ab044c7412
* tinfo.h (old abi): #include "tconfig.h".
* tinfo.cc (convert_to_base): Move into old abi section.
From-SVN: r31725
1136 lines
39 KiB
C++
1136 lines
39 KiB
C++
// Methods for type_info for -*- C++ -*- Run Time Type Identification.
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// Copyright (C) 1994, 1996, 1998, 1999, 2000 Free Software Foundation
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// This file is part of GNU CC.
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// GNU CC is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 2, or (at your option)
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// any later version.
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// GNU CC is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with GNU CC; see the file COPYING. If not, write to
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// the Free Software Foundation, 59 Temple Place - Suite 330,
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// Boston, MA 02111-1307, USA.
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// As a special exception, if you link this library with other files,
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// some of which are compiled with GCC, to produce an executable,
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// this library does not by itself cause the resulting executable
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// to be covered by the GNU General Public License.
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// This exception does not however invalidate any other reasons why
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// the executable file might be covered by the GNU General Public License.
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#pragma implementation "typeinfo"
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#include <stddef.h>
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#include "tinfo.h"
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#include "new" // for placement new
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// This file contains the minimal working set necessary to link with code
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// that uses virtual functions and -frtti but does not actually use RTTI
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// functionality.
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std::type_info::
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~type_info ()
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{ }
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#if !defined(__GXX_ABI_VERSION) || __GXX_ABI_VERSION < 100
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// original (old) abi
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namespace
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{
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// ADDR is a pointer to an object. Convert it to a pointer to a base,
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// using OFFSET.
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inline void*
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convert_to_base (void *addr, bool is_virtual, myint32 offset)
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{
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if (!addr)
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return NULL;
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if (!is_virtual)
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return (char *) addr + offset;
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// Under the old ABI, the offset gives us the address of a pointer
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// to the virtual base.
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return *((void **) ((char *) addr + offset));
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}
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}
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// We can't rely on common symbols being shared between shared objects.
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bool std::type_info::
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operator== (const std::type_info& arg) const
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{
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return (&arg == this) || (strcmp (name (), arg.name ()) == 0);
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}
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extern "C" void
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__rtti_class (void *addr, const char *name,
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const __class_type_info::base_info *bl, size_t bn)
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{ new (addr) __class_type_info (name, bl, bn); }
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extern "C" void
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__rtti_si (void *addr, const char *n, const std::type_info *ti)
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{
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new (addr) __si_type_info
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(n, static_cast <const __user_type_info &> (*ti));
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}
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extern "C" void
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__rtti_user (void *addr, const char *name)
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{ new (addr) __user_type_info (name); }
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// Upcast for catch checking. OBJPTR points to the thrown object and might be
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// NULL. Return 0 on failure, non-zero on success. Set *ADJPTR to adjusted
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// object pointer.
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int __user_type_info::
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upcast (const type_info &target, void *objptr,
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void **adjptr) const
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{
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upcast_result result;
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if (do_upcast (contained_public, target, objptr, result))
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return 0;
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*adjptr = result.target_obj;
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return contained_public_p (result.whole2target);
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}
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// Down or cross cast for dynamic_cast. OBJPTR points to the most derrived
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// object, SUBPTR points to the static base object. Both must not be NULL.
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// TARGET specifies the desired target type, SUBTYPE specifies the static
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// type. Both must be defined. Returns adjusted object pointer on success,
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// NULL on failure. [expr.dynamic.cast]/8 says 'unambiguous public base'. This
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// itself is an ambiguous statement. We choose it to mean the base must be
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// separately unambiguous and public, rather than unambiguous considering only
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// public bases.
