user: 下面的汇编指令对应的C源代码是什么:

```asm
<strstr_GNU_C_Library>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  mov    %rdi,-0x38(%rbp)
  mov    %rsi,-0x40(%rbp)
  mov    -0x38(%rbp),%rax
  mov    %rax,-0x20(%rbp)
  mov    -0x40(%rbp),%rax
  mov    %rax,-0x18(%rbp)
  mov    -0x18(%rbp),%rax
  movzbl (%rax),%eax
  mov    %al,-0x23(%rbp)
  cmpb   $0x0,-0x23(%rbp)
  je     L202
  subq   $0x1,-0x20(%rbp)
L176:
  addq   $0x1,-0x20(%rbp)
  mov    -0x20(%rbp),%rax
  movzbl (%rax),%eax
  mov    %al,-0x22(%rbp)
  cmpb   $0x0,-0x22(%rbp)
  je     L88
  movzbl -0x22(%rbp),%eax
  cmp    -0x23(%rbp),%al
  jne    L176
  addq   $0x1,-0x18(%rbp)
  mov    -0x18(%rbp),%rax
  movzbl (%rax),%eax
  mov    %al,-0x21(%rbp)
  cmpb   $0x0,-0x21(%rbp)
  je     L205
  addq   $0x1,-0x18(%rbp)
  nop
  addq   $0x1,-0x20(%rbp)
  mov    -0x20(%rbp),%rax
  movzbl (%rax),%eax
  mov    %al,-0x25(%rbp)
  movzbl -0x25(%rbp),%eax
  cmp    -0x21(%rbp),%al
  jne    L266
  jmp    L254
L142:
  nop
  addq   $0x1,-0x20(%rbp)
  mov    -0x20(%rbp),%rax
  movzbl (%rax),%eax
  mov    %al,-0x25(%rbp)
  jmp    L266
L52:
  cmpb   $0x0,-0x25(%rbp)
  je     L207
  addq   $0x1,-0x20(%rbp)
  mov    -0x20(%rbp),%rax
  movzbl (%rax),%eax
  mov    %al,-0x25(%rbp)
  movzbl -0x25(%rbp),%eax
  cmp    -0x23(%rbp),%al
  je     L117
  cmpb   $0x0,-0x25(%rbp)
  je     L81
  addq   $0x1,-0x20(%rbp)
  mov    -0x20(%rbp),%rax
  movzbl (%rax),%eax
  mov    %al,-0x25(%rbp)
L266:
  movzbl -0x25(%rbp),%eax
  cmp    -0x23(%rbp),%al
  jne    L52
  jmp    L58
L117:
  nop
L58:
  addq   $0x1,-0x20(%rbp)
  mov    -0x20(%rbp),%rax
  movzbl (%rax),%eax
  mov    %al,-0x25(%rbp)
  movzbl -0x25(%rbp),%eax
  cmp    -0x21(%rbp),%al
  jne    L266
  nop
L254:
  mov    -0x20(%rbp),%rax
  lea    -0x1(%rax),%rdx
  mov    %rdx,-0x20(%rbp)
  add    $0x1,%rax
  mov    %rax,-0x10(%rbp)
  mov    -0x10(%rbp),%rax
  movzbl (%rax),%eax
  movzbl %al,%edx
  mov    -0x18(%rbp),%rax
  mov    %rax,-0x8(%rbp)
  mov    -0x8(%rbp),%rax
  movzbl (%rax),%eax
  mov    %al,-0x24(%rbp)
  movsbl -0x24(%rbp),%eax
  cmp    %eax,%edx
  jne    L47
L236:
  cmpb   $0x0,-0x24(%rbp)
  je     L184
  addq   $0x1,-0x10(%rbp)
  mov    -0x10(%rbp),%rax
  movzbl (%rax),%eax
  movzbl %al,%edx
  addq   $0x1,-0x18(%rbp)
  mov    -0x18(%rbp),%rax
  movzbl (%rax),%eax
  mov    %al,-0x24(%rbp)
  movsbl -0x24(%rbp),%eax
  cmp    %eax,%edx
  jne    L213
  cmpb   $0x0,-0x24(%rbp)
  je     L112
  addq   $0x1,-0x10(%rbp)
  mov    -0x10(%rbp),%rax
  movzbl (%rax),%eax
  movzbl %al,%edx
  addq   $0x1,-0x18(%rbp)
  mov    -0x18(%rbp),%rax
  movzbl (%rax),%eax
  mov    %al,-0x24(%rbp)
  movsbl -0x24(%rbp),%eax
  cmp    %eax,%edx
  je     L236
  jmp    L47
L213:
  nop
L47:
  mov    -0x8(%rbp),%rax
  mov    %rax,-0x18(%rbp)
  cmpb   $0x0,-0x24(%rbp)
  jne    L142
  jmp    L222
L202:
  nop
  jmp    L222
L205:
  nop
  jmp    L222
L184:
  nop
  jmp    L222
L112:
  nop
L222:
  mov    -0x20(%rbp),%rax
  jmp    L195
L88:
  nop
  jmp    L99
L207:
  nop
  jmp    L99
L81:
  nop
L99:
  mov    $0x0,%eax
L195:
  pop    %rbp
  ret
```

assistant: ```c
char *strstr_GNU_C_Library(phaystack, pneedle) const char *phaystack;
const char *pneedle;
{
  const unsigned char *haystack, *needle;
  char b;
  const unsigned char *rneedle;
  haystack = (const unsigned char *)phaystack;
  if ((b = *(needle = (const unsigned char *)pneedle))) {
    char c;
    haystack--;
    {
      char a;
      do
        if (!(a = *++haystack))
          goto ret0;
      while (a != b);
    }
    if (!(c = *++needle))
      goto foundneedle;
    ++needle;
    goto jin;
    for (;;) {
      {
        char a;
        if (0)
        jin : {
          if ((a = *++haystack) == c)
            goto crest;
        }
          else a = *++haystack;
        do {
          for (; a != b; a = *++haystack) {
            if (!a)
              goto ret0;
            if ((a = *++haystack) == b)
              break;
            if (!a)
              goto ret0;
          }
        } while ((a = *++haystack) != c);
      }
    crest : {
      char a;
      {
        const unsigned char *rhaystack;
        if (*(rhaystack = haystack-- + 1) == (a = *(rneedle = needle)))
          do {
            if (!a)
              goto foundneedle;
            if (*++rhaystack != (a = *++needle))
              break;
            if (!a)
              goto foundneedle;
          } while (*++rhaystack == (a = *++needle));
        needle = rneedle;
      }
      if (!a)
        break;
    }
    }
  }
foundneedle:
  return (char *)haystack;
ret0:
  return 0;
}
```