ASM Details for new and delete

Assembly code generated by MSVC++ 6.0 for delete and delete[]:

::delete pf;
::delete [] pf;

mov    edx,dword ptr [ebp-10h]
mov    dword ptr [ebp-24h],edx
mov    eax,dword ptr [ebp-24h]
mov    dword ptr [ebp-20h],eax
cmp    dword ptr [ebp-20h],0
je     main+0B0h (00401700)
push   0
mov    ecx,dword ptr [ebp-20h]
call   @ILT+520(Foo::`scalar destructor')
mov    dword ptr [ebp-2Ch],eax
jmp    main+0B7h (00401707)
mov    dword ptr [ebp-2Ch],0
mov    ecx,dword ptr [ebp-2Ch]
push   ecx
call   operator delete (00406ec0)
add    esp,4


mov    edx,dword ptr [ebp-10h]
mov    dword ptr [ebp-24h],edx
mov    eax,dword ptr [ebp-24h]
mov    dword ptr [ebp-20h],eax
cmp    dword ptr [ebp-20h],0
je     main+0B0h (004016f0)
push   3
mov    ecx,dword ptr [ebp-20h]
call   @ILT+315(Foo::`vector destructor')
mov    dword ptr [ebp-2Ch],eax
jmp    main+0B7h (004016f7)
mov    dword ptr [ebp-2Ch],0

This code:

char *buffer = ::new char[sizeof(Foo)];  // allocate 12 bytes on the heap
Foo *pf2 = ::new (buffer) Foo(1, 2, 3);  // construct a Foo object in buffer (placement)

char *buffer = ::new char[sizeof(Foo)];  // allocate 12 bytes on the heap

push   0Ch
call   operator new (004210b0)
add    esp,4
mov    dword ptr [ebp-20h],eax
mov    eax,dword ptr [ebp-20h]
mov    dword ptr [ebp-10h],eax


Foo *pf2 = ::new (buffer) Foo(1, 2, 3);  // construct a Foo object in buffer (placement)

mov    ecx,dword ptr [ebp-10h]
push   ecx
push   0Ch
call   @ILT+80(operator new) (00401055)
add    esp,8
mov    dword ptr [ebp-28h],eax
mov    dword ptr [ebp-4],0
cmp    dword ptr [ebp-28h],0
je     main+77h (004016d7)
push   3
push   2
push   1
mov    ecx,dword ptr [ebp-28h]
call   @ILT+555(Foo::Foo) (00401230)
mov    dword ptr [ebp-44h],eax
jmp    main+7Eh (004016de)
mov    dword ptr [ebp-44h],0
mov    edx,dword ptr [ebp-44h]
mov    dword ptr [ebp-24h],edx
mov    dword ptr [ebp-4],0FFFFFFFFh
mov    eax,dword ptr [ebp-24h]
mov    dword ptr [ebp-14h],eax

This code:

int main(void)
{
  Foo f(1, 2, 3);  // create Foo on the stack
  return 0;
}

generates this:

  Foo f(1, 2, 3);
  
0041B1AE  push        3    
0041B1B0  push        2    
0041B1B2  push        1    
0041B1B4  lea         ecx,[f] 
0041B1B7  call        Foo::Foo (419C35h)

  return 0;
  
0041B1BC  mov         dword ptr [ebp-0DCh],0 
0041B1C6  lea         ecx,[f] 
0041B1C9  call        Foo::~Foo (419CF3h) 
0041B1CE  mov         eax,dword ptr [ebp-0DCh] 

This code:

int main(void)
{
  Foo *pf1 = ::new Foo(1, 2, 3); // allocate memory, construct
  ::delete pf1;                  // destroy, deallocate memory
}

generates this:

