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b3f27d8150
This patch adds the narrowing fused multiply-add functions from TS 18661-1 / TS 18661-3 / C2X to glibc's libm: ffma, ffmal, dfmal, f32fmaf64, f32fmaf32x, f32xfmaf64 for all configurations; f32fmaf64x, f32fmaf128, f64fmaf64x, f64fmaf128, f32xfmaf64x, f32xfmaf128, f64xfmaf128 for configurations with _Float64x and _Float128; __f32fmaieee128 and __f64fmaieee128 aliases in the powerpc64le case (for calls to ffmal and dfmal when long double is IEEE binary128). Corresponding tgmath.h macro support is also added. The changes are mostly similar to those for the other narrowing functions previously added, especially that for sqrt, so the description of those generally applies to this patch as well. As with sqrt, I reused the same test inputs in auto-libm-test-in as for non-narrowing fma rather than adding extra or separate inputs for narrowing fma. The tests in libm-test-narrow-fma.inc also follow those for non-narrowing fma. The non-narrowing fma has a known bug (bug 6801) that it does not set errno on errors (overflow, underflow, Inf * 0, Inf - Inf). Rather than fixing this or having narrowing fma check for errors when non-narrowing does not (complicating the cases when narrowing fma can otherwise be an alias for a non-narrowing function), this patch does not attempt to check for errors from narrowing fma and set errno; the CHECK_NARROW_FMA macro is still present, but as a placeholder that does nothing, and this missing errno setting is considered to be covered by the existing bug rather than needing a separate open bug. missing-errno annotations are duly added to many of the auto-libm-test-in test inputs for fma. This completes adding all the new functions from TS 18661-1 to glibc, so will be followed by corresponding stdc-predef.h changes to define __STDC_IEC_60559_BFP__ and __STDC_IEC_60559_COMPLEX__, as the support for TS 18661-1 will be at a similar level to that for C standard floating-point facilities up to C11 (pragmas not implemented, but library functions done). (There are still further changes to be done to implement changes to the types of fromfp functions from N2548.) Tested as followed: natively with the full glibc testsuite for x86_64 (GCC 11, 7, 6) and x86 (GCC 11); with build-many-glibcs.py with GCC 11, 7 and 6; cross testing of math/ tests for powerpc64le, powerpc32 hard float, mips64 (all three ABIs, both hard and soft float). The different GCC versions are to cover the different cases in tgmath.h and tgmath.h tests properly (GCC 6 has _Float* only as typedefs in glibc headers, GCC 7 has proper _Float* support, GCC 8 adds __builtin_tgmath).
399 lines
13 KiB
C
399 lines
13 KiB
C
/* Helper macros for functions returning a narrower type.
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Copyright (C) 2018-2021 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_NARROW_H
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#define _MATH_NARROW_H 1
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#include <bits/floatn.h>
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#include <bits/long-double.h>
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#include <errno.h>
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#include <fenv.h>
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#include <ieee754.h>
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#include <math-barriers.h>
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#include <math_private.h>
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#include <fenv_private.h>
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#include <math-narrow-alias.h>
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#include <stdbool.h>
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/* Carry out a computation using round-to-odd. The computation is
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EXPR; the union type in which to store the result is UNION and the
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subfield of the "ieee" field of that union with the low part of the
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mantissa is MANTISSA; SUFFIX is the suffix for both underlying libm
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functions for the argument type (for computations where a libm
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function rather than a C operator is used when argument and result
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types are the same) and the libc_fe* macros to ensure that the
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correct rounding mode is used, for platforms with multiple rounding
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modes where those macros set only the relevant mode.
