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Diffstat (limited to 'js/src/jit/shared/AtomicOperations-feeling-lucky-gcc.h')
| -rw-r--r-- | js/src/jit/shared/AtomicOperations-feeling-lucky-gcc.h | 453 |
1 files changed, 453 insertions, 0 deletions
diff --git a/js/src/jit/shared/AtomicOperations-feeling-lucky-gcc.h b/js/src/jit/shared/AtomicOperations-feeling-lucky-gcc.h new file mode 100644 index 0000000000..8f700aaab3 --- /dev/null +++ b/js/src/jit/shared/AtomicOperations-feeling-lucky-gcc.h @@ -0,0 +1,453 @@ +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- + * vim: set ts=8 sts=2 et sw=2 tw=80: + * 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, both the comment block at the + * beginning and the #ifdef nest near the end. + * + * This is a common file for tier-3 platforms (including simulators for our + * tier-1 platforms) that are not providing hardware-specific implementations of + * the atomic operations. Please keep it reasonably platform-independent by + * adding #ifdefs at the beginning as much as possible, not throughout the file. + * + * + * !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! + * !!!! NOTE !!!! + * !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! + * + * The implementations in this file are NOT SAFE and cannot be safe even in + * principle because they rely on C++ undefined behavior. However, they are + * frequently good enough for tier-3 platforms. + */ + +#ifndef jit_shared_AtomicOperations_feeling_lucky_gcc_h +#define jit_shared_AtomicOperations_feeling_lucky_gcc_h + +#include "mozilla/Assertions.h" +#include "mozilla/Types.h" + +// Explicitly exclude tier-1 platforms. + +#if (defined(__x86_64__) || defined(_M_X64) || defined(__i386__) || \ + defined(_M_IX86) || (defined(__arm__) && __ARM_ARCH >= 7) || \ + defined(__aarch64__)) +# error "Do not use on a tier-1 platform where inline assembly is available" +#endif + +#if !(defined(__clang__) || defined(__GNUC__)) +# error "This file only for gcc/Clang" +#endif + +// 64-bit atomics are not required by the JS spec, and you can compile +// SpiderMonkey without them. 64-bit atomics are required for BigInt +// support. +// +// 64-bit lock-free atomics are required for WebAssembly, but gating in the +// WebAssembly subsystem ensures that no WebAssembly-supporting platforms need +// code in this file. + +#if defined(JS_SIMULATOR_ARM64) || defined(JS_SIMULATOR_ARM) || \ + defined(JS_SIMULATOR_MIPS64) || defined(JS_SIMULATOR_LOONG64) +// On some x86 (32-bit) systems this will not work because the compiler does not +// open-code 64-bit atomics. If so, try linking with -latomic. If that doesn't +// work, you're mostly on your own. +# define HAS_64BIT_ATOMICS +# define HAS_64BIT_LOCKFREE +#endif + +#if defined(__arm__) +# define HAS_64BIT_ATOMICS +#endif + +#if defined(__ppc64__) || defined(__PPC64__) || defined(__ppc64le__) || \ + defined(__PPC64LE__) +# define HAS_64BIT_ATOMICS +# define HAS_64BIT_LOCKFREE +#endif + +#if defined(__riscv) && __riscv_xlen == 64 +# define HAS_64BIT_ATOMICS +# define HAS_64BIT_LOCKFREE +#endif + +#if defined(__loongarch64) +# define HAS_64BIT_ATOMICS +# define HAS_64BIT_LOCKFREE +#endif + +#ifdef __sparc__ +# ifdef __LP64__ +# define HAS_64BIT_ATOMICS +# define HAS_64BIT_LOCKFREE +# endif +#endif + +#ifdef JS_CODEGEN_NONE +# ifdef JS_64BIT +# define HAS_64BIT_ATOMICS +# define HAS_64BIT_LOCKFREE +# endif +#endif + +// 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. Firefox no longer supports compilers that old. + +//#define ATOMICS_IMPLEMENTED_WITH_SYNC_INTRINSICS + +// Sanity check. + +#if defined(HAS_64BIT_LOCKFREE) && !defined(HAS_64BIT_ATOMICS) +# error "This combination of features is senseless, please fix" +#endif + +// Try to avoid platform #ifdefs below this point. + +// When compiling with Clang on 32-bit linux it will be necessary to link with +// -latomic to get the proper 64-bit intrinsics. + +inline bool