/*

 * Copyright (c) 2010, 2017, 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 "code/codeCache.hpp"

#include "runtime/advancedThresholdPolicy.hpp"

#include "runtime/simpleThresholdPolicy.inline.hpp"

#if INCLUDE_JVMCI

#include "jvmci/jvmciRuntime.hpp"

#endif

#ifdef TIERED

// Print an event.

                                             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() {

  int count = CICompilerCount;

#ifdef _LP64

  // Turn on ergonomic compiler count selection

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

    FLAG_SET_DEFAULT(CICompilerCountPerCPU, true);

  }

  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 * 3 / 2, 2);

    FLAG_SET_ERGO(intx, CICompilerCount, count);

  }

#else

  // On 32-bit systems, the number of compiler threads is limited to 3.

  // On these systems, the virtual address space available to the JVM

  // is usually limited to 2-4 GB (the exact value depends on the platform).

  // As the compilers (especially C2) can consume a large amount of

  // memory, scaling the number of compiler threads with the number of

  // available cores can result in the exhaustion of the address space

  /// available to the VM and thus cause the VM to crash.

  if (FLAG_IS_DEFAULT(CICompilerCount)) {

    count = 3;

    FLAG_SET_ERGO(intx, CICompilerCount, count);

  }

#endif

  if (TieredStopAtLevel < CompLevel_full_optimization) {

    // No C2 compiler thread required

    set_c1_count(count);

  } else {

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

    set_c2_count(MAX2(count - c1_count(), 1));

  }

  assert(count == c1_count() + c2_count(), "inconsistent compiler thread count");

  // Some inlining tuning

#ifdef X86

  if (FLAG_IS_DEFAULT(InlineSmallCode)) {

    FLAG_SET_DEFAULT(InlineSmallCode, 2000);

  }

#endif

#if defined SPARC || defined AARCH64

  if (FLAG_IS_DEFAULT(InlineSmallCode)) {

    FLAG_SET_DEFAULT(InlineSmallCode, 2500);

  }

#endif

  set_increase_threshold_at_ratio();

  set_start_time(os::javaTimeMillis());

}

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

void AdvancedThresholdPolicy::update_rate(jlong t, Method* m) {

  // Skip update if counters are absent.

  // Can't allocate them since we are holding compile queue lock.

  if (m->method_counters() == NULL)  return;

  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, Method* 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(Method* method) {

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

}

double AdvancedThresholdPolicy::weight(Method* method) {

  return (double)(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(Method* x, Method* 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(Method* method) {

  MethodData* 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, method);

  }

  return false;

}

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

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

  CompileTask *max_blocking_task = NULL;

  CompileTask *max_task = NULL;

  Method* max_method = NULL;

  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();

    Method* method = task->method();

    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.

      // Blocking tasks and tasks submitted from whitebox API don't become stale

      if (task->can_become_stale() && is_stale(t, TieredCompileTaskTimeout, method) && !is_old(method)) {

        if (PrintTieredEvents) {

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

        }

        compile_queue->remove_and_mark_stale(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;

      }

    }

    if (task->is_blocking()) {

      if (max_blocking_task == NULL || compare_methods(method, max_blocking_task->method())) {

        max_blocking_task = task;

      }

    }

    task = next_task;

  }

  if (max_blocking_task != NULL) {

    // In blocking compilation mode, the CompileBroker will make

    // compilations submitted by a JVMCI compiler thread non-blocking. These

    // compilations should be scheduled after all blocking compilations

    // to service non-compiler related compilations sooner and reduce the

    // chance of such compilations timing out.

    max_task = max_blocking_task;

    max_method = max_task->method();

  }

  if (max_task->comp_level() == CompLevel_full_profile && TieredStopAtLevel > CompLevel_full_profile

      && is_method_profiled(max_method)) {

    max_task->set_comp_level(CompLevel_limited_profile);

    if (PrintTieredEvents) {

      print_event(UPDATE_IN_QUEUE, 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;

  // Increase C1 compile threshold when the code cache is filled more

  // than specified by IncreaseFirstTierCompileThresholdAt percentage.

