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In order to facilitate the fine-tuning of how `libatomic_i.h' and `host-config.h' headers are used by different atomic functions, we define distinct identifier macros for each file which, in implementing atomic operations, imports these headers. The idea is that different parts of these headers could then be conditionally defined depending on the macros set by the file that `#include'd them. Given how it is possible that some file names are generic enough that using them as-is for macro names (e.g. flag.c -> FLAG) may potentially lead to name clashes with other macros, all file names first have LAT_ prepended to them such that, for example, flag.c is assigned the LAT_FLAG macro. Libatomic/ChangeLog: * cas_n.c (LAT_CAS_N): New. * exch_n.c (LAT_EXCH_N): Likewise. * fadd_n.c (LAT_FADD_N): Likewise. * fand_n.c (LAT_FAND_N): Likewise. * fence.c (LAT_FENCE): Likewise. * fenv.c (LAT_FENV): Likewise. * fior_n.c (LAT_FIOR_N): Likewise. * flag.c (LAT_FLAG): Likewise. * fnand_n.c (LAT_FNAND_N): Likewise. * fop_n.c (LAT_FOP_N): Likewise * fsub_n.c (LAT_FSUB_N): Likewise. * fxor_n.c (LAT_FXOR_N): Likewise. * gcas.c (LAT_GCAS): Likewise. * gexch.c (LAT_GEXCH): Likewise. * glfree.c (LAT_GLFREE): Likewise. * gload.c (LAT_GLOAD): Likewise. * gstore.c (LAT_GSTORE): Likewise. * load_n.c (LAT_LOAD_N): Likewise. * store_n.c (LAT_STORE_N): Likewise. * tas_n.c (LAT_TAS_N): Likewise.
118 lines
3.2 KiB
C
118 lines
3.2 KiB
C
/* Copyright (C) 2012-2024 Free Software Foundation, Inc.
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Contributed by Richard Henderson <rth@redhat.com>.
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This file is part of the GNU Atomic Library (libatomic).
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Libatomic is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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Libatomic is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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more details.
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Under Section 7 of GPL version 3, you are granted additional
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permissions described in the GCC Runtime Library Exception, version
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3.1, as published by the Free Software Foundation.
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You should have received a copy of the GNU General Public License and
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a copy of the GCC Runtime Library Exception along with this program;
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see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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<http://www.gnu.org/licenses/>. */
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#define LAT_LOAD_N
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#include "libatomic_i.h"
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/* If we support the builtin, just use it. */
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#if !DONE && SIZE(HAVE_ATOMIC_LDST)
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UTYPE
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SIZE(libat_load) (UTYPE *mptr, int smodel)
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{
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if (maybe_specialcase_relaxed(smodel))
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return __atomic_load_n (mptr, __ATOMIC_RELAXED);
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else if (maybe_specialcase_acqrel(smodel))
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/* Note that REL and ACQ_REL are not valid for loads. */
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return __atomic_load_n (mptr, __ATOMIC_ACQUIRE);
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else
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return __atomic_load_n (mptr, __ATOMIC_SEQ_CST);
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}
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#define DONE 1
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#endif /* HAVE_ATOMIC_LOAD */
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/* If we have compare-and-swap, use it to swap 0 with 0 and as a side
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effect load the original value. */
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#if !DONE && defined(atomic_compare_exchange_n)
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UTYPE
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SIZE(libat_load) (UTYPE *mptr, int smodel)
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{
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UTYPE t = 0;
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if (maybe_specialcase_relaxed(smodel))
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atomic_compare_exchange_n (mptr, &t, 0, true,
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__ATOMIC_RELAXED, __ATOMIC_RELAXED);
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else if (maybe_specialcase_acqrel(smodel))
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atomic_compare_exchange_n (mptr, &t, 0, true,
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__ATOMIC_ACQ_REL, __ATOMIC_ACQ_REL);
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else
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atomic_compare_exchange_n (mptr, &t, 0, true,
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__ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST);
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return t;
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}
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#define DONE 1
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#endif /* atomic_compare_exchange_n */
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/* Similar, but only assume a word-sized compare-and-swap. */
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#if !DONE && N < WORDSIZE && defined(atomic_compare_exchange_w)
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UTYPE
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SIZE(libat_load) (UTYPE *mptr, int smodel)
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{
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UWORD shift, t, *wptr;
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pre_barrier (smodel);
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wptr = (UWORD *)((uintptr_t)mptr & -WORDSIZE);
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shift = (((uintptr_t)mptr % WORDSIZE) * CHAR_BIT) ^ SIZE(INVERT_MASK);
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/* Exchange 0 with 0, placing the old value of *WPTR in T. */
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t = 0;
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atomic_compare_exchange_w (wptr, &t, 0);
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post_barrier (smodel);
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return t >> shift;
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}
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#define DONE 1
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#endif /* HAVE_ATOMIC_CAS && N < WORDSIZE */
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/* Otherwise, fall back to some sort of protection mechanism. */
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#if !DONE
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UTYPE
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SIZE(libat_load) (UTYPE *mptr, int smodel)
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{
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UTYPE ret;
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UWORD magic;
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pre_seq_barrier (smodel);
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magic = protect_start (mptr);
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ret = *mptr;
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protect_end (mptr, magic);
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post_seq_barrier (smodel);
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return ret;
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}
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#endif
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EXPORT_ALIAS (SIZE(load));
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#undef LAT_LOAD_N
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