Я ищу подробности структуры, порядка и содержимого VTable и расположения указателей vtable в объектах.
В идеале это будет охватывать одно наследование, множественное наследование и виртуальное наследование.
Также будут оценены ссылки на внешнюю документацию.
Документация макета класса GCC 4.0x здесь, а документы Itanium и более широко GNU, ABI являются здесь.
Виртуальная таблица обычно рассматривается как массив указателей на функции, хотя компиляторы могут размещать указатели данных (в сценариях MI и VI или typeinfos), целые числа (для исправлений) или элементы часового (такие как указатели NULL ) в него. Макет, как правило, специфичен для компилятора (или специфичен для ABI, когда несколько компиляторов С++ совместно используют ABI), но стабильность при условии, что скомпилированные классы имеют стабильные интерфейсы (в противном случае вам придется перекомпилировать свой код все время и перетащить), Существуют также дополнительные таблицы, которые необходимы для обработки угловых случаев, связанных с виртуальным и множественным наследованием, и чтобы убедиться, что виртуальные вызовы в процессе построения производного класса ведут себя как стандарт, говорят, что они должны в этих обстоятельствах (это то, что VTT и таблицы построения в выход ниже для).
Что касается конкретного случая GCC 4.x: переключатель -fdump-class-hierarchy действительно действует как описано (а затем и некоторые). Я тестировал его на Coliru, используя пример кода ниже:
struct Base
{
virtual ~Base() {}
virtual void f() = 0;
};
struct OtherBase
{
virtual ~OtherBase() {}
virtual void g() {}
};
struct Derived: public Base
{
virtual ~Derived() {}
virtual void f() {}
};
struct MultiplyDerived: public Base, public OtherBase
{
virtual ~MultiplyDerived() {}
virtual void f() {}
virtual void g() {}
};
struct OtherDerived: public Base
{
virtual ~OtherDerived() {}
virtual void f() {}
};
struct DiamondDerived: public Derived, public OtherDerived
{
virtual ~DiamondDerived() {}
virtual void f() {}
};
struct VirtuallyDerived: virtual public Base
{
virtual ~VirtuallyDerived() {}
virtual void f() {}
};
struct OtherVirtuallyDerived: virtual public Base
{
virtual ~OtherVirtuallyDerived() {}
virtual void f() {}
};
struct VirtuallyDiamondDerived: public VirtuallyDerived, public OtherVirtuallyDerived
{
virtual ~VirtuallyDiamondDerived() {}
virtual void f() {}
};
struct DoublyVirtuallyDiamondDerived: virtual public VirtuallyDerived, virtual public OtherVirtuallyDerived
{
virtual ~DoublyVirtuallyDiamondDerived() {}
virtual void f() {}
};
struct MixedVirtuallyDerived: virtual public Base, public OtherBase
{
virtual ~MixedVirtuallyDerived() {}
};
struct MixedVirtuallyDiamondDerived: public VirtuallyDerived, public MixedVirtuallyDerived
{
virtual ~MixedVirtuallyDiamondDerived() {}
virtual void f() {}
virtual void g() {}
};
struct VirtuallyMultiplyDerived: virtual public Base, virtual public OtherBase
{
virtual ~VirtuallyMultiplyDerived() {}
};
struct OtherVirtuallyMultiplyDerived: virtual public Base, virtual public OtherBase
{
virtual ~OtherVirtuallyMultiplyDerived() {}
};
struct MultiplyVirtuallyDiamondDerived: public VirtuallyMultiplyDerived, public OtherVirtuallyMultiplyDerived
{
virtual ~MultiplyVirtuallyDiamondDerived() {}
virtual void f() {}
virtual void g() {}
};