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CLEAR_UNDERFLOW indicates whether underflow exceptions must be
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cleared (in the case where a round-toward-zero underflow might not
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indicate an underflow after narrowing, when that narrowing only
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reduces precision not exponent range and the architecture uses
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before-rounding tininess detection). This macro does not work
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correctly if the sign of an exact zero result depends on the
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rounding mode, so that case must be checked for separately. */
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#define ROUND_TO_ODD(EXPR, UNION, SUFFIX, MANTISSA, CLEAR_UNDERFLOW) \
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({ \
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fenv_t env; \
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UNION u; \
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\
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libc_feholdexcept_setround ## SUFFIX (&env, FE_TOWARDZERO); \
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u.d = (EXPR); \
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math_force_eval (u.d); \
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if (CLEAR_UNDERFLOW) \
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feclearexcept (FE_UNDERFLOW); \
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u.ieee.MANTISSA \
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|= libc_feupdateenv_test ## SUFFIX (&env, FE_INEXACT) != 0; \
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\
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u.d; \
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})
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/* Check for error conditions from a narrowing add function returning
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RET with arguments X and Y and set errno as needed. Overflow and
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underflow can occur for finite arguments and a domain error for
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infinite ones. */
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#define CHECK_NARROW_ADD(RET, X, Y) \
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do \
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{ \
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if (!isfinite (RET)) \
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{ \
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if (isnan (RET)) \
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{ \
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if (!isnan (X) && !isnan (Y)) \
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__set_errno (EDOM); \
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} \
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else if (isfinite (X) && isfinite (Y)) \
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__set_errno (ERANGE); \
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} \
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else if ((RET) == 0 && (X) != -(Y)) \
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__set_errno (ERANGE); \
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} \
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while (0)
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/* Implement narrowing add using round-to-odd. The arguments are X
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and Y, the return type is TYPE and UNION, MANTISSA and SUFFIX are
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as for ROUND_TO_ODD. */
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#define NARROW_ADD_ROUND_TO_ODD(X, Y, TYPE, UNION, SUFFIX, MANTISSA) \
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do \
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{ \
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TYPE ret; \
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\
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/* Ensure a zero result is computed in the original rounding \
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mode. */ \
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if ((X) == -(Y)) \
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ret = (TYPE) ((X) + (Y)); \
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else \
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ret = (TYPE) ROUND_TO_ODD (math_opt_barrier (X) + (Y), \
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UNION, SUFFIX, MANTISSA, false); \
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\
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CHECK_NARROW_ADD (ret, (X), (Y)); \
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return ret; \
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} \
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while (0)
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/* Implement a narrowing add function that is not actually narrowing
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or where no attempt is made to be correctly rounding (the latter
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only applies to IBM long double). The arguments are X and Y and
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the return type is TYPE. */
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#define NARROW_ADD_TRIVIAL(X, Y, TYPE) \
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do \
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{ \
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TYPE ret; \
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\
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ret = (TYPE) ((X) + (Y)); \
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CHECK_NARROW_ADD (ret, (X), (Y)); \
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return ret; \
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} \
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while (0)
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/* Check for error conditions from a narrowing subtract function
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returning RET with arguments X and Y and set errno as needed.
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Overflow and underflow can occur for finite arguments and a domain
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error for infinite ones. */
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#define CHECK_NARROW_SUB(RET, X, Y) \
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do \
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{ \
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if (!isfinite (RET)) \
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{ \
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if (isnan (RET)) \
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{ \
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if (!isnan (X) && !isnan (Y)) \
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__set_errno (EDOM); \
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} \
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else if (isfinite (X) && isfinite (Y)) \
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__set_errno (ERANGE); \
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} \
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else if ((RET) == 0 && (X) != (Y)) \
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__set_errno (ERANGE); \
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} \
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while (0)
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/* Implement narrowing subtract using round-to-odd. The arguments are
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X and Y, the return type is TYPE and UNION, MANTISSA and SUFFIX are
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as for ROUND_TO_ODD. */
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#define NARROW_SUB_ROUND_TO_ODD(X, Y, TYPE, UNION, SUFFIX, MANTISSA) \
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do \
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{ \
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TYPE ret; \
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\
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/* Ensure a zero result is computed in the original rounding \
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mode. */ \
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if ((X) == (Y)) \
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ret = (TYPE) ((X) - (Y)); \
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else \
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ret = (TYPE) ROUND_TO_ODD (math_opt_barrier (X) - (Y), \
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UNION, SUFFIX, MANTISSA, false); \
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\
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CHECK_NARROW_SUB (ret, (X), (Y)); \
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return ret; \
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} \
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while (0)
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/* Implement a narrowing subtract function that is not actually
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narrowing or where no attempt is made to be correctly rounding (the
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latter only applies to IBM long double). The arguments are X and Y
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and the return type is TYPE. */
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#define NARROW_SUB_TRIVIAL(X, Y, TYPE) \
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do \
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{ \
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TYPE ret; \
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\
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ret = (TYPE) ((X) - (Y)); \
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CHECK_NARROW_SUB (ret, (X), (Y)); \
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return ret; \
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} \
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while (0)
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/* Check for error conditions from a narrowing multiply function
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returning RET with arguments X and Y and set errno as needed.