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void *__user_type_info::
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dyncast (int boff,
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const type_info &target, void *objptr,
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const type_info &subtype, void *subptr) const
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{
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dyncast_result result;
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do_dyncast (boff, contained_public,
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target, objptr, subtype, subptr, result);
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if (!result.target_obj)
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return NULL;
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if (contained_public_p (result.target2sub))
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return result.target_obj;
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if (contained_public_p (sub_kind (result.whole2sub & result.whole2target)))
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// Found a valid cross cast
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return result.target_obj;
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if (contained_nonvirtual_p (result.whole2sub))
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// Found an invalid cross cast, which cannot also be a down cast
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return NULL;
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if (result.target2sub == unknown)
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result.target2sub = static_cast <const __user_type_info &> (target)
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.find_public_subobj (boff, subtype,
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result.target_obj, subptr);
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if (contained_public_p (result.target2sub))
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// Found a valid down cast
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return result.target_obj;
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// Must be an invalid down cast, or the cross cast wasn't bettered
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return NULL;
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}
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// Catch cast helper. ACCESS_PATH is the access from the complete thrown
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// object to this base. TARGET is the desired type we want to catch. OBJPTR
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// points to this base within the throw object, it might be NULL. Fill in
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// RESULT with what we find. Return true, should we determine catch must fail.
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bool __user_type_info::
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do_upcast (sub_kind access_path,
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const type_info &target, void *objptr,
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upcast_result &__restrict result) const
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{
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if (*this == target)
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{
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result.target_obj = objptr;
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result.base_type = nonvirtual_base_type;
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result.whole2target = access_path;
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return contained_nonpublic_p (access_path);
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}
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return false;
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}
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// dynamic cast helper. ACCESS_PATH gives the access from the most derived
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// object to this base. TARGET indicates the desired type we want. OBJPTR
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// points to this base within the object. SUBTYPE indicates the static type
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// started from and SUBPTR points to that base within the most derived object.
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// Fill in RESULT with what we find. Return true if we have located an
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// ambiguous match.
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bool __user_type_info::
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do_dyncast (int, sub_kind access_path,
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const type_info &target, void *objptr,
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const type_info &subtype, void *subptr,
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dyncast_result &__restrict result) const
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{
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if (objptr == subptr && *this == subtype)
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{
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// The subobject we started from. Indicate how we are accessible from
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// the most derived object.
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result.whole2sub = access_path;
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return false;
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}
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if (*this == target)
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{
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result.target_obj = objptr;
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result.whole2target = access_path;
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result.target2sub = not_contained;
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return false;
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}
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return false;
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}
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// find_public_subobj helper. Return contained_public if we are the desired
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// subtype. OBJPTR points to this base type, SUBPTR points to the desired base
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// object.
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__user_type_info::sub_kind __user_type_info::
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do_find_public_subobj (int, const type_info &, void *objptr, void *subptr) const
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{
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if (subptr == objptr)
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// Must be our type, as the pointers match.
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return contained_public;
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return not_contained;
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}
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// catch helper for single public inheritance types. See
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// __user_type_info::do_upcast for semantics.
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bool __si_type_info::
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do_upcast (sub_kind access_path,
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const type_info &target, void *objptr,
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upcast_result &__restrict result) const
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{
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if (*this == target)
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{
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result.target_obj = objptr;
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result.base_type = nonvirtual_base_type;
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result.whole2target = access_path;
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return contained_nonpublic_p (access_path);
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}
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return base.do_upcast (access_path, target, objptr, result);
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}
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// dynamic cast helper for single public inheritance types. See
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// __user_type_info::do_dyncast for semantics. BOFF indicates how SUBTYPE
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// types are inherited by TARGET types.
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bool __si_type_info::
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do_dyncast (int boff, sub_kind access_path,
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const type_info &target, void *objptr,
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const type_info &subtype, void *subptr,
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dyncast_result &__restrict result) const
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{
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if (objptr == subptr && *this == subtype)
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{
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// The subobject we started from. Indicate how we are accessible from
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// the most derived object.
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result.whole2sub = access_path;
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return false;
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}
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if (*this == target)
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{
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result.target_obj = objptr;
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result.whole2target = access_path;
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if (boff >= 0)
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result.target2sub = ((char *)subptr - (char *)objptr) == boff
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? contained_public : not_contained;
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else if (boff == -2)
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result.target2sub = not_contained;
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return false;
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}
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return base.do_dyncast (boff, access_path,
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target, objptr, subtype, subptr, result);
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}
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// find_public_subobj helper. See __user_type_info::do_find_public_subobj or
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// semantics. BOFF indicates how SUBTYPE types are inherited by the original
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// target object.