  Foo *pf = ::new Foo(1, 2, 3); // allocate memory, construct
  
0041B1D3  push        0Ch  
0041B1D5  call        operator new (419EA6h)
0041B1DA  add         esp,4 
0041B1DD  mov         dword ptr [ebp-0F8h],eax 
0041B1E3  mov         dword ptr [ebp-4],0 
0041B1EA  cmp         dword ptr [ebp-0F8h],0 
0041B1F1  je          main+6Ch (41B20Ch) 
0041B1F3  push        3    
0041B1F5  push        2    
0041B1F7  push        1    
0041B1F9  mov         ecx,dword ptr [ebp-0F8h] 
0041B1FF  call        Foo::Foo (419C3Fh)
0041B204  mov         dword ptr [ebp-10Ch],eax 
0041B20A  jmp         main+76h (41B216h) 
0041B20C  mov         dword ptr [ebp-10Ch],0 
0041B216  mov         eax,dword ptr [ebp-10Ch] 
0041B21C  mov         dword ptr [ebp-104h],eax 
0041B222  mov         dword ptr [ebp-4],0FFFFFFFFh 
0041B229  mov         ecx,dword ptr [ebp-104h] 
0041B22F  mov         dword ptr [pf],ecx 


  ::delete pf;                  // destroy, deallocate memory
  
0041B232  mov         eax,dword ptr [pf] 
0041B235  mov         dword ptr [ebp-0E0h],eax 
0041B23B  mov         ecx,dword ptr [ebp-0E0h] 
0041B241  mov         dword ptr [ebp-0ECh],ecx 
0041B247  cmp         dword ptr [ebp-0ECh],0 
0041B24E  je          main+0C5h (41B265h) 
0041B250  push        0    
0041B252  mov         ecx,dword ptr [ebp-0ECh] 
0041B258  call        Foo::`scalar deleting destructor' (419BA4h)
0041B25D  mov         dword ptr [ebp-10Ch],eax 
0041B263  jmp         main+0CFh (41B26Fh) 
0041B265  mov         dword ptr [ebp-10Ch],0 
0041B26F  mov         edx,dword ptr [ebp-10Ch] 
0041B275  push        edx  
0041B276  call        operator delete (419591h)
0041B27B  add         esp,4 


  return 0;
  
0041B27E  xor         eax,eax 

int main(void)
{
  try {
    T *pt = ::new T[5];
    ::delete [] pt;
  }
  catch (const char *e) {
    std::cout << e << std::endl;
  }

  return 0;
}

T *pt = ::new T[5];
    
00416DAE  push        9    
00416DB0  call        operator new[] (4155FAh) 
00416DB5  add         esp,4 
00416DB8  mov         dword ptr [ebp-11Ch],eax 
00416DBE  mov         eax,dword ptr [ebp-11Ch] 
00416DC4  mov         dword ptr [ebp-108h],eax 
00416DCA  mov         byte ptr [ebp-4],1 
00416DCE  cmp         dword ptr [ebp-108h],0 
00416DD5  je          main+0A1h (416E11h) 
00416DD7  mov         ecx,dword ptr [ebp-108h] 
00416DDD  mov         dword ptr [ecx],5 
00416DE3  push        offset T::~T (4155C3h) 
00416DE8  push        offset T::T (415B63h) 
00416DED  push        5    
00416DEF  push        1    
00416DF1  mov         edx,dword ptr [ebp-108h] 
00416DF7  add         edx,4 
00416DFA  push        edx  
00416DFB  call        `eh vector constructor iterator' (415A1Eh) 
00416E00  mov         eax,dword ptr [ebp-108h] 
00416E06  add         eax,4 
00416E09  mov         dword ptr [ebp-120h],eax 
00416E0F  jmp         main+0ABh (416E1Bh) 
00416E11  mov         dword ptr [ebp-120h],0 
00416E1B  mov         ecx,dword ptr [ebp-120h] 
00416E21  mov         dword ptr [ebp-114h],ecx 
00416E27  mov         byte ptr [ebp-4],0 
00416E2B  mov         edx,dword ptr [ebp-114h] 
00416E31  mov         dword ptr [pt],edx