user: 下面的汇编指令对应的C源代码是什么：

```asm
<kernel_dgemv_t_1_lib4>:
  endbr64
  push   %r12
  mov    %edi,%r11d
  push   %rbp
  push   %rbx
  mov    0x20(%rsp),%ebp
  test   %edi,%edi
  jle    L132
  mov    %rsi,%rdi
  mov    %rcx,%r10
  cmp    $0x3,%r11d
  jle    L111
  lea    -0x4(%r11),%ebx
  lea    0x0(,%rdx,4),%esi
  pxor   %xmm0,%xmm0
  mov    %edx,%eax
  mov    %ebx,%r12d
  movslq %esi,%rsi
  mov    %rdi,%rdx
  shr    $0x2,%r12d
  shl    $0x3,%rsi
  add    $0x1,%r12d
  cmp    $0x1,%eax
  mov    %rcx,%rax
  mov    $0x0,%ecx
  jne    L64
  xchg   %ax,%ax
L85:
  movupd (%rax),%xmm2
  movupd (%rdx),%xmm4
  add    $0x1,%ecx
  add    $0x20,%rax
  movupd 0x10(%rdx),%xmm5
  movupd -0x10(%rax),%xmm1
  add    %rsi,%rdx
  mulpd  %xmm4,%xmm2
  mulpd  %xmm5,%xmm1
  addsd  %xmm2,%xmm0
  unpckhpd %xmm2,%xmm2
  addsd  %xmm2,%xmm0
  addsd  %xmm1,%xmm0
  unpckhpd %xmm1,%xmm1
  addsd  %xmm1,%xmm0
  cmp    %r12d,%ecx
  jb     L85
L30:
  shr    $0x2,%ebx
  lea    0x1(%rbx),%edx
  imul   %rdx,%rsi
  mov    %rdx,%rax
  shl    $0x5,%rdx
  shl    $0x2,%eax
  add    %rdx,%r10
  add    %rsi,%rdi
  cmp    %eax,%r11d
  jle    L134
L114:
  mov    %r11d,%edx
  sub    %eax,%edx
  cmp    %r11d,%eax
  mov    $0x1,%eax
  cmovl  %edx,%eax
  jge    L0
  cmp    $0x1,%edx
  je     L0
  movupd (%r10),%xmm1
  movupd (%rdi),%xmm6
  mov    %eax,%edx
  shr    %edx
  mulpd  %xmm6,%xmm1
  addsd  %xmm1,%xmm0
  unpckhpd %xmm1,%xmm1
  addsd  %xmm1,%xmm0
  cmp    $0x1,%edx
  je     L52
  movupd 0x10(%r10),%xmm1
  movupd 0x10(%rdi),%xmm7
  mulpd  %xmm7,%xmm1
  addsd  %xmm1,%xmm0
  unpckhpd %xmm1,%xmm1
  addsd  %xmm1,%xmm0
L52:
  mov    %eax,%ecx
  and    $0xfffffffe,%ecx
  mov    %ecx,%edx
  shl    $0x3,%rdx
  add    %rdx,%rdi
  add    %rdx,%r10
  cmp    %ecx,%eax
  je     L134
L0:
  movsd  (%r10),%xmm1
  mulsd  (%rdi),%xmm1
  addsd  %xmm1,%xmm0
L134:
  test   %ebp,%ebp
  je     L91
  movsd  (%r8),%xmm1
  cmp    $0x1,%ebp
  je     L51
  subsd  %xmm0,%xmm1
  movsd  %xmm1,(%r9)
L132:
  pop    %rbx
  pop    %rbp
  pop    %r12
  ret
  nopw   0x0(%rax,%rax,1)
L64:
  movupd (%rdx),%xmm2
  movupd (%rax),%xmm6
  add    $0x1,%ecx
  add    $0x20,%rax
  movupd 0x10(%rdx),%xmm1
  movupd -0x10(%rax),%xmm7
  add    %rsi,%rdx
  mulpd  %xmm6,%xmm2
  mulpd  %xmm7,%xmm1
  addsd  %xmm2,%xmm0
  unpckhpd %xmm2,%xmm2
  addsd  %xmm2,%xmm0
  addsd  %xmm1,%xmm0
  unpckhpd %xmm1,%xmm1
  addsd  %xmm1,%xmm0
  cmp    %r12d,%ecx
  jb     L64
  jmp    L30
  xchg   %ax,%ax
L91:
  pop    %rbx
  movsd  %xmm0,(%r8)
  pop    %rbp
  pop    %r12
  ret
  nopw   0x0(%rax,%rax,1)
L51:
  addsd  %xmm1,%xmm0
  pop    %rbx
  pop    %rbp
  pop    %r12
  movsd  %xmm0,(%r9)
  ret
  xchg   %ax,%ax
L111:
  pxor   %xmm0,%xmm0
  xor    %eax,%eax
  jmp    L114
```

assistant: ```c
void kernel_dgemv_t_1_lib4(int kmax, double *A, int sda, double *x, double *y, double *z, int alg) {
  if (kmax <= 0)
    return;
  const int lda = 4;
  const int bs = 4;
  int k, ka = kmax;
  double x_0, x_1, x_2, x_3, y_0 = 0;
  k = 0;
  for (; k < ka - bs + 1; k += 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;
  }
  for (; k < ka; k++) {
    x_0 = x[0];
    y_0 += A[0 + lda * 0] * x_0;
    A += 1;
    x += 1;
  }
  if (alg == 0) {
    y[0] = y_0;
  } else if (alg == 1) {
    z[0] = y[0] + y_0;
  } else {
    z[0] = y[0] - y_0;
  }
}
```