user: 下面的汇编指令对应的C源代码是什么:

```asm
<expand>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  sub    $0x20,%rsp
  mov    %rdi,-0x18(%rbp)
  mov    %rsi,-0x20(%rbp)
  movl   $0x0,-0xc(%rbp)
  movl   $0x0,-0x8(%rbp)
  jmp    L94
L109:
  mov    -0xc(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  mov    -0x8(%rbp),%edx
  movslq %edx,%rcx
  mov    -0x20(%rbp),%rdx
  add    %rcx,%rdx
  movzbl (%rax),%eax
  mov    %al,(%rdx)
  mov    -0xc(%rbp),%eax
  cltq
  lea    0x1(%rax),%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  cmp    $0x2d,%al
  jne    L146
  mov    -0xc(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movsbl %al,%eax
  mov    %eax,%edi
  call   <isspace@plt>
  test   %eax,%eax
  jne    L146
  mov    -0xc(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movsbl %al,%eax
  mov    %eax,%edi
  call   <isalpha@plt>
  test   %rax,%rax
  je     L66
  mov    -0xc(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movsbl %al,%eax
  mov    %eax,%edi
  call   <islower@plt>
  test   %rax,%rax
  je     L66
  movl   $0x1,-0x4(%rbp)
  jmp    L64
L125:
  mov    -0xc(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  mov    %eax,%edx
  mov    -0x4(%rbp),%eax
  lea    (%rdx,%rax,1),%ecx
  addl   $0x1,-0x8(%rbp)
  mov    -0x8(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x20(%rbp),%rax
  add    %rdx,%rax
  mov    %ecx,%edx
  mov    %dl,(%rax)
  addl   $0x1,-0x4(%rbp)
L64:
  mov    -0xc(%rbp),%eax
  cltq
  lea    0x2(%rax),%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movsbl %al,%eax
  mov    -0xc(%rbp),%edx
  movslq %edx,%rcx
  mov    -0x18(%rbp),%rdx
  add    %rcx,%rdx
  movzbl (%rdx),%edx
  movsbl %dl,%edx
  sub    %edx,%eax
  cmp    %eax,-0x4(%rbp)
  jl     L125
L66:
  mov    -0xc(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movsbl %al,%eax
  mov    %eax,%edi
  call   <isalpha@plt>
  test   %rax,%rax
  je     L116
  mov    -0xc(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movsbl %al,%eax
  mov    %eax,%edi
  call   <isupper@plt>
  test   %rax,%rax
  je     L116
  movl   $0x1,-0x4(%rbp)
  jmp    L31
L100:
  mov    -0xc(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  mov    %eax,%edx
  mov    -0x4(%rbp),%eax
  lea    (%rdx,%rax,1),%ecx
  addl   $0x1,-0x8(%rbp)
  mov    -0x8(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x20(%rbp),%rax
  add    %rdx,%rax
  mov    %ecx,%edx
  mov    %dl,(%rax)
  addl   $0x1,-0x4(%rbp)
L31:
  mov    -0xc(%rbp),%eax
  cltq
  lea    0x2(%rax),%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movsbl %al,%eax
  mov    -0xc(%rbp),%edx
  movslq %edx,%rcx
  mov    -0x18(%rbp),%rdx
  add    %rcx,%rdx
  movzbl (%rdx),%edx
  movsbl %dl,%edx
  sub    %edx,%eax
  cmp    %eax,-0x4(%rbp)
  jl     L100
L116:
  mov    -0xc(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movsbl %al,%eax
  mov    %eax,%edi
  call   <isdigit@plt>
  test   %rax,%rax
  je     L97
  movl   $0x1,-0x4(%rbp)
  jmp    L83
L121:
  mov    -0xc(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  mov    %eax,%edx
  mov    -0x4(%rbp),%eax
  lea    (%rdx,%rax,1),%ecx
  addl   $0x1,-0x8(%rbp)
  mov    -0x8(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x20(%rbp),%rax
  add    %rdx,%rax
  mov    %ecx,%edx
  mov    %dl,(%rax)
  addl   $0x1,-0x4(%rbp)
L83:
  mov    -0xc(%rbp),%eax
  cltq
  lea    0x2(%rax),%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movsbl %al,%eax
  mov    -0xc(%rbp),%edx
  movslq %edx,%rcx
  mov    -0x18(%rbp),%rdx
  add    %rcx,%rdx
  movzbl (%rdx),%edx
  movsbl %dl,%edx
  sub    %edx,%eax
  cmp    %eax,-0x4(%rbp)
  jl     L121
L97:
  addl   $0x1,-0xc(%rbp)
L146:
  addl   $0x1,-0x8(%rbp)
  addl   $0x1,-0xc(%rbp)
L94:
  mov    -0xc(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  test   %al,%al
  jne    L109
  nop
  nop
  leave
  ret
```

assistant: ```c
void expand(char s1[], char s2[]) {
  int i, j, k;
  for (i = 0, j = 0; s1[i] != '\0'; j++, i++) {
    s2[j] = s1[i];
    if (s1[i + 1] == '-' && !isspace(s1[i])) {
      if (isalpha(s1[i]) && islower(s1[i]))
        for (k = 1; k < s1[i + 2] - s1[i]; k++)
          s2[++j] = s1[i] + k;
      if (isalpha(s1[i]) && isupper(s1[i]))
        for (k = 1; k < s1[i + 2] - s1[i]; k++)
          s2[++j] = s1[i] + k;
      if (isdigit(s1[i]))
        for (k = 1; k < s1[i + 2] - s1[i]; k++)
          s2[++j] = s1[i] + k;
      i++;
    }
  }
}
```