user: 下面的汇编指令对应的C源代码是什么：

```asm
<update_r>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0x18,%rsp
  mov    %edi,%r12d
  mov    %esi,%ebp
  mov    %edx,(%rsp)
  mov    %ecx,%r14d
  mov    %r8d,%ebx
  mov    %r8d,%ecx
  mov    %esi,%edx
  mov    %edi,%esi
  mov    $0x0,%edi
  call   <update@plt>
  mov    %ebx,%r13d
  neg    %r13d
  mov    %r14d,0xc(%rsp)
  lea    0x1(%r14),%r15d
  mov    %r13d,%ecx
  mov    %r15d,%edx
  mov    %r12d,%esi
  mov    $0x0,%edi
  call   <update@plt>
  mov    (%rsp),%eax
  lea    0x1(%rax),%r14d
  mov    %r13d,%ecx
  mov    %ebp,%edx
  mov    %r14d,%esi
  mov    $0x0,%edi
  call   <update@plt>
  mov    %ebx,%ecx
  mov    %r15d,%edx
  mov    %r14d,%esi
  mov    $0x0,%edi
  call   <update@plt>
  mov    $0x1,%r13d
  sub    %ebp,%r13d
  imul   %ebx,%r13d
  mov    %r13d,%ecx
  mov    %ebp,%edx
  mov    %r12d,%esi
  mov    $0x1,%edi
  call   <update@plt>
  mov    0xc(%rsp),%eax
  imul   %ebx,%eax
  mov    %eax,0x8(%rsp)
  mov    %eax,%ecx
  mov    %r15d,%edx
  mov    %r12d,%esi
  mov    $0x1,%edi
  call   <update@plt>
  lea    -0x1(%rbp),%esi
  mov    %esi,0x4(%rsp)
  mov    %r13d,%edi
  neg    %edi
  mov    %edi,%ecx
  mov    %ebp,%edx
  mov    %r14d,%esi
  mov    $0x1,%edi
  call   <update@plt>
  mov    0x8(%rsp),%ecx
  neg    %ecx
  mov    %r15d,%edx
  mov    %r14d,%esi
  mov    $0x1,%edi
  call   <update@plt>
  mov    $0x1,%edx
  sub    %r12d,%edx
  mov    %edx,%r13d
  imul   %ebx,%r13d
  mov    %r13d,%ecx
  mov    %ebp,%edx
  mov    %r12d,%esi
  mov    $0x2,%edi
  call   <update@plt>
  lea    -0x1(%r12),%edi
  mov    %edi,0x8(%rsp)
  mov    %r13d,%ecx
  neg    %ecx
  mov    %r15d,%edx
  mov    %r12d,%esi
  mov    $0x2,%edi
  call   <update@plt>
  mov    (%rsp),%edx
  imul   %ebx,%edx
  mov    %edx,%r13d
  mov    %edx,%ecx
  mov    %ebp,%edx
  mov    %r14d,%esi
  mov    $0x2,%edi
  call   <update@plt>
  mov    %r13d,%ecx
  neg    %ecx
  mov    %r15d,%edx
  mov    %r14d,%esi
  mov    $0x2,%edi
  call   <update@plt>
  mov    0x4(%rsp),%ecx
  imul   0x8(%rsp),%ecx
  imul   %ebx,%ecx
  mov    %ebp,%edx
  mov    %r12d,%esi
  mov    $0x3,%edi
  call   <update@plt>
  mov    0xc(%rsp),%r13d
  mov    %r13d,%ecx
  neg    %ecx
  imul   0x8(%rsp),%ecx
  imul   %ebx,%ecx
  mov    %r15d,%edx
  mov    %r12d,%esi
  mov    $0x3,%edi
  call   <update@plt>
  mov    (%rsp),%r12d
  mov    %r12d,%ecx
  neg    %ecx
  imul   0x4(%rsp),%ecx
  imul   %ebx,%ecx
  mov    %ebp,%edx
  mov    %r14d,%esi
  mov    $0x3,%edi
  call   <update@plt>
  mov    %r13d,%ecx
  imul   %r12d,%ecx
  imul   %ebx,%ecx
  mov    %r15d,%edx
  mov    %r14d,%esi
  mov    $0x3,%edi
  call   <update@plt>
  add    $0x18,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
```

assistant: ```c
void update_r(int x1, int y1, int x2, int y2, int val) {
  update(0, x1, y1, val);
  update(0, x1, y2 + 1, -val);
  update(0, x2 + 1, y1, -val);
  update(0, x2 + 1, y2 + 1, val);
  update(1, x1, y1, val * (1 - y1));
  update(1, x1, y2 + 1, val * y2);
  update(1, x2 + 1, y1, val * (y1 - 1));
  update(1, x2 + 1, y2 + 1, -val * y2);
  update(2, x1, y1, val * (1 - x1));
  update(2, x1, y2 + 1, (x1 - 1) * val);
  update(2, x2 + 1, y1, val * x2);
  update(2, x2 + 1, y2 + 1, -x2 * val);
  update(3, x1, y1, (x1 - 1) * (y1 - 1) * val);
  update(3, x1, y2 + 1, -y2 * (x1 - 1) * val);
  update(3, x2 + 1, y1, -x2 * (y1 - 1) * val);
  update(3, x2 + 1, y2 + 1, x2 * y2 * val);
}
```