user: 下面的汇编指令对应的C源代码是什么：

```asm
<kernel_dtrmv_u_t_8_lib4>:
  endbr64
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  mov    %edx,%r11d
  mov    %rcx,%rdx
  prefetcht0 (%rsi)
  prefetcht0 0x40(%rsi)
  prefetcht0 0x80(%rsi)
  prefetcht0 0xc0(%rsi)
  cmp    $0x3,%edi
  jle    L15
  lea    0x0(,%r11,4),%r10d
  movslq %r10d,%r10
  shl    $0x3,%r10
  lea    0x40(%r10),%r13
  lea    0x80(%r10),%r12
  lea    0xc0(%r10),%rbp
  mov    %rsi,%rcx
  lea    -0x4(%rdi),%ebx
  shr    $0x2,%ebx
  add    $0x1,%ebx
  mov    %ebx,%ebx
  mov    %rbx,%rdi
  shl    $0x5,%rdi
  add    %rdx,%rdi
  pxor   %xmm14,%xmm14
  movapd %xmm14,%xmm4
  movapd %xmm14,%xmm5
  movapd %xmm14,%xmm6
  movapd %xmm14,%xmm7
  movapd %xmm14,%xmm8
  movapd %xmm14,%xmm9
  movapd %xmm14,%xmm10
L42:
  mov    %rcx,%rax
  add    %r10,%rcx
  prefetcht0 (%rcx)
  prefetcht0 0x0(%r13,%rax,1)
  prefetcht0 (%r12,%rax,1)
  prefetcht0 0x0(%rbp,%rax,1)
  movsd  (%rdx),%xmm2
  movsd  0x8(%rdx),%xmm1
  movsd  0x10(%rdx),%xmm0
  movsd  0x18(%rdx),%xmm3
  movapd %xmm2,%xmm11
  mulsd  (%rax),%xmm11
  addsd  %xmm10,%xmm11
  movapd %xmm2,%xmm10
  mulsd  0x20(%rax),%xmm10
  addsd  %xmm9,%xmm10
  movapd %xmm2,%xmm12
  mulsd  0x40(%rax),%xmm12
  addsd  %xmm8,%xmm12
  movapd %xmm2,%xmm13
  mulsd  0x60(%rax),%xmm13
  addsd  %xmm7,%xmm13
  movapd %xmm2,%xmm9
  mulsd  0x80(%rax),%xmm9
  addsd  %xmm6,%xmm9
  movapd %xmm2,%xmm8
  mulsd  0xa0(%rax),%xmm8
  addsd  %xmm5,%xmm8
  movapd %xmm2,%xmm7
  mulsd  0xc0(%rax),%xmm7
  addsd  %xmm4,%xmm7
  mulsd  0xe0(%rax),%xmm2
  addsd  %xmm14,%xmm2
  movapd %xmm1,%xmm6
  mulsd  0x8(%rax),%xmm6
  addsd  %xmm11,%xmm6
  movapd %xmm1,%xmm4
  mulsd  0x28(%rax),%xmm4
  addsd  %xmm4,%xmm10
  movapd %xmm1,%xmm11
  mulsd  0x48(%rax),%xmm11
  addsd  %xmm12,%xmm11
  movapd %xmm1,%xmm5
  mulsd  0x68(%rax),%xmm5
  addsd  %xmm13,%xmm5
  movapd %xmm1,%xmm4
  mulsd  0x88(%rax),%xmm4
  addsd  %xmm9,%xmm4
  movapd %xmm1,%xmm9
  mulsd  0xa8(%rax),%xmm9
  addsd  %xmm8,%xmm9
  movapd %xmm1,%xmm8
  mulsd  0xc8(%rax),%xmm8
  addsd  %xmm7,%xmm8
  mulsd  0xe8(%rax),%xmm1
  addsd  %xmm2,%xmm1
  movapd %xmm0,%xmm13
  mulsd  0x10(%rax),%xmm13
  addsd  %xmm6,%xmm13
  movapd %xmm0,%xmm12
  mulsd  0x30(%rax),%xmm12
  addsd  %xmm10,%xmm12
  movapd %xmm0,%xmm7
