author | rbackman |
Tue, 06 Mar 2012 12:36:59 +0100 | |
changeset 12377 | ae6def2813e0 |
parent 7397 | 5b173b4ca846 |
child 14477 | 95e66ea71f71 |
permissions | -rw-r--r-- |
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/* |
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* Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved. |
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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* |
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* This code is free software; you can redistribute it and/or modify it |
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* under the terms of the GNU General Public License version 2 only, as |
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* published by the Free Software Foundation. |
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* |
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* This code is distributed in the hope that it will be useful, but WITHOUT |
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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* version 2 for more details (a copy is included in the LICENSE file that |
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* accompanied this code). |
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* |
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* You should have received a copy of the GNU General Public License version |
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* 2 along with this work; if not, write to the Free Software Foundation, |
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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* |
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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* or visit www.oracle.com if you need additional information or have any |
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* questions. |
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* |
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*/ |
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#ifndef SHARE_VM_INTERPRETER_INVOCATIONCOUNTER_HPP |
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#define SHARE_VM_INTERPRETER_INVOCATIONCOUNTER_HPP |
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#include "memory/allocation.hpp" |
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#include "runtime/handles.hpp" |
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#include "utilities/exceptions.hpp" |
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// InvocationCounters are used to trigger actions when a limit (threshold) is reached. |
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// For different states, different limits and actions can be defined in the initialization |
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// routine of InvocationCounters. |
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// |
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// Implementation notes: For space reasons, state & counter are both encoded in one word, |
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// The state is encoded using some of the least significant bits, the counter is using the |
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// more significant bits. The counter is incremented before a method is activated and an |
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// action is triggered when when count() > limit(). |
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class InvocationCounter VALUE_OBJ_CLASS_SPEC { |
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friend class VMStructs; |
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private: // bit no: |31 3| 2 | 1 0 | |
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unsigned int _counter; // format: [count|carry|state] |
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enum PrivateConstants { |
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number_of_state_bits = 2, |
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number_of_carry_bits = 1, |
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number_of_noncount_bits = number_of_state_bits + number_of_carry_bits, |
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number_of_count_bits = BitsPerInt - number_of_noncount_bits, |
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state_limit = nth_bit(number_of_state_bits), |
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count_grain = nth_bit(number_of_state_bits + number_of_carry_bits), |
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carry_mask = right_n_bits(number_of_carry_bits) << number_of_state_bits, |
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state_mask = right_n_bits(number_of_state_bits), |
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status_mask = right_n_bits(number_of_state_bits + number_of_carry_bits), |
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count_mask = ((int)(-1) ^ status_mask) |
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}; |
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public: |
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static int InterpreterInvocationLimit; // CompileThreshold scaled for interpreter use |
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static int InterpreterBackwardBranchLimit; // A separate threshold for on stack replacement |
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static int InterpreterProfileLimit; // Profiling threshold scaled for interpreter use |
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typedef address (*Action)(methodHandle method, TRAPS); |
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enum PublicConstants { |
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count_increment = count_grain, // use this value to increment the 32bit _counter word |
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count_mask_value = count_mask, // use this value to mask the backedge counter |
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count_shift = number_of_noncount_bits, |
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count_limit = nth_bit(number_of_count_bits - 1) |
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}; |
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enum State { |
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wait_for_nothing, // do nothing when count() > limit() |
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wait_for_compile, // introduce nmethod when count() > limit() |
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number_of_states // must be <= state_limit |
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}; |
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// Manipulation |
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void reset(); // sets state to wait state |
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void init(); // sets state into original state |
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void set_state(State state); // sets state and initializes counter correspondingly |
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inline void set(State state, int count); // sets state and counter |
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inline void decay(); // decay counter (divide by two) |
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void set_carry(); // set the sticky carry bit |
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void set_carry_flag() { _counter |= carry_mask; } |
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// Accessors |
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State state() const { return (State)(_counter & state_mask); } |
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bool carry() const { return (_counter & carry_mask) != 0; } |
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int limit() const { return CompileThreshold; } |
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Action action() const { return _action[state()]; } |
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int count() const { return _counter >> number_of_noncount_bits; } |
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int get_InvocationLimit() const { return InterpreterInvocationLimit >> number_of_noncount_bits; } |
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int get_BackwardBranchLimit() const { return InterpreterBackwardBranchLimit >> number_of_noncount_bits; } |
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int get_ProfileLimit() const { return InterpreterProfileLimit >> number_of_noncount_bits; } |
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// Test counter using scaled limits like the asm interpreter would do rather than doing |
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// the shifts to normalize the counter. |
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bool reached_InvocationLimit() const { return _counter >= (unsigned int) InterpreterInvocationLimit; } |
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bool reached_BackwardBranchLimit() const { return _counter >= (unsigned int) InterpreterBackwardBranchLimit; } |
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// Do this just like asm interpreter does for max speed |
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bool reached_ProfileLimit(InvocationCounter *back_edge_count) const { |
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return (_counter && count_mask) + back_edge_count->_counter >= (unsigned int) InterpreterProfileLimit; |
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} |
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void increment() { _counter += count_increment; } |
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// Printing |
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void print(); |
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void print_short(); |
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// Miscellaneous |
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static ByteSize counter_offset() { return byte_offset_of(InvocationCounter, _counter); } |
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static void reinitialize(bool delay_overflow); |
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private: |
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static int _init [number_of_states]; // the counter limits |
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static Action _action[number_of_states]; // the actions |
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static void def(State state, int init, Action action); |
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static const char* state_as_string(State state); |
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static const char* state_as_short_string(State state); |
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}; |
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inline void InvocationCounter::set(State state, int count) { |
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assert(0 <= state && state < number_of_states, "illegal state"); |
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int carry = (_counter & carry_mask); // the carry bit is sticky |
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_counter = (count << number_of_noncount_bits) | carry | state; |
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} |
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inline void InvocationCounter::decay() { |
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int c = count(); |
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int new_count = c >> 1; |
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// prevent from going to zero, to distinguish from never-executed methods |
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if (c > 0 && new_count == 0) new_count = 1; |
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set(state(), new_count); |
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} |
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#endif // SHARE_VM_INTERPRETER_INVOCATIONCOUNTER_HPP |