user: What would the C source look like for the assembly code provided here?

```asm
<kernel_dtrsv_t_4_lib4_new>:
  endbr64
  test   %edi,%edi
  jle    L49
  shl    $0x2,%edx
  push   %r15
  push   %r14
  mov    %ecx,%r14d
  push   %r13
  push   %r12
  mov    %rsi,%r12
  push   %rbp
  mov    %edi,%ebp
  movslq %edx,%rdi
  push   %rbx
  lea    0x0(,%rdi,8),%rbx
  lea    (%rsi,%rbx,1),%r10
  lea    0x20(%r9),%rsi
  prefetcht0 (%r10)
  prefetcht0 0x40(%r10)
  cmp    $0xb,%ebp
  jle    L0
  lea    -0xc(%rbp),%eax
  pxor   %xmm0,%xmm0
  lea    0x40(%rbx),%r11
  shl    $0x4,%rdi
  shr    $0x3,%eax
  lea    (%r10,%rbx,1),%rdx
  movapd %xmm0,%xmm7
  mov    %rsi,%rcx
  mov    %eax,%r15d
  mov    %eax,-0x4(%rsp)
  movapd %xmm0,%xmm5
  movapd %xmm0,%xmm6
  mov    %r15,%rax
  shl    $0x6,%rax
  lea    0x60(%r9,%rax,1),%r13
  mov    %r10,%rax
  nopl   0x0(%rax)
L71:
  movsd  (%rcx),%xmm4
  movsd  (%rax),%xmm8
  prefetcht0 (%rax,%r11,1)
  prefetcht0 (%rdx)
  movsd  0x8(%rcx),%xmm3
  movsd  0x8(%rax),%xmm9
  prefetcht0 (%r11,%rdx,1)
  add    $0x40,%rcx
  mulsd  %xmm4,%xmm8
  movsd  -0x30(%rcx),%xmm2
  movsd  -0x28(%rcx),%xmm1
  mulsd  %xmm3,%xmm9
  movsd  0x18(%rax),%xmm10
  mulsd  %xmm1,%xmm10
  addsd  %xmm8,%xmm6
  movsd  0x20(%rax),%xmm8
  mulsd  %xmm4,%xmm8
  addsd  %xmm6,%xmm9
  movsd  0x10(%rax),%xmm6
  mulsd  %xmm2,%xmm6
  addsd  %xmm8,%xmm5
  movsd  0x40(%rax),%xmm8
  mulsd  %xmm4,%xmm8
  mulsd  0x60(%rax),%xmm4
  addsd  %xmm9,%xmm6
  movsd  0x38(%rax),%xmm9
  mulsd  %xmm1,%xmm9
  addsd  %xmm6,%xmm10
  movsd  (%rdx),%xmm6
  addsd  %xmm8,%xmm7
  movsd  0x28(%rax),%xmm8
  addsd  %xmm4,%xmm0
  movsd  0x48(%rax),%xmm4
  mulsd  %xmm3,%xmm8
  mulsd  %xmm3,%xmm4
  mulsd  0x68(%rax),%xmm3
  addsd  %xmm5,%xmm8
  movsd  0x30(%rax),%xmm5
  addsd  %xmm7,%xmm4
  movsd  0x50(%rax),%xmm7
  mulsd  %xmm2,%xmm5
  addsd  %xmm0,%xmm3
  movsd  -0x8(%rcx),%xmm0
  mulsd  %xmm2,%xmm7
  mulsd  0x70(%rax),%xmm2
  addsd  %xmm8,%xmm5
  movsd  0x58(%rax),%xmm8
  addsd  %xmm4,%xmm7
  mulsd  %xmm1,%xmm8
  addsd  %xmm3,%xmm2
  movsd  -0x20(%rcx),%xmm3
  mulsd  0x78(%rax),%xmm1
  addsd  %xmm5,%xmm9
  movsd  0x20(%rdx),%xmm5
  add    %rdi,%rax
  mulsd  %xmm3,%xmm6
  prefetcht0 (%rax)
  mulsd  %xmm3,%xmm5
  addsd  %xmm7,%xmm8
  movsd  0x40(%rdx),%xmm7
  movapd %xmm1,%xmm4
  movsd  -0x10(%rcx),%xmm1
  mulsd  %xmm3,%xmm7
  addsd  %xmm2,%xmm4
  movsd  -0x18(%rcx),%xmm2
  addsd  %xmm10,%xmm6
  mulsd  0x60(%rdx),%xmm3
  addsd  %xmm9,%xmm5
  addsd  %xmm8,%xmm7
