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43cfdf8f48
This patch currently only affects aarch64. The roundtoint and converttoint internal functions are only called with small values, so 32 bit result is enough for converttoint and it is a signed int conversion so the return type is changed to int32_t. The original idea was to help the compiler keeping the result in uint64_t, then it's clear that no sign extension is needed and there is no accidental undefined or implementation defined signed int arithmetics. But it turns out gcc does a good job with inlining so changing the type has no overhead and the semantics of the conversion is less surprising this way. Since we want to allow the asuint64 (x + 0x1.8p52) style conversion, the top bits were never usable and the existing code ensures that only the bottom 32 bits of the conversion result are used. On aarch64 the neon intrinsics (which round ties to even) are changed to round and lround (which round ties away from zero) this does not affect the results in a significant way, but more portable (relies on round and lround being inlined which works with -fno-math-errno). The TOINT_SHIFT and TOINT_RINT macros were removed, only keep separate code paths for TOINT_INTRINSICS and !TOINT_INTRINSICS. * sysdeps/aarch64/fpu/math_private.h (roundtoint): Use round. (converttoint): Use lround. * sysdeps/ieee754/flt-32/math_config.h (roundtoint): Declare and document the semantics when TOINT_INTRINSICS is set. (converttoint): Likewise. (TOINT_RINT): Remove. (TOINT_SHIFT): Remove. * sysdeps/ieee754/flt-32/e_expf.c (__expf): Remove the TOINT_RINT code path.
175 lines
4.2 KiB
C
175 lines
4.2 KiB
C
/* Configuration for math routines.
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Copyright (C) 2017-2018 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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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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#ifndef _MATH_CONFIG_H
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#define _MATH_CONFIG_H
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#include <math.h>
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#include <math_private.h>
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#include <nan-high-order-bit.h>
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#include <stdint.h>
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#ifndef WANT_ROUNDING
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/* Correct special case results in non-nearest rounding modes. */
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# define WANT_ROUNDING 1
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#endif
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#ifndef WANT_ERRNO
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/* Set errno according to ISO C with (math_errhandling & MATH_ERRNO) != 0. */
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# define WANT_ERRNO 1
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#endif
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#ifndef WANT_ERRNO_UFLOW
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/* Set errno to ERANGE if result underflows to 0 (in all rounding modes). */
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# define WANT_ERRNO_UFLOW (WANT_ROUNDING && WANT_ERRNO)
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#endif
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#ifndef TOINT_INTRINSICS
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/* When set, the roundtoint and converttoint functions are provided with
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the semantics documented below. */
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# define TOINT_INTRINSICS 0
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#endif
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#if TOINT_INTRINSICS
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/* Round x to nearest int in all rounding modes, ties have to be rounded
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consistently with converttoint so the results match. If the result
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would be outside of [-2^31, 2^31-1] then the semantics is unspecified. */
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static inline double_t
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roundtoint (double_t x);
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/* Convert x to nearest int in all rounding modes, ties have to be rounded
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consistently with roundtoint. If the result is not representible in an
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int32_t then the semantics is unspecified. */
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static inline int32_t
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converttoint (double_t x);
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#endif
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static inline uint32_t
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asuint (float f)
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{
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union
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{
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float f;
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uint32_t i;
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} u = {f};
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return u.i;
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}
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static inline float
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asfloat (uint32_t i)
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{
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union
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{
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uint32_t i;
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float f;
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} u = {i};
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return u.f;
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}
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static inline uint64_t
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asuint64 (double f)
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{
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union
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{
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double f;
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uint64_t i;
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} u = {f};
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return u.i;
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}
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static inline double
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asdouble (uint64_t i)
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{
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union
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{
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uint64_t i;
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double f;
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} u = {i};
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return u.f;
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}
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static inline int
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issignalingf_inline (float x)
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{
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uint32_t ix = asuint (x);
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if (HIGH_ORDER_BIT_IS_SET_FOR_SNAN)
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return (ix & 0x7fc00000) == 0x7fc00000;
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return 2 * (ix ^ 0x00400000) > 2u * 0x7fc00000;
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}
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#define NOINLINE __attribute__ ((noinline))
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attribute_hidden float __math_oflowf (uint32_t);
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attribute_hidden float __math_uflowf (uint32_t);
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attribute_hidden float __math_may_uflowf (uint32_t);
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attribute_hidden float __math_divzerof (uint32_t);
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attribute_hidden float __math_invalidf (float);
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/* Shared between expf, exp2f and powf. */
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#define EXP2F_TABLE_BITS 5
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#define EXP2F_POLY_ORDER 3
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extern const struct exp2f_data
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{
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uint64_t tab[1 << EXP2F_TABLE_BITS];
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double shift_scaled;
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double poly[EXP2F_POLY_ORDER];
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double shift;
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double invln2_scaled;
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double poly_scaled[EXP2F_POLY_ORDER];
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} __exp2f_data attribute_hidden;
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#define LOGF_TABLE_BITS 4
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#define LOGF_POLY_ORDER 4
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extern const struct logf_data
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{
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struct
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{
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double invc, logc;
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} tab[1 << LOGF_TABLE_BITS];
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double ln2;
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double poly[LOGF_POLY_ORDER - 1]; /* First order coefficient is 1. */
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} __logf_data attribute_hidden;
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#define LOG2F_TABLE_BITS 4
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#define LOG2F_POLY_ORDER 4
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extern const struct log2f_data
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{
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struct
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{
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double invc, logc;
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} tab[1 << LOG2F_TABLE_BITS];
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double poly[LOG2F_POLY_ORDER];
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} __log2f_data attribute_hidden;
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#define POWF_LOG2_TABLE_BITS 4
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#define POWF_LOG2_POLY_ORDER 5
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#if TOINT_INTRINSICS
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# define POWF_SCALE_BITS EXP2F_TABLE_BITS
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#else
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# define POWF_SCALE_BITS 0
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#endif
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#define POWF_SCALE ((double) (1 << POWF_SCALE_BITS))
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extern const struct powf_log2_data
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{
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struct
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{
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double invc, logc;
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} tab[1 << POWF_LOG2_TABLE_BITS];
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double poly[POWF_LOG2_POLY_ORDER];
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} __powf_log2_data attribute_hidden;
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#endif
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