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Overflow and underflow can occur for finite arguments and a domain
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error for Inf * 0. */
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#define CHECK_NARROW_MUL(RET, X, Y) \
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do \
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{ \
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if (!isfinite (RET)) \
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{ \
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if (isnan (RET)) \
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{ \
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if (!isnan (X) && !isnan (Y)) \
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__set_errno (EDOM); \
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} \
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else if (isfinite (X) && isfinite (Y)) \
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__set_errno (ERANGE); \
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} \
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else if ((RET) == 0 && (X) != 0 && (Y) != 0) \
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__set_errno (ERANGE); \
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} \
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while (0)
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/* Implement narrowing multiply using round-to-odd. The arguments are
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X and Y, the return type is TYPE and UNION, MANTISSA, SUFFIX and
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CLEAR_UNDERFLOW are as for ROUND_TO_ODD. */
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#define NARROW_MUL_ROUND_TO_ODD(X, Y, TYPE, UNION, SUFFIX, MANTISSA, \
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CLEAR_UNDERFLOW) \
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do \
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{ \
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TYPE ret; \
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\
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ret = (TYPE) ROUND_TO_ODD (math_opt_barrier (X) * (Y), \
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UNION, SUFFIX, MANTISSA, \
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CLEAR_UNDERFLOW); \
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\
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CHECK_NARROW_MUL (ret, (X), (Y)); \
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return ret; \
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} \
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while (0)
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/* Implement a narrowing multiply function that is not actually
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narrowing or where no attempt is made to be correctly rounding (the
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latter only applies to IBM long double). The arguments are X and Y
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and the return type is TYPE. */
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#define NARROW_MUL_TRIVIAL(X, Y, TYPE) \
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do \
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{ \
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TYPE ret; \
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\
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ret = (TYPE) ((X) * (Y)); \
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CHECK_NARROW_MUL (ret, (X), (Y)); \
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return ret; \
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} \
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while (0)
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/* Check for error conditions from a narrowing divide function
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returning RET with arguments X and Y and set errno as needed.
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Overflow, underflow and divide-by-zero can occur for finite
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arguments and a domain error for Inf / Inf and 0 / 0. */
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#define CHECK_NARROW_DIV(RET, X, Y) \
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do \
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{ \
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if (!isfinite (RET)) \
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{ \
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if (isnan (RET)) \
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{ \
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if (!isnan (X) && !isnan (Y)) \
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__set_errno (EDOM); \
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} \
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else if (isfinite (X)) \
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__set_errno (ERANGE); \
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} \
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else if ((RET) == 0 && (X) != 0 && !isinf (Y)) \
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__set_errno (ERANGE); \
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} \
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while (0)
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/* Implement narrowing divide using round-to-odd. The arguments are X
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and Y, the return type is TYPE and UNION, MANTISSA, SUFFIX and
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CLEAR_UNDERFLOW are as for ROUND_TO_ODD. */
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#define NARROW_DIV_ROUND_TO_ODD(X, Y, TYPE, UNION, SUFFIX, MANTISSA, \
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CLEAR_UNDERFLOW) \
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do \
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{ \
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TYPE ret; \
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\
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ret = (TYPE) ROUND_TO_ODD (math_opt_barrier (X) / (Y), \
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UNION, SUFFIX, MANTISSA, \
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CLEAR_UNDERFLOW); \
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\
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CHECK_NARROW_DIV (ret, (X), (Y)); \
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return ret; \
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} \
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while (0)
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/* Implement a narrowing divide function that is not actually
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narrowing or where no attempt is made to be correctly rounding (the
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latter only applies to IBM long double). The arguments are X and Y
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and the return type is TYPE. */
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#define NARROW_DIV_TRIVIAL(X, Y, TYPE) \
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do \
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{ \
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TYPE ret; \
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\
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ret = (TYPE) ((X) / (Y)); \
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CHECK_NARROW_DIV (ret, (X), (Y)); \
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return ret; \
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} \
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while (0)
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/* Check for error conditions from a narrowing square root function
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returning RET with argument X and set errno as needed. Overflow
