user: Demonstrate the C code that generates the assembly output below:

```asm
<cpi_vercmp>:
  endbr64
  push   %r15
  mov    %rdi,%rax
  mov    %rdi,%r15
  push   %r14
  or     %rsi,%rax
  push   %r13
  push   %r12
  mov    %rsi,%r12
  push   %rbp
  push   %rbx
  sub    $0x18,%rsp
  test   %rsi,%rsi
  setne  %dil
  test   %r15,%r15
  jne    L61
  test   %dil,%dil
  jne    L244
L61:
  test   %rax,%rax
  je     L94
  test   %r15,%r15
  setne  %al
  test   %r12,%r12
  jne    L220
  mov    $0x1,%ebx
  test   %al,%al
  je     L220
L9:
  add    $0x18,%rsp
  mov    %ebx,%eax
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
  nopl   0x0(%rax)
L220:
  and    %eax,%edi
  movzbl %dil,%edi
  call   <assert@plt>
L135:
  cmpb   $0x0,(%r15)
  jne    L184
  cmpb   $0x0,(%r12)
  je     L94
L184:
  mov    %r15,%rdi
  call   <vercmp_nondigit_end@plt>
  mov    %r12,%rdi
  mov    %rax,0x8(%rsp)
  mov    %rax,%rbx
  call   <vercmp_nondigit_end@plt>
  mov    %rax,%rbp
  cmp    %rbx,%r15
  jb     L190
  cmp    %rax,%r12
  jb     L190
  jmp    L161
  xchg   %ax,%ax
L63:
  mov    %r13,%r15
L190:
  cmp    %r15,0x8(%rsp)
  jbe    L31
  movsbl (%r15),%edi
  lea    0x1(%r15),%r13
L258:
  xor    %r14d,%r14d
  cmp    %r12,%rbp
  jbe    L245
  movsbl (%r12),%r14d
  add    $0x1,%r12
L245:
  call   <vercmp_char_value@plt>
  mov    %r14d,%edi
  mov    %eax,%ebx
  call   <vercmp_char_value@plt>
  sub    %eax,%ebx
  jne    L9
  mov    0x8(%rsp),%rbx
  cmp    %rbx,%r13
  setbe  %r14b
  xor    %edi,%edi
  cmp    %rbp,%r12
  setbe  %dil
  and    %r14d,%edi
  call   <assert@plt>
  cmp    %rbx,%r13
  setb   0x7(%rsp)
  movzbl 0x7(%rsp),%eax
  cmp    %rbp,%r12
  jb     L171
  test   %al,%al
  je     L13
L171:
  cmp    %r15,0x8(%rsp)
  ja     L63
L255:
  xor    %r15d,%r15d
  cmp    %rbp,%r12
  jae    L127
  movsbl (%r12),%r15d
  add    $0x1,%r12
L127:
  xor    %edi,%edi
  call   <vercmp_char_value@plt>
  mov    %r15d,%edi
  mov    %eax,%ebx
  call   <vercmp_char_value@plt>
  sub    %eax,%ebx
  jne    L9
  xor    %edi,%edi
  cmp    %r12,%rbp
  setae  %dil
  and    %r14d,%edi
  call   <assert@plt>
  cmp    %r12,%rbp
  ja     L255
  cmpb   $0x0,0x7(%rsp)
  jne    L255
L13:
  mov    %r12,%r14
L50:
  cmp    %r13,0x8(%rsp)
  sete   %al
  xor    %edi,%edi
  cmp    %r12,%rbp
  sete   %dil
  and    %eax,%edi
  call   <assert@plt>
  mov    %r13,%rdi
  call   <vercmp_digit_end@plt>
  mov    %r12,%rdi
  mov    %rax,%r15
  call   <vercmp_digit_end@plt>
  mov    %r15,%rsi
  mov    %r13,%rdi
  mov    %rax,%r12
  call   <vercmp_num_value@plt>
  mov    %r12,%rsi
  mov    %r14,%rdi
  mov    %eax,%ebx
  call   <vercmp_num_value@plt>
  sub    %eax,%ebx
  je     L135
  jmp    L9
  nopl   (%rax)
L31:
  mov    %r15,%r13
  xor    %edi,%edi
  jmp    L258
  nopw   0x0(%rax,%rax,1)
L94:
  xor    %ebx,%ebx
  jmp    L9
L244:
  mov    $0xffffffff,%ebx
  jmp    L9
L161:
  mov    %r12,%r14
  mov    %r15,%r13
  jmp    L50
```

assistant: ```c
__attribute__((visibility("hidden"))) int cpi_vercmp(const char *v1, const char *v2) {
  const char *v1n;
  const char *v2n;
  int diff;
  if (v1 == NULL && v2 != NULL) {
    return -1;
  } else if (v1 == NULL && v2 == NULL) {
    return 0;
  } else if (v1 != NULL && v2 == NULL) {
    return 1;
  }
  assert(v1 != NULL && v2 != NULL);
  while (*v1 != '\0' || *v2 != '\0') {
    v1n = vercmp_nondigit_end(v1);
    v2n = vercmp_nondigit_end(v2);
    while (v1 < v1n || v2 < v2n) {
      char c1 = '\0';
      char c2 = '\0';
      if (v1 < v1n) {
        c1 = *v1++;
      }
      if (v2 < v2n) {
        c2 = *v2++;
      }
      diff = vercmp_char_value(c1) - vercmp_char_value(c2);
      if (diff != 0) {
        return diff;
      }
      assert(v1 <= v1n && v2 <= v2n);
    }
    assert(v1 == v1n && v2 == v2n);
    v1n = vercmp_digit_end(v1);
    v2n = vercmp_digit_end(v2);
    {
      int i1 = vercmp_num_value(v1, v1n);
      int i2 = vercmp_num_value(v2, v2n);
      int diff = i1 - i2;
      if (diff != 0) {
        return diff;
      }
    }
    v1 = v1n;
    v2 = v2n;
  }
  return 0;
}
```