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/* Tracking equivalence classes and constraints at a point on an execution path.
Copyright (C) 2019-2022 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
namespace ana {
class constraint_manager;
enum bound_kind
{
BK_LOWER,
BK_UPPER
};
/* One of the end-points of a range. */
struct bound
{
bound () : m_constant (NULL_TREE), m_closed (false) {}
bound (tree constant, bool closed)
: m_constant (constant), m_closed (closed) {}
void ensure_closed (enum bound_kind bound_kind);
const char * get_relation_as_str () const;
tree m_constant;
bool m_closed;
};
/* A range of values, used for determining if a value has been
constrained to just one possible constant value. */
class range
{
public:
range () : m_lower_bound (), m_upper_bound () {}
range (const bound &lower, const bound &upper)
: m_lower_bound (lower), m_upper_bound (upper) {}
void dump_to_pp (pretty_printer *pp) const;
void dump () const;
tree constrained_to_single_element ();
tristate eval_condition (enum tree_code op,
tree rhs_const) const;
bool below_lower_bound (tree rhs_const) const;
bool above_upper_bound (tree rhs_const) const;
bool add_bound (bound b, enum bound_kind bound_kind);
bool add_bound (enum tree_code op, tree rhs_const);
private:
bound m_lower_bound;
bound m_upper_bound;
};
/* A closed range of values with constant integer bounds
e.g. [3, 5] for the set {3, 4, 5}. */
struct bounded_range
{
bounded_range (const_tree lower, const_tree upper);
void dump_to_pp (pretty_printer *pp, bool show_types) const;
void dump (bool show_types) const;
json::object *to_json () const;
bool contains_p (tree cst) const;
bool intersects_p (const bounded_range &other,
bounded_range *out) const;
bool operator== (const bounded_range &other) const;
bool operator!= (const bounded_range &other) const
{
return !(*this == other);
}
static int cmp (const bounded_range &a, const bounded_range &b);
tree m_lower;
tree m_upper;
private:
static void set_json_attr (json::object *obj, const char *name, tree value);
};
/* A collection of bounded_range instances, suitable
for representing the ranges on a case label within a switch
statement. */
struct bounded_ranges
{
public:
typedef bounded_ranges key_t;
bounded_ranges (const bounded_range &range);
bounded_ranges (const vec<bounded_range> &ranges);
bounded_ranges (enum tree_code op, tree rhs_const);
bool operator== (const bounded_ranges &other) const;
hashval_t get_hash () const { return m_hash; }
void dump_to_pp (pretty_printer *pp, bool show_types) const;
void dump (bool show_types) const;
json::value *to_json () const;
tristate eval_condition (enum tree_code op,
tree rhs_const,
bounded_ranges_manager *mgr) const;
bool contain_p (tree cst) const;
bool empty_p () const { return m_ranges.length () == 0; }
static int cmp (const bounded_ranges *a, const bounded_ranges *b);
private:
void canonicalize ();
void validate () const;
friend class bounded_ranges_manager;
auto_vec<bounded_range> m_ranges;
hashval_t m_hash;
};
} // namespace ana
template <> struct default_hash_traits<bounded_ranges::key_t>
: public member_function_hash_traits<bounded_ranges::key_t>
{
static const bool empty_zero_p = true;
};
namespace ana {
/* An object to own and consolidate bounded_ranges instances.
This also caches the mapping from switch_cfg_superedge
bounded_ranges instances, so that get_or_create_ranges_for_switch is
memoized. */
class bounded_ranges_manager
{
public:
~bounded_ranges_manager ();
const bounded_ranges *
get_or_create_ranges_for_switch (const switch_cfg_superedge *edge,
const gswitch *switch_stmt);
const bounded_ranges *get_or_create_empty ();
const bounded_ranges *get_or_create_point (const_tree value);
const bounded_ranges *get_or_create_range (const_tree lower_bound,
const_tree upper_bound);
const bounded_ranges *
get_or_create_union (const vec <const bounded_ranges *> &others);
const bounded_ranges *
get_or_create_intersection (const bounded_ranges *a,
const bounded_ranges *b);
const bounded_ranges *
get_or_create_inverse (const bounded_ranges *other, tree type);
void log_stats (logger *logger, bool show_objs) const;
private:
const bounded_ranges *
create_ranges_for_switch (const switch_cfg_superedge &edge,
const gswitch *switch_stmt);
const bounded_ranges *
make_case_label_ranges (const gswitch *switch_stmt,
tree case_label);
const bounded_ranges *consolidate (bounded_ranges *);
struct hash_traits_t : public typed_noop_remove<bounded_ranges *>
{
typedef bounded_ranges *key_type;
typedef bounded_ranges *value_type;
static inline bool
equal (const key_type &k1, const key_type &k2)
{
return *k1 == *k2;
}
static inline hashval_t
hash (const key_type &k)
{
return k->get_hash ();
}
static inline bool is_empty (key_type k) { return k == NULL; }
static inline void mark_empty (key_type &k) { k = NULL; }
static inline bool is_deleted (key_type k)
{
return k == reinterpret_cast<key_type> (1);
}
static const bool empty_zero_p = true;
};
struct traits_t : public simple_hashmap_traits<hash_traits_t,
bounded_ranges *>
{
};
typedef hash_map<bounded_ranges *, bounded_ranges *, traits_t> map_t;
map_t m_map;
typedef hash_map<const switch_cfg_superedge *,
const bounded_ranges *> edge_cache_t;
edge_cache_t m_edge_cache;
};
/* An equivalence class within a constraint manager: a set of
svalues 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 (const svalue *sval);
bool del (const svalue *sval);
tree get_any_constant () const { return m_constant; }
const svalue *get_representative () const;
void canonicalize ();
void print (pretty_printer *pp) const;
json::object *to_json () const;
bool contains_non_constant_p () 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;
const svalue *m_cst_sval;
// TODO: should this be a set rather than a vec?
