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Diffstat (limited to 'js/src/jit/arm/AtomicOperations-arm.h')
| -rw-r--r-- | js/src/jit/arm/AtomicOperations-arm.h | 247 |
1 files changed, 247 insertions, 0 deletions
diff --git a/js/src/jit/arm/AtomicOperations-arm.h b/js/src/jit/arm/AtomicOperations-arm.h new file mode 100644 index 0000000000..7e988ed29a --- /dev/null +++ b/js/src/jit/arm/AtomicOperations-arm.h @@ -0,0 +1,247 @@ +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- + * vim: set ts=8 sts=4 et sw=4 tw=99: + * This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +/* For documentation, see jit/AtomicOperations.h */ + +#ifndef jit_arm_AtomicOperations_arm_h +#define jit_arm_AtomicOperations_arm_h + +#include "jit/arm/Architecture-arm.h" + +#if defined(__clang__) || defined(__GNUC__) + +// The default implementation tactic for gcc/clang is to use the newer +// __atomic intrinsics added for use in C++11 <atomic>. Where that +// isn't available, we use GCC's older __sync functions instead. +// +// ATOMICS_IMPLEMENTED_WITH_SYNC_INTRINSICS is kept as a backward +// compatible option for older compilers: enable this to use GCC's old +// __sync functions instead of the newer __atomic functions. This +// will be required for GCC 4.6.x and earlier, and probably for Clang +// 3.1, should we need to use those versions. + +//#define ATOMICS_IMPLEMENTED_WITH_SYNC_INTRINSICS + +inline bool +js::jit::AtomicOperations::isLockfree8() +{ + // The JIT and the C++ compiler must agree on whether to use atomics + // for 64-bit accesses. There are two ways to do this: either the + // JIT defers to the C++ compiler (so if the C++ code is compiled + // for ARMv6, say, and __atomic_always_lock_free(8) is false, then the + // JIT ignores the fact that the program is running on ARMv7 or newer); + // or the C++ code in this file calls out to run-time generated code + // to do whatever the JIT does. + // + // For now, make the JIT defer to the C++ compiler when we know what + // the C++ compiler will do, otherwise assume a lock is needed. +# ifndef ATOMICS_IMPLEMENTED_WITH_SYNC_INTRINSICS + MOZ_ASSERT(__atomic_always_lock_free(sizeof(int8_t), 0)); + MOZ_ASSERT(__atomic_always_lock_free(sizeof(int16_t), 0)); + MOZ_ASSERT(__atomic_always_lock_free(sizeof(int32_t), 0)); + return HasLDSTREXBHD() && __atomic_always_lock_free(sizeof(int64_t), 0); +# else + return false; +# endif +} + +inline void +js::jit::AtomicOperations::fenceSeqCst() +{ +# ifdef ATOMICS_IMPLEMENTED_WITH_SYNC_INTRINSICS + __sync_synchronize(); +# else + __atomic_thread_fence(__ATOMIC_SEQ_CST); +# endif +} + +template<typename T> +inline T +js::jit::AtomicOperations::loadSeqCst(T* addr) +{ + MOZ_ASSERT(sizeof(T) < 8 || isLockfree8()); +# ifdef ATOMICS_IMPLEMENTED_WITH_SYNC_INTRINSICS + __sync_synchronize(); + T v = *addr; + __sync_synchronize(); +# else + T v; + __atomic_load(addr, &v, __ATOMIC_SEQ_CST); +# endif + return v; +} + +template<typename T> +inline void +js::jit::AtomicOperations::storeSeqCst(T* addr, T val) +{ + MOZ_ASSERT(sizeof(T) < 8 || isLockfree8()); +# ifdef ATOMICS_IMPLEMENTED_WITH_SYNC_INTRINSICS + __sync_synchronize(); + *addr = val; + __sync_synchronize(); +# else + __atomic_store(addr, &val, __ATOMIC_SEQ_CST); +# endif +} + +template<typename T> +inline T +js::jit::AtomicOperations::exchangeSeqCst(T* addr, T val) +{ + MOZ_ASSERT(sizeof(T) < 8 || isLockfree8()); +# ifdef ATOMICS_IMPLEMENTED_WITH_SYNC_INTRINSICS + T v; + __sync_synchronize(); + do { + v = *addr; + } while (__sync_val_compare_and_swap(addr, v, val) != v); + return v; +# else + T v; + __atomic_exchange(addr, &val, &v, __ATOMIC_SEQ_CST); + return v; +# endif +} + +template<typename T> +inline T +js::jit::AtomicOperations::compareExchangeSeqCst(T* addr, T oldval, T newval) +{ + MOZ_ASSERT(sizeof(T) < 8 || isLockfree8()); +# ifdef ATOMICS_IMPLEMENTED_WITH_SYNC_INTRINSICS + return __sync_val_compare_and_swap(addr, oldval, newval); +# else + __atomic_compare_exchange(addr, &oldval, &newval, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST); + return oldval; +# endif +} + +template<typename T> +inline T +js::jit::AtomicOperations::fetchAddSeqCst(T* addr, T val) +{ + static_assert(sizeof(T) <= 4, "not available for 8-byte values yet"); +# ifdef ATOMICS_IMPLEMENTED_WITH_SYNC_INTRINSICS + return __sync_fetch_and_add(addr, val); +# else + return __atomic_fetch_add(addr, val, __ATOMIC_SEQ_CST); +# endif +} + +template<typename T> +inline T +js::jit::AtomicOperations::fetchSubSeqCst(T* addr, T val) +{ + static_assert(sizeof(T) <= 4, "not available for 8-byte values yet"); +# ifdef ATOMICS_IMPLEMENTED_WITH_SYNC_INTRINSICS + return __sync_fetch_and_sub(addr, val); +# else + return __atomic_fetch_sub(addr, val, __ATOMIC_SEQ_CST); +# endif +} + +template<typename T> +inline T +js::jit::AtomicOperations::fetchAndSeqCst(T* addr, T val) +{ + static_assert(sizeof(T) <= 4, "not available for 8-byte values yet"); +# ifdef ATOMICS_IMPLEMENTED_WITH_SYNC_INTRINSICS + return __sync_fetch_and_and(addr, val); +# else + return __atomic_fetch_and(addr, val, __ATOMIC_SEQ_CST); +# endif +} + +template<typename T> +inline T +js::jit::AtomicOperations::fetchOrSeqCst(T* addr, T val) +{ + static_assert(sizeof(T) <= 4, "not available for 8-byte values yet"); +# ifdef ATOMICS_IMPLEMENTED_WITH_SYNC_INTRINSICS + return __sync_fetch_and_or(addr, val); +# else + return __atomic_fetch_or(addr, val, __ATOMIC_SEQ_CST); +# endif +} + +template<typename T> +inline T +js::jit::AtomicOperations::fetchXorSeqCst(T* addr, T val) +{ + static_assert(sizeof(T) <= 4, "not available for 8-byte values yet"); +# ifdef ATOMICS_IMPLEMENTED_WITH_SYNC_INTRINSICS + return __sync_fetch_and_xor(addr, val); +# else + return __atomic_fetch_xor(addr, val, __ATOMIC_SEQ_CST); +# endif +} + +template<typename T> +inline T +js::jit::AtomicOperations::loadSafeWhenRacy(T* addr) +{ + return *addr; // FIXME (1208663): not yet safe +} + +template<typename T> +inline void +js::jit::AtomicOperations::storeSafeWhenRacy(T* addr, T val) +{ + *addr = val; // FIXME (1208663): not yet safe +} + +inline void +js::jit::AtomicOperations::memcpySafeWhenRacy(void* dest, const void* src, size_t nbytes) +{ + memcpy(dest, src, nbytes); // FIXME (1208663): not yet safe +} + +inline void +js::jit::AtomicOperations::memmoveSafeWhenRacy(void* dest, const void* src, size_t nbytes) +{ + memmove(dest, src, nbytes); // FIXME (1208663): not yet safe +} + +template<size_t nbytes> +inline void +js::jit::RegionLock::acquire(void* addr) +{ +# ifdef ATOMICS_IMPLEMENTED_WITH_SYNC_INTRINSICS + while (!__sync_bool_compare_and_swap(&spinlock, 0, 1)) + ; +# else + uint32_t zero = 0; + uint32_t one = 1; + while (!__atomic_compare_exchange(&spinlock, &zero, &one, false, __ATOMIC_ACQUIRE, __ATOMIC_ACQUIRE)) { + zero = 0; + continue; + } +# endif +} + +template<size_t nbytes> +inline void +js::jit::RegionLock::release(void* addr) +{ + MOZ_ASSERT(AtomicOperations::loadSeqCst(&spinlock) == 1, "releasing unlocked region lock"); +# ifdef ATOMICS_IMPLEMENTED_WITH_SYNC_INTRINSICS + __sync_sub_and_fetch(&spinlock, 1); +# else + uint32_t zero = 0; + __atomic_store(&spinlock, &zero, __ATOMIC_SEQ_CST); +# endif +} + +# undef ATOMICS_IMPLEMENTED_WITH_SYNC_INTRINSICS + +#elif defined(ENABLE_SHARED_ARRAY_BUFFER) + +# error "Either disable JS shared memory at compile time, use GCC or Clang, or add code here" + +#endif + +#endif // jit_arm_AtomicOperations_arm_h |