user: 下面的汇编指令对应的C源代码是什么:

```asm
<test_collapse>:
  endbr64
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0x8,%rsp
  mov    $0x10,%r13d
  jmp    L50
L3:
  sub    $0x1,%r13d
  je     L17
L50:
  mov    $0x10,%r12d
L54:
  mov    $0x10,%ebp
L25:
  mov    $0x10,%ebx
L8:
  mov    $0x0,%eax
  call   <foo@plt>
  sub    $0x1,%ebx
  jne    L8
  sub    $0x1,%ebp
  jne    L25
  sub    $0x1,%r12d
  jne    L54
  jmp    L3
L17:
  add    $0x8,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  ret
```

assistant: ```c
void test_collapse() {
  int i;
#pragma omp target
#pragma omp teams
#pragma omp distribute simd collapse
  for (i = 0; i < 16; ++i)
    ;
#pragma omp target
#pragma omp teams
#pragma omp distribute simd collapse(
  for (i = 0; i < 16; ++i)
    ;
#pragma omp target
#pragma omp teams
#pragma omp distribute simd collapse()
  for (i = 0; i < 16; ++i)
    ;
#pragma omp target
#pragma omp teams
#pragma omp distribute simd collapse(,
  for (i = 0; i < 16; ++i)
    ;
#pragma omp target
#pragma omp teams
#pragma omp distribute simd collapse(, )
  for (i = 0; i < 16; ++i)
    ;
#pragma omp target
#pragma omp teams
#pragma omp distribute simd collapse 4)
  for (i = 0; i < 16; ++i)
    ;
#pragma omp target
#pragma omp teams
#pragma omp distribute simd collapse(4
  for (i = 0; i < 16; ++i)
    ;
#pragma omp target
#pragma omp teams
#pragma omp distribute simd collapse(4,
  for (i = 0; i < 16; ++i)
    ;
#pragma omp target
#pragma omp teams
#pragma omp distribute simd collapse(4, )
  for (i = 0; i < 16; ++i)
    ;
#pragma omp target
#pragma omp teams
#pragma omp distribute simd collapse(4)
  for (i = 0; i < 16; ++i)
    ;
#pragma omp target
#pragma omp teams
#pragma omp distribute simd collapse(4 4)
  for (i = 0; i < 16; ++i)
    ;
#pragma omp target
#pragma omp teams
#pragma omp distribute simd collapse(4, , 4)
  for (i = 0; i < 16; ++i)
    ;
#pragma omp target
#pragma omp teams
#pragma omp distribute simd collapse(4)
  for (int i1 = 0; i1 < 16; ++i1)
    for (int i2 = 0; i2 < 16; ++i2)
      for (int i3 = 0; i3 < 16; ++i3)
        for (int i4 = 0; i4 < 16; ++i4)
          foo();
#pragma omp target
#pragma omp teams
#pragma omp distribute simd collapse(4, 8)
  for (i = 0; i < 16; ++i)
    ;
#pragma omp target
#pragma omp teams
#pragma omp distribute simd collapse(2.5)
  for (i = 0; i < 16; ++i)
    ;
#pragma omp target
#pragma omp teams
#pragma omp distribute simd collapse(foo())
  for (i = 0; i < 16; ++i)
    ;
#pragma omp target
#pragma omp teams
#pragma omp distribute simd collapse(-5)
  for (i = 0; i < 16; ++i)
    ;
#pragma omp target
#pragma omp teams
#pragma omp distribute simd collapse(0)
  for (i = 0; i < 16; ++i)
    ;
#pragma omp target
#pragma omp teams
#pragma omp distribute simd collapse(5 - 5)
  for (i = 0; i < 16; ++i)
    ;
#pragma omp target
#pragma omp teams
#pragma omp distribute simd collapse(2) reduction(+ : i)
  for (i = 0; i < 16; ++i)
    for (int j = 0; j < 16; ++j)
#pragma omp for reduction(+ : i, j)
      for (int k = 0; k < 16; ++k)
        i += j;
#pragma omp target
#pragma omp teams
  for (i = 0; i < 16; ++i)
    for (int j = 0; j < 16; ++j)
#pragma omp distribute simd reduction(+ : i, j)
      for (int k = 0; k < 16; ++k)
        i += j;
}
```