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__user_type_info::sub_kind __si_type_info::
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do_find_public_subobj (int boff, const type_info &subtype, void *objptr, void *subptr) const
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{
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if (subptr == objptr && subtype == *this)
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return contained_public;
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return base.do_find_public_subobj (boff, subtype, objptr, subptr);
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}
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// catch helper for multiple or non-public inheritance types. See
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// __user_type_info::do_upcast for semantics.
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bool __class_type_info::
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do_upcast (sub_kind access_path,
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const type_info &target, void *objptr,
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upcast_result &__restrict result) const
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{
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if (*this == target)
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{
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result.target_obj = objptr;
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result.base_type = nonvirtual_base_type;
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result.whole2target = access_path;
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return contained_nonpublic_p (access_path);
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}
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for (size_t i = n_bases; i--;)
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{
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upcast_result result2;
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void *p = objptr;
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sub_kind sub_access = access_path;
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p = convert_to_base (p,
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base_list[i].is_virtual,
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base_list[i].offset);
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if (base_list[i].is_virtual)
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sub_access = sub_kind (sub_access | contained_virtual_mask);
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if (base_list[i].access != PUBLIC)
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sub_access = sub_kind (sub_access & ~contained_public_mask);
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if (base_list[i].base->do_upcast (sub_access, target, p, result2))
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return true; // must fail
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if (result2.base_type)
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{
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if (result2.base_type == nonvirtual_base_type
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&& base_list[i].is_virtual)
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result2.base_type = base_list[i].base;
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if (!result.base_type)
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result = result2;
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else if (result.target_obj != result2.target_obj)
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{
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// Found an ambiguity.
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result.target_obj = NULL;
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result.whole2target = contained_ambig;
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return true;
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}
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else if (result.target_obj)
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{
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// Ok, found real object via a virtual path.
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result.whole2target
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= sub_kind (result.whole2target | result2.whole2target);
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}
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else
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{
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// Dealing with a null pointer, need to check vbase
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// containing each of the two choices.
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if (result2.base_type == nonvirtual_base_type
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|| result.base_type == nonvirtual_base_type
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|| !(*result2.base_type == *result.base_type))
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{
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// Already ambiguous, not virtual or via different virtuals.
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// Cannot match.
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result.whole2target = contained_ambig;
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return true;
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}
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}
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}
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}
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return false;
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}
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// dynamic cast helper for non-public or multiple inheritance types. See
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// __user_type_info::do_dyncast for overall semantics.
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// This is a big hairy function. Although the run-time behaviour of
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// dynamic_cast is simple to describe, it gives rise to some non-obvious
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// behaviour. We also desire to determine as early as possible any definite
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// answer we can get. Because it is unknown what the run-time ratio of
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// succeeding to failing dynamic casts is, we do not know in which direction
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// to bias any optimizations. To that end we make no particular effort towards
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// early fail answers or early success answers. Instead we try to minimize
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// work by filling in things lazily (when we know we need the information),
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// and opportunisticly take early success or failure results.
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bool __class_type_info::
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do_dyncast (int boff, sub_kind access_path,
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const type_info &target, void *objptr,
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const type_info &subtype, void *subptr,
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dyncast_result &__restrict result) const
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{
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if (objptr == subptr && *this == subtype)
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{
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// The subobject we started from. Indicate how we are accessible from
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// the most derived object.
