1/* Tracking equivalence classes and constraints at a point on an execution path.
2   Copyright (C) 2019-2020 Free Software Foundation, Inc.
3   Contributed by David Malcolm <dmalcolm@redhat.com>.
4
5This file is part of GCC.
6
7GCC is free software; you can redistribute it and/or modify it
8under the terms of the GNU General Public License as published by
9the Free Software Foundation; either version 3, or (at your option)
10any later version.
11
12GCC is distributed in the hope that it will be useful, but
13WITHOUT ANY WARRANTY; without even the implied warranty of
14MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
15General Public License for more details.
16
17You should have received a copy of the GNU General Public License
18along with GCC; see the file COPYING3.  If not see
19<http://www.gnu.org/licenses/>.  */
20
21#ifndef GCC_ANALYZER_CONSTRAINT_MANAGER_H
22#define GCC_ANALYZER_CONSTRAINT_MANAGER_H
23
24namespace ana {
25
26class constraint_manager;
27
28/* Abstract base class for specifying how state should be purged.  */
29
30class purge_criteria
31{
32public:
33  virtual ~purge_criteria () {}
34  virtual bool should_purge_p (svalue_id sid) const = 0;
35};
36
37/* An equivalence class within a constraint manager: a set of
38   svalue_ids that are known to all be equal to each other,
39   together with an optional tree constant that they are equal to.  */
40
41class equiv_class
42{
43public:
44  equiv_class ();
45  equiv_class (const equiv_class &other);
46
47  hashval_t hash () const;
48  bool operator== (const equiv_class &other);
49
50  void add (svalue_id sid, const constraint_manager &cm);
51  bool del (svalue_id sid);
52
53  tree get_any_constant () const { return m_constant; }
54
55  svalue_id get_representative () const;
56
57  void remap_svalue_ids (const svalue_id_map &map);
58
59  void canonicalize ();
60
61  void print (pretty_printer *pp) const;
62
63  /* An equivalence class can contain multiple constants (e.g. multiple
64     different zeroes, for different types); these are just for the last
65     constant added.  */
66  tree m_constant;
67  svalue_id m_cst_sid;
68
69  // TODO: should this be a set rather than a vec?
70  auto_vec<svalue_id> m_vars;
71};
72
73/* The various kinds of constraint.  */
74
75enum constraint_op
76{
77  CONSTRAINT_NE,
78  CONSTRAINT_LT,
79  CONSTRAINT_LE
80};
81
82const char *constraint_op_code (enum constraint_op c_op);
83
84/* An ID for an equiv_class within a constraint_manager.  Internally, this
85   is an index into a vector of equiv_class * within the constraint_manager.  */
86
87class equiv_class_id
88{
89public:
90  static equiv_class_id null () { return equiv_class_id (-1); }
91
92  equiv_class_id (unsigned idx) : m_idx (idx) {}
93  const equiv_class &get_obj (const constraint_manager &cm) const;
94  equiv_class &get_obj (constraint_manager &cm) const;
95
96  bool operator== (const equiv_class_id &other) const
97  {
98    return m_idx == other.m_idx;
99  }
100  bool operator!= (const equiv_class_id &other) const
101  {
102    return m_idx != other.m_idx;
103  }
104
105  bool null_p () const { return m_idx == -1; }
106
107  static equiv_class_id from_int (int idx) { return equiv_class_id (idx); }
108  int as_int () const { return m_idx; }
109
110  void print (pretty_printer *pp) const;
111
112  void update_for_removal (equiv_class_id other)
113  {
114    if (m_idx > other.m_idx)
115      m_idx--;
116  }
117
118  int m_idx;
119};
120
121/* A relationship between two equivalence classes in a constraint_manager.  */
122
123class constraint
124{
125 public:
126  constraint (equiv_class_id lhs, enum constraint_op c_op, equiv_class_id rhs)
127  : m_lhs (lhs), m_op (c_op), m_rhs (rhs)
128  {
129    gcc_assert (!lhs.null_p ());
130    gcc_assert (!rhs.null_p ());
131  }
132
133  void print (pretty_printer *pp, const constraint_manager &cm) const;
134
135  hashval_t hash () const;
136  bool operator== (const constraint &other) const;
137
138  /* Is this an ordering, rather than a "!=".  */
139  bool is_ordering_p () const
140  {
141    return m_op != CONSTRAINT_NE;
142  }
143
144  equiv_class_id m_lhs;
145  enum constraint_op m_op;
146  equiv_class_id m_rhs;
147};
148
149/* An abstract base class for use with constraint_manager::for_each_fact.  */
150
151class fact_visitor
152{
153 public:
154  virtual ~fact_visitor () {}
155  virtual void on_fact (svalue_id lhs, enum tree_code, svalue_id rhs) = 0;
156};
157
158/* A collection of equivalence classes and constraints on them.
