Translate function your_function into LEGv8 assembly instructions. Since external_function is not under your control, you must obey LEGv8 function calling conventions regarding registers and stack usage. The function declaration for the external function is:

int64_t external_function(int64_t x, int64_t y);

The code for your function is as follows:

int64_t your_function(int64_t a, int64_t b, int64_t c, int64_t d) {

int64_t tmp1 = external_function(a,b);

int64_t tmp2 = external_function(c,d);

return tmp1 + tmp2;

}