и получен из g++ (искаженное руководство по именам: TI - typeinfos, TV - vtables, а Th и Tv - это thunks, используемые для правильных виртуальных вызовов при наличии множественного и/или виртуального наследования):
Vtable for Base
Base::_ZTV4Base: 5u entries
0 (int (*)(...))0
8 (int (*)(...))(& _ZTI4Base)
16 0u
24 0u
32 (int (*)(...))__cxa_pure_virtual
Class Base
size=8 align=8
base size=8 base align=8
Base (0x0x7fd42c0355a0) 0 nearly-empty
vptr=((& Base::_ZTV4Base) + 16u)
Vtable for OtherBase
OtherBase::_ZTV9OtherBase: 5u entries
0 (int (*)(...))0
8 (int (*)(...))(& _ZTI9OtherBase)
16 (int (*)(...))OtherBase::~OtherBase
24 (int (*)(...))OtherBase::~OtherBase
32 (int (*)(...))OtherBase::g
Class OtherBase
size=8 align=8
base size=8 base align=8
OtherBase (0x0x7fd42c035600) 0 nearly-empty
vptr=((& OtherBase::_ZTV9OtherBase) + 16u)
Vtable for Derived
Derived::_ZTV7Derived: 5u entries
0 (int (*)(...))0
8 (int (*)(...))(& _ZTI7Derived)
16 (int (*)(...))Derived::~Derived
24 (int (*)(...))Derived::~Derived
32 (int (*)(...))Derived::f
Class Derived
size=8 align=8
base size=8 base align=8
Derived (0x0x7fd42c02d138) 0 nearly-empty
vptr=((& Derived::_ZTV7Derived) + 16u)
Base (0x0x7fd42c035660) 0 nearly-empty
primary-for Derived (0x0x7fd42c02d138)
Vtable for MultiplyDerived
MultiplyDerived::_ZTV15MultiplyDerived: 11u entries
0 (int (*)(...))0
8 (int (*)(...))(& _ZTI15MultiplyDerived)
16 (int (*)(...))MultiplyDerived::~MultiplyDerived
24 (int (*)(...))MultiplyDerived::~MultiplyDerived
32 (int (*)(...))MultiplyDerived::f
40 (int (*)(...))MultiplyDerived::g
48 (int (*)(...))-8
56 (int (*)(...))(& _ZTI15MultiplyDerived)
64 (int (*)(...))MultiplyDerived::_ZThn8_N15MultiplyDerivedD1Ev
72 (int (*)(...))MultiplyDerived::_ZThn8_N15MultiplyDerivedD0Ev
80 (int (*)(...))MultiplyDerived::_ZThn8_N15MultiplyDerived1gEv
Class MultiplyDerived
size=16 align=8
base size=16 base align=8
MultiplyDerived (0x0x7fd42c04aaf0) 0
vptr=((& MultiplyDerived::_ZTV15MultiplyDerived) + 16u)
Base (0x0x7fd42c0356c0) 0 nearly-empty
primary-for MultiplyDerived (0x0x7fd42c04aaf0)
OtherBase (0x0x7fd42c035720) 8 nearly-empty
vptr=((& MultiplyDerived::_ZTV15MultiplyDerived) + 64u)
Vtable for OtherDerived
OtherDerived::_ZTV12OtherDerived: 5u entries
0 (int (*)(...))0
8 (int (*)(...))(& _ZTI12OtherDerived)
16 (int (*)(...))OtherDerived::~OtherDerived
24 (int (*)(...))OtherDerived::~OtherDerived
32 (int (*)(...))OtherDerived::f
Class OtherDerived
size=8 align=8
base size=8 base align=8
OtherDerived (0x0x7fd42c02d1a0) 0 nearly-empty
vptr=((& OtherDerived::_ZTV12OtherDerived) + 16u)
Base (0x0x7fd42c035780) 0 nearly-empty
primary-for OtherDerived (0x0x7fd42c02d1a0)
Vtable for DiamondDerived
DiamondDerived::_ZTV14DiamondDerived: 10u entries
0 (int (*)(...))0
8 (int (*)(...))(& _ZTI14DiamondDerived)
16 (int (*)(...))DiamondDerived::~DiamondDerived
24 (int (*)(...))DiamondDerived::~DiamondDerived
32 (int (*)(...))DiamondDerived::f
40 (int (*)(...))-8
48 (int (*)(...))(& _ZTI14DiamondDerived)
56 (int (*)(...))DiamondDerived::_ZThn8_N14DiamondDerivedD1Ev
64 (int (*)(...))DiamondDerived::_ZThn8_N14DiamondDerivedD0Ev
72 (int (*)(...))DiamondDerived::_ZThn8_N14DiamondDerived1fEv
Class DiamondDerived
size=16 align=8
base size=16 base align=8
DiamondDerived (0x0x7fd42c0625b0) 0
vptr=((& DiamondDerived::_ZTV14DiamondDerived) + 16u)
Derived (0x0x7fd42c02d208) 0 nearly-empty
primary-for DiamondDerived (0x0x7fd42c0625b0)
Base (0x0x7fd42c0357e0) 0 nearly-empty
