176 lines
4.7 KiB
C
176 lines
4.7 KiB
C
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/* Copyright (C) 2005-2022 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 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 a Linux specific implementation of the public OpenMP locking
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primitives. This implementation uses atomic instructions and the futex
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syscall. */
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#include <string.h>
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#include <unistd.h>
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#include <sys/syscall.h>
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#include "wait.h"
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/* Reuse the generic implementation in terms of gomp_mutex_t. */
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#include "../../lock.c"
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#ifdef LIBGOMP_GNU_SYMBOL_VERSIONING
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/* gomp_mutex_* can be safely locked in one thread and
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unlocked in another thread, so the OpenMP 2.5 and OpenMP 3.0
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non-nested locks can be the same. */
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strong_alias (gomp_init_lock_30, gomp_init_lock_25)
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strong_alias (gomp_destroy_lock_30, gomp_destroy_lock_25)
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strong_alias (gomp_set_lock_30, gomp_set_lock_25)
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strong_alias (gomp_unset_lock_30, gomp_unset_lock_25)
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strong_alias (gomp_test_lock_30, gomp_test_lock_25)
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/* The external recursive omp_nest_lock_25_t form requires additional work. */
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/* We need an integer to uniquely identify this thread. Most generally
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this is the thread's TID, which ideally we'd get this straight from
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the TLS block where glibc keeps it. Unfortunately, we can't get at
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that directly.
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If we don't support (or have disabled) TLS, one function call is as
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good (or bad) as any other. Use the syscall all the time.
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On an ILP32 system (defined here as not LP64), we can make do with
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any thread-local pointer. Ideally we'd use the TLS base address,
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since that requires the least amount of arithmetic, but that's not
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always available directly. Make do with the gomp_thread pointer
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since it's handy. */
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# if !defined (HAVE_TLS)
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static inline int gomp_tid (void)
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{
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return syscall (SYS_gettid);
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}
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# elif !defined(__LP64__)
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static inline int gomp_tid (void)
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{
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return (int) gomp_thread ();
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}
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# else
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static __thread int tid_cache;
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static inline int gomp_tid (void)
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{
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int tid = tid_cache;
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if (__builtin_expect (tid == 0, 0))
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tid_cache = tid = syscall (SYS_gettid);
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return tid;
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}
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# endif
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void
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gomp_init_nest_lock_25 (omp_nest_lock_25_t *lock)
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{
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memset (lock, 0, sizeof (*lock));
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}
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void
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gomp_destroy_nest_lock_25 (omp_nest_lock_25_t *lock)
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{
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}
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void
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gomp_set_nest_lock_25 (omp_nest_lock_25_t *lock)
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{
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int otid, tid = gomp_tid ();
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while (1)
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{
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otid = 0;
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if (__atomic_compare_exchange_n (&lock->owner, &otid, tid, false,
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MEMMODEL_ACQUIRE, MEMMODEL_RELAXED))
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{
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lock->count = 1;
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return;
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}
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if (otid == tid)
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{
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lock->count++;
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return;
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}
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do_wait (&lock->owner, otid);
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}
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}
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void
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gomp_unset_nest_lock_25 (omp_nest_lock_25_t *lock)
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{
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/* ??? Validate that we own the lock here. */
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if (--lock->count == 0)
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{
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__atomic_store_n (&lock->owner, 0, MEMMODEL_RELEASE);
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futex_wake (&lock->owner, 1);
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}
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}
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int
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gomp_test_nest_lock_25 (omp_nest_lock_25_t *lock)
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{
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int otid, tid = gomp_tid ();
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otid = 0;
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if (__atomic_compare_exchange_n (&lock->owner, &otid, tid, false,
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MEMMODEL_ACQUIRE, MEMMODEL_RELAXED))
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{
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lock->count = 1;
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return 1;
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}
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if (otid == tid)
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return ++lock->count;
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return 0;
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}
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omp_lock_symver (omp_init_lock)
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omp_lock_symver (omp_destroy_lock)
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omp_lock_symver (omp_set_lock)
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omp_lock_symver (omp_unset_lock)
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omp_lock_symver (omp_test_lock)
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omp_lock_symver (omp_init_nest_lock)
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omp_lock_symver (omp_destroy_nest_lock)
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omp_lock_symver (omp_set_nest_lock)
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omp_lock_symver (omp_unset_nest_lock)
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omp_lock_symver (omp_test_nest_lock)
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#else
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ialias (omp_init_lock)
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ialias (omp_init_nest_lock)
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ialias (omp_destroy_lock)
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ialias (omp_destroy_nest_lock)
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ialias (omp_set_lock)
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ialias (omp_set_nest_lock)
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ialias (omp_unset_lock)
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ialias (omp_unset_nest_lock)
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ialias (omp_test_lock)
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ialias (omp_test_nest_lock)
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#endif
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