path: root/libdw/c++/dwarf_comparator

/* elfutils::dwarf_comparator -- -*- C++ -*- templates for comparing DWARF data
   Copyright (C) 2009 Red Hat, Inc.
   This file is part of Red Hat elfutils.

   Red Hat elfutils is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by the
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#ifndef _ELFUTILS_DWARF_COMPARATOR
#define _ELFUTILS_DWARF_COMPARATOR	1

#include "dwarf"

namespace elfutils
{
  // Prototypical stub for reference tracker object.
  // This keeps no state, and no two contexts ever match.
  template<class dwarf1, class dwarf2>
  struct dwarf_tracker_base
  {
    typedef typename dwarf1::compile_units::const_iterator cu1;
    typedef typename dwarf2::compile_units::const_iterator cu2;
    typedef typename dwarf1::debug_info_entry dwarf1_die;
    typedef typename dwarf2::debug_info_entry dwarf2_die;
    typedef typename dwarf1_die::children_type::const_iterator die1;
    typedef typename dwarf2_die::children_type::const_iterator die2;
    typedef typename dwarf1_die::attributes_type::const_iterator attr1;
    typedef typename dwarf2_die::attributes_type::const_iterator attr2;
    typedef typename dwarf1_die::children_type::iterator dwarf1_ref;

    // This object is created to start a walk and destroyed to finish one.
    struct walk
    {
      inline walk (dwarf_tracker_base *, const cu1 &, const cu2 &)
      {
      }
      inline ~walk ()
      {
      }
    };

    // This object is created in pre-order and destroyed in post-order.
    struct step
    {
      inline step (dwarf_tracker_base *, const die1 &, const die2 &)
      {
      }
      inline ~step ()
      {
      }
    };

    inline void visit (const typename dwarf1::debug_info_entry &,
		       const typename dwarf2::debug_info_entry &)
    {
    }

    inline void mismatch (const cu1 &, const cu1 &, // at, end
			  const cu2 &, const cu2 &)
    {
    }

    inline void mismatch (const die1 &, const die1 &, // at, end
			  const die2 &, const die2 &)
    {
    }

    inline void mismatch (const attr1 &, const attr1 &, // at, end
			  const attr2 &, const attr2 &)
    {
    }

    struct left_context_type {};
    struct right_context_type {};

    // Return the lhs context of an arbitrary DIE.
    inline const left_context_type left_context (const die1 &)
    {
      return left_context_type ();
    }

    // Return the rhs context of an arbitrary DIE.
    inline const right_context_type right_context (const die2 &)
    {
      return right_context_type ();
    }

    inline bool context_quick_mismatch (const left_context_type &,
					const right_context_type &)

    {
      return true;
    }

    inline bool context_match (const left_context_type &,
			       const right_context_type &)
    {
      return false;
    }

    struct reference_match
    {
      inline bool cannot_match () const
      {
	return false;
      }
      inline void notice_match (const die2 &, bool) const
      {
      }
    };

    inline bool reference_matched (reference_match &,
				   const die1 &, const die2 &)
    {
      return false;
    }

    inline dwarf_tracker_base ()
    {}

    inline dwarf_tracker_base (const dwarf_tracker_base &, reference_match &,
			       const left_context_type &,
			       const right_context_type &)
    {}
  };

  template<class dwarf1, class dwarf2,
	   bool ignore_refs = false,
	   class tracker = dwarf_tracker_base<dwarf1, dwarf2>
	   >
  class dwarf_comparator
    : public std::binary_function<dwarf1, dwarf2, bool>
  {
  private:
    tracker &_m_tracker;

    template<typename item1, typename item2>
    struct matcher : public std::binary_function<item1, item2, bool>
    {
      dwarf_comparator &_m_cmp;
      matcher (dwarf_comparator &cmp)
	: _m_cmp (cmp)
      {}

      inline bool operator () (const item1 &a, const item2 &b)
      {
	return _m_cmp.match (a, b);
      }
    };
#define MATCHER(item) \
    matcher<typename dwarf1::item::const_iterator, \
	    typename dwarf2::item::const_iterator> (*this)

    inline bool match (const dwarf1 &a, const dwarf2 &b)
    {
      return match (a.compile_units (), b.compile_units ());
    }

    typedef typename dwarf1::compile_units compile_units1;
    typedef typename dwarf2::compile_units compile_units2;
    typedef typename dwarf1::compile_units::const_iterator cu1_it;
    typedef typename dwarf2::compile_units::const_iterator cu2_it;
    inline bool match (const compile_units1 &a, const compile_units2 &b)
    {
      cu1_it it1 = a.begin ();
      cu2_it it2 = b.begin ();
      const cu1_it end1 = a.end ();
      const cu2_it end2 = b.end ();
      if (subr::container_equal
	  (it1, end1, it2, end2, MATCHER (compile_units)))
	return true;
      _m_tracker.mismatch (it1, end1, it2, end2);
      return false;
    }

