user: 请从给定的汇编指令推导出C源代码：

```asm
<__memcpy>:
  endbr64
  push   %r15
  mov    %rdi,%rax
  push   %r14
  xor    %rsi,%rax
  push   %r13
  lea    (%rdi,%rdx,1),%r13
  push   %r12
  mov    %rdi,%r12
  push   %rbp
  mov    %rsi,%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    L109
  mov    %r12,%r14
  xor    %edi,%edi
  mov    %r12,%rbx
  and    $0x7,%r14d
  setne  %dil
  xor    %esi,%esi
  call   <__builtin_expect@plt>
  test   %rax,%rax
  je     L226
  test   %r14,%r14
  je     L226
  cs nopw 0x0(%rax,%rax,1)
L176:
  movzbl 0x0(%rbp),%eax
  add    $0x1,%rbx
  add    $0x1,%rbp
  mov    %al,-0x1(%rbx)
  test   $0x7,%bl
  jne    L176
L226:
  mov    %r13,%r15
  xor    %edi,%edi
  and    $0xfffffffffffffff8,%r15
  lea    -0x40(%r15),%r14
  cmp    %rbx,%r14
  seta   %dil
  xor    %esi,%esi
  call   <__builtin_expect@plt>
  test   %rax,%rax
  jne    L44
L70:
  cmp    %rbx,%r15
  jbe    L96
  lea    -0x1(%r15),%rdx
  lea    0x8(%rbp),%rax
  sub    %rbx,%rdx
  cmp    %rax,%rbx
  je     L340
  cmp    $0x17,%rdx
  jbe    L340
  mov    %rdx,%rsi
  xor    %eax,%eax
  shr    $0x3,%rsi
  add    $0x1,%rsi
  mov    %rsi,%rcx
  shr    %rcx
  shl    $0x4,%rcx
  nopw   0x0(%rax,%rax,1)
L72:
  movdqu 0x0(%rbp,%rax,1),%xmm4
  movups %xmm4,(%rbx,%rax,1)
  add    $0x10,%rax
  cmp    %rcx,%rax
  jne    L72
  mov    %rsi,%rcx
  and    $0xfffffffffffffffe,%rcx
  lea    0x0(%rbp,%rcx,8),%rax
  cmp    %rcx,%rsi
  je     L276
  mov    (%rax),%rax
  mov    %rax,(%rbx,%rcx,8)
L276:
  shr    $0x3,%rdx
  lea    0x8(,%rdx,8),%rax
  add    %rax,%rbx
  add    %rax,%rbp
L96:
  xor    %r14d,%r14d
  cmp    %rbx,%r13
  seta   %r14b
  xor    %esi,%esi
  mov    %r14d,%edi
  call   <__builtin_expect@plt>
  test   %rax,%rax
  jne    L266
L98:
  add    $0x8,%rsp
  mov    %r12,%rax
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
L44:
  cmp    %rbx,%r14
  jbe    L70
  nopl   0x0(%rax)
L205:
  movdqu 0x0(%rbp),%xmm3
  movdqu 0x10(%rbp),%xmm2
  add    $0x48,%rbp
  add    $0x48,%rbx
  movdqu -0x28(%rbp),%xmm1
  movdqu -0x18(%rbp),%xmm0
  mov    -0x8(%rbp),%rax
  movups %xmm3,-0x48(%rbx)
  movups %xmm2,-0x38(%rbx)
  movups %xmm1,-0x28(%rbx)
  movups %xmm0,-0x18(%rbx)
  mov    %rax,-0x8(%rbx)
  cmp    %rbx,%r14
  ja     L205
  jmp    L70
  xchg   %ax,%ax
L109:
  xor    %r14d,%r14d
  cmp    %r13,%r12
  mov    %r12,%rbx
  setb   %r14b
L266:
  mov    $0x1,%esi
  mov    %r14d,%edi
  call   <__builtin_expect@plt>
  test   %rax,%rax
  je     L98
  cmp    %r13,%rbx
  jae    L98
  mov    %r13,%rdx
  lea    0x1(%rbp),%rsi
  mov    %rbx,%rcx
  sub    %rbx,%rdx
  sub    %rsi,%rcx
  lea    -0x1(%rdx),%rax
  cmp    $0xe,%rcx
  jbe    L74
  cmp    $0x6,%rax
  jbe    L74
  cmp    $0xe,%rax
  jbe    L59
  mov    %rdx,%rcx
  xor    %eax,%eax
  and    $0xfffffffffffffff0,%rcx
  nopw   0x0(%rax,%rax,1)
L199:
  movdqu 0x0(%rbp,%rax,1),%xmm5
  movups %xmm5,(%rbx,%rax,1)
  add    $0x10,%rax
  cmp    %rax,%rcx
  jne    L199
  mov    %rdx,%rsi
  and    $0xfffffffffffffff0,%rsi
  lea    (%rbx,%rsi,1),%rax
  lea    0x0(%rbp,%rsi,1),%rcx
  cmp    %rsi,%rdx
  je     L98
  sub    %rsi,%rdx
  lea    -0x1(%rdx),%rdi
  cmp    $0x6,%rdi
  jbe    L27
L15:
  mov    0x0(%rbp,%rsi,1),%rdi
  mov    %rdi,(%rbx,%rsi,1)
  mov    %rdx,%rsi
  and    $0xfffffffffffffff8,%rsi
  add    %rsi,%rax
  add    %rsi,%rcx
  cmp    %rdx,%rsi
  je     L98
L27:
  movzbl (%rcx),%edx
  mov    %dl,(%rax)
  lea    0x1(%rax),%rdx
  cmp    %rdx,%r13
  jbe    L98
  movzbl 0x1(%rcx),%edx
  mov    %dl,0x1(%rax)
  lea    0x2(%rax),%rdx
  cmp    %rdx,%r13
  jbe    L98
  movzbl 0x2(%rcx),%edx
  mov    %dl,0x2(%rax)
  lea    0x3(%rax),%rdx
  cmp    %rdx,%r13
  jbe    L98
  movzbl 0x3(%rcx),%edx
  mov    %dl,0x3(%rax)
  lea    0x4(%rax),%rdx
  cmp    %rdx,%r13
  jbe    L98
  movzbl 0x4(%rcx),%edx
  mov    %dl,0x4(%rax)
  lea    0x5(%rax),%rdx
  cmp    %rdx,%r13
  jbe    L98
  movzbl 0x5(%rcx),%edx
  mov    %dl,0x5(%rax)
  lea    0x6(%rax),%rdx
  cmp    %rdx,%r13
  jbe    L98
  movzbl 0x6(%rcx),%edx
  mov    %dl,0x6(%rax)
  jmp    L98
  nopw   0x0(%rax,%rax,1)
L340:
  mov    %rbp,%rcx
  mov    %rbx,%rax
  cs nopw 0x0(%rax,%rax,1)
L239:
  mov    (%rcx),%rsi
  add    $0x8,%rax
  add    $0x8,%rcx
  mov    %rsi,-0x8(%rax)
  cmp    %rax,%r15
  ja     L239
  jmp    L276
L74:
  xor    %eax,%eax
  nopl   0x0(%rax,%rax,1)
L160:
  movzbl 0x0(%rbp,%rax,1),%ecx
  mov    %cl,(%rbx,%rax,1)
  add    $0x1,%rax
  cmp    %rax,%rdx
  jne    L160
  jmp    L98
L59:
  mov    %rbp,%rcx
  mov    %rbx,%rax
  xor    %esi,%esi
  jmp    L15
```

assistant: ```c
void *__memcpy(void *aa, const void *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;
}
```