1/* Copyright (C) 2012-2015 Free Software Foundation, Inc. 2 Contributed by Richard Henderson <rth@redhat.com>. 3 4 This file is part of the GNU Atomic Library (libatomic). 5 6 Libatomic is free software; you can redistribute it and/or modify it 7 under the terms of the GNU General Public License as published by 8 the Free Software Foundation; either version 3 of the License, or 9 (at your option) any later version. 10 11 Libatomic is distributed in the hope that it will be useful, but WITHOUT ANY 12 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS 13 FOR A PARTICULAR PURPOSE. See the GNU General Public License for 14 more details. 15 16 Under Section 7 of GPL version 3, you are granted additional 17 permissions described in the GCC Runtime Library Exception, version 18 3.1, as published by the Free Software Foundation. 19 20 You should have received a copy of the GNU General Public License and 21 a copy of the GCC Runtime Library Exception along with this program; 22 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 23 <http://www.gnu.org/licenses/>. */ 24 25#include "libatomic_i.h" 26 27 28/* If we natively support the load, and if we're unconcerned with extra 29 barriers (e.g. fully in-order cpu for which barriers are a nop), then 30 go ahead and expand the operation inline. */ 31#if !defined(WANT_SPECIALCASE_RELAXED) && !defined(__OPTIMIZE_SIZE__) 32# define EXACT_INLINE(N, DEST, SRC, DONE) \ 33 if (C2(HAVE_ATOMIC_LDST_,N)) \ 34 { \ 35 DEST = __atomic_load_n (SRC, __ATOMIC_SEQ_CST); \ 36 DONE; \ 37 } 38#else 39# define EXACT_INLINE(N, DEST, SRC, DONE) 40#endif 41 42 43#define EXACT_(N, DEST, SRC, DONE) \ 44 do { \ 45 EXACT_INLINE (N, DEST, SRC, DONE); \ 46 DEST = C3(local_,load_,N) (SRC, smodel); \ 47 DONE; \ 48 } while (0) 49 50#define EXACT(N) \ 51 do { \ 52 if (!C2(HAVE_INT,N)) break; \ 53 if ((uintptr_t)mptr & (N - 1)) break; \ 54 EXACT_(N, *PTR(N,rptr), PTR(N,mptr), return); \ 55 } while (0) 56 57#define LARGER(N) \ 58 do { \ 59 if (!C2(HAVE_INT,N)) break; \ 60 r = (uintptr_t)mptr & (N - 1); \ 61 a = (uintptr_t)mptr & -N; \ 62 if (r + n <= N) \ 63 EXACT_ (N, u.C2(i,N), PTR(N,a), goto Lfinish); \ 64 } while (0) 65 66 67void 68libat_load (size_t n, void *mptr, void *rptr, int smodel) 69{ 70 union max_size_u u; 71 uintptr_t r, a; 72 73 switch (n) 74 { 75 case 0: return; 76 case 1: EXACT(1); goto L4; 77 case 2: EXACT(2); goto L4; 78 case 4: EXACT(4); goto L8; 79 case 8: EXACT(8); goto L16; 80 case 16: EXACT(16); break; 81 82 case 3: L4: LARGER(4); /* FALLTHRU */ 83 case 5 ... 7: L8: LARGER(8); /* FALLTHRU */ 84 case 9 ... 15: L16: LARGER(16); break; 85 86 Lfinish: 87 memcpy (rptr, u.b + r, n); 88 return; 89 } 90 91 pre_seq_barrier (smodel); 92 libat_lock_n (mptr, n); 93 94 memcpy (rptr, mptr, n); 95 96 libat_unlock_n (mptr, n); 97 post_seq_barrier (smodel); 98} 99 100EXPORT_ALIAS (load); 101