mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-23 13:30:06 +00:00
0b7a5f9201
Similar to various other bugs in this area, some log1p implementations do not raise the underflow exception for subnormal arguments, when the result is tiny and inexact. This patch forces the exception in a similar way to previous fixes. (The ldbl-128ibm implementation doesn't currently need any change as it already generates this exception, albeit through code that would generate spurious exceptions in other cases; special code for this issue will only be needed there when fixing the spurious exceptions.) Tested for x86_64, x86, powerpc and mips64. [BZ #16339] * sysdeps/i386/fpu/s_log1p.S (dbl_min): New object. (__log1p): Force underflow exception for results with small absolute value. * sysdeps/i386/fpu/s_log1pf.S (flt_min): New object. (__log1pf): Force underflow exception for results with small absolute value. * sysdeps/ieee754/dbl-64/s_log1p.c: Include <float.h>. (__log1p): Force underflow exception for results with small absolute value. * sysdeps/ieee754/flt-32/s_log1pf.c: Include <float.h>. (__log1pf): Force underflow exception for results with small absolute value. * sysdeps/ieee754/ldbl-128/s_log1pl.c: Include <float.h>. (__log1pl): Force underflow exception for results with small absolute value. * math/auto-libm-test-in: Do not allow missing underflow exceptions from log1p. * math/auto-libm-test-out: Regenerated.
107 lines
2.7 KiB
C
107 lines
2.7 KiB
C
/* s_log1pf.c -- float version of s_log1p.c.
|
|
* Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
|
|
*/
|
|
|
|
/*
|
|
* ====================================================
|
|
* 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.
|
|
* ====================================================
|
|
*/
|
|
|
|
#include <float.h>
|
|
#include <math.h>
|
|
#include <math_private.h>
|
|
|
|
static const float
|
|
ln2_hi = 6.9313812256e-01, /* 0x3f317180 */
|
|
ln2_lo = 9.0580006145e-06, /* 0x3717f7d1 */
|
|
two25 = 3.355443200e+07, /* 0x4c000000 */
|
|
Lp1 = 6.6666668653e-01, /* 3F2AAAAB */
|
|
Lp2 = 4.0000000596e-01, /* 3ECCCCCD */
|
|
Lp3 = 2.8571429849e-01, /* 3E924925 */
|
|
Lp4 = 2.2222198546e-01, /* 3E638E29 */
|
|
Lp5 = 1.8183572590e-01, /* 3E3A3325 */
|
|
Lp6 = 1.5313838422e-01, /* 3E1CD04F */
|
|
Lp7 = 1.4798198640e-01; /* 3E178897 */
|
|
|
|
static const float zero = 0.0;
|
|
|
|
float
|
|
__log1pf(float x)
|
|
{
|
|
float hfsq,f,c,s,z,R,u;
|
|
int32_t k,hx,hu,ax;
|
|
|
|
GET_FLOAT_WORD(hx,x);
|
|
ax = hx&0x7fffffff;
|
|
|
|
k = 1;
|
|
if (hx < 0x3ed413d7) { /* x < 0.41422 */
|
|
if(ax>=0x3f800000) { /* x <= -1.0 */
|
|
if(x==(float)-1.0) return -two25/zero; /* log1p(-1)=-inf */
|
|
else return (x-x)/(x-x); /* log1p(x<-1)=NaN */
|
|
}
|
|
if(ax<0x31000000) { /* |x| < 2**-29 */
|
|
math_force_eval(two25+x); /* raise inexact */
|
|
if (ax<0x24800000) /* |x| < 2**-54 */
|
|
{
|
|
if (fabsf (x) < FLT_MIN)
|
|
{
|
|
float force_underflow = x * x;
|
|
math_force_eval (force_underflow);
|
|
}
|
|
return x;
|
|
}
|
|
else
|
|
return x - x*x*(float)0.5;
|
|
}
|
|
if(hx>0||hx<=((int32_t)0xbe95f61f)) {
|
|
k=0;f=x;hu=1;} /* -0.2929<x<0.41422 */
|
|
}
|
|
if (hx >= 0x7f800000) return x+x;
|
|
if(k!=0) {
|
|
if(hx<0x5a000000) {
|
|
u = (float)1.0+x;
|
|
GET_FLOAT_WORD(hu,u);
|
|
k = (hu>>23)-127;
|
|
/* correction term */
|
|
c = (k>0)? (float)1.0-(u-x):x-(u-(float)1.0);
|
|
c /= u;
|
|
} else {
|
|
u = x;
|
|
GET_FLOAT_WORD(hu,u);
|
|
k = (hu>>23)-127;
|
|
c = 0;
|
|
}
|
|
hu &= 0x007fffff;
|
|
if(hu<0x3504f7) {
|
|
SET_FLOAT_WORD(u,hu|0x3f800000);/* normalize u */
|
|
} else {
|
|
k += 1;
|
|
SET_FLOAT_WORD(u,hu|0x3f000000); /* normalize u/2 */
|
|
hu = (0x00800000-hu)>>2;
|
|
}
|
|
f = u-(float)1.0;
|
|
}
|
|
hfsq=(float)0.5*f*f;
|
|
if(hu==0) { /* |f| < 2**-20 */
|
|
if(f==zero) {
|
|
if(k==0) return zero;
|
|
else {c += k*ln2_lo; return k*ln2_hi+c;}
|
|
}
|
|
R = hfsq*((float)1.0-(float)0.66666666666666666*f);
|
|
if(k==0) return f-R; else
|
|
return k*ln2_hi-((R-(k*ln2_lo+c))-f);
|
|
}
|
|
s = f/((float)2.0+f);
|
|
z = s*s;
|
|
R = z*(Lp1+z*(Lp2+z*(Lp3+z*(Lp4+z*(Lp5+z*(Lp6+z*Lp7))))));
|
|
if(k==0) return f-(hfsq-s*(hfsq+R)); else
|
|
return k*ln2_hi-((hfsq-(s*(hfsq+R)+(k*ln2_lo+c)))-f);
|
|
}
|