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author | rth <rth@138bc75d-0d04-0410-961f-82ee72b054a4> | 2012-05-01 15:48:28 +0000 |
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committer | rth <rth@138bc75d-0d04-0410-961f-82ee72b054a4> | 2012-05-01 15:48:28 +0000 |
commit | 6db1d2ca83f9327020b75f6c1610649bb18e71db (patch) | |
tree | 729dc91fa97f38042aa7777ca6267ebed2edb3e8 /libatomic/cas_n.c | |
parent | d8219307493056ea48203be157f0cfb468698f2d (diff) | |
download | ppe42-gcc-6db1d2ca83f9327020b75f6c1610649bb18e71db.tar.gz ppe42-gcc-6db1d2ca83f9327020b75f6c1610649bb18e71db.zip |
Add libatomic as a target library.
git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@187018 138bc75d-0d04-0410-961f-82ee72b054a4
Diffstat (limited to 'libatomic/cas_n.c')
-rw-r--r-- | libatomic/cas_n.c | 125 |
1 files changed, 125 insertions, 0 deletions
diff --git a/libatomic/cas_n.c b/libatomic/cas_n.c new file mode 100644 index 00000000000..8463c73b9b4 --- /dev/null +++ b/libatomic/cas_n.c @@ -0,0 +1,125 @@ +/* Copyright (C) 2012 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 support the builtin, just use it. */ +#if !DONE && defined(atomic_compare_exchange_n) +bool +SIZE(libat_compare_exchange) (UTYPE *mptr, UTYPE *eptr, UTYPE newval, + int smodel, int fmodel UNUSED) +{ + if (maybe_specialcase_relaxed(smodel)) + return atomic_compare_exchange_n (mptr, eptr, newval, false, + __ATOMIC_RELAXED, __ATOMIC_RELAXED); + else if (maybe_specialcase_acqrel(smodel)) + return atomic_compare_exchange_n (mptr, eptr, newval, false, + __ATOMIC_ACQ_REL, __ATOMIC_RELAXED); + else + return atomic_compare_exchange_n (mptr, eptr, newval, false, + __ATOMIC_SEQ_CST, __ATOMIC_RELAXED); +} + +#define DONE 1 +#endif /* HAVE_ATOMIC_CAS */ + + +/* If this type is not larger than word-sized, fall back to a word-sized + compare-and-swap loop, possibly assisted by the OS. */ +#if !DONE && N <= WORDSIZE && defined(atomic_compare_exchange_w) +bool +SIZE(libat_compare_exchange) (UTYPE *mptr, UTYPE *eptr, UTYPE newval, + int smodel, int fmodel UNUSED) +{ + UWORD mask, shift, weval, woldval, wnewval, t, *wptr; + bool ret = false; + + pre_barrier (smodel); + + if (N < WORDSIZE) + { + wptr = (UWORD *)((uintptr_t)mptr & -WORDSIZE); + shift = (((uintptr_t)mptr % WORDSIZE) * CHAR_BIT) ^ SIZE(INVERT_MASK); + mask = SIZE(MASK) << shift; + } + else + { + wptr = (UWORD *)mptr; + shift = 0; + mask = -1; + } + + weval = *eptr << shift; + wnewval = (UWORD)newval << shift; + woldval = __atomic_load_n (wptr, __ATOMIC_RELAXED); + do + { + if ((woldval & mask) != weval) + goto failure; + t = (woldval & ~mask) | wnewval; + } + while (!atomic_compare_exchange_w (wptr, &woldval, t, true, + __ATOMIC_RELAXED, __ATOMIC_RELAXED)); + ret = true; + failure: + *eptr = woldval >> shift; + + post_barrier (smodel); + return ret; +} + +#define DONE 1 +#endif /* HAVE_ATOMIC_CAS && N <= WORDSIZE */ + + +/* Otherwise, fall back to some sort of protection mechanism. */ +#if !DONE +bool +SIZE(libat_compare_exchange) (UTYPE *mptr, UTYPE *eptr, UTYPE newval, + int smodel, int fmodel UNUSED) +{ + UTYPE oldval; + UWORD magic; + bool ret = false; + + pre_seq_barrier (smodel); + magic = protect_start (mptr); + + oldval = *mptr; + if (oldval == *eptr) + { + *mptr = newval; + ret = true; + } + *eptr = oldval; + + protect_end (mptr, magic); + post_seq_barrier (smodel); + + return ret; +} +#endif + +EXPORT_ALIAS (SIZE(compare_exchange)); |