[Bug target/17381] Unnecessary register move for float extend

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17381

--- Comment #6 from Andrew Pinski <pinskia at gcc dot gnu.org> 2011-01-05 00:15:50 UTC ---
(In reply to comment #5)
> This is the patch which fixes the issue:Index: regrename.c
> ===================================================================
> --- regrename.c (revision 3023)
> +++ regrename.c (working copy)
> @@ -1374,6 +1374,10 @@ maybe_mode_change (enum machine_mode ori
>                    enum machine_mode new_mode, unsigned int regno,
>                    unsigned int copy_regno ATTRIBUTE_UNUSED)
>  {
> +  if (GET_MODE_SIZE (copy_mode) == GET_MODE_SIZE (new_mode)
> +      && hard_regno_nregs[copy_regno][copy_mode] ==
> hard_regno_nregs[copy_regno][new_mode]
> +      && hard_regno_nregs[regno][copy_mode] ==
> hard_regno_nregs[copy_regno][new_mode])
> +    return gen_rtx_raw_REG (new_mode, regno);
>    if (orig_mode == new_mode)
>      return gen_rtx_raw_REG (new_mode, regno);
>    else if (mode_change_ok (orig_mode, new_mode, regno))

MIPS64 has a similar issue too, take:
long long d;
int test1(int fParm)
{
  d = fParm + 1;
  return fParm + 1;
}

The same regrename.c patch is needed to fix the MIPS64 issue too.