/*

 * Copyright (c) 2010, 2011, 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

 * questions.

 *

 */

#include "precompiled.hpp"

#include "runtime/advancedThresholdPolicy.hpp"

#include "runtime/simpleThresholdPolicy.inline.hpp"

#ifdef TIERED

// Print an event.

void AdvancedThresholdPolicy::print_specific(EventType type, methodHandle mh, methodHandle imh,

                                             int bci, CompLevel level) {

  tty->print(" rate: ");

  if (mh->prev_time() == 0) tty->print("n/a");

  else tty->print("%f", mh->rate());

  tty->print(" k: %.2lf,%.2lf", threshold_scale(CompLevel_full_profile, Tier3LoadFeedback),

                                threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback));

}

void AdvancedThresholdPolicy::initialize() {

  // Turn on ergonomic compiler count selection

  if (FLAG_IS_DEFAULT(CICompilerCountPerCPU) && FLAG_IS_DEFAULT(CICompilerCount)) {

    FLAG_SET_DEFAULT(CICompilerCountPerCPU, true);

  }

  int count = CICompilerCount;

  if (CICompilerCountPerCPU) {

    // Simple log n seems to grow too slowly for tiered, try something faster: log n * log log n

    int log_cpu = log2_intptr(os::active_processor_count());

    int loglog_cpu = log2_intptr(MAX2(log_cpu, 1));

    count = MAX2(log_cpu * loglog_cpu, 1) * 3 / 2;

  }

  set_c1_count(MAX2(count / 3, 1));

  set_c2_count(MAX2(count - count / 3, 1));

  // Some inlining tuning

#ifdef X86

  if (FLAG_IS_DEFAULT(InlineSmallCode)) {

    FLAG_SET_DEFAULT(InlineSmallCode, 2000);

  }

#endif

#ifdef SPARC

  if (FLAG_IS_DEFAULT(InlineSmallCode)) {

    FLAG_SET_DEFAULT(InlineSmallCode, 2500);

  }

#endif

  set_start_time(os::javaTimeMillis());

}

// update_rate() is called from select_task() while holding a compile queue lock.

void AdvancedThresholdPolicy::update_rate(jlong t, methodOop m) {

  if (is_old(m)) {

    // We don't remove old methods from the queue,

    // so we can just zero the rate.

    m->set_rate(0);

    return;

  }

  // We don't update the rate if we've just came out of a safepoint.

  // delta_s is the time since last safepoint in milliseconds.

  jlong delta_s = t - SafepointSynchronize::end_of_last_safepoint();

  jlong delta_t = t - (m->prev_time() != 0 ? m->prev_time() : start_time()); // milliseconds since the last measurement

  // How many events were there since the last time?

  int event_count = m->invocation_count() + m->backedge_count();

  int delta_e = event_count - m->prev_event_count();

  // We should be running for at least 1ms.

  if (delta_s >= TieredRateUpdateMinTime) {

    // And we must've taken the previous point at least 1ms before.

    if (delta_t >= TieredRateUpdateMinTime && delta_e > 0) {

      m->set_prev_time(t);

      m->set_prev_event_count(event_count);

      m->set_rate((float)delta_e / (float)delta_t); // Rate is events per millisecond

    } else

      if (delta_t > TieredRateUpdateMaxTime && delta_e == 0) {

        // If nothing happened for 25ms, zero the rate. Don't modify prev values.

        m->set_rate(0);

      }

  }

}

// Check if this method has been stale from a given number of milliseconds.

// See select_task().

bool AdvancedThresholdPolicy::is_stale(jlong t, jlong timeout, methodOop m) {

  jlong delta_s = t - SafepointSynchronize::end_of_last_safepoint();

  jlong delta_t = t - m->prev_time();

  if (delta_t > timeout && delta_s > timeout) {

    int event_count = m->invocation_count() + m->backedge_count();

    int delta_e = event_count - m->prev_event_count();

    // Return true if there were no events.

    return delta_e == 0;

  }

  return false;

}

// We don't remove old methods from the compile queue even if they have

// very low activity. See select_task().

bool AdvancedThresholdPolicy::is_old(methodOop method) {

  return method->invocation_count() > 50000 || method->backedge_count() > 500000;

}

double AdvancedThresholdPolicy::weight(methodOop method) {

  return (method->rate() + 1) * ((method->invocation_count() + 1) *  (method->backedge_count() + 1));

