musl/src/math/nearbyintl.c
nsz 91c28f61f4 nearbyint optimization (only clear inexact when necessary)
old code saved/restored the fenv (the new code is only as slow
as that when inexact is not set before the call, but some other
flag is set and the rounding is inexact, which is rare)

before:
bench_nearbyint_exact              5000000 N        261 ns/op
bench_nearbyint_inexact_set        5000000 N        262 ns/op
bench_nearbyint_inexact_unset      5000000 N        261 ns/op

after:
bench_nearbyint_exact             10000000 N         94.99 ns/op
bench_nearbyint_inexact_set       25000000 N         65.81 ns/op
bench_nearbyint_inexact_unset     10000000 N         94.97 ns/op
2012-03-20 22:49:19 +01:00

26 lines
377 B
C

#include <math.h>
#include <float.h>
#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
long double nearbyintl(long double x)
{
return nearbyint(x);
}
#else
#include <fenv.h>
long double nearbyintl(long double x)
{
#ifdef FE_INEXACT
int e;
e = fetestexcept(FE_INEXACT);
#endif
x = rintl(x);
#ifdef FE_INEXACT
if (!e)
feclearexcept(FE_INEXACT);
#endif
return x;
}
#endif