61 lines
2.0 KiB
C
61 lines
2.0 KiB
C
/* Copyright (C) 2015-2020 Free Software Foundation, Inc.
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Contributed by Alexander Monakov <amonakov@ispras.ru>
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This file is part of the GNU Offloading and Multi Processing Library
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(libgomp).
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Libgomp 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, or (at your option)
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any later version.
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Libgomp 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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/* This is the NVPTX implementation of doacross spinning. */
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#ifndef GOMP_DOACROSS_H
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#define GOMP_DOACROSS_H 1
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#include "libgomp.h"
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static int zero;
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static inline int
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cpu_relax (void)
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{
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int r;
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/* Here we need a long-latency operation to make the current warp yield.
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We could use ld.cv, uncached load from system (host) memory, but that
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would require allocating locked memory in the plugin. Alternatively,
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we can use ld.cg, which evicts from L1 and caches in L2. */
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asm volatile ("ld.cg.s32 %0, [%1];" : "=r" (r) : "i" (&zero) : "memory");
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return r;
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}
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static inline void doacross_spin (unsigned long *addr, unsigned long expected,
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unsigned long cur)
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{
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/* Prevent compiler from optimizing based on bounds of containing object. */
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asm ("" : "+r" (addr));
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do
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{
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int i = cpu_relax ();
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cur = addr[i];
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}
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while (cur <= expected);
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}
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#endif /* GOMP_DOACROSS_H */
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