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Fix sign of inexact zero results for ldbl-128ibm fmal.

This commit is contained in:
Joseph Myers 2012-11-22 15:00:35 +00:00
parent ef1e0867c0
commit c60d3bf2fa
2 changed files with 11 additions and 1 deletions
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4
ChangeLog
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@ -1,5 +1,9 @@
2012-11-22 Joseph Myers <joseph@codesourcery.com> 2012-11-22 Joseph Myers <joseph@codesourcery.com>
[BZ #14645]
* sysdeps/ieee754/ldbl-128ibm/s_fmal.c (__fmal): Compute result as
x * y if x and y are nonzero and z is zero.
[BZ #14811] [BZ #14811]
* sysdeps/ieee754/ldbl-128ibm/e_powl.c (__ieee754_powl): Saturate * sysdeps/ieee754/ldbl-128ibm/e_powl.c (__ieee754_powl): Saturate
nonzero exponents with absolute value below 0x1p-117 to +/- nonzero exponents with absolute value below 0x1p-117 to +/-

8
sysdeps/ieee754/ldbl-128ibm/s_fmal.c
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@ -1,5 +1,5 @@
/* Compute x * y + z as ternary operation. /* Compute x * y + z as ternary operation.
Copyright (C) 2011 Free Software Foundation, Inc. Copyright (C) 2011-2012 Free Software Foundation, Inc.
This file is part of the GNU C Library. This file is part of the GNU C Library.
Contributed by David Flaherty <flaherty@linux.vnet.ibm.com>. Contributed by David Flaherty <flaherty@linux.vnet.ibm.com>.
@ -29,6 +29,12 @@ __fmal (long double x, long double y, long double z)
if ((finite ((double)x) && finite ((double)y)) && isinf ((double)z)) if ((finite ((double)x) && finite ((double)y)) && isinf ((double)z))
return (z); return (z);
/* If z is zero and x are y are nonzero, compute the result
as x * y to avoid the wrong sign of a zero result if x * y
underflows to 0. */
if (z == 0 && x != 0 && y != 0)
return x * y;
return (x * y) + z; return (x * y) + z;
} }
#ifdef IS_IN_libm #ifdef IS_IN_libm