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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 <>.
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
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
<>. */
namespace ana {
class constraint_manager;
/* Abstract base class for specifying how state should be purged. */
class purge_criteria
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
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
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
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)
int m_idx;
/* A relationship between two equivalence classes in a constraint_manager. */
class constraint
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
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
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;
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);
} // namespace ana