js::jit::AtomicOperations::hasAtomic8() { +#if defined(HAS_64BIT_ATOMICS) + return true; +#else + return false; +#endif +} + +inline bool js::jit::AtomicOperations::isLockfree8() { +#if defined(HAS_64BIT_LOCKFREE) + return true; +#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) { + static_assert(sizeof(T) <= 8, "atomics supported up to 8 bytes only"); +#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; +} + +#ifndef HAS_64BIT_ATOMICS +namespace js { +namespace jit { + +template <> +inline int64_t AtomicOperations::loadSeqCst(int64_t* addr) { + MOZ_CRASH("No 64-bit atomics"); +} + +template <> +inline uint64_t AtomicOperations::loadSeqCst(uint64_t* addr) { + MOZ_CRASH("No 64-bit atomics"); +} + +} // namespace jit +} // namespace js +#endif + +template <typename T> +inline void js::jit::AtomicOperations::storeSeqCst(T* addr, T val) { + static_assert(sizeof(T) <= 8, "atomics supported up to 8 bytes only"); +#ifdef ATOMICS_IMPLEMENTED_WITH_SYNC_INTRINSICS + __sync_synchronize(); + *addr = val; + __sync_synchronize(); +#else + __atomic_store(addr, &val, __ATOMIC_SEQ_CST); +#endif +} + +#ifndef HAS_64BIT_ATOMICS +namespace js { +namespace jit { + +template <> +inline void AtomicOperations::storeSeqCst(int64_t* addr, int64_t val) { + MOZ_CRASH("No 64-bit atomics"); +} + +template <> +inline void AtomicOperations::storeSeqCst(uint64_t* addr, uint64_t val) { + MOZ_CRASH("No 64-bit atomics"); +} + +} // namespace jit +} // namespace js +#endif + +template <typename T> +inline T js::jit::AtomicOperations::exchangeSeqCst(T* addr, T val) { + static_assert(sizeof(T) <= 8, "atomics supported up to 8 bytes only"); +#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 +} + +#ifndef HAS_64BIT_ATOMICS +namespace js { +namespace jit { + +template <> +inline int64_t AtomicOperations::exchangeSeqCst(int64_t* addr, int64_t val) { + MOZ_CRASH("No 64-bit atomics"); +} + +template <> +inline uint64_t AtomicOperations::exchangeSeqCst(uint64_t* addr, uint64_t val) { + MOZ_CRASH("No 64-bit atomics"); +} + +} // namespace jit +} // namespace js +#endif + +template <typename T> +inline T js::jit::AtomicOperations::compareExchangeSeqCst(T* addr, T oldval, + T newval) { + static_assert(sizeof(T) <= 8, "atomics supported up to 8 bytes only"); +#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 +} + +#ifndef HAS_64BIT_ATOMICS +namespace js { +namespace jit { + +template <> +inline int64_t AtomicOperations::compareExchangeSeqCst(int64_t* addr, + int64_t oldval, + int64_t newval) { + MOZ_CRASH("No 64-bit atomics"); +} + +template <> +inline uint64_t AtomicOperations::compareExchangeSeqCst(uint64_t* addr, + uint64_t oldval, + uint64_t newval) { + MOZ_CRASH("No 64-bit atomics"); +} + +} // namespace jit +} // namespace js +#endif + +template <typename T> +inline T js::jit::AtomicOperations::fetchAddSeqCst(T* addr, T val) { + static_assert(sizeof(T) <= 8, "atomics supported up to 8 bytes only"); +#ifdef ATOMICS_IMPLEMENTED_WITH_SYNC_INTRINSICS + return __sync_fetch_and_add(addr, val); +#else + return __atomic_fetch_add(addr, val, __ATOMIC_SEQ_CST); +#endif +} + +#ifndef HAS_64BIT_ATOMICS +namespace js { +namespace jit { + +template <> +inline int64_t AtomicOperations::fetchAddSeqCst(int64_t* addr, int64_t val) { + MOZ_CRASH("No 64-bit atomics"); +} + +template <> +inline uint64_t AtomicOperations::fetchAddSeqCst(uint64_t* addr, uint64_t val) { + MOZ_CRASH("No 64-bit atomics"); +} + +} // namespace jit +} // namespace js +#endif + +template <typename T> +inline T js::jit::AtomicOperations::fetchSubSeqCst(T* addr, T val) { + static_assert(sizeof(T) <= 8, "atomics supported up to 8 bytes only"); +#ifdef ATOMICS_IMPLEMENTED_WITH_SYNC_INTRINSICS + return __sync_fetch_and_sub(addr, val); +#else + return __atomic_fetch_sub(addr, val, __ATOMIC_SEQ_CST); +#endif +} + +#ifndef HAS_64BIT_ATOMICS +namespace js { +namespace jit { + +template <> +inline int64_t AtomicOperations::fetchSubSeqCst(int64_t* addr, int64_t