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result.whole2sub = access_path;
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return false;
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}
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if (*this == target)
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{
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result.target_obj = objptr;
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result.whole2target = access_path;
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if (boff >= 0)
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result.target2sub = ((char *)subptr - (char *)objptr) == boff
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? contained_public : not_contained;
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else if (boff == -2)
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result.target2sub = not_contained;
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return false;
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}
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bool result_ambig = false;
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for (size_t i = n_bases; i--;)
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{
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dyncast_result result2;
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void *p;
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sub_kind sub_access = access_path;
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p = convert_to_base (objptr,
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base_list[i].is_virtual,
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base_list[i].offset);
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if (base_list[i].is_virtual)
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sub_access = sub_kind (sub_access | contained_virtual_mask);
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if (base_list[i].access != PUBLIC)
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sub_access = sub_kind (sub_access & ~contained_public_mask);
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bool result2_ambig
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= base_list[i].base->do_dyncast (boff, sub_access,
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target, p, subtype, subptr, result2);
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result.whole2sub = sub_kind (result.whole2sub | result2.whole2sub);
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if (result2.target2sub == contained_public
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|| result2.target2sub == contained_ambig)
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{
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result.target_obj = result2.target_obj;
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result.whole2target = result2.whole2target;
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result.target2sub = result2.target2sub;
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// Found a downcast which can't be bettered or an ambiguous downcast
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// which can't be disambiguated
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return result2_ambig;
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}
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if (!result_ambig && !result.target_obj)
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{
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// Not found anything yet.
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result.target_obj = result2.target_obj;
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result.whole2target = result2.whole2target;
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result_ambig = result2_ambig;
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}
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else if (result.target_obj && result.target_obj == result2.target_obj)
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{
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// Found at same address, must be via virtual. Pick the most
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// accessible path.
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result.whole2target =
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sub_kind (result.whole2target | result2.whole2target);
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}
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else if ((result.target_obj && result2.target_obj)
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|| (result_ambig && result2.target_obj)
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|| (result2_ambig && result.target_obj))
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{
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// Found two different TARGET bases, or a valid one and a set of
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// ambiguous ones, must disambiguate. See whether SUBOBJ is
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// contained publicly within one of the non-ambiguous choices.
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// If it is in only one, then that's the choice. If it is in
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// both, then we're ambiguous and fail. If it is in neither,
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// we're ambiguous, but don't yet fail as we might later find a
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// third base which does contain SUBPTR.
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sub_kind new_sub_kind = result2.target2sub;
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sub_kind old_sub_kind = result.target2sub;
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if (contained_nonvirtual_p (result.whole2sub))
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{
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// We already found SUBOBJ as a non-virtual base of most
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// derived. Therefore if it is in either choice, it can only be
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// in one of them, and we will already know.
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if (old_sub_kind == unknown)
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old_sub_kind = not_contained;
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if (new_sub_kind == unknown)
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new_sub_kind = not_contained;
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}
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else
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{
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const __user_type_info &t =
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static_cast <const __user_type_info &> (target);
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if (old_sub_kind >= not_contained)
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;// already calculated
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else if (contained_nonvirtual_p (new_sub_kind))
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// Already found non-virtually inside the other choice,
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// cannot be in this.
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old_sub_kind = not_contained;
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else
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old_sub_kind = t.find_public_subobj (boff, subtype,
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result.target_obj, subptr);
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if (new_sub_kind >= not_contained)
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;// already calculated
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else if (contained_nonvirtual_p (old_sub_kind))
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// Already found non-virtually inside the other choice,
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// cannot be in this.
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new_sub_kind = not_contained;
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else
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new_sub_kind = t.find_public_subobj (boff, subtype,
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result2.target_obj, subptr);
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}
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// Neither sub_kind can be contained_ambig -- we bail out early
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// when we find those.
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if (contained_p (sub_kind (new_sub_kind ^ old_sub_kind)))
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{
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// Only on one choice, not ambiguous.
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if (contained_p (new_sub_kind))
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{
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// Only in new.
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result.target_obj = result2.target_obj;
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result.whole2target = result2.whole2target;
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result_ambig = false;
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old_sub_kind = new_sub_kind;
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}
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result.target2sub = old_sub_kind;
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if (result.target2sub == contained_public)
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return false; // Can't be an ambiguating downcast for later discovery.
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}
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else if (contained_p (sub_kind (new_sub_kind & old_sub_kind)))
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{
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// In both.
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result.target_obj = NULL;
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result.target2sub = contained_ambig;
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return true; // Fail.
