1/*
2 * Copyright (c) 1997, 2012, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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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 *
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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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 count() > limit().
40
41class InvocationCounter VALUE_OBJ_CLASS_SPEC {
42  friend class VMStructs;
43  friend class JVMCIVMStructs;
44  friend class ciReplay;
45 private:                             // bit no: |31  3|  2  | 1 0 |
46  unsigned int _counter;              // format: [count|carry|state]
47
48  enum PrivateConstants {
49    number_of_state_bits = 2,
50    number_of_carry_bits = 1,
51    number_of_noncount_bits = number_of_state_bits + number_of_carry_bits,
52    state_limit          = nth_bit(number_of_state_bits),
53    count_grain          = nth_bit(number_of_state_bits + number_of_carry_bits),
54    carry_mask           = right_n_bits(number_of_carry_bits) << number_of_state_bits,
55    state_mask           = right_n_bits(number_of_state_bits),
56    status_mask          = right_n_bits(number_of_state_bits + number_of_carry_bits),
57    count_mask           = ((int)(-1) ^ status_mask)
58  };
59
60 public:
61  static int InterpreterInvocationLimit;        // CompileThreshold scaled for interpreter use
62  static int InterpreterBackwardBranchLimit;    // A separate threshold for on stack replacement
63  static int InterpreterProfileLimit;           // Profiling threshold scaled for interpreter use
64
65  typedef address (*Action)(methodHandle method, TRAPS);
66
67  enum PublicConstants {
68    count_increment      = count_grain,          // use this value to increment the 32bit _counter word
69    count_mask_value     = count_mask,           // use this value to mask the backedge counter
70    count_shift          = number_of_noncount_bits,
71    number_of_count_bits = BitsPerInt - number_of_noncount_bits,
72    count_limit          = nth_bit(number_of_count_bits - 1)
73  };
74
75  enum State {
76    wait_for_nothing,                            // do nothing when count() > limit()
77    wait_for_compile,                            // introduce nmethod when count() > limit()
78    number_of_states                             // must be <= state_limit
79  };
80
81  // Manipulation
82  void reset();                                  // sets state to wait state
83  void init();                                   // sets state into original state
84  void set_state(State state);                   // sets state and initializes counter correspondingly
85  inline void set(State state, int count);       // sets state and counter
86  inline void decay();                           // decay counter (divide by two)
87  void set_carry();                              // set the sticky carry bit
88  void set_carry_flag()                          {  _counter |= carry_mask; }
89
90  int raw_counter()                              { return _counter; }
91
92  // Accessors
93  State  state() const                           { return (State)(_counter & state_mask); }
94  bool   carry() const                           { return (_counter & carry_mask) != 0; }
95  int    limit() const                           { return CompileThreshold; }
96  Action action() const                          { return _action[state()]; }
97  int    count() const                           { return _counter >> number_of_noncount_bits; }
98
99  int   get_InvocationLimit() const              { return InterpreterInvocationLimit >> number_of_noncount_bits; }
100  int   get_BackwardBranchLimit() const          { return InterpreterBackwardBranchLimit >> number_of_noncount_bits; }
101  int   get_ProfileLimit() const                 { return InterpreterProfileLimit >> number_of_noncount_bits; }
102
103#ifdef CC_INTERP
104  // Test counter using scaled limits like the asm interpreter would do rather than doing
105  // the shifts to normalize the counter.
106  // Checks sum of invocation_counter and backedge_counter as the template interpreter does.
107  bool reached_InvocationLimit(InvocationCounter *back_edge_count) const {
108    return (_counter & count_mask) + (back_edge_count->_counter & count_mask) >=
109           (unsigned int) InterpreterInvocationLimit;
110  }
111  bool reached_BackwardBranchLimit(InvocationCounter *back_edge_count) const {
112    return (_counter & count_mask) + (back_edge_count->_counter & count_mask) >=
113           (unsigned int) InterpreterBackwardBranchLimit;
114  }
115  // Do this just like asm interpreter does for max speed.
116  bool reached_ProfileLimit(InvocationCounter *back_edge_count) const {
117    return (_counter & count_mask) + (back_edge_count->_counter & count_mask) >=
118           (unsigned int) InterpreterProfileLimit;
119  }
120#endif // CC_INTERP
121
122  void increment()                               { _counter += count_increment; }
123
124
125  // Printing
126  void   print();
127  void   print_short();
128
129  // Miscellaneous
130  static ByteSize counter_offset()               { return byte_offset_of(InvocationCounter, _counter); }
131  static void reinitialize(bool delay_overflow);
132
133 private:
134  static int         _init  [number_of_states];  // the counter limits
135  static Action      _action[number_of_states];  // the actions
136
137  static void        def(State state, int init, Action action);
138  static const char* state_as_string(State state);
139  static const char* state_as_short_string(State state);
140};
141
142inline void InvocationCounter::set(State state, int count) {
143  assert(0 <= state && state < number_of_states, "illegal state");
144  int carry = (_counter & carry_mask);    // the carry bit is sticky
145  _counter = (count << number_of_noncount_bits) | carry | state;
146}
147
148inline void InvocationCounter::decay() {
149  int c = count();
150  int new_count = c >> 1;
151  // prevent from going to zero, to distinguish from never-executed methods
152  if (c > 0 && new_count == 0) new_count = 1;
153  set(state(), new_count);
154}
155
156
157#endif // SHARE_VM_INTERPRETER_INVOCATIONCOUNTER_HPP
158