[Bug middle-end/56439] extra register moves for global register and local register variables

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56439

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           See Also|                            |https://gcc.gnu.org/bugzill
                   |                            |a/show_bug.cgi?id=43491

--- Comment #11 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
here is a nice reduced testcase:
```
typedef unsigned short uint16_t;

register uint16_t r4 asm ("r4");
register uint16_t r6 asm ("r6");

uint16_t pllExec(void)
{
  r4 += r6;
  return r4>>8;
};
```

See bug 43491 comment #12 for some analysis of this issue really.