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comparison src/share/vm/interpreter/invocationCounter.hpp @ 0:a61af66fc99e jdk7-b24

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author duke
date Sat, 01 Dec 2007 00:00:00 +0000
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1 /*
2 * Copyright 1997-2006 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any 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),
45 count_grain = nth_bit(number_of_state_bits + number_of_carry_bits),
46 count_limit = nth_bit(number_of_count_bits - 1),
47 carry_mask = right_n_bits(number_of_carry_bits) << number_of_state_bits,
48 state_mask = right_n_bits(number_of_state_bits),
49 status_mask = right_n_bits(number_of_state_bits + number_of_carry_bits),
50 count_mask = ((int)(-1) ^ status_mask)
51 };
52
53 public:
54 static int InterpreterInvocationLimit; // CompileThreshold scaled for interpreter use
55 static int Tier1InvocationLimit; // CompileThreshold scaled for tier1 use
56 static int Tier1BackEdgeLimit; // BackEdgeThreshold scaled for tier1 use
57
58 static int InterpreterBackwardBranchLimit; // A separate threshold for on stack replacement
59
60 static int InterpreterProfileLimit; // Profiling threshold scaled for interpreter use
61
62 typedef address (*Action)(methodHandle method, TRAPS);
63
64 enum PublicConstants {
65 count_increment = count_grain, // use this value to increment the 32bit _counter word
66 count_mask_value = count_mask // use this value to mask the backedge counter
67 };
68
69 enum State {
70 wait_for_nothing, // do nothing when count() > limit()
71 wait_for_compile, // introduce nmethod when count() > limit()
72 number_of_states // must be <= state_limit
73 };
74
75 // Manipulation
76 void reset(); // sets state to wait state
77 void init(); // sets state into original state
78 void set_state(State state); // sets state and initializes counter correspondingly
79 inline void set(State state, int count); // sets state and counter
80 inline void decay(); // decay counter (divide by two)
81 void set_carry(); // set the sticky carry bit
82
83 // Accessors
84 State state() const { return (State)(_counter & state_mask); }
85 bool carry() const { return (_counter & carry_mask) != 0; }
86 int limit() const { return CompileThreshold; }
87 Action action() const { return _action[state()]; }
88 int count() const { return _counter >> number_of_noncount_bits; }
89
90 int get_InvocationLimit() const { return InterpreterInvocationLimit >> number_of_noncount_bits; }
91 int get_BackwardBranchLimit() const { return InterpreterBackwardBranchLimit >> number_of_noncount_bits; }
92 int get_ProfileLimit() const { return InterpreterProfileLimit >> number_of_noncount_bits; }
93
94 // Test counter using scaled limits like the asm interpreter would do rather than doing
95 // the shifts to normalize the counter.
96
97 bool reached_InvocationLimit() const { return _counter >= (unsigned int) InterpreterInvocationLimit; }
98 bool reached_BackwardBranchLimit() const { return _counter >= (unsigned int) InterpreterBackwardBranchLimit; }
99
100 // Do this just like asm interpreter does for max speed
101 bool reached_ProfileLimit(InvocationCounter *back_edge_count) const {
102 return (_counter && count_mask) + back_edge_count->_counter >= (unsigned int) InterpreterProfileLimit;
103 }
104
105 void increment() { _counter += count_increment; }
106
107
108 // Printing
109 void print();
110 void print_short();
111
112 // Miscellaneous
113 static ByteSize counter_offset() { return byte_offset_of(InvocationCounter, _counter); }
114 static void reinitialize(bool delay_overflow);
115
116 private:
117 static int _init [number_of_states]; // the counter limits
118 static Action _action[number_of_states]; // the actions
119
120 static void def(State state, int init, Action action);
121 static const char* state_as_string(State state);
122 static const char* state_as_short_string(State state);
123 };
124
125 inline void InvocationCounter::set(State state, int count) {
126 assert(0 <= state && state < number_of_states, "illegal state");
127 int carry = (_counter & carry_mask); // the carry bit is sticky
128 _counter = (count << number_of_noncount_bits) | carry | state;
129 }
130
131 inline void InvocationCounter::decay() {
132 int c = count();
133 int new_count = c >> 1;
134 // prevent from going to zero, to distinguish from never-executed methods
135 if (c > 0 && new_count == 0) new_count = 1;
136 set(state(), new_count);
137 }