159
160   Given N svalues, this can be thought of as representing a subset of
161   N-dimensional space.  When we call add_constraint,
162   we are effectively taking an intersection with that constraint.  */
163
164class constraint_manager
165{
166public:
167  constraint_manager () {}
168  constraint_manager (const constraint_manager &other);
169  virtual ~constraint_manager () {}
170
171  virtual constraint_manager *clone (region_model *) const = 0;
172  virtual tree maybe_get_constant (svalue_id sid) const = 0;
173  virtual svalue_id get_sid_for_constant (tree cst) const = 0;
174  virtual int get_num_svalues () const = 0;
175
176  constraint_manager& operator= (const constraint_manager &other);
177
178  hashval_t hash () const;
179  bool operator== (const constraint_manager &other) const;
180  bool operator!= (const constraint_manager &other) const
181  {
182    return !(*this == other);
183  }
184
185  void print (pretty_printer *pp) const;
186  void dump_to_pp (pretty_printer *pp) const;
187  void dump (FILE *fp) const;
188  void dump () const;
189
190  const equiv_class &get_equiv_class_by_index (unsigned idx) const
191  {
192    return *m_equiv_classes[idx];
193  }
194  equiv_class &get_equiv_class_by_index (unsigned idx)
195  {
196    return *m_equiv_classes[idx];
197  }
198
199  equiv_class &get_equiv_class (svalue_id sid)
200  {
201    equiv_class_id ec_id = get_or_add_equiv_class (sid);
202    return ec_id.get_obj (*this);
203  }
204
205  bool add_constraint (svalue_id lhs, enum tree_code op, svalue_id rhs);
206
207  bool add_constraint (equiv_class_id lhs_ec_id,
208		       enum tree_code op,
209		       equiv_class_id rhs_ec_id);
210
211  bool get_equiv_class_by_sid (svalue_id sid, equiv_class_id *out) const;
212  equiv_class_id get_or_add_equiv_class (svalue_id sid);
213  tristate eval_condition (equiv_class_id lhs,
214			   enum tree_code op,
215			   equiv_class_id rhs);
216  tristate eval_condition (svalue_id lhs,
217			   enum tree_code op,
218			   svalue_id rhs);
219
220  void purge (const purge_criteria &p, purge_stats *stats);
221
222  void remap_svalue_ids (const svalue_id_map &map);
223
224  void canonicalize (unsigned num_svalue_ids);
225
226  static void merge (const constraint_manager &cm_a,
227		     const constraint_manager &cm_b,
228		     constraint_manager *out,
229		     const model_merger &merger);
230
231  void for_each_fact (fact_visitor *) const;
232
233  void validate () const;
234
235  auto_delete_vec<equiv_class> m_equiv_classes;
236  auto_vec<constraint> m_constraints;
237
238 private:
239  static void clean_merger_input (const constraint_manager &cm_in,
240				  const one_way_svalue_id_map &map_sid_to_m,
241				  constraint_manager *out);
242
243  void add_constraint_internal (equiv_class_id lhs_id,
244				enum constraint_op c_op,
245				equiv_class_id rhs_id);
246};
247
248} // namespace ana
249
250#endif /* GCC_ANALYZER_CONSTRAINT_MANAGER_H */
251