我正在寻找VTable结构，顺序和内容的详细信息，以及对象中vtable指针的位置。
理想情况下，这将涵盖单继承，多继承和虚拟继承。
对外部文档的引用也将不胜感激
GCC 4.0x类布局的文档在这里，Itanium以及更广泛的GNU，ABI布局文档在这里。
尽管编译器可以自由地将数据指针(在MI和VI场景中，或者在typeinfos中)，整数(用于修正)或哨兵元素(例如NULL指针)放入其中，但虚拟表通常被视为函数指针的数组。也一样该布局通常是特定于编译器的(或多个A ++特定于ABI的，其中多个C ++编译器共享一个ABI)，但要保持稳定，前提是所编译的类具有稳定的接口(否则，您必须一直重新编译代码，这很麻烦) 。还需要其他表格来处理涉及虚拟继承和多重继承的特殊情况，并确保派生类构造期间的虚拟调用在标准情况下的行为与标准所说的一样(这些是VTT和构造表中的内容)。下面的输出用于)。
关于GCC 4.x的特定情况：-fdump-class-hierarchy开关确实按照描述的(然后是某些)的方式工作。我使用以下示例代码在Coliru上对其进行了测试：
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| 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() {}
}; |
并从G ++接收(纠结的名称指南：TI是typeinfos，TV是vtable，Th和Tv是用于在存在多个和/或虚拟继承的情况下进行正确的虚拟调用的thunk)：
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| 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 |
我看到的大多数编译器实现都只是将基础对象"嵌入"到派生对象中。保持vtable的位置变得无关紧要，因为在评估引用时，将仅在编译时将对象的相对偏移量添加进来。
多重继承和虚拟继承更为复杂，根据所访问的内容，可能需要不同的偏移量。
我强烈建议阅读有关代码项目的文章：不可能的快速C ++委托
它很好地概述了不同的编译器如何处理继承的各个方面。如果您对不同编译器的低级工作感兴趣，则非常棒。
编辑：我在那链接了错误的文章。已更正。
