Mercurial > hg > truffle
view src/share/vm/interpreter/invocationCounter.hpp @ 452:00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
Summary: When we encounter marking stack overflow during precleaning of Reference lists, we were using the overflow list mechanism, which can cause problems on account of mutating the mark word of the header because of conflicts with mutator accesses and updates of that field. Instead we should use the usual mechanism for overflow handling in concurrent phases, namely dirtying of the card on which the overflowed object lies. Since precleaning effectively does a form of discovered list processing, albeit with discovery enabled, we needed to adjust some code to be correct in the face of interleaved processing and discovery.
Reviewed-by: apetrusenko, jcoomes
author | ysr |
---|---|
date | Thu, 20 Nov 2008 12:27:41 -0800 |
parents | a61af66fc99e |
children | c18cbe5936b8 |
line wrap: on
line source
/* * Copyright 1997-2006 Sun Microsystems, Inc. All Rights Reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, * CA 95054 USA or visit www.sun.com if you need additional information or * have any questions. * */ // InvocationCounters are used to trigger actions when a limit (threshold) is reached. // For different states, different limits and actions can be defined in the initialization // routine of InvocationCounters. // // Implementation notes: For space reasons, state & counter are both encoded in one word, // The state is encoded using some of the least significant bits, the counter is using the // more significant bits. The counter is incremented before a method is activated and an // action is triggered when when count() > limit(). class InvocationCounter VALUE_OBJ_CLASS_SPEC { friend class VMStructs; private: // bit no: |31 3| 2 | 1 0 | unsigned int _counter; // format: [count|carry|state] enum PrivateConstants { number_of_state_bits = 2, number_of_carry_bits = 1, number_of_noncount_bits = number_of_state_bits + number_of_carry_bits, number_of_count_bits = BitsPerInt - number_of_noncount_bits, state_limit = nth_bit(number_of_state_bits), count_grain = nth_bit(number_of_state_bits + number_of_carry_bits), count_limit = nth_bit(number_of_count_bits - 1), carry_mask = right_n_bits(number_of_carry_bits) << number_of_state_bits, state_mask = right_n_bits(number_of_state_bits), status_mask = right_n_bits(number_of_state_bits + number_of_carry_bits), count_mask = ((int)(-1) ^ status_mask) }; public: static int InterpreterInvocationLimit; // CompileThreshold scaled for interpreter use static int Tier1InvocationLimit; // CompileThreshold scaled for tier1 use static int Tier1BackEdgeLimit; // BackEdgeThreshold scaled for tier1 use static int InterpreterBackwardBranchLimit; // A separate threshold for on stack replacement static int InterpreterProfileLimit; // Profiling threshold scaled for interpreter use typedef address (*Action)(methodHandle method, TRAPS); enum PublicConstants { count_increment = count_grain, // use this value to increment the 32bit _counter word count_mask_value = count_mask // use this value to mask the backedge counter }; enum State { wait_for_nothing, // do nothing when count() > limit() wait_for_compile, // introduce nmethod when count() > limit() number_of_states // must be <= state_limit }; // Manipulation void reset(); // sets state to wait state void init(); // sets state into original state void set_state(State state); // sets state and initializes counter correspondingly inline void set(State state, int count); // sets state and counter inline void decay(); // decay counter (divide by two) void set_carry(); // set the sticky carry bit // Accessors State state() const { return (State)(_counter & state_mask); } bool carry() const { return (_counter & carry_mask) != 0; } int limit() const { return CompileThreshold; } Action action() const { return _action[state()]; } int count() const { return _counter >> number_of_noncount_bits; } int get_InvocationLimit() const { return InterpreterInvocationLimit >> number_of_noncount_bits; } int get_BackwardBranchLimit() const { return InterpreterBackwardBranchLimit >> number_of_noncount_bits; } int get_ProfileLimit() const { return InterpreterProfileLimit >> number_of_noncount_bits; } // Test counter using scaled limits like the asm interpreter would do rather than doing // the shifts to normalize the counter. bool reached_InvocationLimit() const { return _counter >= (unsigned int) InterpreterInvocationLimit; } bool reached_BackwardBranchLimit() const { return _counter >= (unsigned int) InterpreterBackwardBranchLimit; } // Do this just like asm interpreter does for max speed bool reached_ProfileLimit(InvocationCounter *back_edge_count) const { return (_counter && count_mask) + back_edge_count->_counter >= (unsigned int) InterpreterProfileLimit; } void increment() { _counter += count_increment; } // Printing void print(); void print_short(); // Miscellaneous static ByteSize counter_offset() { return byte_offset_of(InvocationCounter, _counter); } static void reinitialize(bool delay_overflow); private: static int _init [number_of_states]; // the counter limits static Action _action[number_of_states]; // the actions static void def(State state, int init, Action action); static const char* state_as_string(State state); static const char* state_as_short_string(State state); }; inline void InvocationCounter::set(State state, int count) { assert(0 <= state && state < number_of_states, "illegal state"); int carry = (_counter & carry_mask); // the carry bit is sticky _counter = (count << number_of_noncount_bits) | carry | state; } inline void InvocationCounter::decay() { int c = count(); int new_count = c >> 1; // prevent from going to zero, to distinguish from never-executed methods if (c > 0 && new_count == 0) new_count = 1; set(state(), new_count); }