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make fma and lrint functions build without full fenv support

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this is necessary to support archs where fenv is incomplete or
unavailable (presently arm). fma, fmal, and the lrint family should
work perfectly fine with this change; fmaf is slightly broken with
respect to rounding as it depends on non-default rounding modes to do
its work.
This commit is contained in:
Rich Felker
2012-03-16 23:58:49 -04:00
parent 8c071f872b
commit 2e77dc13f8
4 changed files with 28 additions and 4 deletions
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14
src/math/fma.c
View File

@ -199,27 +199,37 @@ double fma(double x, double y, double z)
* modes other than FE_TONEAREST are painful.
*/
if (spread < -DBL_MANT_DIG) {
#ifdef FE_INEXACT
feraiseexcept(FE_INEXACT);
#endif
#ifdef FE_UNDERFLOW
if (!isnormal(z))
feraiseexcept(FE_UNDERFLOW);
#endif
switch (oround) {
case FE_TONEAREST:
default: /* FE_TONEAREST */
return (z);
#ifdef FE_TOWARDZERO
case FE_TOWARDZERO:
if (x > 0.0 ^ y < 0.0 ^ z < 0.0)
return (z);
else
return (nextafter(z, 0));
#endif
#ifdef FE_DOWNWARD
case FE_DOWNWARD:
if (x > 0.0 ^ y < 0.0)
return (z);
else
return (nextafter(z, -INFINITY));
default: /* FE_UPWARD */
#endif
#ifdef FE_UPWARD
case FE_UPWARD:
if (x > 0.0 ^ y < 0.0)
return (nextafter(z, INFINITY));
else
return (z);
#endif
}
}
if (spread <= DBL_MANT_DIG * 2)

2
src/math/fmaf.c
View File

@ -54,7 +54,9 @@ float fmaf(float x, float y, float z)
* If result is inexact, and exactly halfway between two float values,
* we need to adjust the low-order bit in the direction of the error.
*/
#ifdef FE_TOWARDZERO
fesetround(FE_TOWARDZERO);
#endif
volatile double vxy = xy; /* XXX work around gcc CSE bug */
double adjusted_result = vxy + z;
fesetround(FE_TONEAREST);

14
src/math/fmal.c
View File

@ -194,27 +194,37 @@ long double fmal(long double x, long double y, long double z)
* modes other than FE_TONEAREST are painful.
*/
if (spread < -LDBL_MANT_DIG) {
#ifdef FE_INEXACT
feraiseexcept(FE_INEXACT);
#endif
#ifdef FE_UNDERFLOW
if (!isnormal(z))
feraiseexcept(FE_UNDERFLOW);
#endif
switch (oround) {
case FE_TONEAREST:
default: /* FE_TONEAREST */
return (z);
#ifdef FE_TOWARDZERO
case FE_TOWARDZERO:
if (x > 0.0 ^ y < 0.0 ^ z < 0.0)
return (z);
else
return (nextafterl(z, 0));
#endif
#ifdef FE_DOWNWARD
case FE_DOWNWARD:
if (x > 0.0 ^ y < 0.0)
return (z);
else
return (nextafterl(z, -INFINITY));
default: /* FE_UPWARD */
#endif
#ifdef FE_UPWARD
case FE_UPWARD:
if (x > 0.0 ^ y < 0.0)
return (nextafterl(z, INFINITY));
else
return (z);
#endif
}
}
if (spread <= LDBL_MANT_DIG * 2)

2
src/math/lrint.c
View File

@ -49,8 +49,10 @@ dtype fn(type x)
feholdexcept(&env);
d = (dtype)roundit(x);
#if defined(FE_INVALID) && defined(FE_INEXACT)
if (fetestexcept(FE_INVALID))
feclearexcept(FE_INEXACT);
#endif
feupdateenv(&env);
return d;
}