  mulsd  0x50(%rax),%xmm7
  addsd  %xmm11,%xmm7
  movapd %xmm0,%xmm6
  mulsd  0x70(%rax),%xmm6
  addsd  %xmm5,%xmm6
  movapd %xmm0,%xmm5
  mulsd  0x90(%rax),%xmm5
  addsd  %xmm4,%xmm5
  movapd %xmm0,%xmm4
  mulsd  0xb0(%rax),%xmm4
  addsd  %xmm9,%xmm4
  movapd %xmm0,%xmm2
  mulsd  0xd0(%rax),%xmm2
  addsd  %xmm8,%xmm2
  mulsd  0xf0(%rax),%xmm0
  addsd  %xmm1,%xmm0
  movapd %xmm3,%xmm10
  mulsd  0x18(%rax),%xmm10
  addsd  %xmm13,%xmm10
  movapd %xmm3,%xmm9
  mulsd  0x38(%rax),%xmm9
  addsd  %xmm12,%xmm9
  movapd %xmm3,%xmm8
  mulsd  0x58(%rax),%xmm8
  addsd  %xmm7,%xmm8
  movapd %xmm3,%xmm7
  mulsd  0x78(%rax),%xmm7
  addsd  %xmm6,%xmm7
  movapd %xmm3,%xmm6
  mulsd  0x98(%rax),%xmm6
  addsd  %xmm5,%xmm6
  movapd %xmm3,%xmm5
  mulsd  0xb8(%rax),%xmm5
  addsd  %xmm4,%xmm5
  movapd %xmm3,%xmm4
  mulsd  0xd8(%rax),%xmm4
  addsd  %xmm2,%xmm4
  mulsd  0xf8(%rax),%xmm3
  addsd  %xmm0,%xmm3
  movapd %xmm3,%xmm14
  add    $0x20,%rdx
  cmp    %rdi,%rdx
  jne    L42
  imul   %rbx,%r10
  add    %r10,%rsi
L53:
  lea    0x0(,%r11,4),%edx
  movslq %edx,%rdx
  shl    $0x3,%rdx
  lea    (%rsi,%rdx,1),%rax
  prefetcht0 (%rax)
  prefetcht0 0x40(%rsi,%rdx,1)
  prefetcht0 0x80(%rsi,%rdx,1)
  prefetcht0 0xc0(%rsi,%rdx,1)
  movsd  (%rdi),%xmm0
  movsd  0x8(%rdi),%xmm1
  movsd  0x10(%rdi),%xmm3
  movsd  0x18(%rdi),%xmm2
  movapd %xmm0,%xmm11
  mulsd  (%rsi),%xmm11
  movapd %xmm11,%xmm13
  addsd  %xmm10,%xmm13
  movapd %xmm0,%xmm10
  mulsd  0x20(%rsi),%xmm10
  addsd  %xmm10,%xmm9
  movapd %xmm0,%xmm10
  mulsd  0x40(%rsi),%xmm10
  addsd  %xmm8,%xmm10
  movapd %xmm0,%xmm11
  mulsd  0x60(%rsi),%xmm11
  addsd  %xmm7,%xmm11
  movapd %xmm0,%xmm8
  mulsd  0x80(%rsi),%xmm8
  addsd  %xmm6,%xmm8
  movapd %xmm0,%xmm7
  mulsd  0xa0(%rsi),%xmm7
  addsd  %xmm5,%xmm7
  movapd %xmm0,%xmm6
  mulsd  0xc0(%rsi),%xmm6
  addsd  %xmm4,%xmm6
  mulsd  0xe0(%rsi),%xmm0
  addsd  %xmm14,%xmm0
  movapd %xmm1,%xmm4
  mulsd  0x28(%rsi),%xmm4
  addsd  %xmm9,%xmm4
  movapd %xmm4,%xmm12
  movapd %xmm1,%xmm9
  mulsd  0x48(%rsi),%xmm9
  addsd  %xmm10,%xmm9
  movapd %xmm1,%xmm4
  mulsd  0x68(%rsi),%xmm4
  addsd  %xmm11,%xmm4
  movapd %xmm1,%xmm5
  mulsd  0x88(%rsi),%xmm5
  addsd  %xmm8,%xmm5
  movapd %xmm1,%xmm10
  mulsd  0xa8(%rsi),%xmm10
  addsd  %xmm7,%xmm10
  movapd %xmm1,%xmm8
