[Bug tree-optimization/121405] [13/14/15/16 Regression] Another missed VN via a copy (but via an int copy)

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121405

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
This is the .optimized from highway where I saw this:
```
  MEM <unsigned char> [(struct Vec128 *)&D.741237] = _4040;
  MEM <unsigned char> [(struct Vec128 *)&D.741237 + 1B] = _4047;
  MEM <unsigned char> [(struct Vec128 *)&D.741237 + 2B] = _4054;
  MEM <unsigned char> [(struct Vec128 *)&D.741237 + 3B] = _4061;
  MEM <unsigned char> [(struct Vec128 *)&D.741237 + 4B] = _4068;
  MEM <unsigned char> [(struct Vec128 *)&D.741237 + 5B] = _4075;
  MEM <unsigned char> [(struct Vec128 *)&D.741237 + 6B] = _4082;
  MEM <unsigned char> [(struct Vec128 *)&D.741237 + 7B] = _4089;
  MEM <unsigned char> [(struct Vec128 *)&D.741237 + 8B] = _4096;
  MEM <unsigned char> [(struct Vec128 *)&D.741237 + 9B] = _4103;
  MEM <unsigned char> [(struct Vec128 *)&D.741237 + 10B] = _4110;
  MEM <unsigned char> [(struct Vec128 *)&D.741237 + 11B] = _4117;
  MEM <unsigned char> [(struct Vec128 *)&D.741237 + 12B] = _4124;
  MEM <unsigned char> [(struct Vec128 *)&D.741237 + 13B] = _4131;
  MEM <unsigned char> [(struct Vec128 *)&D.741237 + 14B] = _4138;
  MEM <unsigned char> [(struct Vec128 *)&D.741237 + 15B] = _4145;
  SR.14270_2654 = MEM[(struct Vec128 *)&D.741237];
...
  _3521 = (unsigned char) SR.14270_2654;
  _3522 = -_3521;
  _3523 = (signed char) _3522;
  a.raw[0] = _3523;
  _5255 = BIT_FIELD_REF <SR.14270_2654, 8, 8>;
  _3531 = (unsigned char) _5255;
  _3532 = -_3531;
  _3533 = (signed char) _3532;
  a.raw[1] = _3533;
```