// gcc -S -O0
    .file   "x.cpp"
    .text
    .globl  main
    .type   main, @function
main:
.LFB0:
    .cfi_startproc
    pushq   %rbp
    .cfi_def_cfa_offset 16
    .cfi_offset 6, -16
    movq    %rsp, %rbp
    .cfi_def_cfa_register 6
    movl    $10, -20(%rbp)
    movl    $20, -4(%rbp)
    leaq    -20(%rbp), %rax
    movq    %rax, -16(%rbp)
    movq    -16(%rbp), %rax
    movl    -4(%rbp), %edx
    movl    %edx, (%rax)
    movl    $0, %eax
    popq    %rbp
    .cfi_def_cfa 7, 8
    ret
    .cfi_endproc
.LFE0:
    .size   main, .-main
    .globl  _Z1rv
    .type   _Z1rv, @function
_Z1rv:
.LFB1:
    .cfi_startproc
    pushq   %rbp
    .cfi_def_cfa_offset 16
    .cfi_offset 6, -16
    movq    %rsp, %rbp
    .cfi_def_cfa_register 6
    movl    $0, -20(%rbp)
    movl    $0, -4(%rbp)
    leaq    -20(%rbp), %rax
    movq    %rax, -16(%rbp)
    movq    -16(%rbp), %rax
    movl    -4(%rbp), %edx
    movl    %edx, (%rax)
    nop
    popq    %rbp
    .cfi_def_cfa 7, 8
    ret
    .cfi_endproc
.LFE1:
    .size   _Z1rv, .-_Z1rv
    .ident  "GCC: (SUSE Linux) 6.2.1 20160830 [gcc-6-branch revision 239856]"
    .section    .note.GNU-stack,"",@progbits

// source
int main() {
    int a = 10;
    int b = 20;
    int *x = &a;
    *x = b;

    return 0;
}

void r() {
    int a = 0;
    int b = 0;
    int &c = a;
    c = b;
}