You can’t access it directly because there’s no legitimate use case. Having any arbitrary instruction change eip would make branch prediction very difficult, and would probably open up a whole host of security issues. You can edit eip using jmp, call or ret. You just can’t directly read from or write to eip using normal … Read more
No, EIP / IP cannot be accessed directly, but in position-dependent code it’s a link-time constant so you can use a nearby (or distant) symbol as an immediate. mov eax, nearby_label ; in position-dependent code nearby_label: To get EIP or IP in position-independent 32-bit code: call _here _here: pop eax ; eax now holds the … Read more
You will need both always. The program counter (PC) holds the address of the next instruction to be executed, while the instruction register (IR) holds the encoded instruction. Upon fetching the instruction, the program counter is incremented by one “address value” (to the location of the next instruction). The instruction is then decoded and executed … Read more