user: 下面的汇编指令对应的C源代码是什么:

```asm
<null_operand>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  sub    $0x50,%rsp
  mov    %rdi,-0x48(%rbp)
  mov    %fs:0x28,%rax
  mov    %rax,-0x8(%rbp)
  xor    %eax,%eax
  mov    -0x48(%rbp),%rax
  test   %rax,%rax
  jne    L60
  lea    -0x30(%rbp),%rax
  lea    -0x34(%rbp),%rdx
  sub    %rdx,%rax
  sar    $0x2,%rax
  mov    %eax,-0xc(%rbp)
L60:
  mov    -0x48(%rbp),%rax
  test   %rax,%rax
  jne    L21
  lea    -0x30(%rbp),%rax
  lea    -0x34(%rbp),%rdx
  sub    %rdx,%rax
  sar    $0x2,%rax
  mov    %eax,-0x10(%rbp)
L21:
  mov    -0x48(%rbp),%rax
  test   %rax,%rax
  jne    L30
  lea    -0x30(%rbp),%rax
  lea    -0x34(%rbp),%rdx
  sub    %rdx,%rax
  sar    $0x2,%rax
  mov    %eax,-0x14(%rbp)
L30:
  mov    -0x48(%rbp),%rax
  test   %rax,%rax
  jne    L95
  lea    -0x30(%rbp),%rax
  lea    -0x34(%rbp),%rdx
  sub    %rdx,%rax
  sar    $0x2,%rax
  mov    %eax,-0x18(%rbp)
L95:
  mov    -0x48(%rbp),%rax
  test   %rax,%rax
  jne    L1
  lea    -0x30(%rbp),%rax
  lea    -0x34(%rbp),%rdx
  sub    %rdx,%rax
  sar    $0x2,%rax
  mov    %eax,-0x1c(%rbp)
L1:
  mov    -0x48(%rbp),%rax
  test   %rax,%rax
  jne    L37
  lea    -0x30(%rbp),%rax
  lea    -0x34(%rbp),%rdx
  sub    %rdx,%rax
  sar    $0x2,%rax
  mov    %eax,-0x20(%rbp)
L37:
  mov    -0x48(%rbp),%rax
  test   %rax,%rax
  jne    L6
  lea    -0x30(%rbp),%rax
  lea    -0x34(%rbp),%rdx
  sub    %rdx,%rax
  sar    $0x2,%rax
  mov    %eax,-0x24(%rbp)
L6:
  mov    -0x48(%rbp),%rax
  test   %rax,%rax
  jne    L74
  lea    -0x30(%rbp),%rax
  lea    -0x34(%rbp),%rdx
  sub    %rdx,%rax
  sar    $0x2,%rax
  mov    %eax,-0x28(%rbp)
L74:
  mov    -0x48(%rbp),%rax
  test   %rax,%rax
  jne    L27
  lea    -0x30(%rbp),%rax
  lea    -0x34(%rbp),%rdx
  sub    %rdx,%rax
  sar    $0x2,%rax
  mov    %eax,-0x2c(%rbp)
L27:
  nop
  mov    -0x8(%rbp),%rax
  sub    %fs:0x28,%rax
  je     L58
  call   <__stack_chk_fail@plt>
L58:
  leave
  ret
```

assistant: ```c
void null_operand(int *a) {
start:
  if (&&start == 0)
    do {
      int a, b;
      int c = &b - &a;
    } while (0);
  if (&&start < 0)
    do {
      int a, b;
      int c = &b - &a;
    } while (0);
  if (&&start <= 0)
    do {
      int a, b;
      int c = &b - &a;
    } while (0);
  if (!(&&start != 0))
    do {
      int a, b;
      int c = &b - &a;
    } while (0);
  if (!(&&start > 0))
    do {
      int a, b;
      int c = &b - &a;
    } while (0);
  if (!(&&start >= 0))
    do {
      int a, b;
      int c = &b - &a;
    } while (0);
  if (!(&&start - 0))
    do {
      int a, b;
      int c = &b - &a;
    } while (0);
  if (&a == 0)
    do {
      int a, b;
      int c = &b - &a;
    } while (0);
  if (&a < 0)
    do {
      int a, b;
      int c = &b - &a;
    } while (0);
  if (&a <= 0)
    do {
      int a, b;
      int c = &b - &a;
    } while (0);
  if (!(&a != 0))
    do {
      int a, b;
      int c = &b - &a;
    } while (0);
  if (!(&a > 0))
    do {
      int a, b;
      int c = &b - &a;
    } while (0);
  if (!(&a >= 0))
    do {
      int a, b;
      int c = &b - &a;
    } while (0);
  if (!(&a - 0))
    do {
      int a, b;
      int c = &b - &a;
    } while (0);
  if (0 == &a)
    do {
      int a, b;
      int c = &b - &a;
    } while (0);
  if (0 > &a)
    do {
      int a, b;
      int c = &b - &a;
    } while (0);
  if (0 >= &a)
    do {
      int a, b;
      int c = &b - &a;
    } while (0);
  if (!(0 != &a))
    do {
      int a, b;
      int c = &b - &a;
    } while (0);
  if (!(0 < &a))
    do {
      int a, b;
      int c = &b - &a;
    } while (0);
  if (!(0 <= &a))
    do {
      int a, b;
      int c = &b - &a;
    } while (0);
  if (a == 0)
    do {
      int a, b;
      int c = &b - &a;
    } while (0);
  if (a < 0)
    do {
      int a, b;
      int c = &b - &a;
    } while (0);
  if (a <= 0)
    do {
      int a, b;
      int c = &b - &a;
    } while (0);
  if (!(a != 0))
    do {
      int a, b;
      int c = &b - &a;
    } while (0);
  if (!(a > 0))
    do {
      int a, b;
      int c = &b - &a;
    } while (0);
  if (!(a >= 0))
    do {
      int a, b;
      int c = &b - &a;
    } while (0);
  if (!(a - 0))
    do {
      int a, b;
      int c = &b - &a;
    } while (0);
  if (0 == a)
    do {
      int a, b;
      int c = &b - &a;
    } while (0);
  if (0 > a)
    do {
      int a, b;
      int c = &b - &a;
    } while (0);
  if (0 >= a)
    do {
      int a, b;
      int c = &b - &a;
    } while (0);
  if (!(0 != a))
    do {
      int a, b;
      int c = &b - &a;
    } while (0);
  if (!(0 < a))
    do {
      int a, b;
      int c = &b - &a;
    } while (0);
  if (!(0 <= a))
    do {
      int a, b;
      int c = &b - &a;
    } while (0);
}
```