    typedef typename dwarf1::debug_info_entry die1;
    typedef typename dwarf2::debug_info_entry die2;
    inline bool match (const cu1_it &a, const cu2_it &b)
    {
      typename tracker::walk in (&_m_tracker, a, b);
      return match (*a, *b);
    }

    inline bool match (const die1 &a, const die2 &b)
    {
      _m_tracker.visit (a, b);
      return (a.tag () == b.tag ()
	      && match (a.attributes (), b.attributes ())
	      && match (a.children (), b.children ()));
    }

    template<typename in, typename out>
    static inline void populate (out &o, const in &map)
    {
      for (typename in::const_iterator i = map.begin ();
	   i != map.end ();
	   ++i)
	o.insert (std::make_pair ((*i).first, i));
    }

    typedef typename dwarf1::debug_info_entry::attributes_type attributes1;
    typedef typename dwarf2::debug_info_entry::attributes_type attributes2;
    typedef typename attributes1::const_iterator ait1;
    typedef typename attributes2::const_iterator ait2;
    typedef std::map<int, ait1> ait1_map;
    typedef std::map<int, ait2> ait2_map;

    struct match_lhs
      : public std::binary_function<ait1, ait2, bool>
    {
      inline bool operator () (const ait1 &it1, const ait2 &it2)
      {
	return (*it1).first == (*it2).first;
      }
    };

    struct match_rhs
      : public std::binary_function<ait1, ait2, bool>
    {
      dwarf_comparator &_m_cmp;
      match_rhs (dwarf_comparator &cmp)
	: _m_cmp (cmp)
      {}

      inline bool operator () (const ait1 &it1, const ait2 &it2)
      {
	return _m_cmp.match ((*it1).second, (*it2).second);
      }
    };

    struct match_sorted
      : public std::binary_function<typename ait1_map::value_type,
				    typename ait2_map::value_type,
				    bool>
    {
      dwarf_comparator &_m_cmp;
      match_sorted (dwarf_comparator<dwarf1, dwarf2,
		    ignore_refs, tracker> &cmp)
	: _m_cmp (cmp)
      {}

      inline bool operator () (const typename ait1_map::value_type &x,
			       const typename ait2_map::value_type &y)
      {
	return (x.first == y.first
		&& _m_cmp.match ((*x.second).second, (*y.second).second));
      }
    };

    inline bool match (const attributes1 &a, const attributes2 &b)
    {
      ait1 it1 = a.begin ();
      ait2 it2 = b.begin ();
      const ait1 end1 = a.end ();
      const ait2 end2 = b.end ();
      if (subr::container_equal (it1, end1, it2, end2, match_lhs ()))
	{
	  // The set of attributes matches, in order.  Compare the values.
	  it1 = a.begin ();
	  it2 = b.begin ();
	  if (subr::container_equal (it1, end1, it2, end2, match_rhs (*this)))
	    return true;
	  _m_tracker.mismatch (it1, end1, it2, end2);
	  return false;
	}

      if (it1 != end1 && it2 != end2
	  && !(attributes1::ordered () && attributes2::ordered ()))
	{
	  /* We have the same number of attributes, but the names don't match.

	   */

	  ait1_map sorted1;
	  populate (sorted1, a);

	  ait2_map sorted2;
	  populate (sorted2, b);

	  std::pair<typename ait1_map::iterator,
	    	    typename ait2_map::iterator> result
	    = std::mismatch (sorted1.begin (), sorted1.end (),
			     sorted2.begin (), match_sorted (*this));
	  if (result.first == sorted1.end () && result.second == sorted2.end ())
	    return true;

	  it1 = result.first->second;
	  it2 = result.second->second;
	}

      _m_tracker.mismatch (it1, end1, it2, end2);
      return false;
    }

    typedef typename dwarf1::debug_info_entry::children_type children1;
    typedef typename dwarf2::debug_info_entry::children_type children2;
    typedef typename children1::const_iterator cit1;
    typedef typename children2::const_iterator cit2;

    inline bool match_child (const cit1 &a, const cit2 &b)
    {
      typename tracker::step into (&_m_tracker, a, b);
      return match (*a, *b);
    }

    inline bool match (const cit1 &a, const cit2 &b)
    {
      // Maybe the tracker has already cached a correspondence of DIEs.
      typename tracker::reference_match matched;
      if (_m_tracker.reference_matched (matched, a, b))
	return true;

      if (matched.cannot_match ())
	return false;

      bool result = match_child (a, b);

