user: 请从给定的汇编指令推导出C源代码：

```asm
<fib>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0x68,%rsp
  mov    %edi,0x30(%rsp)
  mov    %edi,0x8(%rsp)
  movq   $0x0,0x10(%rsp)
  cmp    $0x1,%edi
  jle    L133
L164:
  movq   $0x0,0x18(%rsp)
  mov    0x8(%rsp),%eax
  sub    $0x1,%eax
  mov    %eax,0xc(%rsp)
  cmp    $0x1,%eax
  je     L140
L194:
  movq   $0x0,0x20(%rsp)
  mov    0xc(%rsp),%eax
  sub    $0x1,%eax
  mov    %eax,%r11d
  cmp    $0x1,%eax
  je     L143
L86:
  movq   $0x0,0x28(%rsp)
  lea    -0x1(%r11),%eax
  cmp    $0x1,%eax
  je     L107
  mov    %r11d,0x34(%rsp)
  mov    %eax,%r11d
L177:
  xor    %edx,%edx
  lea    -0x1(%r11),%r13d
  mov    %rdx,%r15
  cmp    $0x1,%r13d
  je     L189
L42:
  lea    -0x1(%r13),%ebx
  xor    %r14d,%r14d
  cmp    $0x1,%ebx
  je     L28
L99:
  cmp    $0x2,%ebx
  je     L59
  lea    -0x3(%rbx),%r12d
  lea    -0x6(%rbx),%ecx
  xor    %edx,%edx
  mov    %r12d,%eax
  lea    -0x4(%rbx),%esi
  and    $0xfffffffe,%eax
  sub    %eax,%ecx
L41:
  lea    0x2(%rsi),%ebp
  xor    %r8d,%r8d
  cmp    $0xffffffff,%esi
  je     L227
L201:
  lea    -0x1(%rbp),%r10d
  xor    %r9d,%r9d
  cmp    $0x1,%r10d
  je     L178
L213:
  lea    -0x1(%r10),%edi
  mov    %esi,0x5c(%rsp)
  mov    %ecx,0x58(%rsp)
  mov    %r9,0x50(%rsp)
  mov    %r8,0x48(%rsp)
  mov    %rdx,0x40(%rsp)
  mov    %r11d,0x3c(%rsp)
  mov    %r10d,0x38(%rsp)
  call   <fib>
  mov    0x38(%rsp),%r10d
  mov    0x50(%rsp),%r9
  mov    0x3c(%rsp),%r11d
  mov    0x40(%rsp),%rdx
  sub    $0x2,%r10d
  add    %rax,%r9
  mov    0x48(%rsp),%r8
  mov    0x58(%rsp),%ecx
  cmp    $0x1,%r10d
  mov    0x5c(%rsp),%esi
  jg     L213
  lea    -0x3(%rbp),%eax
  and    $0x1,%eax
L212:
  cltq
  sub    $0x2,%ebp
  add    %r9,%rax
  add    %rax,%r8
  cmp    $0x1,%ebp
  jg     L201
  mov    %esi,%ebp
  and    $0x1,%ebp
L227:
  movslq %ebp,%rax
  sub    $0x2,%esi
  add    %r8,%rax
  add    %rax,%rdx
  cmp    %esi,%ecx
  jne    L41
  and    $0x1,%r12d
L1:
  movslq %r12d,%r12
  sub    $0x2,%ebx
  lea    (%r12,%rdx,1),%rax
  add    %rax,%r14
  cmp    $0x1,%ebx
  jg     L99
  lea    -0x3(%r13),%eax
  and    $0x1,%eax
L217:
  cltq
  sub    $0x2,%r13d
  add    %r14,%rax
  add    %rax,%r15
  cmp    $0x1,%r13d
  jg     L42
  lea    -0x3(%r11),%eax
  mov    %r15,%rdx
  and    $0x1,%eax
L170:
  cltq
  sub    $0x2,%r11d
  add    %rdx,%rax
  add    %rax,0x28(%rsp)
  cmp    $0x1,%r11d
  jg     L177
  mov    0x34(%rsp),%r11d
  lea    -0x3(%r11),%eax
  and    $0x1,%eax
L107:
  sub    $0x2,%r11d
  cltq
  add    0x28(%rsp),%rax
  add    %rax,0x20(%rsp)
  cmp    $0x1,%r11d
  jg     L86
  mov    0xc(%rsp),%eax
  sub    $0x3,%eax
  and    $0x1,%eax
L45:
  subl   $0x2,0xc(%rsp)
  mov    0xc(%rsp),%edi
  cltq
  add    0x20(%rsp),%rax
  add    %rax,0x18(%rsp)
  cmp    $0x1,%edi
  jg     L194
  mov    0x8(%rsp),%eax
  sub    $0x3,%eax
  and    $0x1,%eax
L140:
  subl   $0x2,0x8(%rsp)
  mov    0x8(%rsp),%edi
  cltq
  add    0x18(%rsp),%rax
  add    %rax,0x10(%rsp)
  cmp    $0x1,%edi
  jg     L164
  andl   $0x1,0x30(%rsp)
L133:
  movslq 0x30(%rsp),%rax
  add    0x10(%rsp),%rax
  add    $0x68,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
L59:
  xor    %edx,%edx
  mov    $0x1,%r12d
  jmp    L1
  nopl   0x0(%rax)
L178:
  mov    $0x1,%eax
  jmp    L212
L28:
  mov    $0x1,%eax
  jmp    L217
L189:
  mov    $0x1,%eax
  jmp    L170
L143:
  mov    $0x1,%eax
  jmp    L45
```

assistant: ```c
long fib(int n) {
  long x, y;
  if (n < 2)
    return n;
#pragma omp task untied shared(x) firstprivate(n)
  x = fib(n - 1);
#pragma omp task untied shared(y) firstprivate(n)
  y = fib(n - 2);
#pragma omp taskwait
  return x + y;
}
```