primary-for Derived (0x0x7fd42c02d208)
OtherDerived (0x0x7fd42c02d270) 8 nearly-empty
vptr=((& DiamondDerived::_ZTV14DiamondDerived) + 56u)
Base (0x0x7fd42c035840) 8 nearly-empty
primary-for OtherDerived (0x0x7fd42c02d270)
Vtable for VirtuallyDerived
VirtuallyDerived::_ZTV16VirtuallyDerived: 8u entries
0 0u
8 0u
16 0u
24 (int (*)(...))0
32 (int (*)(...))(& _ZTI16VirtuallyDerived)
40 (int (*)(...))VirtuallyDerived::~VirtuallyDerived
48 (int (*)(...))VirtuallyDerived::~VirtuallyDerived
56 (int (*)(...))VirtuallyDerived::f
VTT for VirtuallyDerived
VirtuallyDerived::_ZTT16VirtuallyDerived: 2u entries
0 ((& VirtuallyDerived::_ZTV16VirtuallyDerived) + 40u)
8 ((& VirtuallyDerived::_ZTV16VirtuallyDerived) + 40u)
Class VirtuallyDerived
size=8 align=8
base size=8 base align=8
VirtuallyDerived (0x0x7fd42c02d2d8) 0 nearly-empty
vptridx=0u vptr=((& VirtuallyDerived::_ZTV16VirtuallyDerived) + 40u)
Base (0x0x7fd42c0358a0) 0 nearly-empty virtual
primary-for VirtuallyDerived (0x0x7fd42c02d2d8)
vptridx=8u vbaseoffset=-40
Vtable for OtherVirtuallyDerived
OtherVirtuallyDerived::_ZTV21OtherVirtuallyDerived: 8u entries
0 0u
8 0u
16 0u
24 (int (*)(...))0
32 (int (*)(...))(& _ZTI21OtherVirtuallyDerived)
40 (int (*)(...))OtherVirtuallyDerived::~OtherVirtuallyDerived
48 (int (*)(...))OtherVirtuallyDerived::~OtherVirtuallyDerived
56 (int (*)(...))OtherVirtuallyDerived::f
VTT for OtherVirtuallyDerived
OtherVirtuallyDerived::_ZTT21OtherVirtuallyDerived: 2u entries
0 ((& OtherVirtuallyDerived::_ZTV21OtherVirtuallyDerived) + 40u)
8 ((& OtherVirtuallyDerived::_ZTV21OtherVirtuallyDerived) + 40u)
Class OtherVirtuallyDerived
size=8 align=8
base size=8 base align=8
OtherVirtuallyDerived (0x0x7fd42c02d340) 0 nearly-empty
vptridx=0u vptr=((& OtherVirtuallyDerived::_ZTV21OtherVirtuallyDerived) + 40u)
Base (0x0x7fd42c035900) 0 nearly-empty virtual
primary-for OtherVirtuallyDerived (0x0x7fd42c02d340)
vptridx=8u vbaseoffset=-40
Vtable for VirtuallyDiamondDerived
VirtuallyDiamondDerived::_ZTV23VirtuallyDiamondDerived: 16u entries
0 0u
8 0u
16 0u
24 (int (*)(...))0
32 (int (*)(...))(& _ZTI23VirtuallyDiamondDerived)
40 (int (*)(...))VirtuallyDiamondDerived::~VirtuallyDiamondDerived
48 (int (*)(...))VirtuallyDiamondDerived::~VirtuallyDiamondDerived
56 (int (*)(...))VirtuallyDiamondDerived::f
64 18446744073709551608u
72 18446744073709551608u
80 18446744073709551608u
88 (int (*)(...))-8
96 (int (*)(...))(& _ZTI23VirtuallyDiamondDerived)
104 (int (*)(...))VirtuallyDiamondDerived::_ZThn8_N23VirtuallyDiamondDerivedD1Ev
112 (int (*)(...))VirtuallyDiamondDerived::_ZThn8_N23VirtuallyDiamondDerivedD0Ev
120 (int (*)(...))VirtuallyDiamondDerived::_ZThn8_N23VirtuallyDiamondDerived1fEv
Construction vtable for VirtuallyDerived (0x0x7fd42c02d3a8 instance) in VirtuallyDiamondDerived
VirtuallyDiamondDerived::_ZTC23VirtuallyDiamondDerived0_16VirtuallyDerived: 8u entries
0 0u
8 0u
16 0u
24 (int (*)(...))0
32 (int (*)(...))(& _ZTI16VirtuallyDerived)
40 0u
48 0u
56 (int (*)(...))VirtuallyDerived::f
Construction vtable for OtherVirtuallyDerived (0x0x7fd42c02d410 instance) in VirtuallyDiamondDerived
VirtuallyDiamondDerived::_ZTC23VirtuallyDiamondDerived8_21OtherVirtuallyDerived: 15u entries
0 18446744073709551608u
8 0u
16 0u
24 (int (*)(...))0
32 (int (*)(...))(& _ZTI21OtherVirtuallyDerived)
40 0u
48 0u
56 (int (*)(...))OtherVirtuallyDerived::f
64 8u
72 8u
80 (int (*)(...))8
