assembly.asm

Vector_create:
        push    rbp
        mov     rbp, rsp
        mov     QWORD PTR [rbp-40], rdi
        mov     QWORD PTR [rbp-48], rsi
        pxor    xmm0, xmm0
        movaps  XMMWORD PTR [rbp-32], xmm0
        movq    QWORD PTR [rbp-16], xmm0
        mov     rax, QWORD PTR [rbp-48]
        mov     QWORD PTR [rbp-32], rax
        mov     rcx, QWORD PTR [rbp-40]
        mov     rax, QWORD PTR [rbp-32]
        mov     rdx, QWORD PTR [rbp-24]
        mov     QWORD PTR [rcx], rax
        mov     QWORD PTR [rcx+8], rdx
        mov     rax, QWORD PTR [rbp-16]
        mov     QWORD PTR [rcx+16], rax
        mov     rax, QWORD PTR [rbp-40]
        pop     rbp
        ret
main:
        push    rbp
        mov     rbp, rsp
        sub     rsp, 32
        lea     rax, [rbp-32]
        mov     esi, 100
        mov     rdi, rax
        call    Vector_create
        mov     eax, 0
        leave
        ret

c.c

#include <stddef.h>
#include <stdint.h>

struct Vector {
    uint64_t    size;
    void        *data;
    uint64_t    field2;
};

struct Vector Vector_create(uint64_t size)
{
    struct Vector v = {
        .size = size,
        .data = NULL
    };
    return v;
}

int main()
{
    struct Vector v = Vector_create(100);
}