user: 提供的汇编代码用C语言表示会是什么样子:

```asm
<memcpy>:
  endbr64
  push   %r15
  mov    %rdi,%rax
  push   %r14
  xor    %rsi,%rax
  lea    (%rdi,%rdx,1),%r14
  push   %r13
  mov    %rdi,%r13
  push   %r12
  mov    %rsi,%r12
  push   %rbp
  push   %rbx
  sub    $0x8,%rsp
  test   $0x7,%al
  setne  %dil
  cmp    $0x7,%rdx
  setbe  %al
  xor    %esi,%esi
  or     %eax,%edi
  movzbl %dil,%edi
  call   <__builtin_expect@plt>
  test   %rax,%rax
  jne    L129
  mov    %r13,%rbx
  xor    %edi,%edi
  mov    %r13,%rbp
  and    $0x7,%ebx
  setne  %dil
  xor    %esi,%esi
  call   <__builtin_expect@plt>
  test   %rax,%rax
  je     L14
  test   %rbx,%rbx
  je     L14
  nopl   (%rax)
L74:
  movzbl (%r12),%eax
  add    $0x1,%rbp
  add    $0x1,%r12
  mov    %al,-0x1(%rbp)
  test   $0x7,%bpl
  jne    L74
L14:
  mov    %r14,%rbx
  xor    %edi,%edi
  and    $0xfffffffffffffff8,%rbx
  lea    -0x40(%rbx),%r15
  cmp    %rbp,%r15
  seta   %dil
  xor    %esi,%esi
  call   <__builtin_expect@plt>
  test   %rax,%rax
  jne    L48
L32:
  cmp    %rbp,%rbx
  jbe    L21
  sub    $0x1,%rbx
  mov    %r12,%rsi
  mov    %rbp,%rdi
  sub    %rbp,%rbx
  shr    $0x3,%rbx
  lea    0x8(,%rbx,8),%rbx
  mov    %rbx,%rdx
  add    %rbx,%rbp
  add    %rbx,%r12
  call   <memcpy@plt>
L21:
  xor    %r15d,%r15d
  cmp    %rbp,%r14
  seta   %r15b
  xor    %esi,%esi
  mov    %r15d,%edi
  call   <__builtin_expect@plt>
  test   %rax,%rax
  jne    L1
L35:
  add    $0x8,%rsp
  mov    %r13,%rax
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
  nopl   0x0(%rax)
L48:
  cmp    %rbp,%r15
  jbe    L32
  nopl   (%rax)
L11:
  mov    (%r12),%r11
  mov    0x8(%r12),%r10
  add    $0x48,%r12
  add    $0x48,%rbp
  mov    -0x38(%r12),%r9
  mov    -0x30(%r12),%r8
  mov    -0x28(%r12),%rdi
  mov    -0x20(%r12),%rsi
  mov    %r11,-0x48(%rbp)
  mov    -0x18(%r12),%rcx
  mov    -0x10(%r12),%rdx
  mov    %r10,-0x40(%rbp)
  mov    %r9,-0x38(%rbp)
  mov    -0x8(%r12),%rax
  mov    %r8,-0x30(%rbp)
  mov    %rdi,-0x28(%rbp)
  mov    %rsi,-0x20(%rbp)
  mov    %rcx,-0x18(%rbp)
  mov    %rdx,-0x10(%rbp)
  mov    %rax,-0x8(%rbp)
  cmp    %rbp,%r15
  ja     L11
  jmp    L32
  nopw   0x0(%rax,%rax,1)
L129:
  xor    %r15d,%r15d
  cmp    %r14,%r13
  mov    %r13,%rbp
  setb   %r15b
L1:
  mov    $0x1,%esi
  mov    %r15d,%edi
  call   <__builtin_expect@plt>
  test   %rax,%rax
  je     L35
  cmp    %r14,%rbp
  jae    L35
  mov    %r14,%rdx
  mov    %r12,%rsi
  mov    %rbp,%rdi
  sub    %rbp,%rdx
  call   <memcpy@plt>
  jmp    L35
```

assistant: ```c
void *memcpy(void *__restrict aa, const void *__restrict bb, size_t n) {
  char *a = (char *)aa;
  const char *b = (const char *)bb;
  char *end = a + n;
  uintptr_t msk = sizeof(long) - 1;
  if (__builtin_expect(!!((((uintptr_t)a & msk) != ((uintptr_t)b & msk)) || n < sizeof(long)), 0)) {
  small:
    if (__builtin_expect(a < end, 1))
      while (a < end) {
        char tt = *b;
        a++, b++;
        *(a - 1) = tt;
      };
    return aa;
  }
  if (__builtin_expect(!!(((uintptr_t)a & msk) != 0), 0))
    while ((uintptr_t)a & msk) {
      char tt = *b;
      a++, b++;
      *(a - 1) = tt;
    };
  long *la = (long *)a;
  const long *lb = (const long *)b;
  long *lend = (long *)((uintptr_t)end & ~msk);
  if (__builtin_expect(!!(la < (lend - 8)), 0)) {
    while (la < (lend - 8)) {
      long b0 = *lb++;
      long b1 = *lb++;
      long b2 = *lb++;
      long b3 = *lb++;
      long b4 = *lb++;
      long b5 = *lb++;
      long b6 = *lb++;
      long b7 = *lb++;
      long b8 = *lb++;
      *la++ = b0;
      *la++ = b1;
      *la++ = b2;
      *la++ = b3;
      *la++ = b4;
      *la++ = b5;
      *la++ = b6;
      *la++ = b7;
      *la++ = b8;
    }
  }
  while (la < lend) {
    long tt = *lb;
    la++, lb++;
    *(la - 1) = tt;
  };
  a = (char *)la;
  b = (const char *)lb;
  if (__builtin_expect(!!(a < end), 0))
    goto small;
  return aa;
}
```