[Bug target/44578] GCC generates MMX instructions but fails to generate "emms"

["tejohnson at google dot com" <gcc-bugzilla@gcc.gnu.org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44578

--- Comment #9 from Teresa Johnson <tejohnson at google dot com> 2013-04-29 17:24:42 UTC ---
It does fix the issue I had in this test case. But theoretically can't
this pattern still generate an MMX reference in some cases? And I see
other instances of the same constraint in i386.md - is there a larger
issue here and how can we prevent this?

Thanks!
Teresa

On Mon, Apr 29, 2013 at 10:13 AM, ubizjak at gmail dot com
<gcc-bugzilla@gcc.gnu.org> wrote:
>
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44578
>
> --- Comment #8 from Uros Bizjak <ubizjak at gmail dot com> 2013-04-29 17:13:30 UTC ---
> Please try following patch, it fixes the testcase for me (note "!" for ?*y
> alternative):
>
> --cut here--
> Index: i386.md
> ===================================================================
> --- i386.md     (revision 198401)
> +++ i386.md     (working copy)
> @@ -3049,10 +3049,10 @@
>
>  (define_insn "*zero_extendsidi2"
>    [(set (match_operand:DI 0 "nonimmediate_operand"
> -                       "=r,?r,?o,r   ,o,?*Ym,?*y,?*Yi,?*x")
> +                       "=r,?r,?o,r   ,o,?*Ym,?!*y,?*Yi,?*x")
>         (zero_extend:DI
>          (match_operand:SI 1 "x86_64_zext_operand"
> -                       "0 ,rm,r ,rmWz,0,r   ,m  ,r   ,m")))]
> +                       "0 ,rm,r ,rmWz,0,r   ,m   ,r   ,m")))]
>    ""
>  {
>    switch (get_attr_type (insn))
> --cut here--
>
> --
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