On Tue, Dec 10, 2013 at 8:05 AM, Kirill Yukhin <[email protected]> wrote:
> On 09 Dec 14:08, H.J. Lu wrote:
>>
>> There are no regressions on Linux/x86-64 with -m32 and -m64.
>> Can you check if it improves code quality on x886?
>
> As second thought. If Tejas and Richard are right and it is simply incorrect
> to check any offsets in this hook, may be we can end up with patch in the
> bottom?
What is wrong to pass the correct offset to
CANNOT_CHANGE_MODE_CLASS? Backends are free to
ignore it.
>
> Test is passing (however I still don't know how to prohibit it for 32 bit
> x86),
> bootstrap in progress.
>
> Ideas?
>
> This change belongs to rth.
>
> --
> Thanks, K
>
> diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
> index 382f8fb..0d0bb67 100644
> --- a/gcc/config/i386/i386.c
> +++ b/gcc/config/i386/i386.c
> @@ -35002,22 +35002,13 @@ ix86_cannot_change_mode_class (enum machine_mode
> from, enum machine_mode to,
> if (MAYBE_FLOAT_CLASS_P (regclass))
> return true;
>
> - if (MAYBE_SSE_CLASS_P (regclass) || MAYBE_MMX_CLASS_P (regclass))
> - {
> - /* Vector registers do not support QI or HImode loads. If we don't
> - disallow a change to these modes, reload will assume it's ok to
> - drop the subreg from (subreg:SI (reg:HI 100) 0). This affects
> - the vec_dupv4hi pattern. */
> - if (GET_MODE_SIZE (from) < 4)
> - return true;
> -
> - /* Vector registers do not support subreg with nonzero offsets, which
> - are otherwise valid for integer registers. Since we can't see
> - whether we have a nonzero offset from here, prohibit all
> - nonparadoxical subregs changing size. */
> - if (GET_MODE_SIZE (to) < GET_MODE_SIZE (from))
> - return true;
> - }
> + /* Vector registers do not support QI or HImode loads. If we don't
> + disallow a change to these modes, reload will assume it's ok to
> + drop the subreg from (subreg:SI (reg:HI 100) 0). This affects
> + the vec_dupv4hi pattern. */
> + if ((MAYBE_SSE_CLASS_P (regclass) || MAYBE_MMX_CLASS_P (regclass))
> + && (GET_MODE_SIZE (from) < 4))
> + return true;
>
>
You need to run full "make check" for both -m32 and -m64.
--
H.J.
