user: 提供的汇编代码用C语言表示会是什么样子：

```asm
<strlen>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  mov    %rdi,-0x48(%rbp)
  mov    -0x48(%rbp),%rax
  mov    %rax,-0x38(%rbp)
  jmp    L63
L31:
  mov    -0x38(%rbp),%rax
  movzbl (%rax),%eax
  test   %al,%al
  jne    L129
  mov    -0x38(%rbp),%rax
  sub    -0x48(%rbp),%rax
  jmp    L152
L129:
  addq   $0x1,-0x38(%rbp)
L63:
  mov    -0x38(%rbp),%rax
  and    $0x7,%eax
  test   %rax,%rax
  jne    L31
  mov    -0x38(%rbp),%rax
  mov    %rax,-0x30(%rbp)
  movq   $0x7efefeff,-0x28(%rbp)
  mov    $0x80808080,%eax
  mov    %rax,-0x20(%rbp)
  movq   $0x1010101,-0x18(%rbp)
  movabs $0x7efefefefefefeff,%rax
  mov    %rax,-0x28(%rbp)
  mov    -0x20(%rbp),%rax
  shl    $0x20,%rax
  or     %rax,-0x20(%rbp)
  mov    -0x18(%rbp),%rax
  shl    $0x20,%rax
  or     %rax,-0x18(%rbp)
L194:
  mov    -0x30(%rbp),%rax
  lea    0x8(%rax),%rdx
  mov    %rdx,-0x30(%rbp)
  mov    (%rax),%rax
  mov    %rax,-0x10(%rbp)
  mov    -0x10(%rbp),%rax
  sub    -0x18(%rbp),%rax
  and    -0x20(%rbp),%rax
  test   %rax,%rax
  je     L194
  mov    -0x30(%rbp),%rax
  sub    $0x8,%rax
  mov    %rax,-0x8(%rbp)
  mov    -0x8(%rbp),%rax
  movzbl (%rax),%eax
  test   %al,%al
  jne    L2
  mov    -0x8(%rbp),%rax
  sub    -0x48(%rbp),%rax
  jmp    L152
L2:
  mov    -0x8(%rbp),%rax
  add    $0x1,%rax
  movzbl (%rax),%eax
  test   %al,%al
  jne    L136
  mov    -0x8(%rbp),%rax
  sub    -0x48(%rbp),%rax
  add    $0x1,%rax
  jmp    L152
L136:
  mov    -0x8(%rbp),%rax
  add    $0x2,%rax
  movzbl (%rax),%eax
  test   %al,%al
  jne    L60
  mov    -0x8(%rbp),%rax
  sub    -0x48(%rbp),%rax
  add    $0x2,%rax
  jmp    L152
L60:
  mov    -0x8(%rbp),%rax
  add    $0x3,%rax
  movzbl (%rax),%eax
  test   %al,%al
  jne    L138
  mov    -0x8(%rbp),%rax
  sub    -0x48(%rbp),%rax
  add    $0x3,%rax
  jmp    L152
L138:
  mov    -0x8(%rbp),%rax
  add    $0x4,%rax
  movzbl (%rax),%eax
  test   %al,%al
  jne    L17
  mov    -0x8(%rbp),%rax
  sub    -0x48(%rbp),%rax
  add    $0x4,%rax
  jmp    L152
L17:
  mov    -0x8(%rbp),%rax
  add    $0x5,%rax
  movzbl (%rax),%eax
  test   %al,%al
  jne    L87
  mov    -0x8(%rbp),%rax
  sub    -0x48(%rbp),%rax
  add    $0x5,%rax
  jmp    L152
L87:
  mov    -0x8(%rbp),%rax
  add    $0x6,%rax
  movzbl (%rax),%eax
  test   %al,%al
  jne    L78
  mov    -0x8(%rbp),%rax
  sub    -0x48(%rbp),%rax
  add    $0x6,%rax
  jmp    L152
L78:
  mov    -0x8(%rbp),%rax
  add    $0x7,%rax
  movzbl (%rax),%eax
  test   %al,%al
  jne    L194
  mov    -0x8(%rbp),%rax
  sub    -0x48(%rbp),%rax
  add    $0x7,%rax
L152:
  pop    %rbp
  ret
```

assistant: ```c
size_t strlen(const char *str) {
  const char *char_ptr;
  const unsigned long int *longword_ptr;
  unsigned long int longword, magic_bits, himagic, lomagic;
  for (char_ptr = str; ((unsigned long int)char_ptr & (sizeof(longword) - 1)) != 0; ++char_ptr)
    if (*char_ptr == '\0')
      return char_ptr - str;
  longword_ptr = (unsigned long int *)char_ptr;
  magic_bits = 0x7efefeffL;
  himagic = 0x80808080L;
  lomagic = 0x01010101L;
  if (sizeof(longword) > 4) {
    magic_bits = ((0x7efefefeL << 16) << 16) | 0xfefefeffL;
    himagic = ((himagic << 16) << 16) | himagic;
    lomagic = ((lomagic << 16) << 16) | lomagic;
  }
  if (sizeof(longword) > 8)
    abort();
  for (;;) {
    longword = *longword_ptr++;
    if (((longword - lomagic) & himagic) != 0) {
      const char *cp = (const char *)(longword_ptr - 1);
      if (cp[0] == 0)
        return cp - str;
      if (cp[1] == 0)
        return cp - str + 1;
      if (cp[2] == 0)
        return cp - str + 2;
      if (cp[3] == 0)
        return cp - str + 3;
      if (sizeof(longword) > 4) {
        if (cp[4] == 0)
          return cp - str + 4;
        if (cp[5] == 0)
          return cp - str + 5;
        if (cp[6] == 0)
          return cp - str + 6;
        if (cp[7] == 0)
          return cp - str + 7;
      }
    }
  }
}
```