1 /*
2 * Copyright (c) 2012, 2016, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #ifndef SHARE_VM_RUNTIME_ATOMIC_INLINE_HPP
26 #define SHARE_VM_RUNTIME_ATOMIC_INLINE_HPP
27
28 #include "runtime/atomic.hpp"
29 #include "utilities/macros.hpp"
30
31 #include OS_CPU_HEADER_INLINE(atomic)
32
33 // size_t casts...
34 #if (SIZE_MAX != UINTPTR_MAX)
35 #error size_t is not WORD_SIZE, interesting platform, but missing implementation here
36 #endif
37
38 inline size_t Atomic::add(size_t add_value, volatile size_t* dest) {
39 return (size_t) add_ptr((intptr_t) add_value, (volatile intptr_t*) dest);
40 }
41
42 inline void Atomic::inc(volatile size_t* dest) {
43 inc_ptr((volatile intptr_t*) dest);
44 }
45
46 inline void Atomic::dec(volatile size_t* dest) {
47 dec_ptr((volatile intptr_t*) dest);
48 }
49
50 #ifndef VM_HAS_SPECIALIZED_CMPXCHG_BYTE
51 /*
52 * This is the default implementation of byte-sized cmpxchg. It emulates jbyte-sized cmpxchg
53 * in terms of jint-sized cmpxchg. Platforms may override this by defining their own inline definition
54 * as well as defining VM_HAS_SPECIALIZED_CMPXCHG_BYTE. This will cause the platform specific
55 * implementation to be used instead.
56 */
57 inline jbyte Atomic::cmpxchg(jbyte exchange_value, volatile jbyte *dest, jbyte comparand, cmpxchg_memory_order order)
58 {
59 assert(sizeof(jbyte) == 1, "assumption.");
60 uintptr_t dest_addr = (uintptr_t)dest;
61 uintptr_t offset = dest_addr % sizeof(jint);
62 volatile jint* dest_int = (volatile jint*)(dest_addr - offset);
63 jint cur = *dest_int;
64 jbyte* cur_as_bytes = (jbyte*)(&cur);
65 jint new_val = cur;
66 jbyte* new_val_as_bytes = (jbyte*)(&new_val);
67 new_val_as_bytes[offset] = exchange_value;
68 while (cur_as_bytes[offset] == comparand) {
69 jint res = cmpxchg(new_val, dest_int, cur, order);
70 if (res == cur) break;
71 cur = res;
72 new_val = cur;
73 new_val_as_bytes[offset] = exchange_value;
74 }
75 return cur_as_bytes[offset];
76 }
77 #endif // VM_HAS_SPECIALIZED_CMPXCHG_BYTE
78
79 inline unsigned Atomic::xchg(unsigned int exchange_value, volatile unsigned int* dest) {
80 assert(sizeof(unsigned int) == sizeof(jint), "more work to do");
81 return (unsigned int)Atomic::xchg((jint)exchange_value, (volatile jint*)dest);
82 }
83
84 inline unsigned Atomic::cmpxchg(unsigned int exchange_value,
85 volatile unsigned int* dest, unsigned int compare_value,
86 cmpxchg_memory_order order) {
87 assert(sizeof(unsigned int) == sizeof(jint), "more work to do");
88 return (unsigned int)Atomic::cmpxchg((jint)exchange_value, (volatile jint*)dest,
89 (jint)compare_value, order);
90 }
91
92 inline jlong Atomic::add(jlong add_value, volatile jlong* dest) {
93 jlong old = load(dest);
94 jlong new_value = old + add_value;
95 while (old != cmpxchg(new_value, dest, old)) {
96 old = load(dest);
97 new_value = old + add_value;
98 }
99 return old;
100 }
101
102 inline void Atomic::inc(volatile short* dest) {
103 // Most platforms do not support atomic increment on a 2-byte value. However,
104 // if the value occupies the most significant 16 bits of an aligned 32-bit
105 // word, then we can do this with an atomic add of 0x10000 to the 32-bit word.
106 //
107 // The least significant parts of this 32-bit word will never be affected, even
108 // in case of overflow/underflow.
109 //
110 // Use the ATOMIC_SHORT_PAIR macro to get the desired alignment.
111 #ifdef VM_LITTLE_ENDIAN
112 assert((intx(dest) & 0x03) == 0x02, "wrong alignment");
113 (void)Atomic::add(0x10000, (volatile int*)(dest-1));
114 #else
115 assert((intx(dest) & 0x03) == 0x00, "wrong alignment");
116 (void)Atomic::add(0x10000, (volatile int*)(dest));
117 #endif
118 }
119
120 inline void Atomic::dec(volatile short* dest) {
121 #ifdef VM_LITTLE_ENDIAN
122 assert((intx(dest) & 0x03) == 0x02, "wrong alignment");
123 (void)Atomic::add(-0x10000, (volatile int*)(dest-1));
124 #else
125 assert((intx(dest) & 0x03) == 0x00, "wrong alignment");
126 (void)Atomic::add(-0x10000, (volatile int*)(dest));
127 #endif
128 }
129
130 #endif // SHARE_VM_RUNTIME_ATOMIC_INLINE_HPP