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

[Thomas Huth <thuth@redhat.com>]

  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).

>> +    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?

  Thomas