  mulsd  0xc8(%rsi),%xmm8
  addsd  %xmm6,%xmm8
  mulsd  0xe8(%rsi),%xmm1
  addsd  %xmm0,%xmm1
  movapd %xmm3,%xmm7
  mulsd  0x50(%rsi),%xmm7
  addsd  %xmm7,%xmm9
  movapd %xmm3,%xmm6
  mulsd  0x70(%rsi),%xmm6
  addsd  %xmm4,%xmm6
  movapd %xmm3,%xmm4
  mulsd  0x90(%rsi),%xmm4
  movapd %xmm4,%xmm7
  addsd  %xmm5,%xmm7
  movapd %xmm3,%xmm5
  mulsd  0xb0(%rsi),%xmm5
  addsd  %xmm10,%xmm5
  movapd %xmm5,%xmm11
  movapd %xmm3,%xmm0
  mulsd  0xd0(%rsi),%xmm0
  addsd  %xmm8,%xmm0
  movapd %xmm0,%xmm10
  mulsd  0xf0(%rsi),%xmm3
  movapd %xmm3,%xmm0
  addsd  %xmm1,%xmm0
  movapd %xmm2,%xmm5
  mulsd  0x78(%rsi),%xmm5
  addsd  %xmm6,%xmm5
  movapd %xmm5,%xmm8
  movapd %xmm2,%xmm4
  mulsd  0x98(%rsi),%xmm4
  addsd  %xmm4,%xmm7
  movapd %xmm2,%xmm3
  mulsd  0xb8(%rsi),%xmm3
  addsd  %xmm11,%xmm3
  movapd %xmm3,%xmm5
  movapd %xmm2,%xmm1
  mulsd  0xd8(%rsi),%xmm1
  addsd  %xmm10,%xmm1
  movapd %xmm1,%xmm6
  mulsd  0xf8(%rsi),%xmm2
  addsd  %xmm2,%xmm0
  movsd  0x20(%rdi),%xmm1
  movsd  0x28(%rdi),%xmm2
  movsd  0x30(%rdi),%xmm3
  movapd %xmm1,%xmm4
  mulsd  0x80(%rax),%xmm4
  addsd  %xmm4,%xmm7
  movapd %xmm1,%xmm4
  mulsd  0xa0(%rax),%xmm4
  addsd  %xmm5,%xmm4
  movapd %xmm1,%xmm5
  mulsd  0xc0(%rax),%xmm5
  addsd  %xmm6,%xmm5
  mulsd  0xe0(%rax),%xmm1
  addsd  %xmm0,%xmm1
  movapd %xmm2,%xmm0
  mulsd  0xa8(%rax),%xmm0
  addsd  %xmm4,%xmm0
  movapd %xmm0,%xmm6
  movapd %xmm2,%xmm4
  mulsd  0xc8(%rax),%xmm4
  addsd  %xmm5,%xmm4
  movapd %xmm2,%xmm0
  mulsd  0xe8(%rax),%xmm0
  addsd  %xmm1,%xmm0
  movapd %xmm3,%xmm1
  mulsd  0xd0(%rax),%xmm1
  addsd  %xmm4,%xmm1
  mulsd  0xf0(%rax),%xmm3
  addsd  %xmm0,%xmm3
  movsd  0xf8(%rax),%xmm0
  mulsd  0x38(%rdi),%xmm0
  addsd  %xmm3,%xmm0
  test   %r9d,%r9d
  jne    L9
  movsd  %xmm13,(%r8)
  movsd  %xmm12,0x8(%r8)
  movsd  %xmm9,0x10(%r8)
  movsd  %xmm8,0x18(%r8)
  movsd  %xmm7,0x20(%r8)
  movsd  %xmm6,0x28(%r8)
  movsd  %xmm1,0x30(%r8)
L19:
  movsd  %xmm0,0x38(%r8)
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  ret
L15:
  mov    %rcx,%rdi
  pxor   %xmm14,%xmm14
  movapd %xmm14,%xmm4
  movapd %xmm14,%xmm5
  movapd %xmm14,%xmm6
  movapd %xmm14,%xmm7
  movapd %xmm14,%xmm8
  movapd %xmm14,%xmm9
  movapd %xmm14,%xmm10
  jmp    L53
L9:
  cmp    $0x1,%r9d
  je     L5
