1 /*
2 * Copyright © 2007 Chris Wilson
3 * Copyright © 2009,2010 Red Hat, Inc.
4 * Copyright © 2011,2012 Google, Inc.
5 *
6 * This is part of HarfBuzz, a text shaping library.
7 *
8 * Permission is hereby granted, without written agreement and without
9 * license or royalty fees, to use, copy, modify, and distribute this
10 * software and its documentation for any purpose, provided that the
11 * above copyright notice and the following two paragraphs appear in
12 * all copies of this software.
13 *
14 * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
15 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
16 * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
17 * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
18 * DAMAGE.
19 *
20 * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
21 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
22 * FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
23 * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
24 * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
25 *
26 * Contributor(s):
27 * Chris Wilson <chris@chris-wilson.co.uk>
28 * Red Hat Author(s): Behdad Esfahbod
29 * Google Author(s): Behdad Esfahbod
30 */
31
32 #ifndef HB_ATOMIC_HH
33 #define HB_ATOMIC_HH
34
35 #include "hb.hh"
36 #include "hb-meta.hh"
37
38
39 /*
40 * Atomic integers and pointers.
41 */
42
43
44 /* We need external help for these */
45
46 #if defined(hb_atomic_int_impl_add) \
47 && defined(hb_atomic_ptr_impl_get) \
48 && defined(hb_atomic_ptr_impl_cmpexch)
49
50 /* Defined externally, i.e. in config.h. */
51
52
53 #elif !defined(HB_NO_MT) && defined(__ATOMIC_ACQUIRE)
54
55 /* C++11-style GCC primitives. We prefer these as they don't require linking to libstdc++ / libc++. */
56
57 #define _hb_memory_barrier() __sync_synchronize ()
58
59 #define hb_atomic_int_impl_add(AI, V) __atomic_fetch_add ((AI), (V), __ATOMIC_ACQ_REL)
60 #define hb_atomic_int_impl_set_relaxed(AI, V) __atomic_store_n ((AI), (V), __ATOMIC_RELAXED)
61 #define hb_atomic_int_impl_set(AI, V) __atomic_store_n ((AI), (V), __ATOMIC_RELEASE)
62 #define hb_atomic_int_impl_get_relaxed(AI) __atomic_load_n ((AI), __ATOMIC_RELAXED)
63 #define hb_atomic_int_impl_get(AI) __atomic_load_n ((AI), __ATOMIC_ACQUIRE)
64
65 #define hb_atomic_ptr_impl_set_relaxed(P, V) __atomic_store_n ((P), (V), __ATOMIC_RELAXED)
66 #define hb_atomic_ptr_impl_get_relaxed(P) __atomic_load_n ((P), __ATOMIC_RELAXED)
67 #define hb_atomic_ptr_impl_get(P) __atomic_load_n ((P), __ATOMIC_ACQUIRE)
68 static inline bool
_hb_atomic_ptr_impl_cmplexch(const void ** P,const void * O_,const void * N)69 _hb_atomic_ptr_impl_cmplexch (const void **P, const void *O_, const void *N)
70 {
71 const void *O = O_; // Need lvalue
72 return __atomic_compare_exchange_n ((void **) P, (void **) &O, (void *) N, true, __ATOMIC_ACQ_REL, __ATOMIC_RELAXED);
73 }
74 #define hb_atomic_ptr_impl_cmpexch(P,O,N) _hb_atomic_ptr_impl_cmplexch ((const void **) (P), (O), (N))
75
76
77 #elif !defined(HB_NO_MT)
78
79 /* C++11 atomics. */
80
81 #include <atomic>
82
83 #define _hb_memory_barrier() std::atomic_thread_fence(std::memory_order_ack_rel)
84 #define _hb_memory_r_barrier() std::atomic_thread_fence(std::memory_order_acquire)
85 #define _hb_memory_w_barrier() std::atomic_thread_fence(std::memory_order_release)
86
87 #define hb_atomic_int_impl_add(AI, V) (reinterpret_cast<std::atomic<int> *> (AI)->fetch_add ((V), std::memory_order_acq_rel))
88 #define hb_atomic_int_impl_set_relaxed(AI, V) (reinterpret_cast<std::atomic<int> *> (AI)->store ((V), std::memory_order_relaxed))
89 #define hb_atomic_int_impl_set(AI, V) (reinterpret_cast<std::atomic<int> *> (AI)->store ((V), std::memory_order_release))
90 #define hb_atomic_int_impl_get_relaxed(AI) (reinterpret_cast<std::atomic<int> const *> (AI)->load (std::memory_order_relaxed))
91 #define hb_atomic_int_impl_get(AI) (reinterpret_cast<std::atomic<int> const *> (AI)->load (std::memory_order_acquire))
92
