user: 请从给定的汇编指令推导出C源代码：

```asm
<fn2>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbx
  sub    $0x28,%rsp
  mov    %edi,%r12d
  mov    %fs:0x28,%rax
  mov    %rax,-0x38(%rbp)
  xor    %eax,%eax
  lea    (%rdi,%rdi,2),%ebx
  movslq %ebx,%rbx
  shl    $0x3,%rbx
  lea    0xf(%rbx),%rax
  mov    %rax,%rcx
  and    $0xfffffffffffffff0,%rcx
  and    $0xfffffffffffff000,%rax
  mov    %rsp,%rdx
  sub    %rax,%rdx
L89:
  cmp    %rdx,%rsp
  je     L179
  sub    $0x1000,%rsp
  orq    $0x0,0xff8(%rsp)
  jmp    L89
L179:
  mov    %rcx,%rax
  and    $0xfff,%eax
  sub    %rax,%rsp
  test   %rax,%rax
  je     L61
  orq    $0x0,-0x8(%rsp,%rax,1)
L61:
  mov    %rsp,%r13
  lea    0xf(%rbx),%rax
  mov    %rax,%rcx
  and    $0xfffffffffffffff0,%rcx
  and    $0xfffffffffffff000,%rax
  mov    %rsp,%rdx
  sub    %rax,%rdx
L146:
  cmp    %rdx,%rsp
  je     L1
  sub    $0x1000,%rsp
  orq    $0x0,0xff8(%rsp)
  jmp    L146
L1:
  mov    %rcx,%rax
  and    $0xfff,%eax
  sub    %rax,%rsp
  test   %rax,%rax
  je     L142
  orq    $0x0,-0x8(%rsp,%rax,1)
L142:
  mov    %rsp,%r14
  lea    0xf(%rbx),%rax
  mov    %rax,%rcx
  and    $0xfffffffffffffff0,%rcx
  and    $0xfffffffffffff000,%rax
  mov    %rsp,%rdx
  sub    %rax,%rdx
L153:
  cmp    %rdx,%rsp
  je     L152
  sub    $0x1000,%rsp
  orq    $0x0,0xff8(%rsp)
  jmp    L153
L152:
  mov    %rcx,%rax
  and    $0xfff,%eax
  sub    %rax,%rsp
  test   %rax,%rax
  je     L95
  orq    $0x0,-0x8(%rsp,%rax,1)
L95:
  mov    %rsp,%r15
  lea    0xf(%rbx),%rax
  mov    %rax,%rdx
  and    $0xfffffffffffffff0,%rdx
  and    $0xfffffffffffff000,%rax
  mov    %rsp,%rcx
  sub    %rax,%rcx
L121:
  cmp    %rcx,%rsp
  je     L138
  sub    $0x1000,%rsp
  orq    $0x0,0xff8(%rsp)
  jmp    L121
L138:
  mov    %rdx,%rax
  and    $0xfff,%eax
  sub    %rax,%rsp
  test   %rax,%rax
  je     L115
  orq    $0x0,-0x8(%rsp,%rax,1)
L115:
  mov    %rsp,-0x48(%rbp)
  mov    %r12d,%edx
  mov    %r14,%rsi
  mov    %r13,%rdi
  call   <fn1@plt>
  movslq %r12d,%rax
  lea    (%r15,%rax,8),%r15
  mov    %r12d,%edx
  mov    %r15,%rsi
  mov    -0x48(%rbp),%rdi
  call   <fn1@plt>
  test   %r12d,%r12d
  jle    L128
  mov    %r12d,%r12d
  mov    $0x0,%eax
  pxor   %xmm2,%xmm2
  jmp    L46
L68:
  mov    %rbx,%rdx
  shr    %rdx
  pxor   %xmm1,%xmm1
  cvtsi2sd %rdx,%xmm1
  addsd  %xmm1,%xmm1
L175:
  movsd  0x0(%r13,%rax,8),%xmm0
  mulsd  (%r14,%rax,8),%xmm0
  addsd  (%r15,%rax,8),%xmm0
  addsd  %xmm1,%xmm0
  subsd  %xmm1,%xmm0
  addsd  %xmm0,%xmm2
  add    $0x1,%rax
  cmp    %r12,%rax
  je     L137
L46:
  test   %rbx,%rbx
  js     L68
  pxor   %xmm1,%xmm1
  cvtsi2sd %rbx,%xmm1
  jmp    L175
L128:
  pxor   %xmm2,%xmm2
L137:
  mov    -0x38(%rbp),%rax
  sub    %fs:0x28,%rax
  jne    L122
  movapd %xmm2,%xmm0
  lea    -0x28(%rbp),%rsp
  pop    %rbx
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  pop    %rbp
  ret
L122:
  call   <__stack_chk_fail@plt>
```

assistant: ```c
double fn2(int x) {
  double s = 0;
  double b[3 * x], c[3 * x], d[3 * x], e[3 * x];
  int i;
  fn1(b, c, x);
  fn1(e, d + x, x);
#pragma omp target map(to : b, c[:x], d [x:x], e) map(tofrom : s)
#pragma omp parallel for reduction(+ : s)
  for (i = 0; i < x; i++)
    s += b[i] * c[i] + d[x + i] + sizeof(b) - sizeof(c);
  return s;
}
```