user: 请从给定的汇编指令推导出C源代码:

```asm
<fib>:
  endbr64
  mov    %edi,%r11d
  test   %edi,%edi
  je     L34
  cmp    $0x1,%edi
  je     L34
  push   %r15
  xor    %r11d,%r11d
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0x38,%rsp
  mov    %edi,(%rsp)
  mov    %r11d,0x4(%rsp)
L68:
  mov    (%rsp),%eax
  xor    %r9d,%r9d
  mov    %r9d,0x8(%rsp)
  sub    $0x1,%eax
  mov    %eax,0x24(%rsp)
L171:
  mov    0x24(%rsp),%eax
  cmp    $0x1,%eax
  je     L84
  sub    $0x1,%eax
  xor    %esi,%esi
  mov    %eax,0x28(%rsp)
  mov    %esi,0xc(%rsp)
L98:
  mov    0x28(%rsp),%eax
  cmp    $0x1,%eax
  je     L157
  xor    %esi,%esi
  lea    -0x1(%rax),%r9d
  mov    %esi,0x10(%rsp)
  mov    %r9d,%esi
L102:
  cmp    $0x1,%esi
  je     L140
  xor    %r8d,%r8d
  mov    %esi,0x2c(%rsp)
  lea    -0x1(%rsi),%r10d
  mov    %r8d,0x14(%rsp)
  mov    %r10d,%r15d
L109:
  cmp    $0x1,%r15d
  je     L77
  lea    -0x1(%r15),%r12d
  mov    %r15d,%ecx
  xor    %r8d,%r8d
  mov    %r12d,%r15d
L146:
  cmp    $0x1,%r15d
  je     L141
  xor    %r13d,%r13d
  lea    -0x1(%r15),%ebx
  mov    %r15d,%edx
  mov    %r13d,%r15d
L56:
  cmp    $0x1,%ebx
  je     L174
  mov    %r15d,%eax
  lea    -0x1(%rbx),%r13d
  mov    %ebx,%r15d
  xor    %r12d,%r12d
  mov    %ecx,%ebx
  mov    %eax,%ecx
L184:
  cmp    $0x1,%r13d
  je     L97
  mov    %r13d,0x18(%rsp)
  lea    -0x1(%r13),%ebp
  xor    %r14d,%r14d
  mov    %r8d,%r13d
  mov    %r12d,0x1c(%rsp)
  mov    %edx,%r12d
L82:
  cmp    $0x1,%ebp
  je     L145
  lea    -0x1(%rbp),%edi
  mov    %ecx,0x20(%rsp)
  call   <fib>
  mov    0x20(%rsp),%ecx
  add    %eax,%r14d
  sub    $0x2,%ebp
  jne    L82
  mov    %r12d,%edx
  mov    %r13d,%r8d
  mov    0x1c(%rsp),%r12d
  mov    0x18(%rsp),%r13d
L104:
  add    %r14d,%r12d
  sub    $0x2,%r13d
  jne    L184
  mov    %ecx,%eax
  mov    %ebx,%ecx
  mov    %r15d,%ebx
  mov    %eax,%r15d
L254:
  add    %r12d,%r15d
  sub    $0x2,%ebx
  jne    L56
  mov    %r15d,%r13d
  mov    %edx,%r15d
L154:
  add    %r13d,%r8d
  sub    $0x2,%r15d
  jne    L146
  mov    %ecx,%r15d
L189:
  add    %r8d,0x14(%rsp)
  sub    $0x2,%r15d
  jne    L109
  mov    0x2c(%rsp),%esi
  mov    0x14(%rsp),%r8d
L62:
  add    %r8d,0x10(%rsp)
  sub    $0x2,%esi
  jne    L102
  mov    0x10(%rsp),%esi
L193:
  add    %esi,0xc(%rsp)
  subl   $0x2,0x28(%rsp)
  jne    L98
  mov    0xc(%rsp),%esi
L169:
  add    %esi,0x8(%rsp)
  subl   $0x2,0x24(%rsp)
  jne    L171
  mov    0x8(%rsp),%r9d
  add    %r9d,0x4(%rsp)
  subl   $0x2,(%rsp)
  jne    L18
L244:
  mov    0x4(%rsp),%r11d
  jmp    L245
  nopl   0x0(%rax)
L145:
  mov    %r12d,%edx
  mov    %r13d,%r8d
  mov    0x1c(%rsp),%r12d
  mov    0x18(%rsp),%r13d
  add    $0x1,%r14d
  jmp    L104
  nopl   0x0(%rax)
L97:
  mov    %ecx,%eax
  add    $0x1,%r12d
  mov    %ebx,%ecx
  mov    %r15d,%ebx
  mov    %eax,%r15d
  jmp    L254
L141:
  mov    %ecx,%r15d
  add    $0x1,%r8d
  jmp    L189
L174:
  mov    %r15d,%r13d
  mov    %edx,%r15d
  add    $0x1,%r13d
  jmp    L154
L77:
  mov    0x14(%rsp),%r8d
  mov    0x2c(%rsp),%esi
  add    $0x1,%r8d
  jmp    L62
L140:
  mov    0x10(%rsp),%esi
  add    $0x1,%esi
  jmp    L193
L157:
  mov    0xc(%rsp),%esi
  add    $0x1,%esi
  jmp    L169
L84:
  mov    0x8(%rsp),%r9d
  add    $0x1,%r9d
  add    %r9d,0x4(%rsp)
  subl   $0x2,(%rsp)
  je     L244
L18:
  cmpl   $0x1,(%rsp)
  jne    L68
  mov    0x4(%rsp),%r11d
  add    $0x1,%r11d
L245:
  add    $0x38,%rsp
  mov    %r11d,%eax
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
L34:
  mov    %r11d,%eax
  ret
```

assistant: ```c
unsigned fib(unsigned f) {
  if (f == 0)
    return 0;
  if (f == 1)
    return 1;
  return fib(f - 1) + fib(f - 2);
}
```