}

// Apply heuristics and return true if x should be compiled before y

bool AdvancedThresholdPolicy::compare_methods(methodOop x, methodOop y) {

  if (x->highest_comp_level() > y->highest_comp_level()) {

    // recompilation after deopt

    return true;

  } else

    if (x->highest_comp_level() == y->highest_comp_level()) {

      if (weight(x) > weight(y)) {

        return true;

      }

    }

  return false;

}

// Is method profiled enough?

bool AdvancedThresholdPolicy::is_method_profiled(methodOop method) {

  methodDataOop mdo = method->method_data();

  if (mdo != NULL) {

    int i = mdo->invocation_count_delta();

    int b = mdo->backedge_count_delta();

    return call_predicate_helper<CompLevel_full_profile>(i, b, 1);

  }

  return false;

}

// Called with the queue locked and with at least one element

CompileTask* AdvancedThresholdPolicy::select_task(CompileQueue* compile_queue) {

  CompileTask *max_task = NULL;

  methodOop max_method;

  jlong t = os::javaTimeMillis();

  // Iterate through the queue and find a method with a maximum rate.

  for (CompileTask* task = compile_queue->first(); task != NULL;) {

    CompileTask* next_task = task->next();

    methodOop method = (methodOop)JNIHandles::resolve(task->method_handle());

    methodDataOop mdo = method->method_data();

    update_rate(t, method);

    if (max_task == NULL) {

      max_task = task;

      max_method = method;

    } else {

      // If a method has been stale for some time, remove it from the queue.

      if (is_stale(t, TieredCompileTaskTimeout, method) && !is_old(method)) {

        if (PrintTieredEvents) {

          print_event(KILL, method, method, task->osr_bci(), (CompLevel)task->comp_level());

        }

        CompileTaskWrapper ctw(task); // Frees the task

        compile_queue->remove(task);

        method->clear_queued_for_compilation();

        task = next_task;

        continue;

      }

      // Select a method with a higher rate

      if (compare_methods(method, max_method)) {

        max_task = task;

        max_method = method;

      }

    }

    task = next_task;

  }

  if (max_task->comp_level() == CompLevel_full_profile && is_method_profiled(max_method)) {

    max_task->set_comp_level(CompLevel_limited_profile);

    if (PrintTieredEvents) {

      print_event(UPDATE, max_method, max_method, max_task->osr_bci(), (CompLevel)max_task->comp_level());

    }

  }

  return max_task;

}

double AdvancedThresholdPolicy::threshold_scale(CompLevel level, int feedback_k) {

  double queue_size = CompileBroker::queue_size(level);

  int comp_count = compiler_count(level);

  double k = queue_size / (feedback_k * comp_count) + 1;

  return k;

}

// Call and loop predicates determine whether a transition to a higher

// compilation level should be performed (pointers to predicate functions

// are passed to common()).

// Tier?LoadFeedback is basically a coefficient that determines of

// how many methods per compiler thread can be in the queue before

// the threshold values double.

bool AdvancedThresholdPolicy::loop_predicate(int i, int b, CompLevel cur_level) {

  switch(cur_level) {

  case CompLevel_none:

  case CompLevel_limited_profile: {

    double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback);

    return loop_predicate_helper<CompLevel_none>(i, b, k);

  }

  case CompLevel_full_profile: {

    double k = threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback);

    return loop_predicate_helper<CompLevel_full_profile>(i, b, k);

  }

  default:

    return true;

  }

}

bool AdvancedThresholdPolicy::call_predicate(int i, int b, CompLevel cur_level) {

  switch(cur_level) {

  case CompLevel_none:

  case CompLevel_limited_profile: {

    double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback);

    return call_predicate_helper<CompLevel_none>(i, b, k);

  }

  case CompLevel_full_profile: {

    double k = threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback);

    return call_predicate_helper<CompLevel_full_profile>(i, b, k);

  }

  default:

    return true;

  }

}

// If a method is old enough and is still in the interpreter we would want to

// start profiling without waiting for the compiled method to arrive.