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and underflow can occur for finite positive arguments and a domain
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error for negative arguments. */
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#define CHECK_NARROW_SQRT(RET, X) \
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do \
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{ \
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if (!isfinite (RET)) \
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{ \
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if (isnan (RET)) \
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{ \
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if (!isnan (X)) \
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__set_errno (EDOM); \
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} \
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else if (isfinite (X)) \
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__set_errno (ERANGE); \
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} \
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else if ((RET) == 0 && (X) != 0) \
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__set_errno (ERANGE); \
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} \
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while (0)
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/* Implement narrowing square root using round-to-odd. The argument
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is X, the return type is TYPE and UNION, MANTISSA and SUFFIX are as
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for ROUND_TO_ODD. */
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#define NARROW_SQRT_ROUND_TO_ODD(X, TYPE, UNION, SUFFIX, MANTISSA) \
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do \
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{ \
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TYPE ret; \
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\
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ret = (TYPE) ROUND_TO_ODD (sqrt ## SUFFIX (math_opt_barrier (X)), \
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UNION, SUFFIX, MANTISSA, false); \
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\
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CHECK_NARROW_SQRT (ret, (X)); \
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return ret; \
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} \
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while (0)
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/* Implement a narrowing square root function where no attempt is made
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to be correctly rounding (this only applies to IBM long double; the
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case where the function is not actually narrowing is handled by
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aliasing other sqrt functions in libm, not using this macro). The
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argument is X and the return type is TYPE. */
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#define NARROW_SQRT_TRIVIAL(X, TYPE, SUFFIX) \
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do \
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{ \
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TYPE ret; \
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\
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ret = (TYPE) (sqrt ## SUFFIX (X)); \
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CHECK_NARROW_SQRT (ret, (X)); \
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return ret; \
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} \
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while (0)
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/* Check for error conditions from a narrowing fused multiply-add
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function returning RET with arguments X, Y and Z and set errno as
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needed. Checking for error conditions for fma (either narrowing or
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not) and setting errno is not currently implemented. See bug
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6801. */
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#define CHECK_NARROW_FMA(RET, X, Y, Z) \
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do \
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{ \
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} \
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while (0)
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/* Implement narrowing fused multiply-add using round-to-odd. The
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arguments are X, Y and Z, the return type is TYPE and UNION,
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MANTISSA, SUFFIX and CLEAR_UNDERFLOW are as for ROUND_TO_ODD. */
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#define NARROW_FMA_ROUND_TO_ODD(X, Y, Z, TYPE, UNION, SUFFIX, MANTISSA, \
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CLEAR_UNDERFLOW) \
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do \
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{ \
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typeof (X) tmp; \
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TYPE ret; \
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\
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tmp = ROUND_TO_ODD (fma ## SUFFIX (math_opt_barrier (X), (Y), \
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(Z)), \
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UNION, SUFFIX, MANTISSA, CLEAR_UNDERFLOW); \
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/* If the round-to-odd result is zero, the result is an exact \
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zero and must be recomputed in the original rounding mode. */ \
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if (tmp == 0) \
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ret = (TYPE) (math_opt_barrier (X) * (Y) + (Z)); \
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else \
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ret = (TYPE) tmp; \
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\
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CHECK_NARROW_FMA (ret, (X), (Y), (Z)); \
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return ret; \
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} \
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while (0)
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/* Implement a narrowing fused multiply-add function where no attempt
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is made to be correctly rounding (this only applies to IBM long
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double; the case where the function is not actually narrowing is
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handled by aliasing other fma functions in libm, not using this
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macro). The arguments are X, Y and Z and the return type is
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TYPE. */
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#define NARROW_FMA_TRIVIAL(X, Y, Z, TYPE, SUFFIX) \
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do \
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{ \
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TYPE ret; \
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\
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ret = (TYPE) (fma ## SUFFIX ((X), (Y), (Z))); \
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CHECK_NARROW_FMA (ret, (X), (Y), (Z)); \
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return ret; \
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} \
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while (0)
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#endif /* math-narrow.h. */
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