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8795b4a443
This patch fixes the default mode of scalb to set errno (bugs 6803 and 6804). Previously, the _LIB_VERSION == _SVID_ mode would set errno but only in some relevant cases, and with various peculiarities (such as errno setting when an exact infinity or zero result arises with an argument to scalb being an infinity). This patch leaves this mode bug-compatible, while making the default mode set errno in accordance with normal practice (so an exact infinity from an infinite argument is not an error, and nor is an exact zero result). gen-libm-test.pl is taught new notation such as ERRNO_PLUS_OFLOW to facilitate writing the tests of errno setting for underflow / overflow in libm-test.inc. Note that bug 6803 also covers scalbn and scalbln, but this patch only addresses the scalb parts of that bug (along with the whole of bug 6804). Tested x86_64 and x86. [BZ #6803] [BZ #6804] * math/w_scalb.c (__scalb): For non-SVID mode, check result and set errno as appropriate. * math/w_scalbf.c (__scalbf): Likewise. * math/w_scalbl.c (__scalbl): Likewise. * math/gen-libm-test.pl (parse_args): Handle ERRNO_PLUS_OFLOW, ERRNO_MINUS_OFLOW, ERRNO_PLUS_UFLOW and ERRNO_MINUS_UFLOW. * math/libm-test.inc (scalb_test_data): Add errno expectations. Add more NaN tests.
81 lines
2.0 KiB
C
81 lines
2.0 KiB
C
/* Copyright (C) 2011-2014 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Ulrich Drepper <drepper@gmail.com>, 2011.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <errno.h>
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#include <math.h>
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#include <math_private.h>
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static double
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__attribute__ ((noinline))
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sysv_scalb (double x, double fn)
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{
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double z = __ieee754_scalb (x, fn);
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if (__glibc_unlikely (__isinf (z)))
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{
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if (__finite (x))
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return __kernel_standard (x, fn, 32); /* scalb overflow */
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else
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__set_errno (ERANGE);
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}
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else if (__builtin_expect (z == 0.0, 0) && z != x)
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return __kernel_standard (x, fn, 33); /* scalb underflow */
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return z;
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}
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/* Wrapper scalb */
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double
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__scalb (double x, double fn)
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{
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if (__glibc_unlikely (_LIB_VERSION == _SVID_))
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return sysv_scalb (x, fn);
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else
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{
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double z = __ieee754_scalb (x, fn);
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if (__glibc_unlikely (!__finite (z) || z == 0.0))
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{
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if (__isnan (z))
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{
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if (!__isnan (x) && !__isnan (fn))
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__set_errno (EDOM);
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}
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else if (__isinf_ns (z))
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{
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if (!__isinf_ns (x) && !__isinf_ns (fn))
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__set_errno (ERANGE);
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}
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else
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{
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/* z == 0. */
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if (x != 0.0 && !__isinf_ns (fn))
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__set_errno (ERANGE);
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}
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}
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return z;
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}
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}
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weak_alias (__scalb, scalb)
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#ifdef NO_LONG_DOUBLE
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strong_alias (__scalb, __scalbl)
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weak_alias (__scalb, scalbl)
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#endif
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