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/* Copyright (C) 2012-2024 Free Software Foundation, Inc.
Contributed by Richard Henderson <rth@redhat.com>.
This file is part of the GNU Atomic Library (libatomic).
Libatomic is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
Libatomic is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU General Public License for
more details.
Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.
You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
<http://www.gnu.org/licenses/>. */
#include "libatomic_i.h"
/* If we natively support the load, and if we're unconcerned with extra
barriers (e.g. fully in-order cpu for which barriers are a nop), then
go ahead and expand the operation inline. */
#if !defined(WANT_SPECIALCASE_RELAXED) && !defined(__OPTIMIZE_SIZE__)
# define EXACT_INLINE(N, DEST, SRC, DONE) \
if (C2(HAVE_ATOMIC_LDST_,N)) \
{ \
DEST = __atomic_load_n (SRC, __ATOMIC_SEQ_CST); \
DONE; \
}
#else
# define EXACT_INLINE(N, DEST, SRC, DONE)
#endif
#define EXACT_(N, DEST, SRC, DONE) \
do { \
EXACT_INLINE (N, DEST, SRC, DONE); \
DEST = C3(local_,load_,N) (SRC, smodel); \
DONE; \
} while (0)
#define EXACT(N) \
do { \
if (!C2(HAVE_INT,N)) break; \
if ((uintptr_t)mptr & (N - 1)) break; \
EXACT_(N, *PTR(N,rptr), PTR(N,mptr), return); \
} while (0)
#define LARGER(N) \
do { \
if (!C2(HAVE_INT,N)) break; \
r = (uintptr_t)mptr & (N - 1); \
a = (uintptr_t)mptr & -N; \
if (r + n <= N) \
EXACT_ (N, u.C2(i,N), PTR(N,a), goto Lfinish); \
} while (0)
void
libat_load (size_t n, void *mptr, void *rptr, int smodel)
{
union max_size_u u;
uintptr_t r, a;
switch (n)
{
case 0: return;
case 1: EXACT(1); goto L4;
case 2: EXACT(2); goto L4;
case 4: EXACT(4); goto L8;
case 8: EXACT(8); goto L16;
case 16: EXACT(16); break;
case 3: L4: LARGER(4); /* FALLTHRU */
case 5 ... 7: L8: LARGER(8); /* FALLTHRU */
case 9 ... 15: L16: LARGER(16); break;
Lfinish:
memcpy (rptr, u.b + r, n);
return;
}
pre_seq_barrier (smodel);
libat_lock_n (mptr, n);
memcpy (rptr, mptr, n);
libat_unlock_n (mptr, n);
post_seq_barrier (smodel);
}
EXPORT_ALIAS (load);
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