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tests/lib/libm/t_fe_round: Test nearbyintl. 

This uses inputs that can't be distinguished with only 53 bits of
precision, so it should work in essentially all long double formats
to detect when nearbyintl is incorrectly implemented in terms of
nearbyint.

PR lib/58054
This commit is contained in:
riastradh 2024-05-02 00:01:48 +00:00
parent 02e4b613e1
commit 247fbbb163
1 changed files with 58 additions and 0 deletions
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58
tests/lib/libm/t_fe_round.c
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@ -143,6 +143,61 @@ ATF_TC_BODY(fe_nearbyint, tc)
}
}
#ifdef __HAVE_LONG_DOUBLE
/*
* Use one bit more than fits in IEEE 754 binary64.
*/
static const struct {
int round_mode;
long double input;
long int expected;
} valuesl[] = {
{ FE_TOWARDZERO, 0x2.00000000000008p+52L, 0x20000000000000 },
{ FE_DOWNWARD, 0x2.00000000000008p+52L, 0x20000000000000 },
{ FE_UPWARD, 0x2.00000000000008p+52L, 0x20000000000001 },
{ FE_TONEAREST, 0x2.00000000000008p+52L, 0x20000000000000 },
{ FE_TOWARDZERO, 0x2.00000000000018p+52L, 0x20000000000001 },
{ FE_DOWNWARD, 0x2.00000000000018p+52L, 0x20000000000001 },
{ FE_UPWARD, 0x2.00000000000018p+52L, 0x20000000000002 },
{ FE_TONEAREST, 0x2.00000000000018p+52L, 0x20000000000002 },
};
ATF_TC(fe_nearbyintl);
ATF_TC_HEAD(fe_nearbyintl, tc)
{
atf_tc_set_md_var(tc, "descr",
"Checking IEEE 754 rounding modes using nearbyintl");
}
ATF_TC_BODY(fe_nearbyintl, tc)
{
long double received, ipart, fpart;
for (unsigned int i = 0; i < __arraycount(valuesl); i++) {
fesetround(valuesl[i].round_mode);
received = nearbyintl(valuesl[i].input);
fpart = modfl(received, &ipart);
ATF_CHECK_MSG(fpart == 0,
"%s nearbyintl(%Lf) has fractional part %Lf",
rmname(values[i].round_mode), valuesl[i].input, fpart);
ATF_CHECK_MSG((long int)received == valuesl[i].expected,
"%s [%u] nearbyint(%Lf): got %Lf, expected %ld",
rmname(values[i].round_mode), i,
valuesl[i].input, received, valuesl[i].expected);
/* Do we get the same rounding mode out? */
ATF_CHECK_MSG(fegetround() == valuesl[i].round_mode,
"[%u] set %d (%s), got %d (%s)",
i,
valuesl[i].round_mode, rmname(valuesl[i].round_mode),
fegetround(), rmname(fegetround()));
}
}
#endif
static const struct {
double input;
double toward;
@ -209,6 +264,9 @@ ATF_TP_ADD_TCS(tp)
ATF_TP_ADD_TC(tp, fe_round);
ATF_TP_ADD_TC(tp, fe_nearbyint);
#ifdef __HAVE_LONG_DOUBLE
ATF_TP_ADD_TC(tp, fe_nearbyintl);
#endif
ATF_TP_ADD_TC(tp, fe_nextafter);
ATF_TP_ADD_TC(tp, fe_nexttoward);