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 /*

  * Copyright (c) 2014, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

  * or visit www.oracle.com if you need additional information or have any

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  */

 #ifndef SHARE_VM_RUNTIME_RTMLOCKING_HPP

 #define SHARE_VM_RUNTIME_RTMLOCKING_HPP

 // Generate RTM (Restricted Transactional Memory) locking code for all inflated

 // locks when "UseRTMLocking" option is on with normal locking mechanism as fall back

 // handler.

 //

 // On abort/lock busy the lock will be retried a fixed number of times under RTM

 // as specified by "RTMRetryCount" option. The locks which abort too often

 // can be auto tuned or manually tuned.

 //

 // Auto-tuning can be done on an option like UseRTMDeopt and it will need abort

 // ratio calculation for each lock. The abort ratio will be calculated after

 // "RTMAbortThreshold" number of aborts is reached. The formulas are:

 //

 //     Aborted transactions = abort_count * 100

 //     All transactions = total_count *  RTMTotalCountIncrRate

 //

 //     Aborted transactions >= All transactions * RTMAbortRatio

 //

 // If "UseRTMDeopt" is on and the aborts ratio reaches "RTMAbortRatio"

 // the method containing the lock will be deoptimized and recompiled with

 // all locks as normal locks. If the abort ratio continues to remain low after

 // "RTMLockingThreshold" locks are attempted, then the method will be deoptimized

 // and recompiled with all locks as RTM locks without abort ratio calculation code.

 // The abort ratio calculation can be delayed by specifying flag

 // -XX:RTMLockingCalculationDelay in millisecond.

 //

 // For manual tuning the abort statistics for each lock needs to be provided

 // to the user on some JVM option like "PrintPreciseRTMLockingStatistics".

 // Based on the abort statistics users can create a .hotspot_compiler file

 // or use -XX:CompileCommand=option,class::method,NoRTMLockEliding

 // to specify for which methods to disable RTM locking.

 //

 // When UseRTMForStackLocks option is enabled along with UseRTMLocking option,

 // the RTM locking code is generated for stack locks too.

 // The retries, auto-tuning support and rtm locking statistics are all

 // supported for stack locks just like inflated locks.

 // RTM locking counters

 class RTMLockingCounters VALUE_OBJ_CLASS_SPEC {

  private:

   uintx _total_count; // Total RTM locks count

   uintx _abort_count; // Total aborts count

  public:

   enum { ABORT_STATUS_LIMIT = 6 };

   // Counters per RTM Abort Status. Incremented with +PrintPreciseRTMLockingStatistics

   // RTM uses the EAX register to communicate abort status to software.

   // Following an RTM abort the EAX register has the following definition.

   //

   //   EAX register bit position   Meaning

   //     0     Set if abort caused by XABORT instruction.

   //     1     If set, the transaction may succeed on a retry. This bit is always clear if bit 0 is set.

   //     2     Set if another logical processor conflicted with a memory address that was part of the transaction that aborted.

   //     3     Set if an internal buffer overflowed.

   //     4     Set if a debug breakpoint was hit.

   //     5     Set if an abort occurred during execution of a nested transaction.

  private:

   uintx _abortX_count[ABORT_STATUS_LIMIT];

  public:

   static uintx _calculation_flag;

   static uintx* rtm_calculation_flag_addr() { return &_calculation_flag; }

   static void init();

   RTMLockingCounters() : _total_count(0), _abort_count(0) {

     for (int i = 0; i < ABORT_STATUS_LIMIT; i++) {

       _abortX_count[i] = 0;

     }

   }

   uintx* total_count_addr()               { return &_total_count; }

   uintx* abort_count_addr()               { return &_abort_count; }

   uintx* abortX_count_addr()              { return &_abortX_count[0]; }

   static int total_count_offset()         { return (int)offset_of(RTMLockingCounters, _total_count); }

   static int abort_count_offset()         { return (int)offset_of(RTMLockingCounters, _abort_count); }

   static int abortX_count_offset()        { return (int)offset_of(RTMLockingCounters, _abortX_count[0]); }

   bool nonzero() {  return (_abort_count + _total_count) > 0; }

   void print_on(outputStream* st);

   void print() { print_on(tty); }

 };

 #endif // SHARE_VM_RUNTIME_RTMLOCKING_HPP