: foo ( a -- b ) 1 2 ? ; before: 000000010ac86e60: 4983c608 add r14, 0x8 000000010ac86e64: 48b80800000000000000 mov rax, 0x8 000000010ac86e6e: 48b91000000000000000 mov rcx, 0x10 000000010ac86e78: 498b56f8 mov rdx, [r14-0x8] 000000010ac86e7c: 49890e mov [r14], rcx 000000010ac86e7f: 498946f8 mov [r14-0x8], rax 000000010ac86e83: 4883fa05 cmp rdx, 0x5 000000010ac86e87: 0f8405000000 jz dword 0x10ac86e92 000000010ac86e8d: 4983ee08 sub r14, 0x8 000000010ac86e91: c3 ret 000000010ac86e92: 4983ee08 sub r14, 0x8 000000010ac86e96: 498b5608 mov rdx, [r14+0x8] 000000010ac86e9a: 498916 mov [r14], rdx 000000010ac86e9d: c3 ret after: 000000010c3d6fe0: 48bf0800000000000000 mov rdi, 0x8 000000010c3d6fea: 48b91000000000000000 mov rcx, 0x10 000000010c3d6ff4: 498b1e mov rbx, [r14] 000000010c3d6ff7: 4883fb05 cmp rbx, 0x5 000000010c3d6ffb: 0f8404000000 jz dword 0x10c3d7005 000000010c3d7001: 49893e mov [r14], rdi 000000010c3d7004: c3 ret 000000010c3d7005: 49890e mov [r14], rcx 000000010c3d7008: c3 ret