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+/* Tracking equivalence classes and constraints at a point on an execution path.
+   Copyright (C) 2019-2020 Free Software Foundation, Inc.
+   Contributed by David Malcolm <dmalcolm@redhat.com>.
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify it
+under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 3, or (at your option)
+any later version.
+
+GCC is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GCC; see the file COPYING3.  If not see
+<http://www.gnu.org/licenses/>.  */
+
+#ifndef GCC_ANALYZER_CONSTRAINT_MANAGER_H
+#define GCC_ANALYZER_CONSTRAINT_MANAGER_H
+
+class constraint_manager;
+
+/* Abstract base class for specifying how state should be purged.  */
+
+class purge_criteria
+{
+public:
+  virtual ~purge_criteria () {}
+  virtual bool should_purge_p (svalue_id sid) const = 0;
+};
+
+/* An equivalence class within a constraint manager: a set of
+   svalue_ids that are known to all be equal to each other,
+   together with an optional tree constant that they are equal to.  */
+
+class equiv_class
+{
+public:
+  equiv_class ();
+  equiv_class (const equiv_class &other);
+
+  hashval_t hash () const;
+  bool operator== (const equiv_class &other);
+
+  void add (svalue_id sid, const constraint_manager &cm);
+  bool del (svalue_id sid);
+
+  tree get_any_constant () const { return m_constant; }
+
+  svalue_id get_representative () const;
+
+  void remap_svalue_ids (const svalue_id_map &map);
+
+  void canonicalize ();
+
+  void print (pretty_printer *pp) const;
+
+  /* An equivalence class can contain multiple constants (e.g. multiple
+     different zeroes, for different types); these are just for the last
+     constant added.  */
+  tree m_constant;
+  svalue_id m_cst_sid;
+
+  // TODO: should this be a set rather than a vec?
+  auto_vec<svalue_id> m_vars;
+};
+
+/* The various kinds of constraint.  */
+
+enum constraint_op
+{
+  CONSTRAINT_NE,
+  CONSTRAINT_LT,
+  CONSTRAINT_LE
+};
+
+const char *constraint_op_code (enum constraint_op c_op);
+
+/* An ID for an equiv_class within a constraint_manager.  Internally, this
+   is an index into a vector of equiv_class * within the constraint_manager.  */
+
+class equiv_class_id
+{
+public:
+  static equiv_class_id null () { return equiv_class_id (-1); }
+
+  equiv_class_id (unsigned idx) : m_idx (idx) {}
+  const equiv_class &get_obj (const constraint_manager &cm) const;
+  equiv_class &get_obj (constraint_manager &cm) const;
+
+  bool operator== (const equiv_class_id &other) const
+  {
+    return m_idx == other.m_idx;
+  }
+  bool operator!= (const equiv_class_id &other) const
+  {
+    return m_idx != other.m_idx;
+  }
+
+  bool null_p () const { return m_idx == -1; }
+
+  static equiv_class_id from_int (int idx) { return equiv_class_id (idx); }
+  int as_int () const { return m_idx; }
+
+  void print (pretty_printer *pp) const;
+
+  void update_for_removal (equiv_class_id other)
+  {
+    if (m_idx > other.m_idx)
+      m_idx--;
+  }
+
+  int m_idx;
+};
+
+/* A relationship between two equivalence classes in a constraint_manager.  */
+
+class constraint
+{
+ public:
+  constraint (equiv_class_id lhs, enum constraint_op c_op, equiv_class_id rhs)
+  : m_lhs (lhs), m_op (c_op), m_rhs (rhs)
+  {
+    gcc_assert (!lhs.null_p ());
+    gcc_assert (!rhs.null_p ());
+  }
+
+  void print (pretty_printer *pp, const constraint_manager &cm) const;
+
+  hashval_t hash () const;
+  bool operator== (const constraint &other) const;
+
+  /* Is this an ordering, rather than a "!=".  */
+  bool is_ordering_p () const
+  {
+    return m_op != CONSTRAINT_NE;
+  }
+
+  equiv_class_id m_lhs;
+  enum constraint_op m_op;
+  equiv_class_id m_rhs;
+};
+
+/* An abstract base class for use with constraint_manager::for_each_fact.  */
+
+class fact_visitor
+{
+ public:
+  virtual ~fact_visitor () {}
+  virtual void on_fact (svalue_id lhs, enum tree_code, svalue_id rhs) = 0;
+};
+
+/* A collection of equivalence classes and constraints on them.
+
+   Given N svalues, this can be thought of as representing a subset of
+   N-dimensional space.  When we call add_constraint,
+   we are effectively taking an intersection with that constraint.  */
+
+class constraint_manager
+{
+public:
+  constraint_manager () {}
+  constraint_manager (const constraint_manager &other);
+  virtual ~constraint_manager () {}
+
+  virtual constraint_manager *clone (region_model *) const = 0;
+  virtual tree maybe_get_constant (svalue_id sid) const = 0;
+  virtual svalue_id get_sid_for_constant (tree cst) const = 0;
+  virtual int get_num_svalues () const = 0;
+
+  constraint_manager& operator= (const constraint_manager &other);
+
+  hashval_t hash () const;
+  bool operator== (const constraint_manager &other) const;
+  bool operator!= (const constraint_manager &other) const
+  {
+    return !(*this == other);
+  }
+
+  void print (pretty_printer *pp) const;
+  void dump_to_pp (pretty_printer *pp) const;
+  void dump (FILE *fp) const;
+  void dump () const;
+
+  const equiv_class &get_equiv_class_by_index (unsigned idx) const
+  {
+    return *m_equiv_classes[idx];
+  }
+  equiv_class &get_equiv_class_by_index (unsigned idx)
+  {
+    return *m_equiv_classes[idx];
+  }
+
+  equiv_class &get_equiv_class (svalue_id sid)
+  {
+    equiv_class_id ec_id = get_or_add_equiv_class (sid);
+    return ec_id.get_obj (*this);
+  }
+
+  bool add_constraint (svalue_id lhs, enum tree_code op, svalue_id rhs);
+
+  bool add_constraint (equiv_class_id lhs_ec_id,
+		       enum tree_code op,
+		       equiv_class_id rhs_ec_id);
+
+  bool get_equiv_class_by_sid (svalue_id sid, equiv_class_id *out) const;
+  equiv_class_id get_or_add_equiv_class (svalue_id sid);
+  tristate eval_condition (equiv_class_id lhs,
+			   enum tree_code op,
+			   equiv_class_id rhs);
+  tristate eval_condition (svalue_id lhs,
+			   enum tree_code op,
+			   svalue_id rhs);
+
+  void purge (const purge_criteria &p, purge_stats *stats);
+
+  void remap_svalue_ids (const svalue_id_map &map);
+
+  void canonicalize (unsigned num_svalue_ids);
+
+  static void merge (const constraint_manager &cm_a,
+		     const constraint_manager &cm_b,
+		     constraint_manager *out,
+		     const model_merger &merger);
+
+  void for_each_fact (fact_visitor *) const;
+
+  void validate () const;
+
+  auto_delete_vec<equiv_class> m_equiv_classes;
+  auto_vec<constraint> m_constraints;
+
+ private:
+  static void clean_merger_input (const constraint_manager &cm_in,
+				  const one_way_svalue_id_map &map_sid_to_m,
+				  constraint_manager *out);
+
+  void add_constraint_internal (equiv_class_id lhs_id,
+				enum constraint_op c_op,
+				equiv_class_id rhs_id);
+};
+
+#endif /* GCC_ANALYZER_CONSTRAINT_MANAGER_H */