[Bug c/108439] incorrect optimization with -O2, -O3, -Os

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108439

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |INVALID
             Status|UNCONFIRMED                 |RESOLVED

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Use -fno-strict-aliasing, mayalias attribute, memcpy, etc as you are violating
C/C++ aliasing rules.
You do a store via uint64_t:
        lb_key[0] = 0x1234;

And then do loads via uint32_t:
  const uint32_t  m = 0x83d2e73b, n = 0x97e1cc59, *key4 = (const uint32_t
*)key;
...
    c8mix(key4[0]) c8mix(key4[1]) key4 += 2;