initial commit, 4.5 stable

thirdparty/harfbuzz/src/hb-atomic.hh

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+/*
+ * Copyright © 2007  Chris Wilson
+ * Copyright © 2009,2010  Red Hat, Inc.
+ * Copyright © 2011,2012  Google, Inc.
+ *
+ *  This is part of HarfBuzz, a text shaping library.
+ *
+ * Permission is hereby granted, without written agreement and without
+ * license or royalty fees, to use, copy, modify, and distribute this
+ * software and its documentation for any purpose, provided that the
+ * above copyright notice and the following two paragraphs appear in
+ * all copies of this software.
+ *
+ * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
+ * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
+ * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
+ * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ *
+ * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
+ * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
+ * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
+ * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
+ *
+ * Contributor(s):
+ *	Chris Wilson <chris@chris-wilson.co.uk>
+ * Red Hat Author(s): Behdad Esfahbod
+ * Google Author(s): Behdad Esfahbod
+ */
+
+#ifndef HB_ATOMIC_HH
+#define HB_ATOMIC_HH
+
+#include "hb.hh"
+#include "hb-meta.hh"
+
+
+/*
+ * Atomic integers and pointers.
+ */
+
+
+/* We need external help for these */
+
+#if defined(hb_atomic_int_impl_add) \
+ && defined(hb_atomic_ptr_impl_get) \
+ && defined(hb_atomic_ptr_impl_cmpexch)
+
+/* Defined externally, i.e. in config.h. */
+
+
+#elif !defined(HB_NO_MT) && defined(__ATOMIC_ACQUIRE)
+
+/* C++11-style GCC primitives. We prefer these as they don't require linking to libstdc++ / libc++. */
+
+#define _hb_memory_barrier()			__sync_synchronize ()
+
+#define hb_atomic_int_impl_add(AI, V)		__atomic_fetch_add ((AI), (V), __ATOMIC_ACQ_REL)
+#define hb_atomic_int_impl_set_relaxed(AI, V)	__atomic_store_n ((AI), (V), __ATOMIC_RELAXED)
+#define hb_atomic_int_impl_set(AI, V)		__atomic_store_n ((AI), (V), __ATOMIC_RELEASE)
+#define hb_atomic_int_impl_get_relaxed(AI)	__atomic_load_n ((AI), __ATOMIC_RELAXED)
+#define hb_atomic_int_impl_get(AI)		__atomic_load_n ((AI), __ATOMIC_ACQUIRE)
+
+#define hb_atomic_ptr_impl_set_relaxed(P, V)	__atomic_store_n ((P), (V), __ATOMIC_RELAXED)
+#define hb_atomic_ptr_impl_get_relaxed(P)	__atomic_load_n ((P), __ATOMIC_RELAXED)
+#define hb_atomic_ptr_impl_get(P)		__atomic_load_n ((P), __ATOMIC_ACQUIRE)
+static inline bool
+_hb_atomic_ptr_impl_cmplexch (const void **P, const void *O_, const void *N)
+{
+  const void *O = O_; // Need lvalue
+  return __atomic_compare_exchange_n ((void **) P, (void **) &O, (void *) N, true, __ATOMIC_ACQ_REL, __ATOMIC_RELAXED);
+}
+#define hb_atomic_ptr_impl_cmpexch(P,O,N)	_hb_atomic_ptr_impl_cmplexch ((const void **) (P), (O), (N))
+
+
+#elif !defined(HB_NO_MT)
+
+/* C++11 atomics. */
+
+#include <atomic>
+
+#define _hb_memory_r_barrier()			std::atomic_thread_fence(std::memory_order_acquire)
+#define _hb_memory_w_barrier()			std::atomic_thread_fence(std::memory_order_release)
+
+#define hb_atomic_int_impl_add(AI, V)		(reinterpret_cast<std::atomic<typename std::decay<decltype (*(AI))>::type> *> (AI)->fetch_add ((V), std::memory_order_acq_rel))
+#define hb_atomic_int_impl_set_relaxed(AI, V)	(reinterpret_cast<std::atomic<typename std::decay<decltype (*(AI))>::type> *> (AI)->store ((V), std::memory_order_relaxed))
+#define hb_atomic_int_impl_set(AI, V)		(reinterpret_cast<std::atomic<typename std::decay<decltype (*(AI))>::type> *> (AI)->store ((V), std::memory_order_release))
+#define hb_atomic_int_impl_get_relaxed(AI)	(reinterpret_cast<std::atomic<typename std::decay<decltype (*(AI))>::type> const *> (AI)->load (std::memory_order_relaxed))
+#define hb_atomic_int_impl_get(AI)		(reinterpret_cast<std::atomic<typename std::decay<decltype (*(AI))>::type> const *> (AI)->load (std::memory_order_acquire))
+
+#define hb_atomic_ptr_impl_set_relaxed(P, V)	(reinterpret_cast<std::atomic<void*> *> (P)->store ((V), std::memory_order_relaxed))
+#define hb_atomic_ptr_impl_get_relaxed(P)	(reinterpret_cast<std::atomic<void*> const *> (P)->load (std::memory_order_relaxed))
+#define hb_atomic_ptr_impl_get(P)		(reinterpret_cast<std::atomic<void*> *> (P)->load (std::memory_order_acquire))
+static inline bool
+_hb_atomic_ptr_impl_cmplexch (const void **P, const void *O_, const void *N)
+{
+  const void *O = O_; // Need lvalue
+  return reinterpret_cast<std::atomic<const void*> *> (P)->compare_exchange_weak (O, N, std::memory_order_acq_rel, std::memory_order_relaxed);
+}
+#define hb_atomic_ptr_impl_cmpexch(P,O,N)	_hb_atomic_ptr_impl_cmplexch ((const void **) (P), (O), (N))
+
+
+#else /* defined(HB_NO_MT) */
+
+#define hb_atomic_int_impl_add(AI, V)		((*(AI) += (V)) - (V))
+#define _hb_memory_barrier()			do {} while (0)
+#define hb_atomic_ptr_impl_cmpexch(P,O,N)	(* (void **) (P) == (void *) (O) ? (* (void **) (P) = (void *) (N), true) : false)
+
+#endif
+
+
+/* This should never be disabled, even under HB_NO_MT.