  movsd  (%r8),%xmm2
  subsd  %xmm13,%xmm2
  movsd  %xmm2,(%r8)
  movsd  0x8(%r8),%xmm2
  subsd  %xmm12,%xmm2
  movsd  %xmm2,0x8(%r8)
  movsd  0x10(%r8),%xmm2
  subsd  %xmm9,%xmm2
  movsd  %xmm2,0x10(%r8)
  movsd  0x18(%r8),%xmm2
  subsd  %xmm8,%xmm2
  movsd  %xmm2,0x18(%r8)
  movsd  0x20(%r8),%xmm2
  subsd  %xmm7,%xmm2
  movsd  %xmm2,0x20(%r8)
  movsd  0x28(%r8),%xmm2
  subsd  %xmm6,%xmm2
  movsd  %xmm2,0x28(%r8)
  movsd  0x30(%r8),%xmm2
  subsd  %xmm1,%xmm2
  movsd  %xmm2,0x30(%r8)
  movsd  0x38(%r8),%xmm1
  subsd  %xmm0,%xmm1
  movapd %xmm1,%xmm0
  jmp    L19
L5:
  addsd  (%r8),%xmm13
  movsd  %xmm13,(%r8)
  addsd  0x8(%r8),%xmm12
  movsd  %xmm12,0x8(%r8)
  addsd  0x10(%r8),%xmm9
  movsd  %xmm9,0x10(%r8)
  addsd  0x18(%r8),%xmm8
  movsd  %xmm8,0x18(%r8)
  addsd  0x20(%r8),%xmm7
  movsd  %xmm7,0x20(%r8)
  addsd  0x28(%r8),%xmm6
  movsd  %xmm6,0x28(%r8)
  addsd  0x30(%r8),%xmm1
  movsd  %xmm1,0x30(%r8)
  addsd  0x38(%r8),%xmm0
  jmp    L19
```

assistant: ```c
void kernel_dtrmv_u_t_8_lib4(int kmax, double *A, int sda, double *x, double *y, int alg) {
  __builtin_prefetch(A);
  __builtin_prefetch(A + 8);
  __builtin_prefetch(A + 16);
  __builtin_prefetch(A + 24);
  const int lda = 4;
  const int bs = 4;
  int k;
  double x_0, x_1, x_2, x_3, y_0 = 0, y_1 = 0, y_2 = 0, y_3 = 0, y_4 = 0, y_5 = 0, y_6 = 0, y_7 = 0;
  k = 0;
  for (; k < kmax - 3; k += 4) {
    __builtin_prefetch(A + sda * bs);
    __builtin_prefetch(A + sda * bs + 8);
    __builtin_prefetch(A + sda * bs + 16);
    __builtin_prefetch(A + sda * bs + 24);
    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_1 += A[0 + lda * 1] * x_0;
    y_2 += A[0 + lda * 2] * x_0;
    y_3 += A[0 + lda * 3] * x_0;
    y_4 += A[0 + lda * 4] * x_0;
    y_5 += A[0 + lda * 5] * x_0;
    y_6 += A[0 + lda * 6] * x_0;
    y_7 += A[0 + lda * 7] * x_0;
    y_0 += A[1 + lda * 0] * x_1;
    y_1 += A[1 + lda * 1] * x_1;
    y_2 += A[1 + lda * 2] * x_1;
    y_3 += A[1 + lda * 3] * x_1;
    y_4 += A[1 + lda * 4] * x_1;
    y_5 += A[1 + lda * 5] * x_1;
    y_6 += A[1 + lda * 6] * x_1;
    y_7 += A[1 + lda * 7] * x_1;
    y_0 += A[2 + lda * 0] * x_2;
    y_1 += A[2 + lda * 1] * x_2;
    y_2 += A[2 + lda * 2] * x_2;
    y_3 += A[2 + lda * 3] * x_2;
    y_4 += A[2 + lda * 4] * x_2;