88 (int (*)(...))(& _ZTI21OtherVirtuallyDerived)
96 0u
104 0u
112 (int (*)(...))OtherVirtuallyDerived::_ZTv0_n32_N21OtherVirtuallyDerived1fEv
VTT for VirtuallyDiamondDerived
VirtuallyDiamondDerived::_ZTT23VirtuallyDiamondDerived: 7u entries
0 ((& VirtuallyDiamondDerived::_ZTV23VirtuallyDiamondDerived) + 40u)
8 ((& VirtuallyDiamondDerived::_ZTC23VirtuallyDiamondDerived0_16VirtuallyDerived) + 40u)
16 ((& VirtuallyDiamondDerived::_ZTC23VirtuallyDiamondDerived0_16VirtuallyDerived) + 40u)
24 ((& VirtuallyDiamondDerived::_ZTC23VirtuallyDiamondDerived8_21OtherVirtuallyDerived) + 40u)
32 ((& VirtuallyDiamondDerived::_ZTC23VirtuallyDiamondDerived8_21OtherVirtuallyDerived) + 96u)
40 ((& VirtuallyDiamondDerived::_ZTV23VirtuallyDiamondDerived) + 40u)
48 ((& VirtuallyDiamondDerived::_ZTV23VirtuallyDiamondDerived) + 104u)
Class VirtuallyDiamondDerived
size=16 align=8
base size=16 base align=8
VirtuallyDiamondDerived (0x0x7fd42c07e460) 0
vptridx=0u vptr=((& VirtuallyDiamondDerived::_ZTV23VirtuallyDiamondDerived) + 40u)
VirtuallyDerived (0x0x7fd42c02d3a8) 0 nearly-empty
primary-for VirtuallyDiamondDerived (0x0x7fd42c07e460)
subvttidx=8u
Base (0x0x7fd42c035960) 0 nearly-empty virtual
primary-for VirtuallyDerived (0x0x7fd42c02d3a8)
vptridx=40u vbaseoffset=-40
OtherVirtuallyDerived (0x0x7fd42c02d410) 8 nearly-empty
lost-primary
subvttidx=24u vptridx=48u vptr=((& VirtuallyDiamondDerived::_ZTV23VirtuallyDiamondDerived) + 104u)
Base (0x0x7fd42c035960) alternative-path
Vtable for DoublyVirtuallyDiamondDerived
DoublyVirtuallyDiamondDerived::_ZTV29DoublyVirtuallyDiamondDerived: 18u entries
0 8u
8 0u
16 0u
24 0u
32 0u
40 (int (*)(...))0
48 (int (*)(...))(& _ZTI29DoublyVirtuallyDiamondDerived)
56 (int (*)(...))DoublyVirtuallyDiamondDerived::~DoublyVirtuallyDiamondDerived
64 (int (*)(...))DoublyVirtuallyDiamondDerived::~DoublyVirtuallyDiamondDerived
72 (int (*)(...))DoublyVirtuallyDiamondDerived::f
80 18446744073709551608u
88 18446744073709551608u
96 18446744073709551608u
104 (int (*)(...))-8
112 (int (*)(...))(& _ZTI29DoublyVirtuallyDiamondDerived)
120 (int (*)(...))DoublyVirtuallyDiamondDerived::_ZTv0_n24_N29DoublyVirtuallyDiamondDerivedD1Ev
128 (int (*)(...))DoublyVirtuallyDiamondDerived::_ZTv0_n24_N29DoublyVirtuallyDiamondDerivedD0Ev
136 (int (*)(...))DoublyVirtuallyDiamondDerived::_ZTv0_n32_N29DoublyVirtuallyDiamondDerived1fEv
Construction vtable for VirtuallyDerived in DoublyVirtuallyDiamondDerived
DoublyVirtuallyDiamondDerived::_ZTC29DoublyVirtuallyDiamondDerived0_16VirtuallyDerived: 8u entries
0 0u
8 0u
16 0u
24 (int (*)(...))0
32 (int (*)(...))(& _ZTI16VirtuallyDerived)
40 0u
48 0u
56 (int (*)(...))VirtuallyDerived::f
Construction vtable for OtherVirtuallyDerived in DoublyVirtuallyDiamondDerived
DoublyVirtuallyDiamondDerived::_ZTC29DoublyVirtuallyDiamondDerived8_21OtherVirtuallyDerived: 15u entries
0 18446744073709551608u
8 0u
16 0u
24 (int (*)(...))0
32 (int (*)(...))(& _ZTI21OtherVirtuallyDerived)
40 0u
48 0u
56 (int (*)(...))OtherVirtuallyDerived::f
64 8u
72 8u
80 (int (*)(...))8
88 (int (*)(...))(& _ZTI21OtherVirtuallyDerived)
96 0u
104 0u
112 (int (*)(...))OtherVirtuallyDerived::_ZTv0_n32_N21OtherVirtuallyDerived1fEv
VTT for DoublyVirtuallyDiamondDerived
DoublyVirtuallyDiamondDerived::_ZTT29DoublyVirtuallyDiamondDerived: 8u entries
0 ((& DoublyVirtuallyDiamondDerived::_ZTV29DoublyVirtuallyDiamondDerived) + 56u)