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}
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else
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{
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|
// 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.target_obj = NULL;
|
|
result.target2sub = not_contained;
|
|
result_ambig = true;
|
|
}
|
|
}
|
|
|
|
if (result.whole2sub == contained_private)
|
|
// We found SUBOBJ 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;
|
|
}
|
|
|
|
return result_ambig;
|
|
}
|
|
|
|
// find_public_subobj helper for non-public or multiple inheritance types. See
|
|
// __user_type_info::do_find_public_subobj for semantics. We make use of BOFF
|
|
// to prune the base class walk.
|
|
__user_type_info::sub_kind __class_type_info::
|
|
do_find_public_subobj (int boff, const type_info &subtype, void *objptr, void *subptr) const
|
|
{
|
|
if (objptr == subptr && subtype == *this)
|
|
return contained_public;
|
|
|
|
for (size_t i = n_bases; i--;)
|
|
{
|
|
if (base_list[i].access != PUBLIC)
|
|
continue; // Not public, can't be here.
|
|
void *p;
|
|
|
|
if (base_list[i].is_virtual && boff == -3)
|
|
// Not a virtual base, so can't be here.
|
|
continue;
|
|
|
|
p = convert_to_base (objptr,
|
|
base_list[i].is_virtual,
|
|
base_list[i].offset);
|
|
|
|
sub_kind base_kind = base_list[i].base->do_find_public_subobj
|
|
(boff, subtype, p, subptr);
|
|
if (contained_p (base_kind))
|
|
{
|
|
if (base_list[i].is_virtual)
|
|
base_kind = sub_kind (base_kind | contained_virtual_mask);
|
|
return base_kind;
|
|
}
|
|
}
|
|
|
|
return not_contained;
|
|
}
|
|
#else
|
|
// new abi
|
|
|
|
namespace std {
|
|
|
|
// return true if this is a type_info for a pointer type
|
|
bool type_info::
|
|
is_pointer_p () const
|
|
{
|
|
return false;
|
|
}
|
|
|
|
// return true if this is a type_info for a function type
|
|
bool type_info::
|
|
is_function_p () const
|
|
{
|
|
return false;
|
|
}
|
|
|
|
// try and catch a thrown object.
|
|
bool type_info::
|
|
do_catch (const type_info *thr_type, void **, unsigned) const
|
|
{
|
|
return *this == *thr_type;
|
|
}
|
|
|
|
// upcast from this type to the target. __class_type_info will override
|
|
bool type_info::
|
|
do_upcast (const __class_type_info *, void **) const
|
|
{
|
|
return false;
|
|
}
|
|
|
|
};
|
|
|
|
namespace {
|
|
|
|
using namespace std;
|
|
|
|
// initial part of a vtable, this structure is used with offsetof, so we don't
|
|
// have to keep alignments consistent manually.
|
|
struct vtable_prefix {
|
|
ptrdiff_t whole_object; // offset to most derived object
|
|
const __class_type_info *whole_type; // pointer to most derived type_info
|
|
const void *origin; // what a class's vptr points to
|
|
};
|
|
|
|
template <typename T>
|
|
inline const T *
|
|
adjust_pointer (const void *base, ptrdiff_t offset)
|
|
{
|
|
return reinterpret_cast <const T *>
|
|
(reinterpret_cast <const char *> (base) + offset);
|
|
}
|
|
|
|
// some predicate functions for __class_type_info::sub_kind
|
|
inline bool contained_p (__class_type_info::sub_kind access_path)
|
|
{
|
|
return access_path >= __class_type_info::contained_mask;
|
|
}
|
|
inline bool public_p (__class_type_info::sub_kind access_path)
|
|
{
|
|
return access_path & __class_type_info::contained_public_mask;
|
|
}
|
|
inline bool virtual_p (__class_type_info::sub_kind access_path)
|
|
{
|
|
return (access_path & __class_type_info::contained_virtual_mask);
|
|
}
|
|
inline bool contained_public_p (__class_type_info::sub_kind access_path)
|
|
{
|
|
return (access_path & __class_type_info::contained_public) == __class_type_info::contained_public;
|
|
}
|
|
inline bool contained_nonpublic_p (__class_type_info::sub_kind access_path)
|
|
{
|
|
return (access_path & __class_type_info::contained_public) == __class_type_info::contained_mask;
|
|
}
|
|
inline bool contained_nonvirtual_p (__class_type_info::sub_kind access_path)
|
|
{
|
|
return (access_path & (__class_type_info::contained_mask | __class_type_info::contained_virtual_mask))
|
|
== __class_type_info::contained_mask;
|
|
}
|
|
|
|
static const __class_type_info *const nonvirtual_base_type =
|
|
static_cast <const __class_type_info *> (0) + 1;
|
|
|
|
}; // namespace
|
|
|
|
namespace std {
|
|
|
|
__class_type_info::
|
|
~__class_type_info ()
|
|
{}
|
|
|
|
__si_class_type_info::
|
|
~__si_class_type_info ()
|
|
{}
|
|
|
|
__vmi_class_type_info::
|
|
~__vmi_class_type_info ()
|
|
{}
|
|
|
|
bool __class_type_info::
|
|
do_catch (const type_info *thr_type, void **thr_obj,
|
|
unsigned outer) const
|
|
{
|
|
if (*this == *thr_type)
|
|
return true;
|
|
if (outer >= 4)
|
|
// Neither `A' nor `A *'.