val) { + MOZ_CRASH("No 64-bit atomics"); +} + +template <> +inline uint64_t AtomicOperations::fetchSubSeqCst(uint64_t* addr, uint64_t val) { + MOZ_CRASH("No 64-bit atomics"); +} + +} // namespace jit +} // namespace js +#endif + +template <typename T> +inline T js::jit::AtomicOperations::fetchAndSeqCst(T* addr, T val) { + static_assert(sizeof(T) <= 8, "atomics supported up to 8 bytes only"); +#ifdef ATOMICS_IMPLEMENTED_WITH_SYNC_INTRINSICS + return __sync_fetch_and_and(addr, val); +#else + return __atomic_fetch_and(addr, val, __ATOMIC_SEQ_CST); +#endif +} + +#ifndef HAS_64BIT_ATOMICS +namespace js { +namespace jit { + +template <> +inline int64_t AtomicOperations::fetchAndSeqCst(int64_t* addr, int64_t val) { + MOZ_CRASH("No 64-bit atomics"); +} + +template <> +inline uint64_t AtomicOperations::fetchAndSeqCst(uint64_t* addr, uint64_t val) { + MOZ_CRASH("No 64-bit atomics"); +} + +} // namespace jit +} // namespace js +#endif + +template <typename T> +inline T js::jit::AtomicOperations::fetchOrSeqCst(T* addr, T val) { + static_assert(sizeof(T) <= 8, "atomics supported up to 8 bytes only"); +#ifdef ATOMICS_IMPLEMENTED_WITH_SYNC_INTRINSICS + return __sync_fetch_and_or(addr, val); +#else + return __atomic_fetch_or(addr, val, __ATOMIC_SEQ_CST); +#endif +} + +#ifndef HAS_64BIT_ATOMICS +namespace js { +namespace jit { + +template <> +inline int64_t AtomicOperations::fetchOrSeqCst(int64_t* addr, int64_t val) { + MOZ_CRASH("No 64-bit atomics"); +} + +template <> +inline uint64_t AtomicOperations::fetchOrSeqCst(uint64_t* addr, uint64_t val) { + MOZ_CRASH("No 64-bit atomics"); +} + +} // namespace jit +} // namespace js +#endif + +template <typename T> +inline T js::jit::AtomicOperations::fetchXorSeqCst(T* addr, T val) { + static_assert(sizeof(T) <= 8, "atomics supported up to 8 bytes only"); +#ifdef ATOMICS_IMPLEMENTED_WITH_SYNC_INTRINSICS + return __sync_fetch_and_xor(addr, val); +#else + return __atomic_fetch_xor(addr, val, __ATOMIC_SEQ_CST); +#endif +} + +#ifndef HAS_64BIT_ATOMICS +namespace js { +namespace jit { + +template <> +inline int64_t AtomicOperations::fetchXorSeqCst(int64_t* addr, int64_t val) { + MOZ_CRASH("No 64-bit atomics"); +} + +template <> +inline uint64_t AtomicOperations::fetchXorSeqCst(uint64_t* addr, uint64_t val) { + MOZ_CRASH("No 64-bit atomics"); +} + +} // namespace jit +} // namespace js +#endif + +template <typename T> +inline T js::jit::AtomicOperations::loadSafeWhenRacy(T* addr) { + static_assert(sizeof(T) <= 8, "atomics supported up to 8 bytes only"); + // This is actually roughly right even on 32-bit platforms since in that + // case, double, int64, and uint64 loads need not be access-atomic. + // + // We could use __atomic_load, but it would be needlessly expensive on + // 32-bit platforms that could support it and just plain wrong on others. + return *addr; +} + +template <typename T> +inline void js::jit::AtomicOperations::storeSafeWhenRacy(T* addr, T val) { + static_assert(sizeof(T) <= 8, "atomics supported up to 8 bytes only"); + // This is actually roughly right even on 32-bit platforms since in that + // case, double, int64, and uint64 loads need not be access-atomic. + // + // We could use __atomic_store, but it would be needlessly expensive on + // 32-bit platforms that could support it and just plain wrong on others. + *addr = val; +} + +inline void js::jit::AtomicOperations::memcpySafeWhenRacy(void* dest, + const void* src, + size_t nbytes) { + MOZ_ASSERT(!((char*)dest <= (char*)src && (char*)src < (char*)dest + nbytes)); + MOZ_ASSERT(!((char*)src <= (char*)dest && (char*)dest < (char*)src + nbytes)); + ::memcpy(dest, src, nbytes); +} + +inline void js::jit::AtomicOperations::memmoveSafeWhenRacy(void* dest, + const void* src, + size_t nbytes) { + ::memmove(dest, src, nbytes); +} + +#undef ATOMICS_IMPLEMENTED_WITH_SYNC_INTRINSICS +#undef HAS_64BIT_ATOMICS +#undef HAS_64BIT_LOCKFREE + +#endif // jit_shared_AtomicOperations_feeling_lucky_gcc_h |