8 ((& DoublyVirtuallyDiamondDerived::_ZTV29DoublyVirtuallyDiamondDerived) + 56u)
16 ((& DoublyVirtuallyDiamondDerived::_ZTV29DoublyVirtuallyDiamondDerived) + 56u)
24 ((& DoublyVirtuallyDiamondDerived::_ZTV29DoublyVirtuallyDiamondDerived) + 120u)
32 ((& DoublyVirtuallyDiamondDerived::_ZTC29DoublyVirtuallyDiamondDerived0_16VirtuallyDerived) + 40u)
40 ((& DoublyVirtuallyDiamondDerived::_ZTC29DoublyVirtuallyDiamondDerived0_16VirtuallyDerived) + 40u)
48 ((& DoublyVirtuallyDiamondDerived::_ZTC29DoublyVirtuallyDiamondDerived8_21OtherVirtuallyDerived) + 40u)
56 ((& DoublyVirtuallyDiamondDerived::_ZTC29DoublyVirtuallyDiamondDerived8_21OtherVirtuallyDerived) + 96u)
Class DoublyVirtuallyDiamondDerived
size=16 align=8
base size=8 base align=8
DoublyVirtuallyDiamondDerived (0x0x7fd42c07ea10) 0 nearly-empty
vptridx=0u vptr=((& DoublyVirtuallyDiamondDerived::_ZTV29DoublyVirtuallyDiamondDerived) + 56u)
VirtuallyDerived (0x0x7fd42c02d478) 0 nearly-empty virtual
primary-for DoublyVirtuallyDiamondDerived (0x0x7fd42c07ea10)
subvttidx=32u vptridx=8u vbaseoffset=-48
Base (0x0x7fd42c035a80) 0 nearly-empty virtual
primary-for VirtuallyDerived (0x0x7fd42c02d478)
vptridx=16u vbaseoffset=-40
OtherVirtuallyDerived (0x0x7fd42c02d4e0) 8 nearly-empty virtual
lost-primary
subvttidx=48u vptridx=24u vbaseoffset=-56 vptr=((& DoublyVirtuallyDiamondDerived::_ZTV29DoublyVirtuallyDiamondDerived) + 120u)
Base (0x0x7fd42c035a80) alternative-path
Vtable for MixedVirtuallyDerived
MixedVirtuallyDerived::_ZTV21MixedVirtuallyDerived: 13u entries
0 8u
8 (int (*)(...))0
16 (int (*)(...))(& _ZTI21MixedVirtuallyDerived)
24 0u
32 0u
40 (int (*)(...))OtherBase::g
48 0u
56 18446744073709551608u
64 (int (*)(...))-8
72 (int (*)(...))(& _ZTI21MixedVirtuallyDerived)
80 0u
88 0u
96 (int (*)(...))__cxa_pure_virtual
VTT for MixedVirtuallyDerived
MixedVirtuallyDerived::_ZTT21MixedVirtuallyDerived: 2u entries
0 ((& MixedVirtuallyDerived::_ZTV21MixedVirtuallyDerived) + 24u)
8 ((& MixedVirtuallyDerived::_ZTV21MixedVirtuallyDerived) + 80u)
Class MixedVirtuallyDerived
size=16 align=8
base size=8 base align=8
MixedVirtuallyDerived (0x0x7fd42c07eee0) 0 nearly-empty
vptridx=0u vptr=((& MixedVirtuallyDerived::_ZTV21MixedVirtuallyDerived) + 24u)
Base (0x0x7fd42c035c60) 8 nearly-empty virtual
vptridx=8u vbaseoffset=-24 vptr=((& MixedVirtuallyDerived::_ZTV21MixedVirtuallyDerived) + 80u)
OtherBase (0x0x7fd42c035cc0) 0 nearly-empty
primary-for MixedVirtuallyDerived (0x0x7fd42c07eee0)
Vtable for MixedVirtuallyDiamondDerived
MixedVirtuallyDiamondDerived::_ZTV28MixedVirtuallyDiamondDerived: 15u entries
0 0u
8 0u
16 0u
24 (int (*)(...))0
32 (int (*)(...))(& _ZTI28MixedVirtuallyDiamondDerived)
40 (int (*)(...))MixedVirtuallyDiamondDerived::~MixedVirtuallyDiamondDerived
48 (int (*)(...))MixedVirtuallyDiamondDerived::~MixedVirtuallyDiamondDerived
56 (int (*)(...))MixedVirtuallyDiamondDerived::f
64 (int (*)(...))MixedVirtuallyDiamondDerived::g
72 18446744073709551608u
80 (int (*)(...))-8
88 (int (*)(...))(& _ZTI28MixedVirtuallyDiamondDerived)
96 (int (*)(...))MixedVirtuallyDiamondDerived::_ZThn8_N28MixedVirtuallyDiamondDerivedD1Ev
104 (int (*)(...))MixedVirtuallyDiamondDerived::_ZThn8_N28MixedVirtuallyDiamondDerivedD0Ev
112 (int (*)(...))MixedVirtuallyDiamondDerived::_ZThn8_N28MixedVirtuallyDiamondDerived1gEv
Construction vtable for VirtuallyDerived (0x0x7fd42c02d750 instance) in MixedVirtuallyDiamondDerived
