4b6574a6f6
include/math.h has a mechanism to redirect internal calls to various libm functions, that can often be inlined by the compiler, to call non-exported __* names for those functions in the case when the calls aren't inlined, with the redirection being disabled when NO_MATH_REDIRECT. Add fma to the functions to which this mechanism is applied. At present, libm-internal fma calls (generally to __builtin_fma* functions) are only done when it's known the call will be inlined, with alternative code not relying on an fma operation being used in the caller otherwise. This patch is in preparation for adding the TS 18661 / C2X narrowing fma functions to glibc; it will be natural for the narrowing function implementations to call the underlying fma functions unconditionally, with this either being inlined or resulting in an __fma* call. (Using two levels of round-to-odd computation like that, in the case where there isn't an fma hardware instruction, isn't optimal but is certainly a lot simpler for the initial implementation than writing different narrowing fma implementations for all the various pairs of formats.) Tested with build-many-glibcs.py that installed stripped shared libraries are unchanged by the patch (using <https://sourceware.org/pipermail/libc-alpha/2021-September/130991.html> to fix installed library stripping in build-many-glibcs.py). Also tested for x86_64.
68 lines
2.3 KiB
C
68 lines
2.3 KiB
C
/* Implement fmal using soft-fp.
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Copyright (C) 2013-2021 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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In addition to the permissions in the GNU Lesser General Public
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License, the Free Software Foundation gives you unlimited
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permission to link the compiled version of this file into
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combinations with other programs, and to distribute those
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combinations without any restriction coming from the use of this
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file. (The Lesser General Public License restrictions do apply in
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other respects; for example, they cover modification of the file,
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and distribution when not linked into a combine executable.)
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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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#define NO_MATH_REDIRECT
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#include <math.h>
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#include <libc-diag.h>
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#include <libm-alias-ldouble.h>
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/* R_e is not set in cases where it is not used in packing, but the
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compiler does not see that it is set in all cases where it is
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used, resulting in warnings that it may be used uninitialized.
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The location of the warning differs in different versions of GCC,
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it may be where R is defined using a macro or it may be where the
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macro is defined. */
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DIAG_PUSH_NEEDS_COMMENT;
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DIAG_IGNORE_NEEDS_COMMENT (4.9, "-Wmaybe-uninitialized");
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#include "soft-fp.h"
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#include "quad.h"
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long double
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__fmal (long double a, long double b, long double c)
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{
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FP_DECL_EX;
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FP_DECL_Q (A);
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FP_DECL_Q (B);
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FP_DECL_Q (C);
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FP_DECL_Q (R);
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long double r;
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FP_INIT_ROUNDMODE;
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FP_UNPACK_Q (A, a);
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FP_UNPACK_Q (B, b);
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FP_UNPACK_Q (C, c);
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FP_FMA_Q (R, A, B, C);
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FP_PACK_Q (r, R);
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FP_HANDLE_EXCEPTIONS;
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return r;
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}
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DIAG_POP_NEEDS_COMMENT;
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libm_alias_ldouble (__fma, fma)
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