Re: [kvm-unit-tests PATCH] s390x: Use loop to save and restore fprs

[Pierre Morel <pmorel@xxxxxxxxxxxxx>]

On 11/8/19 10:15 AM, Thomas Huth wrote:
> On 04/11/2019 09.55, Janosch Frank wrote:
> > Let's save some lines in the assembly by using a loop to save and
> > restore the fprs.
> >
> > Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
> > ---
> >   s390x/cstart64.S | 38 ++++++--------------------------------
> >   1 file changed, 6 insertions(+), 32 deletions(-)
> >
> > diff --git a/s390x/cstart64.S b/s390x/cstart64.S
> > index 5dc1577..8e2b21e 100644
> > --- a/s390x/cstart64.S
> > +++ b/s390x/cstart64.S
> > @@ -99,44 +99,18 @@ memsetxc:
> >       lctlg    %c0, %c0, 0(%r1)
> >       /* save fprs 0-15 + fpc */
> >       la    %r1, GEN_LC_SW_INT_FPRS
> > -    std    %f0, 0(%r1)
> > -    std    %f1, 8(%r1)
> > -    std    %f2, 16(%r1)
> > -    std    %f3, 24(%r1)
> > -    std    %f4, 32(%r1)
> > -    std    %f5, 40(%r1)
> > -    std    %f6, 48(%r1)
> > -    std    %f7, 56(%r1)
> > -    std    %f8, 64(%r1)
> > -    std    %f9, 72(%r1)
> > -    std    %f10, 80(%r1)
> > -    std    %f11, 88(%r1)
> > -    std    %f12, 96(%r1)
> > -    std    %f13, 104(%r1)
> > -    std    %f14, 112(%r1)
> > -    std    %f15, 120(%r1)
> > +    .irp i, 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
> > +    std    \i, \i * 8(%r1)
> > +    .endr
> >       stfpc    GEN_LC_SW_INT_FPC
> >       .endm
> >         .macro RESTORE_REGS
> >       /* restore fprs 0-15 + fpc */
> >       la    %r1, GEN_LC_SW_INT_FPRS
> > -    ld    %f0, 0(%r1)
> > -    ld    %f1, 8(%r1)
> > -    ld    %f2, 16(%r1)
> > -    ld    %f3, 24(%r1)
> > -    ld    %f4, 32(%r1)
> > -    ld    %f5, 40(%r1)
> > -    ld    %f6, 48(%r1)
> > -    ld    %f7, 56(%r1)
> > -    ld    %f8, 64(%r1)
> > -    ld    %f9, 72(%r1)
> > -    ld    %f10, 80(%r1)
> > -    ld    %f11, 88(%r1)
> > -    ld    %f12, 96(%r1)
> > -    ld    %f13, 104(%r1)
> > -    ld    %f14, 112(%r1)
> > -    ld    %f15, 120(%r1)
> > +    .irp i, 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
> > +    ld    \i, \i * 8(%r1)
> > +    .endr
> >       lfpc    GEN_LC_SW_INT_FPC
> >       /* restore cr0 */
> >       lctlg    %c0, %c0, GEN_LC_SW_INT_CR0
>
> Produces exactly the same code as before.
>
> Tested-by: Thomas Huth <thuth@xxxxxxxxxx>
Good for me, makes the code smaller ... is better

Reviewed-by: Pierre Morel <pmorel@xxxxxxxxxxxxx>



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Pierre Morel
IBM Lab Boeblingen