MixedVirtuallyDiamondDerived::_ZTC28MixedVirtuallyDiamondDerived0_16VirtuallyDerived: 8u entries
0 0u
8 0u
16 0u
24 (int (*)(...))0
32 (int (*)(...))(& _ZTI16VirtuallyDerived)
40 0u
48 0u
56 (int (*)(...))VirtuallyDerived::f
Construction vtable for MixedVirtuallyDerived (0x0x7fd42c0b5380 instance) in MixedVirtuallyDiamondDerived
MixedVirtuallyDiamondDerived::_ZTC28MixedVirtuallyDiamondDerived8_21MixedVirtuallyDerived: 13u entries
0 18446744073709551608u
8 (int (*)(...))0
16 (int (*)(...))(& _ZTI21MixedVirtuallyDerived)
24 0u
32 0u
40 (int (*)(...))OtherBase::g
48 0u
56 8u
64 (int (*)(...))8
72 (int (*)(...))(& _ZTI21MixedVirtuallyDerived)
80 0u
88 0u
96 (int (*)(...))__cxa_pure_virtual
VTT for MixedVirtuallyDiamondDerived
MixedVirtuallyDiamondDerived::_ZTT28MixedVirtuallyDiamondDerived: 7u entries
0 ((& MixedVirtuallyDiamondDerived::_ZTV28MixedVirtuallyDiamondDerived) + 40u)
8 ((& MixedVirtuallyDiamondDerived::_ZTC28MixedVirtuallyDiamondDerived0_16VirtuallyDerived) + 40u)
16 ((& MixedVirtuallyDiamondDerived::_ZTC28MixedVirtuallyDiamondDerived0_16VirtuallyDerived) + 40u)
24 ((& MixedVirtuallyDiamondDerived::_ZTC28MixedVirtuallyDiamondDerived8_21MixedVirtuallyDerived) + 24u)
32 ((& MixedVirtuallyDiamondDerived::_ZTC28MixedVirtuallyDiamondDerived8_21MixedVirtuallyDerived) + 80u)
40 ((& MixedVirtuallyDiamondDerived::_ZTV28MixedVirtuallyDiamondDerived) + 40u)
48 ((& MixedVirtuallyDiamondDerived::_ZTV28MixedVirtuallyDiamondDerived) + 96u)
Class MixedVirtuallyDiamondDerived
size=16 align=8
base size=16 base align=8
MixedVirtuallyDiamondDerived (0x0x7fd42c0b5310) 0
vptridx=0u vptr=((& MixedVirtuallyDiamondDerived::_ZTV28MixedVirtuallyDiamondDerived) + 40u)
VirtuallyDerived (0x0x7fd42c02d750) 0 nearly-empty
primary-for MixedVirtuallyDiamondDerived (0x0x7fd42c0b5310)
subvttidx=8u
Base (0x0x7fd42c035d20) 0 nearly-empty virtual
primary-for VirtuallyDerived (0x0x7fd42c02d750)
vptridx=40u vbaseoffset=-40
MixedVirtuallyDerived (0x0x7fd42c0b5380) 8 nearly-empty
subvttidx=24u vptridx=48u vptr=((& MixedVirtuallyDiamondDerived::_ZTV28MixedVirtuallyDiamondDerived) + 96u)
Base (0x0x7fd42c035d20) alternative-path
OtherBase (0x0x7fd42c035d80) 8 nearly-empty
primary-for MixedVirtuallyDerived (0x0x7fd42c0b5380)
Vtable for VirtuallyMultiplyDerived
VirtuallyMultiplyDerived::_ZTV24VirtuallyMultiplyDerived: 16u entries
0 8u
8 0u
16 0u
24 0u
32 (int (*)(...))0
40 (int (*)(...))(& _ZTI24VirtuallyMultiplyDerived)
48 0u
56 0u
64 (int (*)(...))__cxa_pure_virtual
72 0u
80 18446744073709551608u
88 (int (*)(...))-8
96 (int (*)(...))(& _ZTI24VirtuallyMultiplyDerived)
104 0u
112 0u
120 (int (*)(...))OtherBase::g
VTT for VirtuallyMultiplyDerived
VirtuallyMultiplyDerived::_ZTT24VirtuallyMultiplyDerived: 3u entries
0 ((& VirtuallyMultiplyDerived::_ZTV24VirtuallyMultiplyDerived) + 48u)
8 ((& VirtuallyMultiplyDerived::_ZTV24VirtuallyMultiplyDerived) + 48u)
16 ((& VirtuallyMultiplyDerived::_ZTV24VirtuallyMultiplyDerived) + 104u)
Class VirtuallyMultiplyDerived
size=16 align=8
base size=8 base align=8
VirtuallyMultiplyDerived (0x0x7fd42c0b59a0) 0 nearly-empty
vptridx=0u vptr=((& VirtuallyMultiplyDerived::_ZTV24VirtuallyMultiplyDerived) + 48u)
Base (0x0x7fd42c035e40) 0 nearly-empty virtual
primary-for VirtuallyMultiplyDerived (0x0x7fd42c0b59a0)
vptridx=8u vbaseoffset=-40
OtherBase (0x0x7fd42c035ea0) 8 nearly-empty virtual
vptridx=16u vbaseoffset=-48 vptr=((& VirtuallyMultiplyDerived::_ZTV24VirtuallyMultiplyDerived) + 104u)
