Re: [PATCH] tests/tcg/s390x: Test overflow conditions

[Gautam Agrawal]

Hi,
On Mon, 30 May 2022 at 16:05, Thomas Huth <thuth@redhat.com> wrote:
>
>   Hi!
>
> On 30/05/2022 11.50, David Hildenbrand wrote:
> > On 27.05.22 12:11, Gautam Agrawal wrote:
> >> Add a test to check for overflow conditions in s390x.
> >> This patch is based on the following patches :
> >> * https://git.qemu.org/?p=qemu.git;a=commitdiff;h=5a2e67a691501
> >> * https://git.qemu.org/?p=qemu.git;a=commitdiff;h=fc6e0d0f2db51
> >>
> >> Signed-off-by: Gautam Agrawal <gautamnagrawal@gmail.com>
> >> ---
> >>   tests/tcg/s390x/Makefile.target |  1 +
> >>   tests/tcg/s390x/overflow.c      | 58 +++++++++++++++++++++++++++++++++
> >>   2 files changed, 59 insertions(+)
> >>   create mode 100644 tests/tcg/s390x/overflow.c
> >>
> >> diff --git a/tests/tcg/s390x/Makefile.target 
> >> b/tests/tcg/s390x/Makefile.target
> >> index 3124172736..7f86de85b9 100644
> >> --- a/tests/tcg/s390x/Makefile.target
> >> +++ b/tests/tcg/s390x/Makefile.target
> >> @@ -16,6 +16,7 @@ TESTS+=shift
> >>   TESTS+=trap
> >>   TESTS+=signals-s390x
> >>   TESTS+=branch-relative-long
> >> +TESTS+=overflow
> >>
> >>   VECTOR_TESTS=vxeh2_vs
> >>   VECTOR_TESTS+=vxeh2_vcvt
> >> diff --git a/tests/tcg/s390x/overflow.c b/tests/tcg/s390x/overflow.c
> >> new file mode 100644
> >> index 0000000000..ea8a410b1a
> >> --- /dev/null
> >> +++ b/tests/tcg/s390x/overflow.c
> >> @@ -0,0 +1,58 @@
> >> +#include <stdio.h>
> >> +
> >> +int overflow_add_32(int x, int y)
> >> +{
> >> +    int sum;
> >> +    return __builtin_add_overflow(x, y, &sum);
> >> +}
> >> +
> >> +int overflow_add_64(long long x, long long y)
> >> +{
> >> +    long sum;
> >
> > Just wondering, why "long long" in input and "long" in output?

> It's been like this in the original test program that has been supplied in
> https://gitlab.com/qemu-project/qemu/-/issues/616 and .../618 - but I agree
> it likely makes more sense to use the same type everywhere (i.e. switch sum
> from long to long long).

I will correct the type in next patch.

>
> >> +    return __builtin_add_overflow(x, y, &sum);
> >> +}
> >> +
> >> +int overflow_sub_32(int x, int y)
> >> +{
> >> +    int sum;
> >> +    return __builtin_sub_overflow(x, y, &sum);
> >> +}
> >> +
> >> +int overflow_sub_64(long long x, long long y)
> >> +{
> >> +    long sum;
> >> +    return __builtin_sub_overflow(x, y, &sum);
> >
> > nit: I'd call all local variables "ret" or "res".
>
> Well, "sum" is not the return value here, so "ret" could be confusing, too.
> "res" or "diff" might be a good choice here, though. Gautam, what do you 
> think?

I agree "res" sounds better.

Regards,
Gautam Agrawal