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75ad83f564
C23 adds various <math.h> function families originally defined in TS 18661-4. Add the pown functions, which are like pow but with an integer exponent. That exponent has type long long int in C23; it was intmax_t in TS 18661-4, and as with other interfaces changed after their initial appearance in the TS, I don't think we need to support the original version of the interface. The test inputs are based on the subset of test inputs for pow that use integer exponents that fit in long long. As the first such template implementation that saves and restores the rounding mode internally (to avoid possible issues with directed rounding and intermediate overflows or underflows in the wrong rounding mode), support also needed to be added for using SET_RESTORE_ROUND* in such template function implementations. This required math-type-macros-float128.h to include <fenv_private.h>, so it can tell whether SET_RESTORE_ROUNDF128 is defined. In turn, the include order with <fenv_private.h> included before <math_private.h> broke loongarch builds, showing up that sysdeps/loongarch/math_private.h is really a fenv_private.h file (maybe implemented internally before the consistent split of those headers in 2018?) and needed to be renamed to fenv_private.h to avoid errors with duplicate macro definitions if <math_private.h> is included after <fenv_private.h>. The underlying implementation uses __ieee754_pow functions (called more than once in some cases, where the exponent does not fit in the floating type). I expect a custom implementation for a given format, that only handles integer exponents but handles larger exponents directly, could be faster and more accurate in some cases. I encourage searching for worst cases for ulps error for these implementations (necessarily non-exhaustively, given the size of the input space). Tested for x86_64 and x86, and with build-many-glibcs.py.
144 lines
4.4 KiB
C
144 lines
4.4 KiB
C
/* Helper macros for type generic function implementations within libm.
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Copyright (C) 2016-2025 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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<https://www.gnu.org/licenses/>. */
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#ifndef _MATH_TYPE_MACROS
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#define _MATH_TYPE_MACROS
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/* Each type imports a header which is expected to
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define:
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M_LIT(x) - Paste the type specific suffix onto the constant x.
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M_MLIT(x) - Paste the type specific suffix used by the macro
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constants in math.h, i.e M_PI or M_PIl.
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M_PFX - The prefixed used by float.h macros like FLT_MANT_DIG.
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M_SUF(x) - Paste the the type specific suffix used by functions
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i.e expf expl exp.
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FLOAT - Resolves to the C typename of M_TYPE.
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CFLOAT - Resolves to the complex typename of M_TYPE.
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M_STRTO_NAN - Resolves to the internal libc function which
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converts a string into the appropriate FLOAT nan
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value.
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M_SET_RESTORE_ROUND - Resolves to a SET_RESTORE_ROUND call for M_TYPE.
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declare_mgen_alias(from,to)
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This exposes the appropriate symbol(s) for a
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function f of type FLOAT.
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declare_mgen_alias_r(from,to)
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This exposes the appropriate symbol(s) for a
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function f_r of type FLOAT.
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declare_mgen_alias_narrow(from,to)
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This exposes the appropriate symbol(s) for narrowing aliases of a
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function f of type FLOAT.
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SET_NAN_PAYLOAD(flt, mant)
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Set the NaN payload bits of the variable FLT of type FLOAT to
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the mantissa MANT. */
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#ifndef M_PFX
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# error "M_PFX must be defined."
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#endif
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#ifndef M_LIT
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# error "M_LIT must be defined."
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#endif
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#ifndef M_MLIT
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# error "M_MLIT must be defined."
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#endif
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#ifndef M_SUF
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# error "M_SUF must be defined."
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#endif
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#ifndef FLOAT
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# error "FLOAT must be defined."
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#endif
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#ifndef CFLOAT
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# error "CFLOAT must be defined."
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#endif
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#ifndef declare_mgen_alias
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# error "declare_mgen_alias must be defined."
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#endif
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#ifndef declare_mgen_alias_r
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# error "declare_mgen_alias_r must be defined."
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#endif
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#ifndef declare_mgen_alias_narrow
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# error "declare_mgen_alias_narrow must be defined."
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#endif
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#ifndef SET_NAN_PAYLOAD
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# error "SET_NAN_PAYLOAD must be defined."
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#endif
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#ifndef declare_mgen_finite_alias_x
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#define declare_mgen_finite_alias_x(from, to) \
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libm_alias_finite (from, to)
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#endif
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#ifndef declare_mgen_finite_alias_s
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# define declare_mgen_finite_alias_s(from,to) \
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declare_mgen_finite_alias_x (from, to)
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#endif
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#ifndef declare_mgen_finite_alias
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# define declare_mgen_finite_alias(from, to) \
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declare_mgen_finite_alias_s (M_SUF (from), M_SUF (to))
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#endif
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#define __M_CONCAT(a,b) a ## b
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#define __M_CONCATX(a,b) __M_CONCAT(a,b)
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#define M_NAN M_SUF (__builtin_nan) ("")
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#define M_MIN_EXP __M_CONCATX (M_PFX, _MIN_EXP)
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#define M_MAX_EXP __M_CONCATX (M_PFX, _MAX_EXP)
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#define M_MIN __M_CONCATX (M_PFX, _MIN)
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#define M_MAX __M_CONCATX (M_PFX, _MAX)
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#define M_MANT_DIG __M_CONCATX (M_PFX, _MANT_DIG)
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#define M_HUGE_VAL (M_SUF (__builtin_huge_val) ())
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/* Helper macros for commonly used functions. */
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#define M_COPYSIGN M_SUF (copysign)
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#define M_FABS M_SUF (fabs)
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#define M_SINCOS M_SUF (__sincos)
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#define M_SCALBN M_SUF (__scalbn)
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#define M_LOG1P M_SUF (__log1p)
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#define M_ATAN2 M_SUF (__ieee754_atan2)
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#define M_COSH M_SUF (__ieee754_cosh)
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#define M_EXP M_SUF (__ieee754_exp)
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#define M_HYPOT M_SUF (__ieee754_hypot)
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#define M_LOG M_SUF (__ieee754_log)
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#define M_SINH M_SUF (__ieee754_sinh)
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#define M_SQRT M_SUF (sqrt)
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/* Needed to evaluate M_MANT_DIG below. */
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#include <float.h>
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#include <libm-alias-finite.h>
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/* Use a special epsilon value for IBM long double
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to avoid spurious overflows/underflows. */
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#if M_MANT_DIG != 106
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# define M_EPSILON __M_CONCATX (M_PFX, _EPSILON)
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#else
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# define M_EPSILON M_LIT (0x1p-106)
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#endif
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/* Enable overloading of function name to assist reuse. */
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#ifndef M_DECL_FUNC
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# define M_DECL_FUNC(f) M_SUF (f)
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#endif
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#endif /* _MATH_TYPE_MACROS */
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