What are the single-operand arithmetic instructions in x86-64?

They modify one operand in place: inc (+1), dec (−1), neg (two's-complement negate), and not (bitwise complement).

These are compact, common operations on a single value:

incq %rax       # rax++
decl (%rbx)     # (*rbx)-- on a 32-bit value in memory
negq %rcx       # rcx = -rcx
notl %edx       # edx = ~edx

The important gotcha: inc and dec deliberately do not set the carry flag (CF), unlike add $1 and sub $1. This was chosen so a loop can increment a counter without disturbing a carry that a surrounding multi-precision computation depends on — but it means you can't use inc/dec when you actually need the carry out.

Go deeper:

• Felix Cloutier — INC — INC and the crucial CF-preservation gotcha.
• Felix Cloutier — NEG — NEG two's-complement negate.