ai_storage.h

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/*******************************************************************\
 
Module: Abstract Interpretation
 
Author: Martin Brain, martin.brain@cs.ox.ac.uk
 
\*******************************************************************/
 
 
#ifndef CPROVER_ANALYSES_AI_STORAGE_H
#define CPROVER_ANALYSES_AI_STORAGE_H
 
#include <util/deprecate.h>
 
#include <goto-programs/goto_program.h>
 
#include "ai_domain.h"
#include "ai_history.h"
 
class ai_storage_baset
{
protected:
  ai_storage_baset()
  {
  }
 
public:
  virtual ~ai_storage_baset()
  {
  }
 
  typedef ai_domain_baset statet;
  typedef std::shared_ptr<statet> state_ptrt;
  typedef std::shared_ptr<const statet> cstate_ptrt;
  typedef ai_history_baset tracet;
  typedef ai_history_baset::trace_ptrt trace_ptrt;
  typedef ai_history_baset::trace_sett trace_sett;
  typedef std::shared_ptr<trace_sett> trace_set_ptrt;
  typedef std::shared_ptr<const trace_sett> ctrace_set_ptrt;
  typedef goto_programt::const_targett locationt;
 
  virtual ctrace_set_ptrt abstract_traces_before(locationt l) const = 0;
 
  virtual cstate_ptrt abstract_state_before(
    trace_ptrt p,
    const ai_domain_factory_baset &fac) const = 0;
 
  virtual cstate_ptrt abstract_state_before(
    locationt l,
    const ai_domain_factory_baset &fac) const = 0;
 
  virtual statet &
  get_state(trace_ptrt p, const ai_domain_factory_baset &fac) = 0;
 
  virtual void clear()
  {
    return;
  }
 
  virtual void prune(locationt l)
  {
    return;
  }
};
 
// There are a number of options for how to store the history objects.
// This implements a simple one.  It is not in ai_storage_baset so that
// storage implementations can implement their own, more specific, approaches
class trace_map_storaget : public ai_storage_baset
{
protected:
  typedef std::map<locationt, trace_set_ptrt, goto_programt::target_less_than>
    trace_mapt;
  trace_mapt trace_map;
 
  // This retains one part of a shared_ptr to the history object
  void register_trace(trace_ptrt p)
  {
    // Save the trace_ptrt
    trace_mapt::iterator it = trace_map.find(p->current_location());
    if(it == trace_map.end())
    {
      trace_set_ptrt s(new trace_sett());
      auto ins = trace_map.emplace(p->current_location(), s);
      CHECK_RETURN(ins.second);
      it = ins.first;
    }
    // Strictly this should be "it->second points to a trace_set"
    POSTCONDITION(it->second != nullptr);
 
    it->second->insert(p);
 
    return;
  }
 
public:
  ctrace_set_ptrt abstract_traces_before(locationt l) const override
  {
    trace_mapt::const_iterator it = trace_map.find(l);
    if(it == trace_map.end())
      return trace_set_ptrt(new trace_sett());
 
    // Strictly this should be "it->second points to a trace_set"
    POSTCONDITION(it->second != nullptr);
    return it->second;
  }
 
  void clear() override
  {
    ai_storage_baset::clear();
    trace_map.clear();
    return;
  }
};
 
// A couple of older domains make direct use of the state map
class invariant_propagationt;
class dependence_grapht;
class variable_sensitivity_dependence_grapht;
 
class location_sensitive_storaget : public trace_map_storaget
{
protected:
  typedef std::unordered_map<
    locationt,
    state_ptrt,
    const_target_hash,
    pointee_address_equalt>
    state_mapt;
  state_mapt state_map;
 
  // Support some older domains that explicitly iterate across the state map
  friend invariant_propagationt;
  friend dependence_grapht;
  friend variable_sensitivity_dependence_grapht; // Based on dependence_grapht
  state_mapt &internal(void)
  {
    return state_map;
  }
 
public:
  cstate_ptrt abstract_state_before(
    trace_ptrt p,
    const ai_domain_factory_baset &fac) const override
  {
    return abstract_state_before(p->current_location(), fac);
  }
 
  cstate_ptrt abstract_state_before(
    locationt l,
    const ai_domain_factory_baset &fac) const override
  {
    typename state_mapt::const_iterator it = state_map.find(l);
    if(it == state_map.end())
      return fac.make(l);
 
    return it->second;
  }
 
  statet &get_state(trace_ptrt p, const ai_domain_factory_baset &fac) override
  {
    register_trace(p);
    return get_state(p->current_location(), fac);
  }
 
  // For backwards compatability
  // Care should be exercised in using this.  It is possible to create domains
  // without any corresponding history object(s).  This can lead to somewhat
  // unexpected behaviour depending on which APIs you use.
  DEPRECATED(SINCE(2019, 08, 01, "use get_state(trace_ptrt p) instead"))
  statet &get_state(locationt l, const ai_domain_factory_baset &fac)
  {
    typename state_mapt::const_iterator it = state_map.find(l);
    if(it == state_map.end())
    {
      std::shared_ptr<statet> d(fac.make(l));
      auto p = state_map.emplace(l, d);
      CHECK_RETURN(p.second);
      it = p.first;
    }
 
    return *(it->second);
  }
 
  void clear() override
  {
    trace_map_storaget::clear();
    state_map.clear();
    return;
  }
};
 
// The most precise form of storage
class history_sensitive_storaget : public trace_map_storaget
{
protected:
  typedef std::map<trace_ptrt, state_ptrt, ai_history_baset::compare_historyt>
    domain_mapt;
  domain_mapt domain_map;
 
public:
  cstate_ptrt abstract_state_before(
    trace_ptrt p,
    const ai_domain_factory_baset &fac) const override
  {
    auto it = domain_map.find(p);
    if(it == domain_map.end())
      return fac.make(p->current_location());
 
    return it->second;
  }
 
  cstate_ptrt abstract_state_before(
    locationt t,
    const ai_domain_factory_baset &fac) const override
  {
    auto traces = abstract_traces_before(t);
 
    if(traces->size() == 0)
    {
      return fac.make(t);
    }
    else if(traces->size() == 1)
    {
      auto it = domain_map.find(*(traces->begin()));
      DATA_INVARIANT(
        it != domain_map.end(), "domain_map must be in sync with trace_map");
      return it->second;
    }
    else
    {
      // Need to merge all of the traces that reach this location
      auto res = fac.make(t);
 
      for(auto p : *traces)
      {
        auto it = domain_map.find(p);
        DATA_INVARIANT(
          it != domain_map.end(), "domain_map must be in sync with trace_map");
        fac.merge(*res, *(it->second), p, p);
      }
 
      return cstate_ptrt(res.release());
    }
  }
 
  statet &get_state(trace_ptrt p, const ai_domain_factory_baset &fac) override
  {
    register_trace(p);
 
    auto it = domain_map.find(p);
    if(it == domain_map.end())
    {
      std::shared_ptr<statet> d(fac.make(p->current_location()));
      auto jt = domain_map.emplace(p, d);
      CHECK_RETURN(jt.second);
      it = jt.first;
    }
 
    return *(it->second);
  }
 
  void clear() override
  {
    trace_map_storaget::clear();
    domain_map.clear();
    return;
  }
};
 
#endif