    y_5 += A[2 + lda * 5] * x_2;
    y_6 += A[2 + lda * 6] * x_2;
    y_7 += A[2 + lda * 7] * x_2;
    y_0 += A[3 + lda * 0] * x_3;
    y_1 += A[3 + lda * 1] * x_3;
    y_2 += A[3 + lda * 2] * x_3;
    y_3 += A[3 + lda * 3] * x_3;
    y_4 += A[3 + lda * 4] * x_3;
    y_5 += A[3 + lda * 5] * x_3;
    y_6 += A[3 + lda * 6] * x_3;
    y_7 += A[3 + lda * 7] * x_3;
    A += sda * bs;
    x += 4;
  }
  __builtin_prefetch(A + sda * bs);
  __builtin_prefetch(A + sda * bs + 8);
  __builtin_prefetch(A + sda * bs + 16);
  __builtin_prefetch(A + sda * bs + 24);
  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_1 += A[0 + lda * 1] * x_0;
  y_2 += A[0 + lda * 2] * x_0;
  y_3 += A[0 + lda * 3] * x_0;
  y_4 += A[0 + lda * 4] * x_0;
  y_5 += A[0 + lda * 5] * x_0;
  y_6 += A[0 + lda * 6] * x_0;
  y_7 += A[0 + lda * 7] * x_0;
  y_1 += A[1 + lda * 1] * x_1;
  y_2 += A[1 + lda * 2] * x_1;
  y_3 += A[1 + lda * 3] * x_1;
  y_4 += A[1 + lda * 4] * x_1;
  y_5 += A[1 + lda * 5] * x_1;
  y_6 += A[1 + lda * 6] * x_1;
  y_7 += A[1 + lda * 7] * x_1;
  y_2 += A[2 + lda * 2] * x_2;
  y_3 += A[2 + lda * 3] * x_2;
  y_4 += A[2 + lda * 4] * x_2;
  y_5 += A[2 + lda * 5] * x_2;
  y_6 += A[2 + lda * 6] * x_2;
  y_7 += A[2 + lda * 7] * x_2;
  y_3 += A[3 + lda * 3] * x_3;
  y_4 += A[3 + lda * 4] * x_3;
  y_5 += A[3 + lda * 5] * x_3;
  y_6 += A[3 + lda * 6] * x_3;
  y_7 += A[3 + lda * 7] * x_3;
  A += sda * bs;
  x += 4;
  x_0 = x[0];
  x_1 = x[1];
  x_2 = x[2];
  x_3 = x[3];
  y_4 += A[0 + lda * 4] * x_0;
  y_5 += A[0 + lda * 5] * x_0;
  y_6 += A[0 + lda * 6] * x_0;
  y_7 += A[0 + lda * 7] * x_0;
  y_5 += A[1 + lda * 5] * x_1;
  y_6 += A[1 + lda * 6] * x_1;
  y_7 += A[1 + lda * 7] * x_1;
  y_6 += A[2 + lda * 6] * x_2;
  y_7 += A[2 + lda * 7] * x_2;
  y_7 += A[3 + lda * 7] * x_3;
  if (alg == 0) {
    y[0] = y_0;
    y[1] = y_1;
    y[2] = y_2;
    y[3] = y_3;
    y[4] = y_4;
    y[5] = y_5;
    y[6] = y_6;
    y[7] = y_7;
  } else if (alg == 1) {
    y[0] += y_0;
    y[1] += y_1;
    y[2] += y_2;
    y[3] += y_3;
    y[4] += y_4;
    y[5] += y_5;
    y[6] += y_6;
    y[7] += y_7;
  } else {
    y[0] -= y_0;
    y[1] -= y_1;
    y[2] -= y_2;
    y[3] -= y_3;
    y[4] -= y_4;
    y[5] -= y_5;
    y[6] -= y_6;
    y[7] -= y_7;
  }
}
```