/* Copyright (C) 2012-2019 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> /* This file is included multiple times with required defines: NAME the name of the operation that we're implementing; OP a two-operand functional macro the implements the operation. */ /* If we support the builtin, just use it. */ #if !DONE && SIZE(HAVE_ATOMIC_FETCH_OP) UTYPE SIZE(C2(libat_fetch_,NAME)) (UTYPE *mptr, UTYPE opval, int smodel) { if (maybe_specialcase_relaxed(smodel)) return C2(__atomic_fetch_,NAME) (mptr, opval, __ATOMIC_RELAXED); else if (maybe_specialcase_acqrel(smodel)) return C2(__atomic_fetch_,NAME) (mptr, opval, __ATOMIC_ACQ_REL); else return C2(__atomic_fetch_,NAME) (mptr, opval, __ATOMIC_SEQ_CST); } UTYPE SIZE(C3(libat_,NAME,_fetch)) (UTYPE *mptr, UTYPE opval, int smodel) { if (maybe_specialcase_relaxed(smodel)) return C3(__atomic_,NAME,_fetch) (mptr, opval, __ATOMIC_RELAXED); else if (maybe_specialcase_acqrel(smodel)) return C3(__atomic_,NAME,_fetch) (mptr, opval, __ATOMIC_ACQ_REL); else return C3(__atomic_,NAME,_fetch) (mptr, opval, __ATOMIC_SEQ_CST); } #define DONE 1 #endif /* HAVE_ATOMIC_FETCH_OP */ #if !DONE && defined(atomic_compare_exchange_n) UTYPE SIZE(C2(libat_fetch_,NAME)) (UTYPE *mptr, UTYPE opval, int smodel) { UTYPE oldval, t; pre_barrier (smodel); oldval = *mptr; do { t = OP(oldval, opval); } while (!atomic_compare_exchange_n (mptr, &oldval, t, true, __ATOMIC_RELAXED, __ATOMIC_RELAXED)); post_barrier (smodel); return oldval; } UTYPE SIZE(C3(libat_,NAME,_fetch)) (UTYPE *mptr, UTYPE opval, int smodel) { UTYPE oldval, t; pre_barrier (smodel); oldval = *mptr; do { t = OP(oldval, opval); } while (!atomic_compare_exchange_n (mptr, &oldval, t, true, __ATOMIC_RELAXED, __ATOMIC_RELAXED)); post_barrier (smodel); return t; } #define DONE 1 #endif /* atomic_compare_exchange_n */ /* If this type is no larger than word-sized, fall back to a word-sized compare-and-swap loop. */ #if !DONE && N < WORDSIZE && defined(atomic_compare_exchange_w) UTYPE SIZE(C2(libat_fetch_,NAME)) (UTYPE *mptr, UTYPE opval, int smodel) { UWORD mask, shift, woldval, wopval, t, *wptr; pre_barrier (smodel); wptr = (UWORD *)((uintptr_t)mptr & -WORDSIZE); shift = (((uintptr_t)mptr % WORDSIZE) * CHAR_BIT) ^ SIZE(INVERT_MASK); mask = SIZE(MASK) << shift; wopval = (UWORD)opval << shift; woldval = __atomic_load_n (wptr, __ATOMIC_RELAXED); do { t = (woldval & ~mask) | (OP(woldval, wopval) & mask); } while (!atomic_compare_exchange_w (wptr, &woldval, t, true, __ATOMIC_RELAXED, __ATOMIC_RELAXED)); post_barrier (smodel); return woldval >> shift; } UTYPE SIZE(C3(libat_,NAME,_fetch)) (UTYPE *mptr, UTYPE opval, int smodel) { UWORD mask, shift, woldval, wopval, t, *wptr; pre_barrier (smodel); wptr = (UWORD *)((uintptr_t)mptr & -WORDSIZE); shift = (((uintptr_t)mptr % WORDSIZE) * CHAR_BIT) ^ SIZE(INVERT_MASK); mask = SIZE(MASK) << shift; wopval = (UWORD)opval << shift; woldval = __atomic_load_n (wptr, __ATOMIC_RELAXED); do { t = (woldval & ~mask) | (OP(woldval, wopval) & mask); } while (!atomic_compare_exchange_w (wptr, &woldval, t, true, __ATOMIC_RELAXED, __ATOMIC_RELAXED)); post_barrier (smodel); return t >> shift; } #define DONE 1 #endif /* atomic_compare_exchange_w */ /* Otherwise, fall back to some sort of protection mechanism. */ #if !DONE UTYPE SIZE(C2(libat_fetch_,NAME)) (UTYPE *mptr, UTYPE opval, int smodel UNUSED) { UTYPE ret; UWORD magic; pre_seq_barrier (smodel); magic = protect_start (mptr); ret = *mptr; *mptr = OP(ret, opval); protect_end (mptr, magic); post_seq_barrier (smodel); return ret; } UTYPE SIZE(C3(libat_,NAME,_fetch)) (UTYPE *mptr, UTYPE opval, int smodel UNUSED) { UTYPE ret; UWORD magic; pre_seq_barrier (smodel); magic = protect_start (mptr); ret = OP (*mptr, opval); *mptr = ret; protect_end (mptr, magic); post_seq_barrier (smodel); return ret; } #endif EXPORT_ALIAS (SIZE(C2(fetch_,NAME))); EXPORT_ALIAS (SIZE(C2(NAME,_fetch)));