user: 请从给定的汇编指令推导出C源代码：

```asm
<benchmark>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  mov    %edi,%r12d
  push   %rbx
  mov    %esi,%ebx
  sub    $0x38,%rsp
  mov    %fs:0x28,%rax
  mov    %rax,-0x38(%rbp)
  xor    %eax,%eax
  movslq %esi,%rax
  mov    %rsp,%rcx
  lea    0xf(,%rax,8),%rax
  mov    %rax,%rdx
  and    $0xfffffffffffff000,%rax
  sub    %rax,%rcx
  and    $0xfffffffffffffff0,%rdx
  cmp    %rcx,%rsp
  je     L85
L11:
  sub    $0x1000,%rsp
  orq    $0x0,0xff8(%rsp)
  cmp    %rcx,%rsp
  jne    L11
L85:
  and    $0xfff,%edx
  sub    %rdx,%rsp
  test   %rdx,%rdx
  jne    L17
L135:
  mov    %rsp,%r13
  test   %ebx,%ebx
  jle    L73
  mov    %ebx,%eax
  mov    %r13,%r15
  lea    0x0(%r13,%rax,8),%r14
  nopl   0x0(%rax)
L103:
  xor    %eax,%eax
  add    $0x8,%r15
  call   <rand_double@plt>
  mulsd  D20(%rip),%xmm0
  subsd  D49(%rip),%xmm0
  movsd  %xmm0,-0x8(%r15)
  cmp    %r14,%r15
  jne    L103
L73:
  xor    %eax,%eax
  movq   $0x0,-0x50(%rbp)
  movq   $0x0,-0x48(%rbp)
  call   <tic@plt>
  xor    %edx,%edx
  movsd  %xmm0,-0x58(%rbp)
  test   %r12d,%r12d
  jle    L27
  xor    %r14d,%r14d
  lea    -0x50(%rbp),%r15
  jmp    L3
  nopw   0x0(%rax,%rax,1)
L111:
  add    $0x1,%r14d
  cmp    %r14d,%r12d
  je     L36
L3:
  mov    D4(%rip),%rax
  mov    %r15,%rcx
  mov    %r13,%rsi
  mov    %ebx,%edi
  mov    $0x1,%edx
  mov    $0x1,%r8d
  movq   %rax,%xmm0
  call   <stdlib_strided_dmeanstdevpn@plt>
  mov    %r14d,%edx
  and    $0x1,%edx
  movsd  -0x50(%rbp,%rdx,8),%xmm0
  ucomisd %xmm0,%xmm0
  jnp    L111
  lea    D33(%rip),%rdi
  mov    %rdx,-0x60(%rbp)
  call   <printf@plt>
  mov    -0x60(%rbp),%rdx
L27:
  xor    %eax,%eax
  mov    %rdx,-0x60(%rbp)
  call   <tic@plt>
  mov    -0x60(%rbp),%rdx
  subsd  -0x58(%rbp),%xmm0
  movsd  -0x50(%rbp,%rdx,8),%xmm1
  ucomisd %xmm1,%xmm1
  jp     L42
L118:
  mov    -0x38(%rbp),%rax
  sub    %fs:0x28,%rax
  jne    L82
  lea    -0x28(%rbp),%rsp
  pop    %rbx
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  pop    %rbp
  ret
  nopl   (%rax)
L36:
  mov    %r12d,%edx
  and    $0x1,%edx
  jmp    L27
L42:
  lea    D33(%rip),%rdi
  movsd  %xmm0,-0x58(%rbp)
  call   <printf@plt>
  movsd  -0x58(%rbp),%xmm0
  jmp    L118
  nopl   0x0(%rax,%rax,1)
L17:
  orq    $0x0,-0x8(%rsp,%rdx,1)
  jmp    L135
L82:
  call   <__stack_chk_fail@plt>
```

tool_calls: name: disassemble_data
arguments: data_label: D20
type_guessed: f64
name: disassemble_data
arguments: data_label: D49
type_guessed: f64
name: disassemble_data
arguments: data_label: D4
type_guessed: f64
name: disassemble_data
arguments: data_label: D33
type_guessed: string

tool: D20: 20000

tool: D49: 10000

tool: D4: 1

tool: D33: should not return NaN


assistant: ```c
double benchmark(int iterations, int len) {
  double elapsed;
  double out[2];
  double x[len];
  double t;
  int i;
  for (i = 0; i < len; i++) {
    x[i] = (rand_double() * 20000.0) - 10000.0;
  }
  out[0] = 0.0;
  out[1] = 0.0;
  t = tic();
  for (i = 0; i < iterations; i++) {
    stdlib_strided_dmeanstdevpn(len, 1.0, x, 1, out, 1);
    if (out[i % 2] != out[i % 2]) {
      printf("should not return NaN\n");
      break;
    }
  }
  elapsed = tic() - t;
  if (out[i % 2] != out[i % 2]) {
    printf("should not return NaN\n");
  }
  return elapsed;
}
```