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| // Compile with "cl /c /Zi /GR- SimplePaddingTest.cpp"
// Link with "link SimplePaddingTest.obj /debug /nodefaultlib /entry:main"
#include <stdint.h>
extern "C" using at_exit_handler = void();
int atexit(at_exit_handler handler) { return 0; }
struct SimplePadNoPadding {
int32_t X;
int32_t Y;
// No padding anywhere, sizeof(T) = 8
} A;
struct SimplePadUnion {
union {
int32_t X;
int64_t Y;
struct {
int32_t X;
// 4 bytes of padding here
int64_t Y;
} Z;
};
// Since the padding occurs at a location that is occupied by other storage
// (namely the Y member), the storage will still be considered used, and so
// there will be no unused bytes in the larger class. But in the debug
// info for the nested struct, we should see padding.
// sizeof(SimplePadUnion) == sizeof(Z) == 16
} B;
struct SimplePadNoPadding2 {
bool A;
bool B;
bool C;
bool D;
// No padding anywhere, sizeof(T) = 4
} C;
struct alignas(4) SimplePadFields1 {
char A;
char B;
char C;
// 1 byte of padding here, sizeof(T) = 4
} E;
struct SimplePadFields2 {
int32_t Y;
char X;
} F;
struct SimplePadBase {
// Make sure this class is 4 bytes, and the derived class requires 8 byte
// alignment, so that padding is inserted between base and derived.
int32_t X;
// No padding here
} G;
struct SimplePadDerived : public SimplePadBase {
// 4 bytes of padding here due to Y requiring 8 byte alignment.
// Thus, sizeof(T) = 16
int64_t Y;
} H;
struct SimplePadEmptyBase1 {};
struct SimplePadEmptyBase2 {};
struct SimplePadEmpty : public SimplePadEmptyBase1, SimplePadEmptyBase2 {
// Bases have to occupy at least 1 byte of storage, so this requires
// 2 bytes of padding, plus 1 byte for each base, yielding sizeof(T) = 8
int32_t X;
} I;
struct SimplePadVfptr {
virtual ~SimplePadVfptr() {}
static void operator delete(void *ptr, size_t sz) {}
int32_t X;
} J;
struct NonEmptyBase1 {
bool X;
};
struct NonEmptyBase2 {
bool Y;
};
struct SimplePadMultiInherit : public NonEmptyBase1, public NonEmptyBase2 {
// X and Y from the 2 bases will get squished together, leaving 2 bytes
// of padding necessary for proper alignment of an int32.
// Therefore, sizeof(T) = 2 + 2 + 4 = 8
int32_t X;
} K;
struct SimplePadMultiInherit2 : public SimplePadFields1, SimplePadFields2 {
// There should be 1 byte of padding after the first class, and
// 3 bytes of padding after the second class.
int32_t X;
} L;
struct OneLevelInherit : public NonEmptyBase1 {
short Y;
};
struct SimplePadTwoLevelInherit : public OneLevelInherit {
// OneLevelInherit has nested padding because of its base,
// and then padding again because of this class. So each
// class should be 4 bytes, yielding sizeof(T) = 12.
int64_t Z;
} M;
struct SimplePadAggregate {
NonEmptyBase1 X;
int32_t Y;
// the presence of X will cause 3 bytes of padding to be injected.
SimplePadFields1 Fields;
} N;
struct SimplePadVtable1 {
static void operator delete(void *ptr, size_t sz) {}
virtual ~SimplePadVtable1() {}
virtual void A1() {}
virtual void B1() {}
} O;
struct SimplePadVtable2 {
static void operator delete(void *ptr, size_t sz) {}
virtual ~SimplePadVtable2() {}
virtual void X2() {}
virtual void Y2() {}
virtual void Z2() {}
} P;
struct SimplePadVtable3 {
static void operator delete(void *ptr, size_t sz) {}
virtual ~SimplePadVtable3() {}
virtual void Foo3() {}
virtual void Bar3() {}
virtual void Baz3() {}
virtual void Buzz3() {}
} Q;
struct SimplePadMultiVTables
: public SimplePadVtable1,
public SimplePadVtable2,
public SimplePadVtable3 {
~SimplePadMultiVTables() override {}
static void operator delete(void *ptr, size_t sz) {}
// SimplePadVtable1 overrides
void A1() override {}
// SimplePadVtable2 overrides
void Y2() override {}
void Z2() override {}
// SimplePadVtable3 overrides
void Bar3() override {}
void Baz3() override {}
void Buzz3() override {}
} R;
int main(int argc, char **argv) {
return 0;
}
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