+ * except that MSVC gives me an internal compiler error, so disabled there.
+ *
+ * https://github.com/harfbuzz/harfbuzz/pull/4119
+ */
+#ifndef _hb_compiler_memory_r_barrier
+#if defined(__ATOMIC_ACQUIRE) // gcc-like
+static inline void _hb_compiler_memory_r_barrier () { asm volatile("": : :"memory"); }
+#elif !defined(_MSC_VER)
+#include <atomic>
+#define _hb_compiler_memory_r_barrier() std::atomic_signal_fence (std::memory_order_acquire)
+#else
+static inline void _hb_compiler_memory_r_barrier () {}
+#endif
+#endif
+
+
+
+#ifndef _hb_memory_r_barrier
+#define _hb_memory_r_barrier()			_hb_memory_barrier ()
+#endif
+#ifndef _hb_memory_w_barrier
+#define _hb_memory_w_barrier()			_hb_memory_barrier ()
+#endif
+#ifndef hb_atomic_int_impl_set_relaxed
+#define hb_atomic_int_impl_set_relaxed(AI, V)	(*(AI) = (V))
+#endif
+#ifndef hb_atomic_int_impl_get_relaxed
+#define hb_atomic_int_impl_get_relaxed(AI)	(*(AI))
+#endif
+
+#ifndef hb_atomic_ptr_impl_set_relaxed
+#define hb_atomic_ptr_impl_set_relaxed(P, V)	(*(P) = (V))
+#endif
+#ifndef hb_atomic_ptr_impl_get_relaxed
+#define hb_atomic_ptr_impl_get_relaxed(P)	(*(P))
+#endif
+#ifndef hb_atomic_int_impl_set
+template <typename T>
+inline void hb_atomic_int_impl_set (T *AI, T v)	{ _hb_memory_w_barrier (); *AI = v; }
+#endif
+#ifndef hb_atomic_int_impl_get
+template <typename T>
+inline T hb_atomic_int_impl_get (const T *AI)	{ T v = *AI; _hb_memory_r_barrier (); return v; }
+#endif
+#ifndef hb_atomic_ptr_impl_get
+inline void *hb_atomic_ptr_impl_get (void ** const P)	{ void *v = *P; _hb_memory_r_barrier (); return v; }
+#endif
+
+
+template <typename T>
+struct hb_atomic_t
+{
+  hb_atomic_t () = default;
+  constexpr hb_atomic_t (T v) : v (v) {}
+
+  hb_atomic_t& operator = (T v_) { set_relaxed (v_); return *this; }
+  operator T () const { return get_relaxed (); }
+
+  void set_relaxed (T v_) { hb_atomic_int_impl_set_relaxed (&v, v_); }
+  void set_release (T v_) { hb_atomic_int_impl_set (&v, v_); }
+  T get_relaxed () const { return hb_atomic_int_impl_get_relaxed (&v); }
+  T get_acquire () const { return hb_atomic_int_impl_get (&v); }
+  T inc () { return hb_atomic_int_impl_add (&v,  1); }
+  T dec () { return hb_atomic_int_impl_add (&v, -1); }
+
+  int operator ++ (int) { return inc (); }
+  int operator -- (int) { return dec (); }
+  long operator |= (long v_) { set_relaxed (get_relaxed () | v_); return *this; }
+
+  T v = 0;
+};
+
+template <typename T>
+struct hb_atomic_t<T*>
+{
+  hb_atomic_t () = default;
+  constexpr hb_atomic_t (T* v) : v (v) {}
+  hb_atomic_t (const hb_atomic_t &other) = delete;
+
+  void init (T* v_ = nullptr) { set_relaxed (v_); }
+  void set_relaxed (T* v_) { hb_atomic_ptr_impl_set_relaxed (&v, v_); }
+  T *get_relaxed () const { return (T *) hb_atomic_ptr_impl_get_relaxed (&v); }
+  T *get_acquire () const { return (T *) hb_atomic_ptr_impl_get ((void **) &v); }
+  bool cmpexch (const T *old, T *new_) { return hb_atomic_ptr_impl_cmpexch ((void **) &v, (void *) old, (void *) new_); }
+
+  operator bool () const { return get_acquire () != nullptr; }
+  T * operator -> () const                    { return get_acquire (); }
+  template <typename C> operator C * () const { return get_acquire (); }
+
+  T *v = nullptr;
+};
+
+static inline bool hb_barrier ()
+{
+  _hb_compiler_memory_r_barrier ();
+  return true;
+}
+
+
+#endif /* HB_ATOMIC_HH */