      // Let the tracker cache a result for its reference_matched.
      matched.notice_match (b, result);

      return result;
    }

    inline bool match (const children1 &a, const children2 &b)
    {
      cit1 it1 = a.begin ();
      cit2 it2 = b.begin ();
      const cit1 end1 = a.end ();
      const cit2 end2 = b.end ();
      if (subr::container_equal (it1, end1, it2, end2,
				 MATCHER (debug_info_entry::children_type)))
	return true;
      _m_tracker.mismatch (it1, end1, it2, end2);
      return false;
    }

    typedef typename dwarf1::attribute attribute1;
    typedef typename dwarf2::attribute attribute2;
    inline bool match (const attribute1 &a, const attribute2 &b)
    {
      return a.first == b.first && match (a.second, b.second);
    }

    typedef typename dwarf1::attr_value attr_value1;
    typedef typename dwarf2::attr_value attr_value2;
    inline bool match (const attr_value1 &a, const attr_value2 &b)
    {
      const dwarf::value_space what = a.what_space ();
      if (what == b.what_space ())
	switch (what)
	  {
	  case dwarf::VS_reference:
	    return reference_match (a.reference (), b.reference ());

	  case dwarf::VS_flag:
	    return a.flag () == b.flag ();

	  case dwarf::VS_rangelistptr:
	    return a.ranges () == b.ranges ();

	  case dwarf::VS_lineptr:
	    return a.line_info () == b.line_info ();

	  case dwarf::VS_macptr:	// XXX punt for now, treat as constant
	    return a.constant () == b.constant ();

	  case dwarf::VS_dwarf_constant:
	    return a.dwarf_constant () == b.dwarf_constant ();

	  case dwarf::VS_constant:
	    if (a.constant_is_integer ())
	      return (b.constant_is_integer ()
		      && a.constant () == b.constant ());
	    return (!b.constant_is_integer ()
		    && subr::container_equal (a.constant_block (),
					      b.constant_block ()));

	  case dwarf::VS_source_line:
	    return a.source_line () == b.source_line ();
	  case dwarf::VS_source_column:
	    return a.source_column () == b.source_column ();

	  case dwarf::VS_identifier:
	    return subr::name_equal<typeof (b.identifier ())> ()
	      (a.identifier (), b.identifier ());

	  case dwarf::VS_string:
	    return subr::name_equal<typeof (b.string ())> ()
	      (a.string (), b.string ());

	  case dwarf::VS_address:
	    return a.address () == b.address ();

	  case dwarf::VS_source_file:
	    return a.source_file () == b.source_file ();

	  case dwarf::VS_location:
	    return a.location () == b.location ();

	  case dwarf::VS_discr_list:
	    throw std::runtime_error ("XXX unimplemented");
	  }
      return false;
    }

    /* We call references equal if they are literally the same DIE,
       or if they are identical subtrees sitting in matching contexts.
       The tracker's context_match method decides what that means.  */
    inline bool reference_match (const cit1 &ref1, const cit2 &ref2)
    {
      if (ignore_refs)
	return true;

      const die1 &a = *ref1;
      const die2 &b = *ref2;

      if (a.identity () == b.identity ()) // Object identity.
	return true;

      // Simplest mismatches with the cheapest checks first.
      if (a.tag () != b.tag ())
	return false;

      const bool has_children = a.has_children ();
      if (has_children != b.has_children ())
	return false;

      // Maybe the tracker has already cached a correspondence of references.
      typename tracker::reference_match matched;
      if (_m_tracker.reference_matched (matched, ref1, ref2))
	return true;

      if (matched.cannot_match ())
	return false;

      // Now we really have to get the tracker involved.
      const typename tracker::left_context_type &lhs
	= _m_tracker.left_context (ref1);
      const typename tracker::right_context_type &rhs
	= _m_tracker.right_context (ref2);

      /* First do the cheap mismatch check on the contexts, then check the
	 contents and contexts in ascending order of costliness of a check.  */
      if (_m_tracker.context_quick_mismatch (lhs, rhs)
	  || !match (a.attributes (), b.attributes ())
	  || !_m_tracker.context_match (lhs, rhs))
	return false;

      /* To compare the children, we have to clone the tracker and use a
	 new one, in case of any reference attributes in their subtrees.
	 The new tracker jump-starts its walk to the referenced DIE from
	 the root of the CU.  */
      bool result = !has_children;
      if (has_children)
	{
	  tracker t (_m_tracker, matched, lhs, rhs);
	  result = dwarf_comparator (t).match (a.children (), b.children ());
	}

      // Let the tracker cache a result for its reference_matched.
      matched.notice_match (ref2, result);

      return result;
    }

  public:
    inline explicit dwarf_comparator (tracker &t)
      : _m_tracker (t)
    {}

    inline bool operator () (const dwarf1 &a, const dwarf2 &b)
    {
      return match (a, b);
    }

    template<typename item1, typename item2>
    inline bool equals (const item1 &a, const item2 &b)
    {
      return match (a, b);
    }
  };
};

#endif	// <elfutils/dwarf_comparator>