auto_vec<const svalue *> 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;
json::object *to_json () 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;
}
bool implied_by (const constraint &other,
const constraint_manager &cm) const;
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 (const svalue *lhs,
enum tree_code,
const svalue *rhs) = 0;
virtual void on_ranges (const svalue *lhs,
const bounded_ranges *ranges) = 0;
};
class bounded_ranges_constraint
{
public:
bounded_ranges_constraint (equiv_class_id ec_id,
const bounded_ranges *ranges)
: m_ec_id (ec_id), m_ranges (ranges)
{
}
void print (pretty_printer *pp, const constraint_manager &cm) const;
json::object *to_json () const;
bool operator== (const bounded_ranges_constraint &other) const;
bool operator!= (const bounded_ranges_constraint &other) const
{
return !(*this == other);
}
void add_to_hash (inchash::hash *hstate) const;
equiv_class_id m_ec_id;
const bounded_ranges *m_ranges;
};
/* 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 (region_model_manager *mgr) : m_mgr (mgr) {}
constraint_manager (const constraint_manager &other);
virtual ~constraint_manager () {}
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, bool multiline) const;
void dump (FILE *fp) const;
void dump () const;
json::object *to_json () 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 (const svalue *sval)
{
equiv_class_id ec_id = get_or_add_equiv_class (sval);
return ec_id.get_obj (*this);
}
bool add_constraint (const svalue *lhs,
enum tree_code op,
const svalue *rhs);
bool add_constraint (equiv_class_id lhs_ec_id,
enum tree_code op,
equiv_class_id rhs_ec_id);
void add_unknown_constraint (equiv_class_id lhs_ec_id,
enum tree_code op,
equiv_class_id rhs_ec_id);
bool add_bounded_ranges (const svalue *sval,
const bounded_ranges *ranges);
bool get_equiv_class_by_svalue (const svalue *sval,
equiv_class_id *out) const;
equiv_class_id get_or_add_equiv_class (const svalue *sval);
tristate eval_condition (equiv_class_id lhs,
enum tree_code op,
equiv_class_id rhs) const;
tristate eval_condition (equiv_class_id lhs_ec,
enum tree_code op,
tree rhs_const) const;
tristate eval_condition (const svalue *lhs,
enum tree_code op,
const svalue *rhs) const;
range get_ec_bounds (equiv_class_id ec_id) const;
/* PurgeCriteria should have:
bool should_purge_p (const svalue *sval) const. */
template <typename PurgeCriteria>
void purge (const PurgeCriteria &p, purge_stats *stats);
void on_liveness_change (const svalue_set &live_svalues,
const region_model *model);
void purge_state_involving (const svalue *sval);
void canonicalize ();
static void merge (const constraint_manager &cm_a,
const constraint_manager &cm_b,
constraint_manager *out);
void for_each_fact (fact_visitor *) const;
void validate () const;
bounded_ranges_manager *get_range_manager () const;
auto_delete_vec<equiv_class> m_equiv_classes;
auto_vec<constraint> m_constraints;
auto_vec<bounded_ranges_constraint> m_bounded_ranges_constraints;
private:
void add_constraint_internal (equiv_class_id lhs_id,
enum constraint_op c_op,
equiv_class_id rhs_id);
region_model_manager *m_mgr;
};
} // namespace ana
#endif /* GCC_ANALYZER_CONSTRAINT_MANAGER_H */
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