/*

 * Copyright (c) 2010, 2018, 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 "compiler/compileBroker.hpp"

#include "memory/resourceArea.hpp"

#include "runtime/arguments.hpp"

#include "runtime/handles.inline.hpp"

#include "runtime/safepointVerifiers.hpp"

#include "runtime/simpleThresholdPolicy.hpp"

#include "runtime/simpleThresholdPolicy.inline.hpp"

#include "code/scopeDesc.hpp"

#if INCLUDE_JVMCI

#include "jvmci/jvmciRuntime.hpp"

#endif

#ifdef TIERED

void SimpleThresholdPolicy::print_counters(const char* prefix, const methodHandle& mh) {

  int invocation_count = mh->invocation_count();

  int backedge_count = mh->backedge_count();

  MethodData* mdh = mh->method_data();

  int mdo_invocations = 0, mdo_backedges = 0;

  int mdo_invocations_start = 0, mdo_backedges_start = 0;

  if (mdh != NULL) {

    mdo_invocations = mdh->invocation_count();

    mdo_backedges = mdh->backedge_count();

    mdo_invocations_start = mdh->invocation_count_start();

    mdo_backedges_start = mdh->backedge_count_start();

  }

  tty->print(" %stotal=%d,%d %smdo=%d(%d),%d(%d)", prefix,

      invocation_count, backedge_count, prefix,

      mdo_invocations, mdo_invocations_start,

      mdo_backedges, mdo_backedges_start);

  tty->print(" %smax levels=%d,%d", prefix,

      mh->highest_comp_level(), mh->highest_osr_comp_level());

}

// Print an event.

void SimpleThresholdPolicy::print_event(EventType type, const methodHandle& mh, const methodHandle& imh,

                                        int bci, CompLevel level) {

  bool inlinee_event = mh() != imh();

  ttyLocker tty_lock;

  tty->print("%lf: [", os::elapsedTime());

  switch(type) {

  case CALL:

    tty->print("call");

    break;

  case LOOP:

    tty->print("loop");

    break;

  case COMPILE:

    tty->print("compile");

    break;

  case REMOVE_FROM_QUEUE:

    tty->print("remove-from-queue");

    break;

  case UPDATE_IN_QUEUE:

    tty->print("update-in-queue");

    break;

  case REPROFILE:

    tty->print("reprofile");

    break;

  case MAKE_NOT_ENTRANT:

    tty->print("make-not-entrant");

    break;

  default:

    tty->print("unknown");

  }

  tty->print(" level=%d ", level);

  ResourceMark rm;

  char *method_name = mh->name_and_sig_as_C_string();

  tty->print("[%s", method_name);

  if (inlinee_event) {

    char *inlinee_name = imh->name_and_sig_as_C_string();

    tty->print(" [%s]] ", inlinee_name);

  }

  else tty->print("] ");

  tty->print("@%d queues=%d,%d", bci, CompileBroker::queue_size(CompLevel_full_profile),

                                      CompileBroker::queue_size(CompLevel_full_optimization));

  print_specific(type, mh, imh, bci, level);

  if (type != COMPILE) {

    print_counters("", mh);

    if (inlinee_event) {

      print_counters("inlinee ", imh);

    }

    tty->print(" compilable=");

    bool need_comma = false;

    if (!mh->is_not_compilable(CompLevel_full_profile)) {

      tty->print("c1");

      need_comma = true;

    }

    if (!mh->is_not_osr_compilable(CompLevel_full_profile)) {

      if (need_comma) tty->print(",");

      tty->print("c1-osr");

      need_comma = true;

    }

    if (!mh->is_not_compilable(CompLevel_full_optimization)) {

      if (need_comma) tty->print(",");

      tty->print("c2");

      need_comma = true;

    }

    if (!mh->is_not_osr_compilable(CompLevel_full_optimization)) {

      if (need_comma) tty->print(",");

      tty->print("c2-osr");

    }

    tty->print(" status=");

    if (mh->queued_for_compilation()) {

      tty->print("in-queue");

    } else tty->print("idle");

  }

  tty->print_cr("]");

}

void SimpleThresholdPolicy::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());

}

void SimpleThresholdPolicy::set_carry_if_necessary(InvocationCounter *counter) {

  if (!counter->carry() && counter->count() > InvocationCounter::count_limit / 2) {

    counter->set_carry_flag();

  }

}

// Set carry flags on the counters if necessary

void SimpleThresholdPolicy::handle_counter_overflow(Method* method) {

  MethodCounters *mcs = method->method_counters();

  if (mcs != NULL) {

    set_carry_if_necessary(mcs->invocation_counter());

    set_carry_if_necessary(mcs->backedge_counter());

