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 // InvocationCounters are used to trigger actions when a limit (threshold) is reached.
26 // For different states, different limits and actions can be defined in the initialization
27 // routine of InvocationCounters.
28 //
29 // Implementation notes: For space reasons, state & counter are both encoded in one word,
30 // The state is encoded using some of the least significant bits, the counter is using the
31 // more significant bits. The counter is incremented before a method is activated and an
32 // action is triggered when when count() > limit().
33
34 class InvocationCounter VALUE_OBJ_CLASS_SPEC {
35 friend class VMStructs;
36 private: // bit no: |31 3| 2 | 1 0 |
37 unsigned int _counter; // format: [count|carry|state]
38
39 enum PrivateConstants {
40 number_of_state_bits = 2,
41 number_of_carry_bits = 1,
42 number_of_noncount_bits = number_of_state_bits + number_of_carry_bits,
43 number_of_count_bits = BitsPerInt - number_of_noncount_bits,
44 state_limit = nth_bit(number_of_state_bits),
117
118 static void def(State state, int init, Action action);
119 static const char* state_as_string(State state);
120 static const char* state_as_short_string(State state);
121 };
122
123 inline void InvocationCounter::set(State state, int count) {
124 assert(0 <= state && state < number_of_states, "illegal state");
125 int carry = (_counter & carry_mask); // the carry bit is sticky
126 _counter = (count << number_of_noncount_bits) | carry | state;
127 }
128
129 inline void InvocationCounter::decay() {
130 int c = count();
131 int new_count = c >> 1;
132 // prevent from going to zero, to distinguish from never-executed methods
133 if (c > 0 && new_count == 0) new_count = 1;
134 set(state(), new_count);
135 }
136
|
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_INTERPRETER_INVOCATIONCOUNTER_HPP
26 #define SHARE_VM_INTERPRETER_INVOCATIONCOUNTER_HPP
27
28 #include "memory/allocation.hpp"
29 #include "runtime/handles.hpp"
30 #include "utilities/exceptions.hpp"
31
32 // InvocationCounters are used to trigger actions when a limit (threshold) is reached.
33 // For different states, different limits and actions can be defined in the initialization
34 // routine of InvocationCounters.
35 //
36 // Implementation notes: For space reasons, state & counter are both encoded in one word,
37 // The state is encoded using some of the least significant bits, the counter is using the
38 // more significant bits. The counter is incremented before a method is activated and an
39 // action is triggered when when count() > limit().
40
41 class InvocationCounter VALUE_OBJ_CLASS_SPEC {
42 friend class VMStructs;
43 private: // bit no: |31 3| 2 | 1 0 |
44 unsigned int _counter; // format: [count|carry|state]
45
46 enum PrivateConstants {
47 number_of_state_bits = 2,
48 number_of_carry_bits = 1,
49 number_of_noncount_bits = number_of_state_bits + number_of_carry_bits,
50 number_of_count_bits = BitsPerInt - number_of_noncount_bits,
51 state_limit = nth_bit(number_of_state_bits),
124
125 static void def(State state, int init, Action action);
126 static const char* state_as_string(State state);
127 static const char* state_as_short_string(State state);
128 };
129
130 inline void InvocationCounter::set(State state, int count) {
131 assert(0 <= state && state < number_of_states, "illegal state");
132 int carry = (_counter & carry_mask); // the carry bit is sticky
133 _counter = (count << number_of_noncount_bits) | carry | state;
134 }
135
136 inline void InvocationCounter::decay() {
137 int c = count();
138 int new_count = c >> 1;
139 // prevent from going to zero, to distinguish from never-executed methods
140 if (c > 0 && new_count == 0) new_count = 1;
141 set(state(), new_count);
142 }
143
144
145 #endif // SHARE_VM_INTERPRETER_INVOCATIONCOUNTER_HPP
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