|
|
return false;
|
|
return thr_type->do_upcast (this, thr_obj);
|
|
}
|
|
|
|
bool __class_type_info::
|
|
do_upcast (const __class_type_info *dst_type, void **obj_ptr) const
|
|
{
|
|
upcast_result result (details);
|
|
|
|
if (do_upcast (contained_public, dst_type, *obj_ptr, result))
|
|
return false;
|
|
*obj_ptr = const_cast <void *> (result.dst_ptr);
|
|
return contained_public_p (result.whole2dst);
|
|
}
|
|
|
|
inline __class_type_info::sub_kind __class_type_info::
|
|
find_public_src (ptrdiff_t src2dst,
|
|
const void *obj_ptr,
|
|
const __class_type_info *src_type,
|
|
const void *src_ptr) const
|
|
{
|
|
if (src2dst >= 0)
|
|
return adjust_pointer <void> (obj_ptr, src2dst) == src_ptr
|
|
? contained_public : not_contained;
|
|
if (src2dst == -2)
|
|
return not_contained;
|
|
return do_find_public_src (src2dst, obj_ptr, src_type, src_ptr);
|
|
}
|
|
|
|
__class_type_info::sub_kind __class_type_info::
|
|
do_find_public_src (ptrdiff_t,
|
|
const void *obj_ptr,
|
|
const __class_type_info *,
|
|
const void *src_ptr) const
|
|
{
|
|
if (src_ptr == obj_ptr)
|
|
// Must be our type, as the pointers match.
|
|
return contained_public;
|
|
return not_contained;
|
|
}
|
|
|
|
__class_type_info::sub_kind __si_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 (src_ptr == obj_ptr && *this == *src_type)
|
|
return contained_public;
|
|
return base->do_find_public_src (src2dst, obj_ptr, src_type, src_ptr);
|
|
}
|
|
|
|
__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 (size_t i = n_bases; i--;)
|
|
{
|
|
if (!base_list[i].is_public_p ())
|
|
continue; // Not public, can't be here.
|
|
|
|
const void *base = obj_ptr;
|
|
ptrdiff_t offset = base_list[i].offset;
|
|
|
|
if (base_list[i].is_virtual_p ())
|
|
{
|
|
if (src2dst == -3)
|
|
continue; // Not a virtual base, so can't be here.