Vtable for OtherVirtuallyMultiplyDerived
OtherVirtuallyMultiplyDerived::_ZTV29OtherVirtuallyMultiplyDerived: 16u entries
0 8u
8 0u
16 0u
24 0u
32 (int (*)(...))0
40 (int (*)(...))(& _ZTI29OtherVirtuallyMultiplyDerived)
48 0u
56 0u
64 (int (*)(...))__cxa_pure_virtual
72 0u
80 18446744073709551608u
88 (int (*)(...))-8
96 (int (*)(...))(& _ZTI29OtherVirtuallyMultiplyDerived)
104 0u
112 0u
120 (int (*)(...))OtherBase::g
VTT for OtherVirtuallyMultiplyDerived
OtherVirtuallyMultiplyDerived::_ZTT29OtherVirtuallyMultiplyDerived: 3u entries
0 ((& OtherVirtuallyMultiplyDerived::_ZTV29OtherVirtuallyMultiplyDerived) + 48u)
8 ((& OtherVirtuallyMultiplyDerived::_ZTV29OtherVirtuallyMultiplyDerived) + 48u)
16 ((& OtherVirtuallyMultiplyDerived::_ZTV29OtherVirtuallyMultiplyDerived) + 104u)
Class OtherVirtuallyMultiplyDerived
size=16 align=8
base size=8 base align=8
OtherVirtuallyMultiplyDerived (0x0x7fd42c0b5d90) 0 nearly-empty
vptridx=0u vptr=((& OtherVirtuallyMultiplyDerived::_ZTV29OtherVirtuallyMultiplyDerived) + 48u)
Base (0x0x7fd42c035f00) 0 nearly-empty virtual
primary-for OtherVirtuallyMultiplyDerived (0x0x7fd42c0b5d90)
vptridx=8u vbaseoffset=-40
OtherBase (0x0x7fd42c035f60) 8 nearly-empty virtual
vptridx=16u vbaseoffset=-48 vptr=((& OtherVirtuallyMultiplyDerived::_ZTV29OtherVirtuallyMultiplyDerived) + 104u)
Vtable for MultiplyVirtuallyDiamondDerived
MultiplyVirtuallyDiamondDerived::_ZTV31MultiplyVirtuallyDiamondDerived: 26u entries
0 16u
8 0u
16 0u
24 0u
32 (int (*)(...))0
40 (int (*)(...))(& _ZTI31MultiplyVirtuallyDiamondDerived)
48 (int (*)(...))MultiplyVirtuallyDiamondDerived::~MultiplyVirtuallyDiamondDerived
56 (int (*)(...))MultiplyVirtuallyDiamondDerived::~MultiplyVirtuallyDiamondDerived
64 (int (*)(...))MultiplyVirtuallyDiamondDerived::f
72 (int (*)(...))MultiplyVirtuallyDiamondDerived::g
80 8u
88 18446744073709551608u
96 18446744073709551608u
104 18446744073709551608u
112 (int (*)(...))-8
120 (int (*)(...))(& _ZTI31MultiplyVirtuallyDiamondDerived)
128 (int (*)(...))MultiplyVirtuallyDiamondDerived::_ZThn8_N31MultiplyVirtuallyDiamondDerivedD1Ev
136 (int (*)(...))MultiplyVirtuallyDiamondDerived::_ZThn8_N31MultiplyVirtuallyDiamondDerivedD0Ev
144 0u
152 18446744073709551600u
160 18446744073709551600u
168 (int (*)(...))-16
176 (int (*)(...))(& _ZTI31MultiplyVirtuallyDiamondDerived)
184 (int (*)(...))MultiplyVirtuallyDiamondDerived::_ZTv0_n24_N31MultiplyVirtuallyDiamondDerivedD1Ev
192 (int (*)(...))MultiplyVirtuallyDiamondDerived::_ZTv0_n24_N31MultiplyVirtuallyDiamondDerivedD0Ev
200 (int (*)(...))MultiplyVirtuallyDiamondDerived::_ZTv0_n32_N31MultiplyVirtuallyDiamondDerived1gEv
Construction vtable for VirtuallyMultiplyDerived (0x0x7fd42bcdf230 instance) in MultiplyVirtuallyDiamondDerived
MultiplyVirtuallyDiamondDerived::_ZTC31MultiplyVirtuallyDiamondDerived0_24VirtuallyMultiplyDerived: 16u entries
0 16u
8 0u
16 0u
24 0u
32 (int (*)(...))0
40 (int (*)(...))(& _ZTI24VirtuallyMultiplyDerived)
48 0u
56 0u
64 (int (*)(...))__cxa_pure_virtual
72 0u
80 18446744073709551600u
88 (int (*)(...))-16
96 (int (*)(...))(& _ZTI24VirtuallyMultiplyDerived)
104 0u
112 0u
120 (int (*)(...))OtherBase::g
Construction vtable for OtherVirtuallyMultiplyDerived (0x0x7fd42bcdf2a0 instance) in MultiplyVirtuallyDiamondDerived
MultiplyVirtuallyDiamondDerived::_ZTC31MultiplyVirtuallyDiamondDerived8_29OtherVirtuallyMultiplyDerived: 23u entries