// We also take the load on compilers into the account.

bool AdvancedThresholdPolicy::should_create_mdo(methodOop method, CompLevel cur_level) {

  if (cur_level == CompLevel_none &&

      CompileBroker::queue_size(CompLevel_full_optimization) <=

      Tier3DelayOn * compiler_count(CompLevel_full_optimization)) {

    int i = method->invocation_count();

    int b = method->backedge_count();

    double k = Tier0ProfilingStartPercentage / 100.0;

    return call_predicate_helper<CompLevel_none>(i, b, k) || loop_predicate_helper<CompLevel_none>(i, b, k);

  }

  return false;

}

// Create MDO if necessary.

void AdvancedThresholdPolicy::create_mdo(methodHandle mh, TRAPS) {

  if (mh->is_native() || mh->is_abstract() || mh->is_accessor()) return;

  if (mh->method_data() == NULL) {

    methodOopDesc::build_interpreter_method_data(mh, THREAD);

    if (HAS_PENDING_EXCEPTION) {

      CLEAR_PENDING_EXCEPTION;

    }

  }

}

/*

 * Method states:

 *   0 - interpreter (CompLevel_none)

 *   1 - pure C1 (CompLevel_simple)

 *   2 - C1 with invocation and backedge counting (CompLevel_limited_profile)

 *   3 - C1 with full profiling (CompLevel_full_profile)

 *   4 - C2 (CompLevel_full_optimization)

 *

 * Common state transition patterns:

 * a. 0 -> 3 -> 4.

 *    The most common path. But note that even in this straightforward case

 *    profiling can start at level 0 and finish at level 3.

 *

 * b. 0 -> 2 -> 3 -> 4.

 *    This case occures when the load on C2 is deemed too high. So, instead of transitioning

 *    into state 3 directly and over-profiling while a method is in the C2 queue we transition to

 *    level 2 and wait until the load on C2 decreases. This path is disabled for OSRs.

 *

 * c. 0 -> (3->2) -> 4.

 *    In this case we enqueue a method for compilation at level 3, but the C1 queue is long enough

 *    to enable the profiling to fully occur at level 0. In this case we change the compilation level

 *    of the method to 2, because it'll allow it to run much faster without full profiling while c2

 *    is compiling.

 *

 * d. 0 -> 3 -> 1 or 0 -> 2 -> 1.

 *    After a method was once compiled with C1 it can be identified as trivial and be compiled to

 *    level 1. These transition can also occur if a method can't be compiled with C2 but can with C1.

 *

 * e. 0 -> 4.

 *    This can happen if a method fails C1 compilation (it will still be profiled in the interpreter)

 *    or because of a deopt that didn't require reprofiling (compilation won't happen in this case because

 *    the compiled version already exists).

 *

 * Note that since state 0 can be reached from any other state via deoptimization different loops

 * are possible.

 *

 */

// Common transition function. Given a predicate determines if a method should transition to another level.

CompLevel AdvancedThresholdPolicy::common(Predicate p, methodOop method, CompLevel cur_level) {

  if (is_trivial(method)) return CompLevel_simple;

  CompLevel next_level = cur_level;

  int i = method->invocation_count();

  int b = method->backedge_count();

  switch(cur_level) {

  case CompLevel_none:

    // If we were at full profile level, would we switch to full opt?

    if (common(p, method, CompLevel_full_profile) == CompLevel_full_optimization) {

      next_level = CompLevel_full_optimization;

    } else if ((this->*p)(i, b, cur_level)) {

      // C1-generated fully profiled code is about 30% slower than the limited profile

      // code that has only invocation and backedge counters. The observation is that

      // if C2 queue is large enough we can spend too much time in the fully profiled code

      // while waiting for C2 to pick the method from the queue. To alleviate this problem

      // we introduce a feedback on the C2 queue size. If the C2 queue is sufficiently long

      // we choose to compile a limited profiled version and then recompile with full profiling

      // when the load on C2 goes down.

      if (CompileBroker::queue_size(CompLevel_full_optimization) >

          Tier3DelayOn * compiler_count(CompLevel_full_optimization)) {

        next_level = CompLevel_limited_profile;

      } else {

        next_level = CompLevel_full_profile;

      }

    }

    break;

  case CompLevel_limited_profile:

    if (is_method_profiled(method)) {

      // Special case: we got here because this method was fully profiled in the interpreter.

      next_level = CompLevel_full_optimization;

