gcc/vr-values.h

   1 /* Support routines for Value Range Propagation (VRP).
   2    Copyright (C) 2016-2018 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 /* The VR_VALUES class holds the current view of range information
  24    for all the SSA_NAMEs in the IL.
  25
  26    It can be used to hold context sensitive range information during
  27    a dominator walk or it may be used to hold range information in the
  28    standard VRP pass as ranges are propagated through the lattice to a
  29    steady state.
  30
  31    This information is independent of the range information that gets
  32    attached to SSA_NAMEs.  A pass such as VRP may choose to transfer
  33    the global information it produces into global range information that
  34    gets attached to an SSA_NAME.  It's unclear how useful that global
  35    information will be in a world where we can compute context sensitive
  36    range information fast or perform on-demand queries.  */
  37 class vr_values
  38 {
  39  public:
  40   vr_values (void);
  41   ~vr_values (void);
  42
  43   value_range *get_value_range (const_tree);
  44
  45   void set_vr_value (tree, value_range *);
  46   void set_defs_to_varying (gimple *);
  47   bool update_value_range (const_tree, value_range *);
  48   tree op_with_constant_singleton_value_range (tree);
  49   void adjust_range_with_scev (value_range *, struct loop *, gimple *, tree);
  50   tree vrp_evaluate_conditional (tree_code, tree, tree, gimple *);
  51   void dump_all_value_ranges (FILE *);
  52
  53   void extract_range_for_var_from_comparison_expr (tree, enum tree_code,
  54                                                    tree, tree, value_range *);
  55   void extract_range_from_phi_node (gphi *, value_range *);
  56   void extract_range_basic (value_range *, gimple *);
  57   void extract_range_from_stmt (gimple *, edge *, tree *, value_range *);
  58
  59   void vrp_visit_cond_stmt (gcond *, edge *);
  60
  61   void simplify_cond_using_ranges_2 (gcond *);
  62   bool simplify_stmt_using_ranges (gimple_stmt_iterator *);
  63
  64   /* Indicate that propagation through the lattice is complete.  */
  65   void set_lattice_propagation_complete (void) { values_propagated = true; }
  66
  67   /* Allocate a new value_range object.  */
  68   value_range *allocate_value_range (void)
  69     { return vrp_value_range_pool.allocate (); }
  70
  71   /* */
  72   void cleanup_edges_and_switches (void);
  73
  74  private:
  75   bool vrp_stmt_computes_nonzero (gimple *);
  76   bool op_with_boolean_value_range_p (tree);
  77   bool check_for_binary_op_overflow (enum tree_code, tree, tree, tree, bool *);
  78   value_range *get_vr_for_comparison (int, value_range *);
  79   tree compare_name_with_value (enum tree_code, tree, tree, bool *, bool);
  80   tree compare_names (enum tree_code, tree, tree, bool *);
  81   bool two_valued_val_range_p (tree, tree *, tree *);
  82   tree vrp_evaluate_conditional_warnv_with_ops_using_ranges (enum tree_code,
  83                                                              tree, tree,
  84                                                              bool *);
  85   tree vrp_evaluate_conditional_warnv_with_ops (enum tree_code,
  86                                                 tree, tree, bool,
  87                                                 bool *, bool *);
  88   void extract_range_from_assignment (value_range *, gassign *);
  89   void extract_range_from_assert (value_range *, tree);
  90   void extract_range_from_ssa_name (value_range *, tree);
  91   void extract_range_from_binary_expr (value_range *, enum tree_code,
  92                                        tree, tree, tree);
  93   void extract_range_from_unary_expr (value_range *, enum tree_code,
  94                                       tree, tree);
  95   void extract_range_from_cond_expr (value_range *, gassign *);
  96   void extract_range_from_comparison (value_range *, enum tree_code,
  97                                       tree, tree, tree);
  98   void vrp_visit_assignment_or_call (gimple*, tree *, value_range *);
  99   void vrp_visit_switch_stmt (gswitch *, edge *);
 100   bool simplify_truth_ops_using_ranges (gimple_stmt_iterator *, gimple *);
 101   bool simplify_div_or_mod_using_ranges (gimple_stmt_iterator *, gimple *);
 102   bool simplify_abs_using_ranges (gimple_stmt_iterator *, gimple *);
 103   bool simplify_bit_ops_using_ranges (gimple_stmt_iterator *, gimple *);
 104   bool simplify_min_or_max_using_ranges (gimple_stmt_iterator *, gimple *);
 105   bool simplify_cond_using_ranges_1 (gcond *);
 106   bool simplify_switch_using_ranges (gswitch *);
 107   bool simplify_float_conversion_using_ranges (gimple_stmt_iterator *,
 108                                                gimple *);
 109   bool simplify_internal_call_using_ranges (gimple_stmt_iterator *, gimple *);
 110
 111   /* Allocation pools for value_range objects.  */
 112   object_allocator<value_range> vrp_value_range_pool;
 113
 114   /* This probably belongs in the lattice rather than in here.  */
 115   bool values_propagated;
 116
 117   /* Allocations for equivalences all come from this obstack.  */
 118   bitmap_obstack vrp_equiv_obstack;
 119
 120   /* Value range array.  After propagation, VR_VALUE[I] holds the range
 121      of values that SSA name N_I may take.  */
 122   unsigned int num_vr_values;
 123   value_range **vr_value;
 124
 125   /* For a PHI node which sets SSA name N_I, VR_COUNTS[I] holds the
 126      number of executable edges we saw the last time we visited the
 127      node.  */
 128   int *vr_phi_edge_counts;
 129
 130   /* Vectors of edges that need removing and switch statements that
 131      need updating.  It is expected that a pass using the simplification
 132      routines will, at the end of the pass, clean up the edges and
 133      switch statements.  The class dtor will try to detect cases
 134      that do not follow that expectation.  */
 135   struct switch_update {
 136     gswitch *stmt;
 137     tree vec;
 138   };
 139
 140   vec<edge> to_remove_edges;
 141   vec<switch_update> to_update_switch_stmts;
 142 };
 143
 144 extern tree get_output_for_vrp (gimple *);
 145 #endif /* GCC_VR_VALUES_H */