  }

  MethodData* mdo = method->method_data();

  if (mdo != NULL) {

    set_carry_if_necessary(mdo->invocation_counter());

    set_carry_if_necessary(mdo->backedge_counter());

  }

}

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

CompileTask* SimpleThresholdPolicy::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();

  }

    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;

}

void SimpleThresholdPolicy::reprofile(ScopeDesc* trap_scope, bool is_osr) {

  for (ScopeDesc* sd = trap_scope;; sd = sd->sender()) {

    if (PrintTieredEvents) {

      methodHandle mh(sd->method());

      print_event(REPROFILE, mh, mh, InvocationEntryBci, CompLevel_none);

    }

    MethodData* mdo = sd->method()->method_data();

    if (mdo != NULL) {

      mdo->reset_start_counters();

    }

    if (sd->is_top()) break;

  }

}

nmethod* SimpleThresholdPolicy::event(const methodHandle& method, const methodHandle& inlinee,

                                      int branch_bci, int bci, CompLevel comp_level, CompiledMethod* nm, JavaThread* thread) {

  if (comp_level == CompLevel_none &&

      JvmtiExport::can_post_interpreter_events() &&

      thread->is_interp_only_mode()) {

    return NULL;

  }

  if (CompileTheWorld || ReplayCompiles) {

    // Don't trigger other compiles in testing mode

    return NULL;

  }

  handle_counter_overflow(method());

  if (method() != inlinee()) {

    handle_counter_overflow(inlinee());

  }

  if (PrintTieredEvents) {

    print_event(bci == InvocationEntryBci ? CALL : LOOP, method, inlinee, bci, comp_level);

  }

  if (bci == InvocationEntryBci) {

    method_invocation_event(method, inlinee, comp_level, nm, thread);

  } else {

    // method == inlinee if the event originated in the main method

    method_back_branch_event(method, inlinee, bci, comp_level, nm, thread);

    // Check if event led to a higher level OSR compilation

    nmethod* osr_nm = inlinee->lookup_osr_nmethod_for(bci, comp_level, false);

    if (osr_nm != NULL && osr_nm->comp_level() > comp_level) {

      // Perform OSR with new nmethod

      return osr_nm;

    }

  }

  return NULL;

}

// Check if the method can be compiled, change level if necessary

void SimpleThresholdPolicy::compile(const methodHandle& mh, int bci, CompLevel level, JavaThread* thread) {

  assert(level <= TieredStopAtLevel, "Invalid compilation level");

  if (level == CompLevel_none) {

    return;

  }

  if (level == CompLevel_aot) {

    if (mh->has_aot_code()) {

      if (PrintTieredEvents) {

        print_event(COMPILE, mh, mh, bci, level);

      }

      MutexLocker ml(Compile_lock);

      NoSafepointVerifier nsv;

      if (mh->has_aot_code() && mh->code() != mh->aot_code()) {

        mh->aot_code()->make_entrant();

        if (mh->has_compiled_code()) {

          mh->code()->make_not_entrant();

        }

        Method::set_code(mh, mh->aot_code());

      }

    }

    return;

  }

  // Check if the method can be compiled. If it cannot be compiled with C1, continue profiling

  // in the interpreter and then compile with C2 (the transition function will request that,

  // see common() ). If the method cannot be compiled with C2 but still can with C1, compile it with

  // pure C1.

  if (!can_be_compiled(mh, level)) {

    if (level == CompLevel_full_optimization && can_be_compiled(mh, CompLevel_simple)) {

        compile(mh, bci, CompLevel_simple, thread);

    }

    return;

  }

  if (bci != InvocationEntryBci && mh->is_not_osr_compilable(level)) {

    return;

  }

  if (!CompileBroker::compilation_is_in_queue(mh)) {

    if (PrintTieredEvents) {

      print_event(COMPILE, mh, mh, bci, level);

    }

    submit_compile(mh, bci, level, thread);

  }

}

// Update the rate and submit compile

void SimpleThresholdPolicy::submit_compile(const methodHandle& mh, int bci, CompLevel level, JavaThread* thread) {

  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, CompileTask::Reason_Tiered, thread);

}

// Print an event.

void SimpleThresholdPolicy::print_specific(EventType type, const methodHandle& mh, const 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));

}

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

void SimpleThresholdPolicy::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 SimpleThresholdPolicy::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 SimpleThresholdPolicy::is_old(Method* method) {

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

}

double SimpleThresholdPolicy::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 SimpleThresholdPolicy::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 SimpleThresholdPolicy::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;

}

double SimpleThresholdPolicy::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;