|
|
const ptrdiff_t *vtable = *static_cast <const ptrdiff_t *const *> (base);
|
|
|
|
offset = vtable[offset];
|
|
}
|
|
base = adjust_pointer <void> (base, offset);
|
|
|
|
sub_kind base_kind = base_list[i].type->do_find_public_src
|
|
(src2dst, base, src_type, src_ptr);
|
|
if (contained_p (base_kind))
|
|
{
|
|
if (base_list[i].is_virtual_p ())
|
|
base_kind = sub_kind (base_kind | contained_virtual_mask);
|
|
return base_kind;
|
|
}
|
|
}
|
|
|
|
return not_contained;
|
|
}
|
|
|
|
bool __class_type_info::
|
|
do_dyncast (ptrdiff_t,
|
|
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 (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;
|
|
result.dst2src = not_contained;
|
|
return false;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
bool __si_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 (*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 (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;
|
|
}
|
|
return base->do_dyncast (src2dst, access_path, dst_type, obj_ptr,
|
|
src_type, src_ptr, result);
|
|
}
|
|
|
|
// 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 (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;
|
|
}
|
|
bool result_ambig = false;
|
|
for (size_t i = n_bases; i--;)
|
|
{
|
|
dyncast_result result2;
|
|
void const *base = obj_ptr;
|
|
sub_kind base_access = access_path;
|
|
ptrdiff_t offset = base_list[i].offset;
|
|
|
|
if (base_list[i].is_virtual_p ())
|
|
{
|
|
base_access = sub_kind (base_access | contained_virtual_mask);
|
|
const ptrdiff_t *vtable = *static_cast <const ptrdiff_t *const *> (base);
|
|
|
|
offset = vtable[offset];
|
|
}
|
|
base = adjust_pointer <void> (base, offset);
|
|
|
|
if (!base_list[i].is_public_p ())
|
|
base_access = sub_kind (base_access & ~contained_public_mask);
|
|
|
|
bool result2_ambig
|
|
= base_list[i].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;
|
|
}
|
|
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 && result2.dst_ptr)
|
|
|| (result_ambig && result2.dst_ptr)
|
|
|| (result2_ambig && result.dst_ptr))
|
|
{
|
|
// 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_nonvirtual_p (result.whole2src))
|
|
{
|
|
// We already found SRC_PTR as a non-virtual base of most
|
|
// derived. 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_nonvirtual_p (new_sub_kind))
|
|
// Already found non-virtually inside the other choice,
|
|
// cannot be in this.
|
|
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_nonvirtual_p (old_sub_kind))
|
|
// Already found non-virtually inside the other choice,
|
|
// cannot be in this.
|
|
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;
|
|
}
|
|
|
|
return result_ambig;
|
|
}
|
|
|
|
bool __class_type_info::
|
|
do_upcast (sub_kind access_path,
|
|
const __class_type_info *dst, const void *obj,
|
|
upcast_result &__restrict result) const
|
|
{
|
|
if (*this == *dst)
|
|
{
|
|
result.dst_ptr = obj;
|
|
result.base_type = nonvirtual_base_type;
|
|
result.whole2dst = access_path;
|
|
return contained_nonpublic_p (access_path);
|
|
}
|
|
return false;
|
|
}
|
|
|
|
bool __si_class_type_info::
|
|
do_upcast (sub_kind access_path,
|
|
const __class_type_info *dst, const void *obj_ptr,
|
|
upcast_result &__restrict result) const
|
|
{
|
|
if (*this == *dst)
|
|
{
|
|
result.dst_ptr = obj_ptr;
|
|
result.base_type = nonvirtual_base_type;
|
|
result.whole2dst = access_path;
|
|
return contained_nonpublic_p (access_path);
|
|
}
|
|
return base->do_upcast (access_path, dst, obj_ptr, result);
|
|
}
|
|
|
|
bool __vmi_class_type_info::
|
|
do_upcast (sub_kind access_path,
|
|
const __class_type_info *dst, const void *obj_ptr,
|
|
upcast_result &__restrict result) const
|
|
{
|
|
if (*this == *dst)
|
|
{
|
|
result.dst_ptr = obj_ptr;
|
|
result.base_type = nonvirtual_base_type;
