Re: [PATCH v2 06/14] tcg/{i386, s390x}: Add earlyclobber to the op_add2's first output

[Ilya Leoshkevich <iii@linux.ibm.com>]

On Wed, 2023-07-19 at 14:08 +0200, Philippe Mathieu-Daudé wrote:
> Hi Ilya,
> 
> On 19/7/23 11:44, Ilya Leoshkevich wrote:
> > i386 and s390x implementations of op_add2 require an earlyclobber,
> > which is currently missing. This breaks VCKSM in s390x guests.
> > E.g., on
> > x86_64 the following op:
> > 
> >      add2_i32 tmp2,tmp3,tmp2,tmp3,tmp3,tmp2   dead: 0 2 3 4 5 
> > pref=none,0xffff
> > 
> > is translated to:
> > 
> >      addl     %ebx, %r12d
> >      adcl     %r12d, %ebx
> > 
> > Introduce a new C_N1_O1_I4 constraint, and make sure that
> > earlyclobber
> > of aliased outputs is honored.
> > 
> > Cc: qemu-stable@nongnu.org
> > Fixes: 82790a870992 ("tcg: Add markup for output requires new
> > register")
> > Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
> > ---
> >   tcg/i386/tcg-target-con-set.h  | 2 +-
> >   tcg/i386/tcg-target.c.inc      | 2 +-
> >   tcg/s390x/tcg-target-con-set.h | 5 ++---
> >   tcg/s390x/tcg-target.c.inc     | 4 ++--
> >   tcg/tcg.c                      | 8 +++++++-
> >   5 files changed, 13 insertions(+), 8 deletions(-)
> 
> 
> > diff --git a/tcg/tcg.c b/tcg/tcg.c
> > index 652e8ea6b93..ddfe9a96cb7 100644
> > --- a/tcg/tcg.c
> > +++ b/tcg/tcg.c
> > @@ -648,6 +648,7 @@ static void tcg_out_movext3(TCGContext *s,
> > const TCGMovExtend *i1,
> >   #define C_O2_I2(O1, O2, I1, I2)         C_PFX4(c_o2_i2_, O1, O2,
> > I1, I2),
> >   #define C_O2_I3(O1, O2, I1, I2, I3)     C_PFX5(c_o2_i3_, O1, O2,
> > I1, I2, I3),
> >   #define C_O2_I4(O1, O2, I1, I2, I3, I4) C_PFX6(c_o2_i4_, O1, O2,
> > I1, I2, I3, I4),
> > +#define C_N1_O1_I4(O1, O2, I1, I2, I3, I4) C_PFX6(c_n1_o1_i4_, O1,
> > O2, I1, I2, I3, I4),
> 
> No need for O2. Also can you place it earlier just after C_N1_I2?

Shouldn't it still be a 6-argument constraint?
INDEX_op_add2_i32 and friends take 6 arguments after all.

> -- >8 --
> @@ -643,6 +643,7 @@ static void tcg_out_movext3(TCGContext *s, const 
> TCGMovExtend *i1,
>   #define C_O1_I4(O1, I1, I2, I3, I4)     C_PFX5(c_o1_i4_, O1, I1,
> I2, 
> I3, I4),
> 
>   #define C_N1_I2(O1, I1, I2)             C_PFX3(c_n1_i2_, O1, I1,
> I2),
> +#define C_N1_O1_I4(O1, I1, I2, I3, I4)  C_PFX5(c_n1_o1_i4_, O1, I1,
> I2, 
> I3, I4),
> 
>   #define C_O2_I1(O1, O2, I1)             C_PFX3(c_o2_i1_, O1, O2,
> I1),
>   #define C_O2_I2(O1, O2, I1, I2)         C_PFX4(c_o2_i2_, O1, O2,
> I1, I2),
> ---
> 
> Thanks,
> 
> Phil.