0 8u
8 18446744073709551608u
16 18446744073709551608u
24 0u
32 (int (*)(...))0
40 (int (*)(...))(& _ZTI29OtherVirtuallyMultiplyDerived)
48 0u
56 0u
64 (int (*)(...))__cxa_pure_virtual
72 0u
80 8u
88 (int (*)(...))8
96 (int (*)(...))(& _ZTI29OtherVirtuallyMultiplyDerived)
104 0u
112 0u
120 (int (*)(...))__cxa_pure_virtual
128 0u
136 18446744073709551608u
144 (int (*)(...))-8
152 (int (*)(...))(& _ZTI29OtherVirtuallyMultiplyDerived)
160 0u
168 0u
176 (int (*)(...))OtherBase::g
VTT for MultiplyVirtuallyDiamondDerived
MultiplyVirtuallyDiamondDerived::_ZTT31MultiplyVirtuallyDiamondDerived: 10u entries
0 ((& MultiplyVirtuallyDiamondDerived::_ZTV31MultiplyVirtuallyDiamondDerived) + 48u)
8 ((& MultiplyVirtuallyDiamondDerived::_ZTC31MultiplyVirtuallyDiamondDerived0_24VirtuallyMultiplyDerived) + 48u)
16 ((& MultiplyVirtuallyDiamondDerived::_ZTC31MultiplyVirtuallyDiamondDerived0_24VirtuallyMultiplyDerived) + 48u)
24 ((& MultiplyVirtuallyDiamondDerived::_ZTC31MultiplyVirtuallyDiamondDerived0_24VirtuallyMultiplyDerived) + 104u)
32 ((& MultiplyVirtuallyDiamondDerived::_ZTC31MultiplyVirtuallyDiamondDerived8_29OtherVirtuallyMultiplyDerived) + 48u)
40 ((& MultiplyVirtuallyDiamondDerived::_ZTC31MultiplyVirtuallyDiamondDerived8_29OtherVirtuallyMultiplyDerived) + 104u)
48 ((& MultiplyVirtuallyDiamondDerived::_ZTC31MultiplyVirtuallyDiamondDerived8_29OtherVirtuallyMultiplyDerived) + 160u)
56 ((& MultiplyVirtuallyDiamondDerived::_ZTV31MultiplyVirtuallyDiamondDerived) + 48u)
64 ((& MultiplyVirtuallyDiamondDerived::_ZTV31MultiplyVirtuallyDiamondDerived) + 184u)
72 ((& MultiplyVirtuallyDiamondDerived::_ZTV31MultiplyVirtuallyDiamondDerived) + 128u)
Class MultiplyVirtuallyDiamondDerived
size=24 align=8
base size=16 base align=8
MultiplyVirtuallyDiamondDerived (0x0x7fd42bcdf1c0) 0
vptridx=0u vptr=((& MultiplyVirtuallyDiamondDerived::_ZTV31MultiplyVirtuallyDiamondDerived) + 48u)
VirtuallyMultiplyDerived (0x0x7fd42bcdf230) 0 nearly-empty
primary-for MultiplyVirtuallyDiamondDerived (0x0x7fd42bcdf1c0)
subvttidx=8u
Base (0x0x7fd42bce2000) 0 nearly-empty virtual
primary-for VirtuallyMultiplyDerived (0x0x7fd42bcdf230)
vptridx=56u vbaseoffset=-40
OtherBase (0x0x7fd42bce2060) 16 nearly-empty virtual
vptridx=64u vbaseoffset=-48 vptr=((& MultiplyVirtuallyDiamondDerived::_ZTV31MultiplyVirtuallyDiamondDerived) + 184u)
OtherVirtuallyMultiplyDerived (0x0x7fd42bcdf2a0) 8 nearly-empty
lost-primary
subvttidx=32u vptridx=72u vptr=((& MultiplyVirtuallyDiamondDerived::_ZTV31MultiplyVirtuallyDiamondDerived) + 128u)
Base (0x0x7fd42bce2000) alternative-path
OtherBase (0x0x7fd42bce2060) alternative-path
Большинство реализаций компилятора, которые я видел, просто "внедряют" базовый объект в производный объект. Это становится неуместным, когда vtable поддерживается, поскольку относительное смещение в объект будет просто добавляться во время компиляции по мере оценки ссылок.
Множественное и виртуальное наследование сложнее и может потребовать другого смещения в зависимости от того, к чему обращаются.
Я очень рекомендую прочитать эту статью в Code Project: Невозможно быстро С++ делегаты
Это блестяще дает широкую картину того, как разные компиляторы обрабатывают различные аспекты наследования. Фантастическое чтение, если вас интересуют низкоуровневые работы разных компиляторов.
Изменить: я связал неправильную статью. Исправленный.