x86-64 Assembly Quick Reference

Data Movement

mov rax, rbx      ; reg ← reg
mov rax, [rsp+8]  ; load from memory
mov [rsp+8], rax  ; store to memory
lea rax, [rsp+8]  ; load effective address
push rax ; push to stack (rsp -= 8)
pop rax  ; pop from stack (rsp += 8)

Arithmetic

add rax, rbx      ; rax += rbx
sub rax, rbx      ; rax -= rbx
imul rax, rbx     ; rax *= rbx (signed)
idiv rbx          ; rdx:rax ÷ rbx → rax=quotient, rdx=remainder
inc / dec rax     ; ++ / --
neg rax           ; rax = -rax

Bitwise & Logic

and rax, rbx      ; bitwise AND
or  rax, rbx      ; bitwise OR
xor rax, rax      ; zero register (common idiom)
not rax           ; bitwise NOT
shl rax, cl       ; left shift
shr rax, cl       ; logical right shift
sar rax, cl       ; arithmetic right shift

Control Flow

cmp rax, rbx      ; set flags
jz / je label     ; jump if zero / equal
jnz / jne label   ; jump if not zero / not equal
jg label          ; jump if greater (signed)
jl label          ; jump if less (signed)
call func         ; push rip; jmp func
ret               ; pop rip
jmp label         ; unconditional jump

System Calls (Linux)

; syscall number → RAX, args → RDI,RSI,RDX,R10,R8,R9
mov rax, 1        ; sys_write
mov rdi, 1        ; fd=stdout
mov rsi, msg
mov rdx, len
syscall