  addsd  %xmm4,%xmm3
  movsd  0x8(%rdx),%xmm4
  movsd  0x28(%rdx),%xmm8
  mulsd  %xmm2,%xmm4
  mulsd  %xmm2,%xmm8
  addsd  %xmm6,%xmm4
  movsd  0x48(%rdx),%xmm6
  addsd  %xmm5,%xmm8
  movsd  0x10(%rdx),%xmm5
  mulsd  %xmm2,%xmm6
  mulsd  0x68(%rdx),%xmm2
  mulsd  %xmm1,%xmm5
  addsd  %xmm7,%xmm6
  movsd  0x58(%rdx),%xmm7
  addsd  %xmm3,%xmm2
  movsd  0x50(%rdx),%xmm3
  addsd  %xmm4,%xmm5
  movsd  0x30(%rdx),%xmm4
  mulsd  %xmm0,%xmm7
  mulsd  %xmm1,%xmm3
  mulsd  %xmm1,%xmm4
  mulsd  0x70(%rdx),%xmm1
  addsd  %xmm6,%xmm3
  movsd  0x18(%rdx),%xmm6
  addsd  %xmm8,%xmm4
  mulsd  %xmm0,%xmm6
  addsd  %xmm2,%xmm1
  addsd  %xmm3,%xmm7
  addsd  %xmm5,%xmm6
  movsd  0x38(%rdx),%xmm5
  mulsd  %xmm0,%xmm5
  mulsd  0x78(%rdx),%xmm0
  add    %rdi,%rdx
  addsd  %xmm4,%xmm5
  addsd  %xmm1,%xmm0
  cmp    %rcx,%r13
  jne    L71
  add    $0x1,%r15
  mov    -0x4(%rsp),%eax
  imul   %r15,%rdi
  shl    $0x6,%r15
  add    %r15,%rsi
  add    %rdi,%r10
  lea    0xc(,%rax,8),%edi
L22:
  lea    -0x3(%rbp),%eax
  cmp    %edi,%eax
  jle    L29
  lea    -0x4(%rbp),%r13d
  lea    0x40(%rbx),%r11
  mov    %r10,%rdx
  sub    %edi,%r13d
  shr    $0x2,%r13d
  lea    0x1(%r13),%r15d
  mov    %r15,%rcx
  shl    $0x5,%rcx
  add    %rsi,%rcx
  nopl   (%rax)
L18:
  mov    %rdx,%rax
  movsd  (%rsi),%xmm2
  movsd  0x8(%rsi),%xmm1
  add    %rbx,%rdx
  movsd  (%rax),%xmm8
  movsd  0x10(%rsi),%xmm3
  add    $0x20,%rsi
  prefetcht0 (%rdx)
  movsd  0x10(%rax),%xmm9
  movsd  -0x8(%rsi),%xmm4
  prefetcht0 (%r11,%rax,1)
  mulsd  %xmm2,%xmm8
  mulsd  %xmm3,%xmm9
  addsd  %xmm8,%xmm6
  movsd  0x20(%rax),%xmm8
  mulsd  %xmm2,%xmm8
  addsd  %xmm8,%xmm5
  movsd  0x40(%rax),%xmm8
  mulsd  %xmm2,%xmm8
  mulsd  0x60(%rax),%xmm2
  addsd  %xmm8,%xmm7
  movsd  0x30(%rax),%xmm8
  addsd  %xmm0,%xmm2
  movsd  0x8(%rax),%xmm0
  mulsd  %xmm3,%xmm8
  mulsd  %xmm1,%xmm0
  addsd  %xmm0,%xmm6
  movsd  0x28(%rax),%xmm0
  mulsd  %xmm1,%xmm0
  addsd  %xmm6,%xmm9
  movsd  0x18(%rax),%xmm6
  mulsd  %xmm4,%xmm6
  addsd  %xmm0,%xmm5
  movsd  0x48(%rax),%xmm0
  mulsd  %xmm1,%xmm0
  mulsd  0x68(%rax),%xmm1
  addsd  %xmm5,%xmm8
  movsd  0x38(%rax),%xmm5
  addsd  %xmm9,%xmm6
  mulsd  %xmm4,%xmm5
  addsd  %xmm0,%xmm7
  addsd  %xmm2,%xmm1
  movsd  0x50(%rax),%xmm2
  mulsd  %xmm3,%xmm2
  addsd  %xmm8,%xmm5
  mulsd  0x70(%rax),%xmm3
  addsd  %xmm7,%xmm2
  movsd  0x58(%rax),%xmm7
  movapd %xmm3,%xmm0
  addsd  %xmm1,%xmm0
  movsd  0x78(%rax),%xmm1
  mulsd  %xmm4,%xmm7
  mulsd  %xmm4,%xmm1
