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TS 18661-1 generally defines libm functions taking sNaN arguments to return qNaN and raise "invalid", even for the cases where a corresponding qNaN argument would not result in a qNaN return. This includes hypot with one argument being an infinity and the other being an sNaN. This patch duly fixes hypot implementatations in glibc (generic and powerpc) to ensure qNaN, computed by arithmetic on the arguments, is returned in that case. Various implementations do their checks for infinities and NaNs inline by manipulating the representations of the arguments. For simplicity, this patch just uses issignaling to check for sNaN arguments. This could be inlined like the existing code (with due care about reversed quiet NaN conventions, for implementations where that is relevant), but given that all these checks are in cases where it's already known at least one argument is not finite, which should be the uncommon case, that doesn't seem worthwhile unless performance issues are observed in practice. Tested for x86_64, x86, mips64 and powerpc. [BZ #20940] * sysdeps/ieee754/dbl-64/e_hypot.c (__ieee754_hypot): Do not return Inf for arguments Inf and sNaN. * sysdeps/ieee754/flt-32/e_hypotf.c (__ieee754_hypotf): Likewise. * sysdeps/ieee754/ldbl-128/e_hypotl.c (__ieee754_hypotl): Likewise. * sysdeps/ieee754/ldbl-128ibm/e_hypotl.c (__ieee754_hypotl): Likewise. * sysdeps/ieee754/ldbl-96/e_hypotl.c (__ieee754_hypotl): Likewise. * sysdeps/powerpc/fpu/e_hypot.c (TEST_INF_NAN): Do not return Inf for arguments Inf and sNaN. When returning a NaN, compute it by arithmetic on the arguments. * sysdeps/powerpc/fpu/e_hypotf.c (TEST_INF_NAN): Likewise. * math/libm-test.inc (pow_test_data): Add tests of sNaN arguments.
77 lines
3.2 KiB
C
77 lines
3.2 KiB
C
/* Pythagorean addition using floats
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Copyright (C) 2011-2016 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Adhemerval Zanella <azanella@br.ibm.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 Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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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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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If
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not, see <http://www.gnu.org/licenses/>. */
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#include <math.h>
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#include <math_private.h>
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#include <stdint.h>
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/* __ieee754_hypotf(x,y)
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This a FP only version without any FP->INT conversion.
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It is similar to default C version, making appropriates
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overflow and underflows checks as using double precision
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instead of scaling. */
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#ifdef _ARCH_PWR7
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/* POWER7 isinf and isnan optimizations are fast. */
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# define TEST_INF_NAN(x, y) \
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if ((isinff(x) || isinff(y)) \
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&& !issignaling (x) && !issignaling (y)) \
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return INFINITY; \
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if (isnanf(x) || isnanf(y)) \
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return x + y;
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# else
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/* For POWER6 and below isinf/isnan triggers LHS and PLT calls are
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* costly (especially for POWER6). */
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# define GET_TWO_FLOAT_WORD(f1,f2,i1,i2) \
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do { \
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ieee_float_shape_type gf_u1; \
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ieee_float_shape_type gf_u2; \
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gf_u1.value = (f1); \
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gf_u2.value = (f2); \
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(i1) = gf_u1.word & 0x7fffffff; \
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(i2) = gf_u2.word & 0x7fffffff; \
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} while (0)
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# define TEST_INF_NAN(x, y) \
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do { \
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uint32_t hx, hy; \
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GET_TWO_FLOAT_WORD(x, y, hx, hy); \
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if (hy > hx) { \
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uint32_t ht = hx; hx = hy; hy = ht; \
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} \
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if (hx >= 0x7f800000) { \
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if ((hx == 0x7f800000 || hy == 0x7f800000) \
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&& !issignaling (x) && !issignaling (y)) \
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return INFINITY; \
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return x + y; \
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} \
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} while (0)
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#endif
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float
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__ieee754_hypotf (float x, float y)
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{
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TEST_INF_NAN (x, y);
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return __ieee754_sqrt ((double) x * x + (double) y * y);
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}
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strong_alias (__ieee754_hypotf, __hypotf_finite)
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