93 #define hb_atomic_ptr_impl_set_relaxed(P, V) (reinterpret_cast<std::atomic<void*> *> (P)->store ((V), std::memory_order_relaxed))
94 #define hb_atomic_ptr_impl_get_relaxed(P) (reinterpret_cast<std::atomic<void*> const *> (P)->load (std::memory_order_relaxed))
95 #define hb_atomic_ptr_impl_get(P) (reinterpret_cast<std::atomic<void*> *> (P)->load (std::memory_order_acquire))
96 static inline bool
_hb_atomic_ptr_impl_cmplexch(const void ** P,const void * O_,const void * N)97 _hb_atomic_ptr_impl_cmplexch (const void **P, const void *O_, const void *N)
98 {
99 const void *O = O_; // Need lvalue
100 return reinterpret_cast<std::atomic<const void*> *> (P)->compare_exchange_weak (O, N, std::memory_order_acq_rel, std::memory_order_relaxed);
101 }
102 #define hb_atomic_ptr_impl_cmpexch(P,O,N) _hb_atomic_ptr_impl_cmplexch ((const void **) (P), (O), (N))
103
104
105 #else /* defined(HB_NO_MT) */
106
107 #define hb_atomic_int_impl_add(AI, V) ((*(AI) += (V)) - (V))
108 #define _hb_memory_barrier() do {} while (0)
109 #define hb_atomic_ptr_impl_cmpexch(P,O,N) (* (void **) (P) == (void *) (O) ? (* (void **) (P) = (void *) (N), true) : false)
110
111 #endif
112
113
114 #ifndef _hb_memory_r_barrier
115 #define _hb_memory_r_barrier() _hb_memory_barrier ()
116 #endif
117 #ifndef _hb_memory_w_barrier
118 #define _hb_memory_w_barrier() _hb_memory_barrier ()
119 #endif
120 #ifndef hb_atomic_int_impl_set_relaxed
121 #define hb_atomic_int_impl_set_relaxed(AI, V) (*(AI) = (V))
122 #endif
123 #ifndef hb_atomic_int_impl_get_relaxed
124 #define hb_atomic_int_impl_get_relaxed(AI) (*(AI))
125 #endif
126
127 #ifndef hb_atomic_ptr_impl_set_relaxed
128 #define hb_atomic_ptr_impl_set_relaxed(P, V) (*(P) = (V))
129 #endif
130 #ifndef hb_atomic_ptr_impl_get_relaxed
131 #define hb_atomic_ptr_impl_get_relaxed(P) (*(P))
132 #endif
133 #ifndef hb_atomic_int_impl_set
hb_atomic_int_impl_set(int * AI,int v)134 inline void hb_atomic_int_impl_set (int *AI, int v) { _hb_memory_w_barrier (); *AI = v; }
135 #endif
136 #ifndef hb_atomic_int_impl_get
hb_atomic_int_impl_get(const int * AI)137 inline int hb_atomic_int_impl_get (const int *AI) { int v = *AI; _hb_memory_r_barrier (); return v; }
138 #endif
139 #ifndef hb_atomic_ptr_impl_get
hb_atomic_ptr_impl_get(void ** const P)140 inline void *hb_atomic_ptr_impl_get (void ** const P) { void *v = *P; _hb_memory_r_barrier (); return v; }
141 #endif
142
143
144 struct hb_atomic_int_t
145 {
146 hb_atomic_int_t () = default;
hb_atomic_int_thb_atomic_int_t147 constexpr hb_atomic_int_t (int v) : v (v) {}
148
set_relaxedhb_atomic_int_t149 void set_relaxed (int v_) { hb_atomic_int_impl_set_relaxed (&v, v_); }
sethb_atomic_int_t150 void set (int v_) { hb_atomic_int_impl_set (&v, v_); }
get_relaxedhb_atomic_int_t151 int get_relaxed () const { return hb_atomic_int_impl_get_relaxed (&v); }
gethb_atomic_int_t152 int get () const { return hb_atomic_int_impl_get (&v); }
inchb_atomic_int_t153 int inc () { return hb_atomic_int_impl_add (&v, 1); }
dechb_atomic_int_t154 int dec () { return hb_atomic_int_impl_add (&v, -1); }
155
156 int v = 0;
157 };
158
159 template <typename P>
160 struct hb_atomic_ptr_t
161 {
162 typedef hb_remove_pointer<P> T;
163
164 hb_atomic_ptr_t () = default;
hb_atomic_ptr_thb_atomic_ptr_t165 constexpr hb_atomic_ptr_t (T* v) : v (v) {}
166
inithb_atomic_ptr_t167 void init (T* v_ = nullptr) { set_relaxed (v_); }
set_relaxedhb_atomic_ptr_t168 void set_relaxed (T* v_) { hb_atomic_ptr_impl_set_relaxed (&v, v_); }
get_relaxedhb_atomic_ptr_t169 T *get_relaxed () const { return (T *) hb_atomic_ptr_impl_get_relaxed (&v); }
gethb_atomic_ptr_t170 T *get () const { return (T *) hb_atomic_ptr_impl_get ((void **) &v); }
cmpexchhb_atomic_ptr_t171 bool cmpexch (const T *old, T *new_) const { return hb_atomic_ptr_impl_cmpexch ((void **) &v, (void *) old, (void *) new_); }
172
operator ->hb_atomic_ptr_t173 T * operator -> () const { return get (); }
operator C*hb_atomic_ptr_t174 template <typename C> operator C * () const { return get (); }
175
176 T *v = nullptr;
177 };
178
179
180 #endif /* HB_ATOMIC_HH */
181