1/* Support routines for Value Range Propagation (VRP).
2   Copyright (C) 2016-2020 Free Software Foundation, Inc.
3
4This file is part of GCC.
5
6GCC is free software; you can redistribute it and/or modify
7it under the terms of the GNU General Public License as published by
8the Free Software Foundation; either version 3, or (at your option)
9any later version.
10
11GCC is distributed in the hope that it will be useful,
12but WITHOUT ANY WARRANTY; without even the implied warranty of
13MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14GNU General Public License for more details.
15
16You should have received a copy of the GNU General Public License
17along 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.  */
37class vr_values
38{
39 public:
40  vr_values (void);
41  ~vr_values (void);
42
43  const value_range_equiv *get_value_range (const_tree);
44  void set_vr_value (tree, value_range_equiv *);
45  value_range_equiv *swap_vr_value (tree, value_range_equiv *);
46
47  void set_def_to_varying (const_tree);
48  void set_defs_to_varying (gimple *);
49  bool update_value_range (const_tree, value_range_equiv *);
50  tree op_with_constant_singleton_value_range (tree);
51  void adjust_range_with_scev (value_range_equiv *, class loop *,
52			       gimple *, tree);
53  tree vrp_evaluate_conditional (tree_code, tree, tree, gimple *);
54  void dump_all_value_ranges (FILE *);
55
56  void extract_range_for_var_from_comparison_expr (tree, enum tree_code,
57						   tree, tree,
58						   value_range_equiv *);
59  void extract_range_from_phi_node (gphi *, value_range_equiv *);
60  void extract_range_basic (value_range_equiv *, gimple *);
61  void extract_range_from_stmt (gimple *, edge *, tree *, value_range_equiv *);
62
63  void vrp_visit_cond_stmt (gcond *, edge *);
64
65  void simplify_cond_using_ranges_2 (gcond *);
66  bool simplify_stmt_using_ranges (gimple_stmt_iterator *);
67
68  /* Indicate that propagation through the lattice is complete.  */
69  void set_lattice_propagation_complete (void) { values_propagated = true; }
70
71  /* Allocate a new value_range object.  */
72  value_range_equiv *allocate_value_range_equiv (void)
73    { return vrp_value_range_pool.allocate (); }
74  void free_value_range (value_range_equiv *vr)
75    { vrp_value_range_pool.remove (vr); }
76
77  /* */
78  void cleanup_edges_and_switches (void);
79
80 private:
81  value_range_equiv *get_lattice_entry (const_tree);
82  bool vrp_stmt_computes_nonzero (gimple *);
83  bool op_with_boolean_value_range_p (tree);
84  bool check_for_binary_op_overflow (enum tree_code, tree, tree, tree, bool *);
85  const value_range_equiv *get_vr_for_comparison (int, value_range_equiv *);
86  tree compare_name_with_value (enum tree_code, tree, tree, bool *, bool);
87  tree compare_names (enum tree_code, tree, tree, bool *);
88  bool two_valued_val_range_p (tree, tree *, tree *);
89  tree vrp_evaluate_conditional_warnv_with_ops_using_ranges (enum tree_code,
90							     tree, tree,
91							     bool *);
92  tree vrp_evaluate_conditional_warnv_with_ops (enum tree_code,
93						tree, tree, bool,
94						bool *, bool *);
95  void extract_range_from_assignment (value_range_equiv *, gassign *);
96  void extract_range_from_assert (value_range_equiv *, tree);
97  void extract_range_from_ssa_name (value_range_equiv *, tree);
98  void extract_range_from_binary_expr (value_range_equiv *, enum tree_code,
99				       tree, tree, tree);
100  void extract_range_from_unary_expr (value_range_equiv *, enum tree_code,
101				      tree, tree);
102  void extract_range_from_cond_expr (value_range_equiv *, gassign *);
103  void extract_range_from_comparison (value_range_equiv *, enum tree_code,
104				      tree, tree, tree);
105  void vrp_visit_assignment_or_call (gimple*, tree *, value_range_equiv *);
106  void vrp_visit_switch_stmt (gswitch *, edge *);
107  bool simplify_truth_ops_using_ranges (gimple_stmt_iterator *, gimple *);
108  bool simplify_div_or_mod_using_ranges (gimple_stmt_iterator *, gimple *);
109  bool simplify_abs_using_ranges (gimple_stmt_iterator *, gimple *);
110  bool simplify_bit_ops_using_ranges (gimple_stmt_iterator *, gimple *);
111  bool simplify_min_or_max_using_ranges (gimple_stmt_iterator *, gimple *);
112  bool simplify_cond_using_ranges_1 (gcond *);
113  bool simplify_switch_using_ranges (gswitch *);
114  bool simplify_float_conversion_using_ranges (gimple_stmt_iterator *,
115					       gimple *);
116  bool simplify_internal_call_using_ranges (gimple_stmt_iterator *, gimple *);
117
118  /* Allocation pools for value_range objects.  */
119  object_allocator<value_range_equiv> vrp_value_range_pool;
120
121  /* This probably belongs in the lattice rather than in here.  */
122  bool values_propagated;
123
124  /* Allocations for equivalences all come from this obstack.  */
125  bitmap_obstack vrp_equiv_obstack;
126
127  /* Value range array.  After propagation, VR_VALUE[I] holds the range
128     of values that SSA name N_I may take.  */
129  unsigned int num_vr_values;
130  value_range_equiv **vr_value;
131
132  /* For a PHI node which sets SSA name N_I, VR_COUNTS[I] holds the
133     number of executable edges we saw the last time we visited the
134     node.  */
135  int *vr_phi_edge_counts;
136
137  /* Vectors of edges that need removing and switch statements that
138     need updating.  It is expected that a pass using the simplification
139     routines will, at the end of the pass, clean up the edges and
140     switch statements.  The class dtor will try to detect cases
141     that do not follow that expectation.  */
142  struct switch_update {
143    gswitch *stmt;
144    tree vec;
145  };
146
147  vec<edge> to_remove_edges;
148  vec<switch_update> to_update_switch_stmts;
149};
150
151extern tree get_output_for_vrp (gimple *);
152#endif /* GCC_VR_VALUES_H */
153