user: 下面的汇编指令对应的C源代码是什么：

```asm
<kernel_dtrmv_u_t_1_lib4>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  mov    %edi,-0x44(%rbp)
  mov    %rsi,-0x50(%rbp)
  mov    %edx,-0x48(%rbp)
  mov    %rcx,-0x58(%rbp)
  mov    %r8,-0x60(%rbp)
  mov    %r9d,-0x64(%rbp)
  mov    -0x50(%rbp),%rax
  prefetcht0 (%rax)
  movl   $0x4,-0x30(%rbp)
  movl   $0x4,-0x2c(%rbp)
  pxor   %xmm0,%xmm0
  movsd  %xmm0,-0x28(%rbp)
  movl   $0x0,-0x34(%rbp)
  jmp    L59
L54:
  mov    -0x48(%rbp),%eax
  imul   -0x2c(%rbp),%eax
  cltq
  lea    0x0(,%rax,8),%rdx
  mov    -0x50(%rbp),%rax
  add    %rdx,%rax
  prefetcht0 (%rax)
  mov    -0x58(%rbp),%rax
  movsd  (%rax),%xmm0
  movsd  %xmm0,-0x20(%rbp)
  mov    -0x58(%rbp),%rax
  movsd  0x8(%rax),%xmm0
  movsd  %xmm0,-0x18(%rbp)
  mov    -0x58(%rbp),%rax
  movsd  0x10(%rax),%xmm0
  movsd  %xmm0,-0x10(%rbp)
  mov    -0x58(%rbp),%rax
  movsd  0x18(%rax),%xmm0
  movsd  %xmm0,-0x8(%rbp)
  mov    -0x50(%rbp),%rax
  movsd  (%rax),%xmm0
  mulsd  -0x20(%rbp),%xmm0
  movsd  -0x28(%rbp),%xmm1
  addsd  %xmm1,%xmm0
  movsd  %xmm0,-0x28(%rbp)
  mov    -0x50(%rbp),%rax
  add    $0x8,%rax
  movsd  (%rax),%xmm0
  mulsd  -0x18(%rbp),%xmm0
  movsd  -0x28(%rbp),%xmm1
  addsd  %xmm1,%xmm0
  movsd  %xmm0,-0x28(%rbp)
  mov    -0x50(%rbp),%rax
  add    $0x10,%rax
  movsd  (%rax),%xmm0
  mulsd  -0x10(%rbp),%xmm0
  movsd  -0x28(%rbp),%xmm1
  addsd  %xmm1,%xmm0
  movsd  %xmm0,-0x28(%rbp)
  mov    -0x50(%rbp),%rax
  add    $0x18,%rax
  movsd  (%rax),%xmm0
  mulsd  -0x8(%rbp),%xmm0
  movsd  -0x28(%rbp),%xmm1
  addsd  %xmm1,%xmm0
  movsd  %xmm0,-0x28(%rbp)
  mov    -0x48(%rbp),%eax
  imul   -0x2c(%rbp),%eax
  cltq
  shl    $0x3,%rax
  add    %rax,-0x50(%rbp)
  addq   $0x20,-0x58(%rbp)
  addl   $0x4,-0x34(%rbp)
L59:
  mov    -0x44(%rbp),%eax
  sub    $0x3,%eax
  cmp    %eax,-0x34(%rbp)
  jl     L54
  mov    -0x44(%rbp),%eax
  sub    $0x1,%eax
  cmp    %eax,-0x34(%rbp)
  jge    L66
  mov    -0x58(%rbp),%rax
  movsd  (%rax),%xmm0
  movsd  %xmm0,-0x20(%rbp)
  mov    -0x58(%rbp),%rax
  movsd  0x8(%rax),%xmm0
  movsd  %xmm0,-0x18(%rbp)
  mov    -0x50(%rbp),%rax
  movsd  (%rax),%xmm0
  mulsd  -0x20(%rbp),%xmm0
  movsd  -0x28(%rbp),%xmm1
  addsd  %xmm1,%xmm0
  movsd  %xmm0,-0x28(%rbp)
  mov    -0x50(%rbp),%rax
  add    $0x8,%rax
  movsd  (%rax),%xmm0
  mulsd  -0x18(%rbp),%xmm0
  movsd  -0x28(%rbp),%xmm1
  addsd  %xmm1,%xmm0
  movsd  %xmm0,-0x28(%rbp)
  addq   $0x10,-0x50(%rbp)
  addq   $0x10,-0x58(%rbp)
L66:
  mov    -0x58(%rbp),%rax
  movsd  (%rax),%xmm0
  movsd  %xmm0,-0x20(%rbp)
  mov    -0x50(%rbp),%rax
  movsd  (%rax),%xmm0
  mulsd  -0x20(%rbp),%xmm0
  movsd  -0x28(%rbp),%xmm1
  addsd  %xmm1,%xmm0
  movsd  %xmm0,-0x28(%rbp)
  cmpl   $0x0,-0x64(%rbp)
  jne    L40
  mov    -0x60(%rbp),%rax
  movsd  -0x28(%rbp),%xmm0
  movsd  %xmm0,(%rax)
  jmp    L62
L40:
  cmpl   $0x1,-0x64(%rbp)
  jne    L16
  mov    -0x60(%rbp),%rax
  movsd  (%rax),%xmm0
  addsd  -0x28(%rbp),%xmm0
  mov    -0x60(%rbp),%rax
  movsd  %xmm0,(%rax)
  jmp    L62
L16:
  mov    -0x60(%rbp),%rax
  movsd  (%rax),%xmm0
  subsd  -0x28(%rbp),%xmm0
  mov    -0x60(%rbp),%rax
  movsd  %xmm0,(%rax)
L62:
  nop
  pop    %rbp
  ret
```

assistant: ```c
void kernel_dtrmv_u_t_1_lib4(int kmax, double *A, int sda, double *x, double *y, int alg) {
  __builtin_prefetch(A);
  const int lda = 4;
  const int bs = 4;
  int k;
  double x_0, x_1, x_2, x_3, y_0 = 0;
  k = 0;
  for (; k < kmax - 3; k += 4) {
    __builtin_prefetch(A + sda * bs);
    x_0 = x[0];
    x_1 = x[1];
    x_2 = x[2];
    x_3 = x[3];
    y_0 += A[0 + lda * 0] * x_0;
    y_0 += A[1 + lda * 0] * x_1;
    y_0 += A[2 + lda * 0] * x_2;
    y_0 += A[3 + lda * 0] * x_3;
    A += sda * bs;
    x += 4;
  }
  if (k < kmax - 1) {
    x_0 = x[0];
    x_1 = x[1];
    y_0 += A[0 + lda * 0] * x_0;
    y_0 += A[1 + lda * 0] * x_1;
    A += 2;
    x += 2;
  }
  x_0 = x[0];
  y_0 += A[0 + lda * 0] * x_0;
  if (alg == 0) {
    y[0] = y_0;
  } else if (alg == 1) {
    y[0] += y_0;
  } else {
    y[0] -= y_0;
  }
}
```