  addsd  %xmm2,%xmm7
  addsd  %xmm1,%xmm0
  cmp    %rcx,%rsi
  jne    L18
  imul   %r15,%rbx
  lea    0x4(%rdi,%r13,4),%edi
  add    %rbx,%r10
L76:
  cmp    %edi,%ebp
  jle    L84
  sub    $0x1,%ebp
  sub    %edi,%ebp
  lea    0x8(%rcx,%rbp,8),%rax
L44:
  movsd  (%rcx),%xmm1
  movsd  (%r10),%xmm2
  add    $0x8,%rcx
  add    $0x8,%r10
  mulsd  %xmm1,%xmm2
  addsd  %xmm2,%xmm6
  movsd  0x18(%r10),%xmm2
  mulsd  %xmm1,%xmm2
  addsd  %xmm2,%xmm5
  movsd  0x38(%r10),%xmm2
  mulsd  %xmm1,%xmm2
  mulsd  0x58(%r10),%xmm1
  addsd  %xmm2,%xmm7
  addsd  %xmm1,%xmm0
  cmp    %rax,%rcx
  jne    L44
L84:
  movsd  0x18(%r9),%xmm2
  movsd  0x10(%r9),%xmm1
  movsd  0x8(%r9),%xmm3
  movsd  (%r9),%xmm4
  subsd  %xmm0,%xmm2
  test   %r14d,%r14d
  jne    L53
  divsd  0x78(%r12),%xmm2
  movsd  %xmm2,0x18(%r9)
  pop    %rbx
  pop    %rbp
  movsd  0x58(%r12),%xmm8
  mulsd  %xmm2,%xmm8
  subsd  %xmm8,%xmm1
  movapd %xmm1,%xmm0
  subsd  %xmm7,%xmm0
  divsd  0x50(%r12),%xmm0
  movsd  %xmm0,0x10(%r9)
  movsd  0x10(%r12),%xmm1
  movsd  0x18(%r12),%xmm7
  mulsd  %xmm0,%xmm1
  mulsd  %xmm2,%xmm7
  mulsd  0x30(%r12),%xmm0
  mulsd  0x38(%r12),%xmm2
  addsd  %xmm7,%xmm1
  addsd  %xmm2,%xmm0
  addsd  %xmm6,%xmm1
  addsd  %xmm5,%xmm0
  subsd  %xmm0,%xmm3
  divsd  0x28(%r12),%xmm3
  movsd  %xmm3,0x8(%r9)
  mulsd  0x8(%r12),%xmm3
  subsd  %xmm3,%xmm4
  subsd  %xmm1,%xmm4
  divsd  (%r12),%xmm4
  pop    %r12
  movsd  %xmm4,(%r9)
  pop    %r13
  pop    %r14
  pop    %r15
  ret
  nopl   (%rax)
L53:
  mulsd  0x18(%r8),%xmm2
  pop    %rbx
  pop    %rbp
  movsd  %xmm2,0x18(%r9)
  movsd  0x58(%r12),%xmm0
  mulsd  %xmm2,%xmm0
  subsd  %xmm0,%xmm1
  subsd  %xmm7,%xmm1
  mulsd  0x10(%r8),%xmm1
  movsd  %xmm1,0x10(%r9)
  movsd  0x10(%r12),%xmm0
  movsd  0x18(%r12),%xmm7
  mulsd  %xmm1,%xmm0
  mulsd  %xmm2,%xmm7
  mulsd  0x30(%r12),%xmm1
  mulsd  0x38(%r12),%xmm2
  addsd  %xmm7,%xmm0
  addsd  %xmm2,%xmm1
  addsd  %xmm6,%xmm0
  addsd  %xmm5,%xmm1
  subsd  %xmm1,%xmm3
  mulsd  0x8(%r8),%xmm3
  movsd  %xmm3,0x8(%r9)
  mulsd  0x8(%r12),%xmm3
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  subsd  %xmm3,%xmm4
  subsd  %xmm0,%xmm4
  mulsd  (%r8),%xmm4
  movsd  %xmm4,(%r9)
  ret
  nopl   0x0(%rax,%rax,1)
L49:
  ret
  nopl   0x0(%rax)
L29:
  mov    %rsi,%rcx
  jmp    L76
L0:
  pxor   %xmm0,%xmm0
  mov    $0x4,%edi
  movapd %xmm0,%xmm7
  movapd %xmm0,%xmm5
  movapd %xmm0,%xmm6
  jmp    L22
```

assistant: ```c
