information fast or perform on-demand queries.  */
 105 class vr_values : public range_query
 106 {
 107  public:
 108   vr_values (void);
 109   ~vr_values (void);
 110
 111   virtual bool range_of_expr (irange &r, tree expr, gimple *stmt) OVERRIDE;
 112   virtual tree value_of_expr (tree, gimple * = NULL) OVERRIDE;
 113   virtual tree value_on_edge (edge, tree) OVERRIDE;
 114   virtual tree value_of_stmt (gimple *, tree = NULL_TREE) OVERRIDE;
 115   virtual const value_range_equiv *get_value_range (const_tree,
 116                                                     gimple * = NULL) OVERRIDE;
 117   void set_vr_value (tree, value_range_equiv *);
 118   value_range_equiv *swap_vr_value (tree, value_range_equiv *);
 119
 120   void set_def_to_varying (const_tree);
 121   void set_defs_to_varying (gimple *);
 122   bool update_value_range (const_tree, value_range_equiv *);
 123   tree op_with_constant_singleton_value_range (tree);
 124   void adjust_range_with_scev (value_range_equiv *, class loop *,
 125                                gimple *, tree);
 126   virtual void dump (FILE *) OVERRIDE;
 127
 128   void extract_range_for_var_from_comparison_expr (tree, enum tree_code,
 129                                                    tree, tree,
 130                                                    value_range_equiv *);
 131   void extract_range_from_phi_node (gphi *, value_range_equiv *);
 132   void extract_range_basic (value_range_equiv *, gimple *);
 133   void extract_range_from_stmt (gimple *, edge *, tree *, value_range_equiv *);
 134
 135   /* Indicate that propagation through the lattice is complete.  */
 136   void set_lattice_propagation_complete (void) { values_propagated = true; }
 137
 138   /* Allocate a new value_range object.  */
 139   value_range_equiv *allocate_value_range_equiv (void)
 140     { return range_query::allocate_value_range_equiv (); }
 141   void free_value_range (value_range_equiv *vr)
 142     { free_value_range_equiv (vr); }
 143
 144  private:
 145   value_range_equiv *get_lattice_entry (const_tree);
 146   bool vrp_stmt_computes_nonzero (gimple *);
 147   void extract_range_from_assignment (value_range_equiv *, gassign *);
 148   void extract_range_from_assert (value_range_equiv *, tree);
 149   void extract_range_from_ssa_name (value_range_equiv *, tree);
 150   void extract_range_from_binary_expr (value_range_equiv *, enum tree_code,
 151                                        tree, tree, tree);
 152   void extract_range_from_unary_expr (value_range_equiv *, enum tree_code,
 153                                       tree, tree);
 154   void extract_range_from_cond_expr (value_range_equiv *, gassign *);
 155   void extract_range_from_comparison (value_range_equiv *, gimple *);
 156   void vrp_visit_assignment_or_call (gimple*, tree *, value_range_equiv *);
 157   void vrp_visit_switch_stmt (gswitch *, edge *);
 158   bool extract_range_from_ubsan_builtin (value_range_equiv *, gimple *);
 159
 160   /* This probably belongs in the lattice rather than in here.  */
 161   bool values_propagated;
 162
 163   /* Allocations for equivalences all come from this obstack.  */
 164   bitmap_obstack vrp_equiv_obstack;
 165
 166   /* Value range array.  After propagation, VR_VALUE[I] holds the range
 167      of values that SSA name N_I may take.  */
 168   unsigned int num_vr_values;
 169   value_range_equiv **vr_value;
 170
 171   /* For a PHI node which sets SSA name N_I, VR_COUNTS[I] holds the
 172      number of executable edges we saw the last time we visited the
 173      node.  */
 174   int *vr_phi_edge_counts;
 175   simplify_using_ranges simplifier;
 176 };
 177
 178 extern tree get_output_for_vrp (gimple *);
 179
 180 extern bool range_fits_type_p (const value_range *vr,
 181                                unsigned dest_precision, signop dest_sgn);
 182 extern bool bounds_of_var_in_loop (tree *min, tree *max, range_query *,
 183                                    class loop *loop, gimple *stmt, tree var);
 184
 185 #endif /* GCC_VR_VALUES_H */