text: // Copyright (C) 1994-2015 Free Software Foundation, Inc.
  //
  // 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.
  
  // Under Section 7 of GPL version 3, you are granted additional
  // permissions described in the GCC Runtime Library Exception, version
  // 3.1, as published by the Free Software Foundation.
  
  // You should have received a copy of the GNU General Public License and
  // a copy of the GCC Runtime Library Exception along with this program;
  // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  // <http://www.gnu.org/licenses/>.
  
  #include "tinfo.h"
  
  namespace __cxxabiv1 {
  
  __vmi_class_type_info::
  ~__vmi_class_type_info ()
  {}
  
  __class_type_info::__sub_kind __vmi_class_type_info::
  __do_find_public_src (ptrdiff_t src2dst,
                        const void *obj_ptr,
                        const __class_type_info *src_type,
                        const void *src_ptr) const
  {
    if (obj_ptr == src_ptr && *this == *src_type)
      return __contained_public;
    
    for (std::size_t i = __base_count; i--;)
      {
        if (!__base_info[i].__is_public_p ())
          continue; // Not public, can't be here.
        
        const void *base = obj_ptr;
        ptrdiff_t offset = __base_info[i].__offset ();
        bool is_virtual = __base_info[i].__is_virtual_p ();
        
        if (is_virtual)
          {
            if (src2dst == -3)
              continue; // Not a virtual base, so can't be here.
          }
        base = convert_to_base (base, is_virtual, offset);
        
        __sub_kind base_kind = __base_info[i].__base_type->__do_find_public_src
                                (src2dst, base, src_type, src_ptr);
        if (contained_p (base_kind))
          {
            if (is_virtual)
              base_kind = __sub_kind (base_kind | __contained_virtual_mask);
            return base_kind;
          }
      }
    
    return __not_contained;
  }
  
  // This is a big hairy function. Although the run-time behaviour of
  // dynamic_cast is simple to describe, it gives rise to some non-obvious
  // behaviour. We also desire to determine as early as possible any definite
  // answer we can get. Because it is unknown what the run-time ratio of
  // succeeding to failing dynamic casts is, we do not know in which direction
  // to bias any optimizations. To that end we make no particular effort towards
  // early fail answers or early success answers. Instead we try to minimize
  // work by filling in things lazily (when we know we need the information),
  // and opportunisticly take early success or failure results.
  bool __vmi_class_type_info::
  __do_dyncast (ptrdiff_t src2dst,
                __sub_kind access_path,
                const __class_type_info *dst_type,
                const void *obj_ptr,
                const __class_type_info *src_type,
                const void *src_ptr,
                __dyncast_result &__restrict result) const
  {
    if (result.whole_details & __flags_unknown_mask)
      result.whole_details = __flags;
    
    if (obj_ptr == src_ptr && *this == *src_type)
      {
        // The src object we started from. Indicate how we are accessible from
        // the most derived object.
        result.whole2src = access_path;
        return false;
      }
    if (*this == *dst_type)
      {
        result.dst_ptr = obj_ptr;
        result.whole2dst = access_path;
        if (src2dst >= 0)
          result.dst2src = adjust_pointer <void> (obj_ptr, src2dst) == src_ptr
                ? __contained_public : __not_contained;
        else if (src2dst == -2)
          result.dst2src = __not_contained;
        return false;
      }
  
    // If src_type is a unique non-virtual base of dst_type, we have a good
    // guess at the address we want, so in the first pass try skipping any
    // bases which don't contain that address.
    const void *dst_cand = NULL;
    if (src2dst >= 0)
      dst_cand = adjust_pointer<void>(src_ptr, -src2dst);
    bool first_pass = true;
    bool skipped = false;
  
    bool result_ambig = false;
   again:
    for (std::size_t i = __base_count; i--;)
      {
        __dyncast_result result2 (result.whole_details);
        void const *base = obj_ptr;
        __sub_kind base_access = access_path;
        ptrdiff_t offset = __base_info[i].__offset ();
        bool is_virtual = __base_info[i].__is_virtual_p ();
        
        if (is_virtual)
          base_access = __sub_kind (base_access | __contained_virtual_mask);
        base = convert_to_base (base, is_virtual, offset);
  
        if (dst_cand)
  	{
  	  bool skip_on_first_pass = base > dst_cand;
  	  if (skip_on_first_pass == first_pass)
  	    {
  	      // We aren't interested in this base on this pass: either
  	      // we're on the first pass and this base doesn't contain the
  	      // likely address, or we're on the second pass and we checked
  	      // this base on the first pass.
  	      skipped = true;
  	      continue;
  	    }
  	}
  
