user: Demonstrate the C code that generates the assembly output below:

```asm
<vec_subtract>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  sub    $0x60,%rsp
  mov    %rdi,-0x48(%rbp)
  mov    %rsi,-0x50(%rbp)
  mov    %rdx,-0x58(%rbp)
  mov    -0x48(%rbp),%rax
  mov    $0x40,%esi
  mov    %rax,%rdi
  call   <__assume_aligned@plt>
  mov    -0x50(%rbp),%rax
  mov    $0x40,%esi
  mov    %rax,%rdi
  call   <__assume_aligned@plt>
  movq   $0x40,-0x10(%rbp)
  movq   $0x0,-0x38(%rbp)
  jmp    L97
L34:
  movq   $0x0,-0x30(%rbp)
  jmp    L95
L85:
  movq   $0x0,-0x28(%rbp)
  jmp    L83
L30:
  mov    -0x30(%rbp),%rax
  imul   -0x58(%rbp),%rax
  mov    %rax,%rdx
  mov    -0x28(%rbp),%rax
  add    %rdx,%rax
  lea    0x0(,%rax,8),%rdx
  mov    -0x48(%rbp),%rax
  add    %rdx,%rax
  movsd  (%rax),%xmm0
  mov    -0x30(%rbp),%rax
  imul   -0x58(%rbp),%rax
  mov    %rax,%rdx
  mov    -0x28(%rbp),%rax
  add    %rdx,%rax
  lea    0x0(,%rax,8),%rdx
  mov    -0x50(%rbp),%rax
  add    %rdx,%rax
  movsd  (%rax),%xmm1
  mov    -0x30(%rbp),%rax
  imul   -0x58(%rbp),%rax
  mov    %rax,%rdx
  mov    -0x28(%rbp),%rax
  add    %rdx,%rax
  lea    0x0(,%rax,8),%rdx
  mov    -0x48(%rbp),%rax
  add    %rdx,%rax
  subsd  %xmm1,%xmm0
  movsd  %xmm0,(%rax)
  addq   $0x1,-0x28(%rbp)
L83:
  mov    -0x28(%rbp),%rax
  cmp    -0x10(%rbp),%rax
  jb     L30
  addq   $0x1,-0x30(%rbp)
L95:
  mov    -0x30(%rbp),%rax
  cmp    -0x58(%rbp),%rax
  jb     L85
  mov    -0x10(%rbp),%rax
  add    %rax,-0x38(%rbp)
L97:
  mov    -0x58(%rbp),%rax
  sub    -0x10(%rbp),%rax
  cmp    %rax,-0x38(%rbp)
  jb     L34
  mov    -0x58(%rbp),%rax
  mov    $0x0,%edx
  divq   -0x10(%rbp)
  mov    -0x58(%rbp),%rax
  sub    %rdx,%rax
  mov    %rax,-0x8(%rbp)
  movq   $0x0,-0x20(%rbp)
  jmp    L96
L31:
  mov    -0x8(%rbp),%rax
  mov    %rax,-0x18(%rbp)
  jmp    L65
L53:
  mov    -0x20(%rbp),%rax
  imul   -0x58(%rbp),%rax
  mov    %rax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  lea    0x0(,%rax,8),%rdx
  mov    -0x48(%rbp),%rax
  add    %rdx,%rax
  movsd  (%rax),%xmm0
  mov    -0x20(%rbp),%rax
  imul   -0x58(%rbp),%rax
  mov    %rax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  lea    0x0(,%rax,8),%rdx
  mov    -0x50(%rbp),%rax
  add    %rdx,%rax
  movsd  (%rax),%xmm1
  mov    -0x20(%rbp),%rax
  imul   -0x58(%rbp),%rax
  mov    %rax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  lea    0x0(,%rax,8),%rdx
  mov    -0x48(%rbp),%rax
  add    %rdx,%rax
  subsd  %xmm1,%xmm0
  movsd  %xmm0,(%rax)
  addq   $0x1,-0x18(%rbp)
L65:
  mov    -0x18(%rbp),%rax
  cmp    -0x58(%rbp),%rax
  jb     L53
  addq   $0x1,-0x20(%rbp)
L96:
  mov    -0x20(%rbp),%rax
  cmp    -0x58(%rbp),%rax
  jb     L31
  nop
  nop
  leave
  ret
```

assistant: ```c
void vec_subtract(double *restrict u, const double *restrict v, size_t n) {
  __assume_aligned(u, 64);
  __assume_aligned(v, 64);
  size_t block = 64;
  for (size_t i = 0; i < n - block; i += block)
    for (size_t j = 0; j < n; ++j) {
      for (size_t b = 0; b < block; ++b) {
        u[j * n + b] -= v[j * n + b];
      }
    }
  size_t start = n - n % block;
  for (size_t j = 0; j < n; ++j)
    for (size_t b = start; b < n; ++b) {
      u[j * n + b] -= v[j * n + b];
    }
}
```