glibc/sysdeps/ieee754/ldbl-128/s_nearbyintl.c
Stefan Liebler ae3577f607 Use GCC builtins for nearbyint functions if desired.
This patch is using the corresponding GCC builtin for nearbyintf, nearbyint,
nearbintl and nearbyintf128 if the USE_FUNCTION_BUILTIN macros are defined to one
in math-use-builtins.h.

This is the case for s390 if build with at least --march=z196 --mzarch.
Otherwise the generic implementation is used.  The code of the generic
implementation is not changed.

Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
2019-12-11 15:12:15 +01:00

75 lines
2.0 KiB
C

/* s_nearbyintl.c -- long double version of s_nearbyint.c.
* Conversion to IEEE quad long double by Jakub Jelinek, jj@ultra.linux.cz.
*/
/*
* ====================================================
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
*
* Developed at SunPro, a Sun Microsystems, Inc. business.
* Permission to use, copy, modify, and distribute this
* software is freely granted, provided that this notice
* is preserved.
* ====================================================
*/
/*
* nearbyintl(x)
* Return x rounded to integral value according to the prevailing
* rounding mode.
* Method:
* Using floating addition.
* Exception:
* Inexact flag raised if x not equal to rintl(x).
*/
#include <fenv.h>
#include <math.h>
#include <math-barriers.h>
#include <math_private.h>
#include <libm-alias-ldouble.h>
#include <math-use-builtins.h>
_Float128 __nearbyintl(_Float128 x)
{
#if USE_NEARBYINTL_BUILTIN
return __builtin_nearbyintl (x);
#else
/* Use generic implementation. */
static const _Float128
TWO112[2] = {
L(5.19229685853482762853049632922009600E+33), /* 0x406F000000000000, 0 */
L(-5.19229685853482762853049632922009600E+33) /* 0xC06F000000000000, 0 */
};
fenv_t env;
int64_t i0,j0,sx;
uint64_t i1 __attribute__ ((unused));
_Float128 w,t;
GET_LDOUBLE_WORDS64(i0,i1,x);
sx = (((uint64_t)i0)>>63);
j0 = ((i0>>48)&0x7fff)-0x3fff;
if(j0<112) {
if(j0<0) {
feholdexcept (&env);
w = TWO112[sx] + math_opt_barrier (x);
t = w-TWO112[sx];
math_force_eval (t);
fesetenv (&env);
GET_LDOUBLE_MSW64(i0,t);
SET_LDOUBLE_MSW64(t,(i0&0x7fffffffffffffffLL)|(sx<<63));
return t;
}
} else {
if(j0==0x4000) return x+x; /* inf or NaN */
else return x; /* x is integral */
}
feholdexcept (&env);
w = TWO112[sx] + math_opt_barrier (x);
t = w-TWO112[sx];
math_force_eval (t);
fesetenv (&env);
return t;
#endif /* ! USE_NEARBYINTL_BUILTIN */
}
libm_alias_ldouble (__nearbyint, nearbyint)