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1 /*
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2 * Copyright 1997-2006 Sun Microsystems, Inc. All Rights Reserved.
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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20 * CA 95054 USA or visit www.sun.com if you need additional information or
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21 * have any questions.
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22 *
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23 */
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24
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25 // InvocationCounters are used to trigger actions when a limit (threshold) is reached.
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26 // For different states, different limits and actions can be defined in the initialization
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27 // routine of InvocationCounters.
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28 //
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29 // Implementation notes: For space reasons, state & counter are both encoded in one word,
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30 // The state is encoded using some of the least significant bits, the counter is using the
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31 // more significant bits. The counter is incremented before a method is activated and an
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32 // action is triggered when when count() > limit().
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33
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34 class InvocationCounter VALUE_OBJ_CLASS_SPEC {
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35 friend class VMStructs;
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36 private: // bit no: |31 3| 2 | 1 0 |
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37 unsigned int _counter; // format: [count|carry|state]
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38
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39 enum PrivateConstants {
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40 number_of_state_bits = 2,
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41 number_of_carry_bits = 1,
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42 number_of_noncount_bits = number_of_state_bits + number_of_carry_bits,
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43 number_of_count_bits = BitsPerInt - number_of_noncount_bits,
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44 state_limit = nth_bit(number_of_state_bits),
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45 count_grain = nth_bit(number_of_state_bits + number_of_carry_bits),
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46 count_limit = nth_bit(number_of_count_bits - 1),
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47 carry_mask = right_n_bits(number_of_carry_bits) << number_of_state_bits,
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48 state_mask = right_n_bits(number_of_state_bits),
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49 status_mask = right_n_bits(number_of_state_bits + number_of_carry_bits),
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50 count_mask = ((int)(-1) ^ status_mask)
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51 };
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52
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53 public:
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54 static int InterpreterInvocationLimit; // CompileThreshold scaled for interpreter use
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55 static int Tier1InvocationLimit; // CompileThreshold scaled for tier1 use
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56 static int Tier1BackEdgeLimit; // BackEdgeThreshold scaled for tier1 use
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57
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58 static int InterpreterBackwardBranchLimit; // A separate threshold for on stack replacement
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59
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60 static int InterpreterProfileLimit; // Profiling threshold scaled for interpreter use
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61
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62 typedef address (*Action)(methodHandle method, TRAPS);
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63
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64 enum PublicConstants {
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65 count_increment = count_grain, // use this value to increment the 32bit _counter word
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66 count_mask_value = count_mask // use this value to mask the backedge counter
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67 };
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68
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69 enum State {
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70 wait_for_nothing, // do nothing when count() > limit()
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71 wait_for_compile, // introduce nmethod when count() > limit()
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72 number_of_states // must be <= state_limit
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73 };
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74
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75 // Manipulation
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76 void reset(); // sets state to wait state
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77 void init(); // sets state into original state
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78 void set_state(State state); // sets state and initializes counter correspondingly
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79 inline void set(State state, int count); // sets state and counter
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80 inline void decay(); // decay counter (divide by two)
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81 void set_carry(); // set the sticky carry bit
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82
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83 // Accessors
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84 State state() const { return (State)(_counter & state_mask); }
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85 bool carry() const { return (_counter & carry_mask) != 0; }
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86 int limit() const { return CompileThreshold; }
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87 Action action() const { return _action[state()]; }
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88 int count() const { return _counter >> number_of_noncount_bits; }
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89
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90 int get_InvocationLimit() const { return InterpreterInvocationLimit >> number_of_noncount_bits; }
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91 int get_BackwardBranchLimit() const { return InterpreterBackwardBranchLimit >> number_of_noncount_bits; }
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92 int get_ProfileLimit() const { return InterpreterProfileLimit >> number_of_noncount_bits; }
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93
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94 // Test counter using scaled limits like the asm interpreter would do rather than doing
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95 // the shifts to normalize the counter.
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96
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97 bool reached_InvocationLimit() const { return _counter >= (unsigned int) InterpreterInvocationLimit; }
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98 bool reached_BackwardBranchLimit() const { return _counter >= (unsigned int) InterpreterBackwardBranchLimit; }
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99
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100 // Do this just like asm interpreter does for max speed
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101 bool reached_ProfileLimit(InvocationCounter *back_edge_count) const {
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102 return (_counter && count_mask) + back_edge_count->_counter >= (unsigned int) InterpreterProfileLimit;
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103 }
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104
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105 void increment() { _counter += count_increment; }
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106
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107
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108 // Printing
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109 void print();
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110 void print_short();
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111
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112 // Miscellaneous
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113 static ByteSize counter_offset() { return byte_offset_of(InvocationCounter, _counter); }
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114 static void reinitialize(bool delay_overflow);
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115
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116 private:
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117 static int _init [number_of_states]; // the counter limits
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118 static Action _action[number_of_states]; // the actions
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119
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120 static void def(State state, int init, Action action);
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121 static const char* state_as_string(State state);
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122 static const char* state_as_short_string(State state);
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123 };
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124
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125 inline void InvocationCounter::set(State state, int count) {
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126 assert(0 <= state && state < number_of_states, "illegal state");
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127 int carry = (_counter & carry_mask); // the carry bit is sticky
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128 _counter = (count << number_of_noncount_bits) | carry | state;
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129 }
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130
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131 inline void InvocationCounter::decay() {
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132 int c = count();
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133 int new_count = c >> 1;
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134 // prevent from going to zero, to distinguish from never-executed methods
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135 if (c > 0 && new_count == 0) new_count = 1;
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136 set(state(), new_count);
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137 }
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