| /* Copyright (C) 2012-2018 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); |