  // The main intention is to keep enough free space for C2 compiled code

  // to achieve peak performance if the code cache is under stress.

  if ((TieredStopAtLevel == CompLevel_full_optimization) && (level != CompLevel_full_optimization))  {

    double current_reverse_free_ratio = CodeCache::reverse_free_ratio(CodeCache::get_code_blob_type(level));

    if (current_reverse_free_ratio > _increase_threshold_at_ratio) {

      k *= exp(current_reverse_free_ratio - _increase_threshold_at_ratio);

    }

  }

  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, Method* method) {

  switch(cur_level) {

  case CompLevel_aot: {

    double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback);

    return loop_predicate_helper<CompLevel_aot>(i, b, k, method);

  }

  case CompLevel_none:

  case CompLevel_limited_profile: {

    double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback);

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

  }

  case CompLevel_full_profile: {

    double k = threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback);

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

  }

  default:

    return true;

  }

}

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

  switch(cur_level) {

  case CompLevel_aot: {

    double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback);

    return call_predicate_helper<CompLevel_aot>(i, b, k, method);

  }

  case CompLevel_none:

  case CompLevel_limited_profile: {

    double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback);

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

  }

  case CompLevel_full_profile: {

    double k = threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback);

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

  }

  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(Method* 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, method) || loop_predicate_helper<CompLevel_none>(i, b, k, method);

  }

  return false;

}

// Inlining control: if we're compiling a profiled method with C1 and the callee

// is known to have OSRed in a C2 version, don't inline it.

bool AdvancedThresholdPolicy::should_not_inline(ciEnv* env, ciMethod* callee) {

  CompLevel comp_level = (CompLevel)env->comp_level();

  if (comp_level == CompLevel_full_profile ||

      comp_level == CompLevel_limited_profile) {

    return callee->highest_osr_comp_level() == CompLevel_full_optimization;

  }

  return false;

}

// Create MDO if necessary.

  if (mh->is_native() ||

      mh->is_abstract() ||

      mh->is_accessor() ||

      mh->is_constant_getter()) {

    return;

  }

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

    Method::build_interpreter_method_data(mh, CHECK_AND_CLEAR);

  }

}

/*

 * 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 occurs 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 while the request is still in-queue, 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, Method* method, CompLevel cur_level, bool disable_feedback) {

  CompLevel next_level = cur_level;

  int i = method->invocation_count();

  int b = method->backedge_count();

  if (is_trivial(method)) {

    next_level = CompLevel_simple;

  } else {

    switch(cur_level) {

      default: break;

      case CompLevel_aot: {

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

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

        next_level = CompLevel_full_optimization;

      } else if (disable_feedback || (CompileBroker::queue_size(CompLevel_full_optimization) <=

                               Tier3DelayOff * compiler_count(CompLevel_full_optimization) &&

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

        next_level = CompLevel_full_profile;

      }

    }

    break;

    case CompLevel_none:

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

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

        next_level = CompLevel_full_optimization;

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

#if INCLUDE_JVMCI

        if (EnableJVMCI && UseJVMCICompiler) {

          // Since JVMCI takes a while to warm up, its queue inevitably backs up during

          // early VM execution. As of 2014-06-13, JVMCI's inliner assumes that the root

          // compilation method and all potential inlinees have mature profiles (which

          // includes type profiling). If it sees immature profiles, JVMCI's inliner

          // can perform pathologically bad (e.g., causing OutOfMemoryErrors due to

          // exploring/inlining too many graphs). Since a rewrite of the inliner is

          // in progress, we simply disable the dialing back heuristic for now and will

          // revisit this decision once the new inliner is completed.

          next_level = CompLevel_full_profile;

        } else

#endif

        {

          // 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 (!disable_feedback && 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 {

        MethodData* mdo = method->method_data();

        if (mdo != NULL) {

          if (mdo->would_profile()) {

            if (disable_feedback || (CompileBroker::queue_size(CompLevel_full_optimization) <=

                                     Tier3DelayOff * compiler_count(CompLevel_full_optimization) &&

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

              next_level = CompLevel_full_profile;

            }

          } else {

            next_level = CompLevel_full_optimization;

          }

        } else {

          // If there is no MDO we need to profile

          if (disable_feedback || (CompileBroker::queue_size(CompLevel_full_optimization) <=

                                   Tier3DelayOff * compiler_count(CompLevel_full_optimization) &&

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

            next_level = CompLevel_full_profile;

          }

        }

      }

      break;

    case CompLevel_full_profile:

      {

        MethodData* 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, method)) {

              next_level = CompLevel_full_optimization;

            }

          } else {

            next_level = CompLevel_full_optimization;

          }

        }

      }

      break;

    }

  }

  return MIN2(next_level, (CompLevel)TieredStopAtLevel);

}

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

CompLevel AdvancedThresholdPolicy::call_event(Method* method, CompLevel cur_level, JavaThread * thread) {

  CompLevel osr_level = MIN2((CompLevel) method->highest_osr_comp_level(),

                             common(&AdvancedThresholdPolicy::loop_predicate, method, cur_level, true));

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