user: What would the C source look like for the assembly code provided here?

```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    L211
L121:
  movq   $0x0,0x18(%rsp)
  mov    0x8(%rsp),%eax
  sub    $0x1,%eax
  mov    %eax,0xc(%rsp)
  cmp    $0x1,%eax
  je     L49
L38:
  movq   $0x0,0x20(%rsp)
  mov    0xc(%rsp),%eax
  sub    $0x1,%eax
  mov    %eax,%r11d
  cmp    $0x1,%eax
  je     L169
L15:
  movq   $0x0,0x28(%rsp)
  lea    -0x1(%r11),%eax
  cmp    $0x1,%eax
  je     L17
  mov    %r11d,0x34(%rsp)
  mov    %eax,%r11d
L135:
  xor    %edx,%edx
  lea    -0x1(%r11),%r13d
  mov    %rdx,%r15
  cmp    $0x1,%r13d
  je     L0
L136:
  lea    -0x1(%r13),%ebx
  xor    %r14d,%r14d
  cmp    $0x1,%ebx
  je     L2
L76:
  cmp    $0x2,%ebx
  je     L132
  lea    -0x3(%rbx),%r12d
  lea    -0x6(%rbx),%ecx
  xor    %edx,%edx
  mov    %r12d,%eax
  lea    -0x4(%rbx),%esi
  and    $0xfffffffe,%eax
  sub    %eax,%ecx
L44:
  lea    0x2(%rsi),%ebp
  xor    %r8d,%r8d
  cmp    $0xffffffff,%esi
  je     L123
L101:
  lea    -0x1(%rbp),%r10d
  xor    %r9d,%r9d
  cmp    $0x1,%r10d
  je     L73
L207:
  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     L207
  lea    -0x3(%rbp),%eax
  and    $0x1,%eax
L50:
  cltq
  sub    $0x2,%ebp
  add    %r9,%rax
  add    %rax,%r8
  cmp    $0x1,%ebp
  jg     L101
  mov    %esi,%ebp
  and    $0x1,%ebp
L123:
  movslq %ebp,%rax
  sub    $0x2,%esi
  add    %r8,%rax
  add    %rax,%rdx
  cmp    %esi,%ecx
  jne    L44
  and    $0x1,%r12d
L58:
  movslq %r12d,%r12
  sub    $0x2,%ebx
  lea    (%r12,%rdx,1),%rax
  add    %rax,%r14
  cmp    $0x1,%ebx
  jg     L76
  lea    -0x3(%r13),%eax
  and    $0x1,%eax
L141:
  cltq
  sub    $0x2,%r13d
  add    %r14,%rax
  add    %rax,%r15
  cmp    $0x1,%r13d
  jg     L136
  lea    -0x3(%r11),%eax
  mov    %r15,%rdx
  and    $0x1,%eax
L153:
  cltq
  sub    $0x2,%r11d
  add    %rdx,%rax
  add    %rax,0x28(%rsp)
  cmp    $0x1,%r11d
  jg     L135
  mov    0x34(%rsp),%r11d
  lea    -0x3(%r11),%eax
  and    $0x1,%eax
L17:
  sub    $0x2,%r11d
  cltq
  add    0x28(%rsp),%rax
  add    %rax,0x20(%rsp)
  cmp    $0x1,%r11d
  jg     L15
  mov    0xc(%rsp),%eax
  sub    $0x3,%eax
  and    $0x1,%eax
L170:
  subl   $0x2,0xc(%rsp)
  mov    0xc(%rsp),%edi
  cltq
  add    0x20(%rsp),%rax
  add    %rax,0x18(%rsp)
  cmp    $0x1,%edi
  jg     L38
  mov    0x8(%rsp),%eax
  sub    $0x3,%eax
  and    $0x1,%eax
L49:
  subl   $0x2,0x8(%rsp)
  mov    0x8(%rsp),%edi
  cltq
  add    0x18(%rsp),%rax
  add    %rax,0x10(%rsp)
  cmp    $0x1,%edi
  jg     L121
  andl   $0x1,0x30(%rsp)
L211:
  movslq 0x30(%rsp),%rax
  add    0x10(%rsp),%rax
  add    $0x68,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
L132:
  xor    %edx,%edx
  mov    $0x1,%r12d
  jmp    L58
  nopl   0x0(%rax)
L73:
  mov    $0x1,%eax
  jmp    L50
L2:
  mov    $0x1,%eax
  jmp    L141
L0:
  mov    $0x1,%eax
  jmp    L153
L169:
  mov    $0x1,%eax
  jmp    L170
```

assistant: ```c
unsigned long long int fib(int n) {
  if (n < 2)
    return n;
  else
    return fib(n - 1) + fib(n - 2);
}
```