    } else {

      methodDataOop mdo = method->method_data();

      if (mdo != NULL) {

        if (mdo->would_profile()) {

          if (CompileBroker::queue_size(CompLevel_full_optimization) <=

              Tier3DelayOff * compiler_count(CompLevel_full_optimization) &&

              (this->*p)(i, b, cur_level)) {

            next_level = CompLevel_full_profile;

          }

        } else {

          next_level = CompLevel_full_optimization;

        }

      }

    }

    break;

  case CompLevel_full_profile:

    {

      methodDataOop mdo = method->method_data();

      if (mdo != NULL) {

        if (mdo->would_profile()) {

          int mdo_i = mdo->invocation_count_delta();

          int mdo_b = mdo->backedge_count_delta();

          if ((this->*p)(mdo_i, mdo_b, cur_level)) {

            next_level = CompLevel_full_optimization;

          }

        } else {

          next_level = CompLevel_full_optimization;

        }

      }

    }

    break;

  }

  return next_level;

}

// Determine if a method should be compiled with a normal entry point at a different level.

  CompLevel next_level = common(&AdvancedThresholdPolicy::call_predicate, method, cur_level);

  // If OSR method level is greater than the regular method level, the levels should be

  // equalized by raising the regular method level in order to avoid OSRs during each

  // invocation of the method.

  if (osr_level == CompLevel_full_optimization && cur_level == CompLevel_full_profile) {

    methodDataOop mdo = method->method_data();

    guarantee(mdo != NULL, "MDO should not be NULL");

    if (mdo->invocation_count() >= 1) {

      next_level = CompLevel_full_optimization;

    }

  } else {

    next_level = MAX2(osr_level, next_level);

  }

  return next_level;

}

// Determine if we should do an OSR compilation of a given method.

CompLevel AdvancedThresholdPolicy::loop_event(methodOop method, CompLevel cur_level) {

  if (cur_level == CompLevel_none) {

    // If there is a live OSR method that means that we deopted to the interpreter

    // for the transition.

    if (osr_level > CompLevel_none) {

      return osr_level;

    }

  }

}

// Update the rate and submit compile

void AdvancedThresholdPolicy::submit_compile(methodHandle mh, int bci, CompLevel level, TRAPS) {

  int hot_count = (bci == InvocationEntryBci) ? mh->invocation_count() : mh->backedge_count();

  update_rate(os::javaTimeMillis(), mh());

  CompileBroker::compile_method(mh, bci, level, mh, hot_count, "tiered", THREAD);

}

// Handle the invocation event.

void AdvancedThresholdPolicy::method_invocation_event(methodHandle mh, methodHandle imh,

                                                      CompLevel level, TRAPS) {

  if (should_create_mdo(mh(), level)) {

    create_mdo(mh, THREAD);

  }

  if (is_compilation_enabled() && !CompileBroker::compilation_is_in_queue(mh, InvocationEntryBci)) {

    CompLevel next_level = call_event(mh(), level);

    if (next_level != level) {

      compile(mh, InvocationEntryBci, next_level, THREAD);

    }

  }

}

// Handle the back branch event. Notice that we can compile the method

// with a regular entry from here.

void AdvancedThresholdPolicy::method_back_branch_event(methodHandle mh, methodHandle imh,

                                                       int bci, CompLevel level, TRAPS) {

  if (should_create_mdo(mh(), level)) {

    create_mdo(mh, THREAD);

  }

  // If the method is already compiling, quickly bail out.

  if (is_compilation_enabled() && !CompileBroker::compilation_is_in_queue(mh, bci)) {

    // Use loop event as an opportinity to also check there's been

    // enough calls.

    CompLevel cur_level = comp_level(mh());

    CompLevel next_level = call_event(mh(), cur_level);

    CompLevel next_osr_level = loop_event(mh(), level);

    if (next_osr_level  == CompLevel_limited_profile) {

      next_osr_level = CompLevel_full_profile; // OSRs are supposed to be for very hot methods.

    }

    next_level = MAX2(next_level,

                      next_osr_level < CompLevel_full_optimization ? next_osr_level : cur_level);

    bool is_compiling = false;

    if (next_level != cur_level) {

      compile(mh, InvocationEntryBci, next_level, THREAD);

      is_compiling = true;

    }

    // Do the OSR version

    if (!is_compiling && next_osr_level != level) {

      compile(mh, bci, next_osr_level, THREAD);

    }

  }

}

#endif // TIERED