        if (!__base_info[i].__is_public_p ())
          {
            if (src2dst == -2 &&
                !(result.whole_details
                  & (__non_diamond_repeat_mask | __diamond_shaped_mask)))
              // The hierarchy has no duplicate bases (which might ambiguate
              // things) and where we started is not a public base of what we
              // want (so it cannot be a downcast). There is nothing of interest
              // hiding in a non-public base.
              continue;
            base_access = __sub_kind (base_access & ~__contained_public_mask);
          }
        
        bool result2_ambig
            = __base_info[i].__base_type->__do_dyncast (src2dst, base_access,
                                               dst_type, base,
                                               src_type, src_ptr, result2);
        result.whole2src = __sub_kind (result.whole2src | result2.whole2src);
        if (result2.dst2src == __contained_public
            || result2.dst2src == __contained_ambig)
          {
            result.dst_ptr = result2.dst_ptr;
            result.whole2dst = result2.whole2dst;
            result.dst2src = result2.dst2src;
            // Found a downcast which can't be bettered or an ambiguous downcast
            // which can't be disambiguated
            return result2_ambig;
          }
        
        if (!result_ambig && !result.dst_ptr)
          {
            // Not found anything yet.
            result.dst_ptr = result2.dst_ptr;
            result.whole2dst = result2.whole2dst;
            result_ambig = result2_ambig;
            if (result.dst_ptr && result.whole2src != __unknown
                && !(__flags & __non_diamond_repeat_mask))
              // Found dst and src and we don't have repeated bases.
              return result_ambig;
          }
        else if (result.dst_ptr && result.dst_ptr == result2.dst_ptr)
          {
            // Found at same address, must be via virtual.  Pick the most
            // accessible path.
            result.whole2dst =
                __sub_kind (result.whole2dst | result2.whole2dst);
          }
        else if ((result.dst_ptr != 0 && result2.dst_ptr != 0)
  	       || (result.dst_ptr != 0 && result2_ambig)
  	       || (result2.dst_ptr != 0 && result_ambig))
          {
            // Found two different DST_TYPE bases, or a valid one and a set of
            // ambiguous ones, must disambiguate. See whether SRC_PTR is
            // contained publicly within one of the non-ambiguous choices. If it
            // is in only one, then that's the choice. If it is in both, then
            // we're ambiguous and fail. If it is in neither, we're ambiguous,
            // but don't yet fail as we might later find a third base which does
            // contain SRC_PTR.
          
            __sub_kind new_sub_kind = result2.dst2src;
            __sub_kind old_sub_kind = result.dst2src;
            
            if (contained_p (result.whole2src)
                && (!virtual_p (result.whole2src)
                    || !(result.whole_details & __diamond_shaped_mask)))
              {
                // We already found SRC_PTR as a base of most derived, and
                // either it was non-virtual, or the whole hierarchy is
                // not-diamond shaped. Therefore if it is in either choice, it
                // can only be in one of them, and we will already know.
                if (old_sub_kind == __unknown)
                  old_sub_kind = __not_contained;
                if (new_sub_kind == __unknown)
                  new_sub_kind = __not_contained;
              }
            else
              {
                if (old_sub_kind >= __not_contained)
                  ;// already calculated
                else if (contained_p (new_sub_kind)
                         && (!virtual_p (new_sub_kind)
                             || !(__flags & __diamond_shaped_mask)))
                  // Already found inside the other choice, and it was
                  // non-virtual or we are not diamond shaped.
                  old_sub_kind = __not_contained;
                else
                  old_sub_kind = dst_type->__find_public_src
                                  (src2dst, result.dst_ptr, src_type, src_ptr);
            
                if (new_sub_kind >= __not_contained)
                  ;// already calculated
                else if (contained_p (old_sub_kind)
                         && (!virtual_p (old_sub_kind)
                             || !(__flags & __diamond_shaped_mask)))
                  // Already found inside the other choice, and it was
                  // non-virtual or we are not diamond shaped.
                  new_sub_kind = __not_contained;
                else
                  new_sub_kind = dst_type->__find_public_src
                                  (src2dst, result2.dst_ptr, src_type, src_ptr);
              }
            
