Re: [PATCH v3 4/5] tests/tcg/s390x: Fix EXRL tests

[Thomas Huth <thuth@redhat.com>]

On 11/01/2021 17.38, David Hildenbrand wrote:
> The current EXRL tests crash on real machines: we must not use r0 as a base
> register for trt/trtr, otherwise the content gets ignored. Also, we must
> not use r0 for exrl, otherwise it gets ignored.
> 
> Let's use the "a" constraint so we get a general purpose register != r0.
> For op2, we can simply specify a memory operand directly via "Q" (Memory
> reference without index register and with short displacement).
> 
> Fixes: ad8c851d2e77 ("target/s390x: add EX support for TRT and TRTR")
> Signed-off-by: David Hildenbrand <david@redhat.com>
> ---
>   tests/tcg/s390x/exrl-trt.c  | 8 ++++----
>   tests/tcg/s390x/exrl-trtr.c | 8 ++++----
>   2 files changed, 8 insertions(+), 8 deletions(-)
> 
> diff --git a/tests/tcg/s390x/exrl-trt.c b/tests/tcg/s390x/exrl-trt.c
> index 3c5323aecb..16711a3181 100644
> --- a/tests/tcg/s390x/exrl-trt.c
> +++ b/tests/tcg/s390x/exrl-trt.c
> @@ -19,7 +19,7 @@ int main(void)
>       }
>       asm volatile(
>           "    j 2f\n"
> -        "1:  trt 0(1,%[op1]),0(%[op2])\n"
> +        "1:  trt 0(1,%[op1]),%[op2]\n"
>           "2:  exrl %[op1_len],1b\n"
>           "    lgr %[r1],%%r1\n"
>           "    lgr %[r2],%%r2\n"
> @@ -27,9 +27,9 @@ int main(void)
>           : [r1] "+r" (r1),
>             [r2] "+r" (r2),
>             [cc] "=r" (cc)
> -        : [op1] "r" (&op1),
> -          [op1_len] "r" (5),
> -          [op2] "r" (&op2)
> +        : [op1] "a" (&op1),
> +          [op1_len] "a" (5),

I think op1_len could still stay with "r" instead of "a" ... OTOH "a" also 
does not hurt here, so:

Reviewed-by: Thomas Huth <thuth@redhat.com>