|
|
result.whole2dst = access_path;
|
|
return contained_nonpublic_p (access_path);
|
|
}
|
|
|
|
for (size_t i = n_bases; i--;)
|
|
{
|
|
upcast_result result2 (result.src_details);
|
|
const void *base = obj_ptr;
|
|
sub_kind sub_access = access_path;
|
|
ptrdiff_t offset = base_list[i].offset;
|
|
|
|
if (!base_list[i].is_public_p ())
|
|
{
|
|
if (!(result.src_details & multiple_base_mask))
|
|
// original cannot have an ambiguous base
|
|
continue;
|
|
sub_access = sub_kind (sub_access & ~contained_public_mask);
|
|
}
|
|
if (base_list[i].is_virtual_p ())
|
|
{
|
|
sub_access = sub_kind (sub_access | contained_virtual_mask);
|
|
|
|
if (base)
|
|
{
|
|
const ptrdiff_t *vtable = *static_cast <const ptrdiff_t *const *> (base);
|
|
offset = vtable[offset];
|
|
}
|
|
}
|
|
if (base)
|
|
base = adjust_pointer <void> (base, offset);
|
|
|
|
if (base_list[i].type->do_upcast (sub_access, dst, base, result2))
|
|
return true; // must fail
|
|
if (result2.base_type)
|
|
{
|
|
if (result2.base_type == nonvirtual_base_type
|
|
&& base_list[i].is_virtual_p ())
|
|
result2.base_type = base_list[i].type;
|
|
if (!result.base_type)
|
|
{
|
|
result = result2;
|
|
if (!(details & multiple_base_mask))
|
|
// cannot have an ambiguous other base
|
|
return false;
|
|
}
|
|
else if (result.dst_ptr != result2.dst_ptr)
|
|
{
|
|
// Found an ambiguity.
|
|
result.dst_ptr = NULL;
|
|
result.whole2dst = contained_ambig;
|
|
return true;
|
|
}
|
|
else if (result.dst_ptr)
|
|
{
|
|
// Ok, found real object via a virtual path.
|
|
result.whole2dst
|
|
= sub_kind (result.whole2dst | result2.whole2dst);
|
|
}
|
|
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.whole2dst = contained_ambig;
|
|
return true;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
return false;
|
|
}
|
|
|
|
// this is the external interface to the dynamic cast machinery
|
|
void *
|
|
__dynamic_cast (const void *src_ptr, // object started from
|
|
const __class_type_info *src_type, // type of the starting object
|
|
const __class_type_info *dst_type, // desired target type
|
|
ptrdiff_t src2dst) // how src and dst are related
|
|
{
|
|
const void *vtable = *static_cast <const void *const *> (src_ptr);
|
|
const vtable_prefix *prefix =
|
|
adjust_pointer <vtable_prefix> (vtable, 0);
|
|
// FIXME: the above offset should be -offsetof (vtable_prefix, origin));
|
|
// but we don't currently layout vtables correctly.
|
|
const void *whole_ptr =
|
|
adjust_pointer <void> (src_ptr, prefix->whole_object);
|
|
const __class_type_info *whole_type = prefix->whole_type;
|
|
__class_type_info::dyncast_result result;
|
|
|
|
whole_type->do_dyncast (src2dst, __class_type_info::contained_public,
|
|
dst_type, whole_ptr, src_type, src_ptr, result);
|
|
if (!result.dst_ptr)
|
|
return NULL;
|
|
if (contained_public_p (result.dst2src))
|
|
return const_cast <void *> (result.dst_ptr);
|
|
if (contained_public_p (__class_type_info::sub_kind (result.whole2src & result.whole2dst)))
|
|
// Found a valid cross cast
|
|
return const_cast <void *> (result.dst_ptr);
|
|
if (contained_nonvirtual_p (result.whole2src))
|
|
// Found an invalid cross cast, which cannot also be a down cast
|
|
return NULL;
|
|
if (!(whole_type->details & __class_type_info::private_base_mask))
|
|
// whole type has no private bases
|
|
return const_cast <void *> (result.dst_ptr);
|
|
if (result.dst2src == __class_type_info::unknown)
|
|
result.dst2src = dst_type->find_public_src (src2dst, result.dst_ptr,
|
|
src_type, src_ptr);
|
|
if (contained_public_p (result.dst2src))
|
|
// Found a valid down cast
|
|
return const_cast <void *> (result.dst_ptr);
|
|
// Must be an invalid down cast, or the cross cast wasn't bettered
|
|
return NULL;
|
|
}
|
|
|
|
}; // namespace std
|
|
#endif
|