diff options
| -rw-r--r-- | ChangeLog | 7 | ||||
| -rw-r--r-- | NEWS | 2 | ||||
| -rw-r--r-- | sysdeps/ieee754/ldbl-128/e_powl.c | 26 |
3 files changed, 21 insertions, 14 deletions
diff --git a/ChangeLog b/ChangeLog index 33ce8eded7..070be3c6a5 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,10 @@ +2014-06-29 Joseph Myers <joseph@codesourcery.com> + + [BZ #17097] + * sysdeps/ieee754/ldbl-128/e_powl.c (__ieee754_powl): Return + result with correct sign in case of exponents that produce + overflow except for X very close to 1. + 2014-06-28 Paul Eggert <eggert@cs.ucla.edu> mktime: merge #if/#ifdef usage from glibc diff --git a/NEWS b/NEWS index 02e3cd83ff..a07ea6615c 100644 --- a/NEWS +++ b/NEWS @@ -21,7 +21,7 @@ Version 2.20 16882, 16885, 16888, 16890, 16912, 16915, 16916, 16917, 16918, 16922, 16927, 16928, 16932, 16943, 16958, 16965, 16966, 16967, 16977, 16978, 16984, 16990, 16996, 17009, 17022, 17031, 17042, 17048, 17050, 17058, - 17061, 17062, 17069, 17075, 17079, 17084, 17086, 17092. + 17061, 17062, 17069, 17075, 17079, 17084, 17086, 17092, 17097. * Optimized strchr implementation for AArch64. Contributed by ARM Ltd. diff --git a/sysdeps/ieee754/ldbl-128/e_powl.c b/sysdeps/ieee754/ldbl-128/e_powl.c index d131750718..f531385232 100644 --- a/sysdeps/ieee754/ldbl-128/e_powl.c +++ b/sysdeps/ieee754/ldbl-128/e_powl.c @@ -148,7 +148,7 @@ long double __ieee754_powl (long double x, long double y) { long double z, ax, z_h, z_l, p_h, p_l; - long double y1, t1, t2, r, s, t, u, v, w; + long double y1, t1, t2, r, s, sgn, t, u, v, w; long double s2, s_h, s_l, t_h, t_l, ay; int32_t i, j, k, yisint, n; u_int32_t ix, iy; @@ -262,6 +262,11 @@ __ieee754_powl (long double x, long double y) if (((((u_int32_t) hx >> 31) - 1) | yisint) == 0) return (x - x) / (x - x); + /* sgn (sign of result -ve**odd) = -1 else = 1 */ + sgn = one; + if (((((u_int32_t) hx >> 31) - 1) | (yisint - 1)) == 0) + sgn = -one; /* (-ve)**(odd int) */ + /* |y| is huge. 2^-16495 = 1/2 of smallest representable value. If (1 - 1/131072)^y underflows, y > 1.4986e9 */ @@ -277,9 +282,9 @@ __ieee754_powl (long double x, long double y) } /* over/underflow if x is not close to one */ if (ix < 0x3ffeffff) - return (hy < 0) ? huge * huge : tiny * tiny; + return (hy < 0) ? sgn * huge * huge : sgn * tiny * tiny; if (ix > 0x3fff0000) - return (hy > 0) ? huge * huge : tiny * tiny; + return (hy > 0) ? sgn * huge * huge : sgn * tiny * tiny; } ay = y > 0 ? y : -y; @@ -366,11 +371,6 @@ __ieee754_powl (long double x, long double y) t1 = o.value; t2 = z_l - (((t1 - t) - dp_h[k]) - z_h); - /* s (sign of result -ve**odd) = -1 else = 1 */ - s = one; - if (((((u_int32_t) hx >> 31) - 1) | (yisint - 1)) == 0) - s = -one; /* (-ve)**(odd int) */ - /* split up y into y1+y2 and compute (y1+y2)*(t1+t2) */ y1 = y; o.value = y1; @@ -386,11 +386,11 @@ __ieee754_powl (long double x, long double y) { /* if z > 16384 */ if (((j - 0x400d0000) | o.parts32.w1 | o.parts32.w2 | o.parts32.w3) != 0) - return s * huge * huge; /* overflow */ + return sgn * huge * huge; /* overflow */ else { if (p_l + ovt > z - p_h) - return s * huge * huge; /* overflow */ + return sgn * huge * huge; /* overflow */ } } else if ((j & 0x7fffffff) >= 0x400d01b9) /* z <= -16495 */ @@ -398,11 +398,11 @@ __ieee754_powl (long double x, long double y) /* z < -16495 */ if (((j - 0xc00d01bc) | o.parts32.w1 | o.parts32.w2 | o.parts32.w3) != 0) - return s * tiny * tiny; /* underflow */ + return sgn * tiny * tiny; /* underflow */ else { if (p_l <= z - p_h) - return s * tiny * tiny; /* underflow */ + return sgn * tiny * tiny; /* underflow */ } } /* compute 2**(p_h+p_l) */ @@ -441,6 +441,6 @@ __ieee754_powl (long double x, long double y) o.parts32.w0 = j; z = o.value; } - return s * z; + return sgn * z; } strong_alias (__ieee754_powl, __powl_finite) |