diff -r 000000000000 -r f90c822e73f8 src/share/vm/runtime/atomic.hpp --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/share/vm/runtime/atomic.hpp Wed Apr 27 01:25:04 2016 +0800 @@ -0,0 +1,120 @@ +/* + * Copyright (c) 1999, 2013, Oracle and/or its affiliates. All rights reserved. + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This code is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 only, as + * published by the Free Software Foundation. + * + * This code is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * version 2 for more details (a copy is included in the LICENSE file that + * accompanied this code). + * + * You should have received a copy of the GNU General Public License version + * 2 along with this work; if not, write to the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. + * + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA + * or visit www.oracle.com if you need additional information or have any + * questions. + * + */ + +#ifndef SHARE_VM_RUNTIME_ATOMIC_HPP +#define SHARE_VM_RUNTIME_ATOMIC_HPP + +#include "memory/allocation.hpp" + +class Atomic : AllStatic { + public: + // Atomic operations on jlong types are not available on all 32-bit + // platforms. If atomic ops on jlongs are defined here they must only + // be used from code that verifies they are available at runtime and + // can provide an alternative action if not - see supports_cx8() for + // a means to test availability. + + // Atomically store to a location + inline static void store (jbyte store_value, jbyte* dest); + inline static void store (jshort store_value, jshort* dest); + inline static void store (jint store_value, jint* dest); + // See comment above about using jlong atomics on 32-bit platforms + inline static void store (jlong store_value, jlong* dest); + inline static void store_ptr(intptr_t store_value, intptr_t* dest); + inline static void store_ptr(void* store_value, void* dest); + + inline static void store (jbyte store_value, volatile jbyte* dest); + inline static void store (jshort store_value, volatile jshort* dest); + inline static void store (jint store_value, volatile jint* dest); + // See comment above about using jlong atomics on 32-bit platforms + inline static void store (jlong store_value, volatile jlong* dest); + inline static void store_ptr(intptr_t store_value, volatile intptr_t* dest); + inline static void store_ptr(void* store_value, volatile void* dest); + + // See comment above about using jlong atomics on 32-bit platforms + inline static jlong load(volatile jlong* src); + + // Atomically add to a location, return updated value + inline static jint add (jint add_value, volatile jint* dest); + inline static intptr_t add_ptr(intptr_t add_value, volatile intptr_t* dest); + inline static void* add_ptr(intptr_t add_value, volatile void* dest); + // See comment above about using jlong atomics on 32-bit platforms + static jlong add (jlong add_value, volatile jlong* dest); + + // Atomically increment location + inline static void inc (volatile jint* dest); + static void inc (volatile jshort* dest); + inline static void inc_ptr(volatile intptr_t* dest); + inline static void inc_ptr(volatile void* dest); + + // Atomically decrement a location + inline static void dec (volatile jint* dest); + static void dec (volatile jshort* dest); + inline static void dec_ptr(volatile intptr_t* dest); + inline static void dec_ptr(volatile void* dest); + + // Performs atomic exchange of *dest with exchange_value. Returns old prior value of *dest. + inline static jint xchg(jint exchange_value, volatile jint* dest); + static unsigned int xchg(unsigned int exchange_value, volatile unsigned int* dest); + + inline static intptr_t xchg_ptr(intptr_t exchange_value, volatile intptr_t* dest); + inline static void* xchg_ptr(void* exchange_value, volatile void* dest); + + // Performs atomic compare of *dest and compare_value, and exchanges *dest with exchange_value + // if the comparison succeeded. Returns prior value of *dest. Guarantees a two-way memory + // barrier across the cmpxchg. I.e., it's really a 'fence_cmpxchg_acquire'. + static jbyte cmpxchg (jbyte exchange_value, volatile jbyte* dest, jbyte compare_value); + inline static jint cmpxchg (jint exchange_value, volatile jint* dest, jint compare_value); + // See comment above about using jlong atomics on 32-bit platforms + inline static jlong cmpxchg (jlong exchange_value, volatile jlong* dest, jlong compare_value); + + static unsigned int cmpxchg(unsigned int exchange_value, + volatile unsigned int* dest, + unsigned int compare_value); + + inline static intptr_t cmpxchg_ptr(intptr_t exchange_value, volatile intptr_t* dest, intptr_t compare_value); + inline static void* cmpxchg_ptr(void* exchange_value, volatile void* dest, void* compare_value); +}; + +// To use Atomic::inc(jshort* dest) and Atomic::dec(jshort* dest), the address must be specially +// aligned, such that (*dest) occupies the upper 16 bits of an aligned 32-bit word. The best way to +// achieve is to place your short value next to another short value, which doesn't need atomic ops. +// +// Example +// ATOMIC_SHORT_PAIR( +// volatile short _refcount, // needs atomic operation +// unsigned short _length // number of UTF8 characters in the symbol (does not need atomic op) +// ); + +#ifdef VM_LITTLE_ENDIAN +#define ATOMIC_SHORT_PAIR(atomic_decl, non_atomic_decl) \ + non_atomic_decl; \ + atomic_decl +#else +#define ATOMIC_SHORT_PAIR(atomic_decl, non_atomic_decl) \ + atomic_decl ; \ + non_atomic_decl +#endif + +#endif // SHARE_VM_RUNTIME_ATOMIC_HPP