            // Neither sub_kind can be contained_ambig -- we bail out early
            // when we find those.
            if (contained_p (__sub_kind (new_sub_kind ^ old_sub_kind)))
              {
                // Only on one choice, not ambiguous.
                if (contained_p (new_sub_kind))
                  {
                    // Only in new.
                    result.dst_ptr = result2.dst_ptr;
                    result.whole2dst = result2.whole2dst;
                    result_ambig = false;
                    old_sub_kind = new_sub_kind;
                  }
                result.dst2src = old_sub_kind;
                if (public_p (result.dst2src))
                  return false; // Can't be an ambiguating downcast for later discovery.
                if (!virtual_p (result.dst2src))
                  return false; // Found non-virtually can't be bettered
              }
            else if (contained_p (__sub_kind (new_sub_kind & old_sub_kind)))
              {
                // In both.
                result.dst_ptr = NULL;
                result.dst2src = __contained_ambig;
                return true;  // Fail.
              }
            else
              {
                // In neither publicly, ambiguous for the moment, but keep
                // looking. It is possible that it was private in one or
                // both and therefore we should fail, but that's just tough.
                result.dst_ptr = NULL;
                result.dst2src = __not_contained;
                result_ambig = true;
              }
          }
        
        if (result.whole2src == __contained_private)
          // We found SRC_PTR as a private non-virtual base, therefore all
          // cross casts will fail. We have already found a down cast, if
          // there is one.
          return result_ambig;
      }
  
    if (skipped && first_pass)
      {
        // We didn't find dst where we expected it, so let's go back and try
        // the bases we skipped (if any).
        first_pass = false;
        goto again;
      }
  
    return result_ambig;
  }
  
  bool __vmi_class_type_info::
  __do_upcast (const __class_type_info *dst, const void *obj_ptr,
               __upcast_result &__restrict result) const
  {
    if (__class_type_info::__do_upcast (dst, obj_ptr, result))
      return true;
    
    int src_details = result.src_details;
    if (src_details & __flags_unknown_mask)
      src_details = __flags;
    
    for (std::size_t i = __base_count; i--;)
      {
        __upcast_result result2 (src_details);
        const void *base = obj_ptr;
        ptrdiff_t offset = __base_info[i].__offset ();
        bool is_virtual = __base_info[i].__is_virtual_p ();
        bool is_public = __base_info[i].__is_public_p ();
        
        if (!is_public && !(src_details & __non_diamond_repeat_mask))
          // original cannot have an ambiguous base, so skip private bases
          continue;
  
        if (base)
          base = convert_to_base (base, is_virtual, offset);
        
        if (__base_info[i].__base_type->__do_upcast (dst, base, result2))
          {
            if (result2.base_type == nonvirtual_base_type && is_virtual)
              result2.base_type = __base_info[i].__base_type;
            if (contained_p (result2.part2dst) && !is_public)
              result2.part2dst = __sub_kind (result2.part2dst & ~__contained_public_mask);
            
            if (!result.base_type)
              {
                result = result2;
                if (!contained_p (result.part2dst))
                  return true; // found ambiguously
                
                if (result.part2dst & __contained_public_mask)
                  {
                    if (!(__flags & __non_diamond_repeat_mask))
                      return true;  // cannot have an ambiguous other base
                  }
                else
                  {
                    if (!virtual_p (result.part2dst))
                      return true; // cannot have another path
                    if (!(__flags & __diamond_shaped_mask))
                      return true; // cannot have a more accessible path
                  }
              }
            else if (result.dst_ptr != result2.dst_ptr)
              {
                // Found an ambiguity.
  	      result.dst_ptr = NULL;
  	      result.part2dst = __contained_ambig;
  	      return true;
              }
            else if (result.dst_ptr)
              {
                // Ok, found real object via a virtual path.
                result.part2dst
                    = __sub_kind (result.part2dst | result2.part2dst);
              }
            else
              {
                // Dealing with a null pointer, need to check vbase
                // containing each of the two choices.
                if (result2.base_type == nonvirtual_base_type
                    || result.base_type == nonvirtual_base_type
                    || !(*result2.base_type == *result.base_type))
                  {
                    // Already ambiguous, not virtual or via different virtuals.
                    // Cannot match.
                    result.part2dst = __contained_ambig;
                    return true;
                  }
                result.part2dst
                    = __sub_kind (result.part2dst | result2.part2dst);
              }
          }
      }
    return result.part2dst != __unknown;
  }
  
  }
  