Conditional Compare (immediate) sets the value of the condition flags to the result of the comparison of a register value and an immediate value if the condition is TRUE, and an immediate value otherwise.
此指令一般出现在 cmp 指令之后，表示双重比较。
条件比较（立即数）将条件标志的值设置为寄存器值和立即数（如果条件为真）的比较结果，否则把条件标志设置为#<nzcv>的值。
<nzcv> = 1 1 1 1
n = 0x8
z = 0x4
c = 0x2
v = 0x1
32-bit variant
Applies when sf == 0.
CCMP <Wn>, #<imm>, #<nzcv>, <cond>
64-bit variant
Applies when sf == 1.
CCMP <Xn>, #<imm>, #<nzcv>, <cond>
Decode for all variants of this encoding
integer n = UInt(Rn);
integer datasize = if sf == '1' then 64 else 32;
bits(4) flags = nzcv;
bits(datasize) imm = ZeroExtend(imm5, datasize);
bits(N) ZeroExtend(bits(M) x, integer N)
assert N >= M;
return Zeros(N-M) : x;
bits(N) Zeros(integer N)
return Replicate('0',N);
bits(N) Replicate(bits(M) x)
assert N MOD M == 0;
return Replicate(x, N DIV M);
Operation
bits(datasize) operand1 = Xn;
bits(datasize) operand2;
if ConditionHolds(cond) then
operand2 = NOT(imm);
(-, flags) = AddWithCarry(operand1, operand2, '1');
PSTATE.<N,Z,C,V> = flags;
(bits(N), bits(4)) AddWithCarry(bits(N) x, bits(N) y, bit carry_in)
integer unsigned_sum = UInt(x) + UInt(y) + UInt(carry_in);
integer signed_sum = SInt(x) + SInt(y) + UInt(carry_in);
bits(N) result = unsigned_sum<N-1:0>; // same value as signed_sum<N-1:0>
bit n = result<N-1>;
bit z = if IsZero(result) then '1' else '0';
bit c = if UInt(result) == unsigned_sum then '0' else '1';
bit v = if SInt(result) == signed_sum then '0' else '1';
return (result, n:z:c:v);
ccmp x19, #0x0, #0x4, ne # 判断 x19 是否等于 0 ，如果不等于(ne)零，z标志位为0；如果等于(eq)零，把标志位设置0x4。
4034f4: f9405a94 ldr x20, x20, #176 // x20=walk_b->children
4034f8: f9405a73 ldr x19, x19, #176 // x19=walk_a->children
4034fc: f100029f cmp x20, #0x0 // x20=walk_b ? 0
403500: fa401a64 ccmp x19, #0x0, #0x4, ne // x19=walk_a, 如果x19=0,ccmp会设置标志位0x4, b.eq将会跳转
403504: 54000140 b.eq 40352c <ferror@plt+0x164c> // b.none
for (walk_a = a->children, walk_b = b->children; walk_a && walk_b;
walk_a = walk_a->next, walk_b = walk_b->next) {
#<nzcv>：