void kernel_dtrsv_t_4_lib4_new(int kmax, double *A, int sda, int use_inv_diag_A, double *inv_diag_A, double *x) {
  if (kmax <= 0)
    return;
  const int lda = 4;
  const int bs = 4;
  int k;
  double *tA, *tx;
  tA = A;
  tx = x;
  double x_0, x_1, x_2, x_3, y_0 = 0, y_1 = 0, y_2 = 0, y_3 = 0;
  k = 4;
  A += 4 + (sda - 1) * lda;
  x += 4;
  __builtin_prefetch(A);
  __builtin_prefetch(A + 8);
  for (; k < kmax - 7; k += 8) {
    __builtin_prefetch(A + sda * bs);
    __builtin_prefetch(A + sda * bs + 8);
    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_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_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_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;
    A += sda * bs;
    x += 4;
    __builtin_prefetch(A + sda * bs);
    __builtin_prefetch(A + sda * bs + 8);
    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_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_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_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;
    A += sda * bs;
    x += 4;
  }
  for (; k < kmax - 3; k += 4) {
    __builtin_prefetch(A + sda * bs);
    __builtin_prefetch(A + sda * bs + 8);
    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_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_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_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;
    A += sda * bs;
    x += 4;
  }
  for (; k < kmax; k++) {
    x_0 = x[0];
    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;
    A += 1;
    x += 1;
  }
  A = tA;
  x = tx;
  if (use_inv_diag_A) {
    y_3 = x[3] - y_3;
    y_3 *= inv_diag_A[3];
    x[3] = y_3;
    y_2 = x[2] - A[3 + lda * 2] * y_3 - y_2;
    y_2 *= inv_diag_A[2];
    x[2] = y_2;
    y_0 += A[2 + lda * 0] * y_2 + A[3 + lda * 0] * y_3;
    y_1 += A[2 + lda * 1] * y_2 + A[3 + lda * 1] * y_3;
    y_1 = x[1] - y_1;
    y_1 *= inv_diag_A[1];
    x[1] = y_1;
    y_0 = x[0] - A[1 + lda * 0] * y_1 - y_0;
    y_0 *= inv_diag_A[0];
    x[0] = y_0;
  } else {
    y_3 = x[3] - y_3;
    y_3 /= A[3 + lda * 3];
    x[3] = y_3;
    y_2 = x[2] - A[3 + lda * 2] * y_3 - y_2;
    y_2 /= A[2 + lda * 2];
    x[2] = y_2;
    y_0 += A[2 + lda * 0] * y_2 + A[3 + lda * 0] * y_3;
    y_1 += A[2 + lda * 1] * y_2 + A[3 + lda * 1] * y_3;
    y_1 = x[1] - y_1;
    y_1 /= A[1 + lda * 1];
    x[1] = y_1;
    y_0 = x[0] - A[1 + lda * 0] * y_1 - y_0;
    y_0 /= A[0 + lda * 0];
    x[0] = y_0;
  }
}
```