Where is code of the instantiation of C vector?-CodePudding

I have a very simple code as below, which use C vector:

#include <iostream>
#include <vector>
  
using namespace std;
  
int main()
{
    vector<int> g1;
  
    return 0;
}

By coping the code to the website https://godbolt.org/, I know the generated assembly code is as below:

main:
        stp     x29, x30, [sp, -64]!
        mov     x29, sp
        str     x19, [sp, 16]
        add     x0, sp, 40
        bl      std::vector<int, std::allocator<int> >::vector()** [complete object constructor]
        mov     w19, 0
        add     x0, sp, 40
        bl      std::vector<int, std::allocator<int> >::~vector() [complete object destructor]
        mov     w0, w19
        ldr     x19, [sp, 16]
        ldp     x29, x30, [sp], 64
        ret
__static_initialization_and_destruction_0(int, int):
        stp     x29, x30, [sp, -32]!
        mov     x29, sp
        str     w0, [sp, 28]
        str     w1, [sp, 24]
        ldr     w0, [sp, 28]
        cmp     w0, 1
        bne     .L27
        ldr     w1, [sp, 24]
        mov     w0, 65535
        cmp     w1, w0
        bne     .L27
        adrp    x0, _ZStL8__ioinit
        add     x0, x0, :lo12:_ZStL8__ioinit
        bl      std::ios_base::Init::Init() [complete object constructor]
        adrp    x0, __dso_handle
        add     x2, x0, :lo12:__dso_handle
        adrp    x0, _ZStL8__ioinit
        add     x1, x0, :lo12:_ZStL8__ioinit
        adrp    x0, _ZNSt8ios_base4InitD1Ev
        add     x0, x0, :lo12:_ZNSt8ios_base4InitD1Ev
        bl      __cxa_atexit
.L27:
        nop
        ldp     x29, x30, [sp], 32
        ret
_GLOBAL__sub_I_main:
        stp     x29, x30, [sp, -16]!
        mov     x29, sp
        mov     w1, 65535
        mov     w0, 1
        bl      __static_initialization_and_destruction_0(int, int)
        ldp     x29, x30, [sp], 16
        ret
DW.ref.__gxx_personality_v0:
        .xword  __gxx_personality_v0

Now my question is where I can find the code of std::vector<int, std::allocator >::vector().

If I define a new template class in my code as below:

#include <iostream>
using namespace std;
  
template <class T, class U> class A {
    T x;
    U y;
  
public:
    A() { cout << "Constructor Called" << endl; }
};
  
int main()
{
    A<char, char> a;
    A<int, double> b;
    return 0;
}

I know the code of A<char, char> and A<int, double> is generated in the object file of my own code. But for the template class and template function of C STL, where is the code of their instantiated object?

There is in the library file of C standard library, e.g. libstdc .so, but I think compiler will not generate the code inside that .so file.

Thanks!

CodePudding user response：

I know the code of A<char, char> and A<int, double> is generated in the object file of my own code. But for the template class and template function of C STL, where is the code of their instantiated object?

Exactly the same: they are templated types, and only your specific instantiation makes std::vector<int, std::allocator >::vector() exist.

You'll need to think about this in terms of translation units; so, this machine code will be found in each translation unit that includes the header and instantiates that specific type.