cmp

Compare Two Operands

CMP r/m, r

Subtracts src from dest and updates flags (dest not modified).

Details

The Compare Two Operands instruction subtracts src from dest and updates flags (dest not modified).

Pseudocode Operation

// Flags <- DEST - SRC (result discarded)
// Flags affected: OF, SF, ZF, AF, CF, PF

Example

CMP rbx, rax

Encoding

Binary Layout
38+ow
+0
ModRM
+1
 
Format Legacy
Opcode 38-3D
Extension Base

Operands

  • dest
    Register or memory operand
  • src
    General-purpose register