On 2026-07-26 17:13:04+0700, Ammar Faizi wrote:
(...)
> Cc: Alviro Iskandar Setiawan <[email protected]>
> Signed-off-by: Ammar Faizi <[email protected]>
> ---
> tools/testing/selftests/nolibc/nolibc-test.c | 47 ++++++++++++++++++++
> 1 file changed, 47 insertions(+)
>
> diff --git a/tools/testing/selftests/nolibc/nolibc-test.c
> b/tools/testing/selftests/nolibc/nolibc-test.c
> index 996e8d13508e..4dc2ffea63bd 100644
> --- a/tools/testing/selftests/nolibc/nolibc-test.c
> +++ b/tools/testing/selftests/nolibc/nolibc-test.c
> @@ -1728,6 +1728,52 @@ int test_alloca(void)
> return *x - 0x1234;
> }
>
> +/* abs(), labs() and llabs() over the whole range of their argument type */
> +int test_abs_range(void)
> +{
> + int i, ri;
> + long l, rl;
> + long long ll, rll;
Reverse xmas?
> +
> + /*
> + * Both the inputs and the results have to stay opaque: the compiler
> + * knows abs() and friends never return a negative value and would
> + * otherwise fold the comparisons below at build time, which would also
> + * hide the undefined behavior that is being tested for.
> + */
> + i = INT_MIN; l = LONG_MIN; ll = LLONG_MIN;
> + __asm__ ("" : "+r" (i), "+r" (l), "+r" (ll));
We have _NOLIBC_OPTIMIZER_HIDE_VAR() for this.
Maybe it can be made variadic.
> + ri = abs(i); rl = labs(l); rll = llabs(ll);
> + __asm__ ("" : "+r" (ri), "+r" (rl), "+r" (rll));
> + /* the absolute value is not representable, the input is returned */
> + if (ri != INT_MIN || rl != LONG_MIN || rll != LLONG_MIN)
> + return 1;
(...)
