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 /*

  * Copyright (c) 2010, 2013, 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, Method* m) {

   JavaThread* THREAD = JavaThread::current();

   if (is_old(m)) {

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

     // so we can just zero the rate.

     m->set_rate(0, THREAD);

     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, THREAD);

       m->set_prev_event_count(event_count, THREAD);

       m->set_rate((float)delta_e / (float)delta_t, THREAD); // 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, THREAD);

       }

   }

 }

 // 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 (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);

   }

   return false;

 }

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

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

   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();

     MethodData* 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(REMOVE_FROM_QUEUE, 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 && 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;

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

   }

   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.

 void AdvancedThresholdPolicy::create_mdo(methodHandle mh, JavaThread* THREAD) {

   if (mh->is_native() || mh->is_abstract() || mh->is_accessor()) 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 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, 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) {

     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)) {

         // 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))) {

               next_level = CompLevel_full_profile;

             }

           } else {

             next_level = CompLevel_full_optimization;

           }

         }

       }

       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)) {

               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) {

   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);

   // 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) {

     MethodData* 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(Method* method, CompLevel cur_level) {

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

   if (cur_level == CompLevel_none) {

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

     // for the transition.

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

     if (osr_level > CompLevel_none) {

       return osr_level;

     }

   }

   return next_level;

 }

 // Update the rate and submit compile

 void AdvancedThresholdPolicy::submit_compile(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, "tiered", thread);

 }

 // Handle the invocation event.

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

                                                       CompLevel level, nmethod* nm, JavaThread* thread) {

   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, nmethod* nm, JavaThread* thread) {

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

     create_mdo(mh, thread);

   }

   // Check if MDO should be created for the inlined method

   if (should_create_mdo(imh(), level)) {

     create_mdo(imh, thread);

   }

   if (is_compilation_enabled()) {

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

     CompLevel max_osr_level = (CompLevel)imh->highest_osr_comp_level();

     // At the very least compile the OSR version

     if (!CompileBroker::compilation_is_in_queue(imh, bci) && next_osr_level != level) {

       compile(imh, bci, next_osr_level, thread);

     }

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

     // enough calls.

     CompLevel cur_level, next_level;

     if (mh() != imh()) { // If there is an enclosing method

       guarantee(nm != NULL, "Should have nmethod here");

       cur_level = comp_level(mh());

       next_level = call_event(mh(), cur_level);

       if (max_osr_level == CompLevel_full_optimization) {

         // The inlinee OSRed to full opt, we need to modify the enclosing method to avoid deopts

         bool make_not_entrant = false;

         if (nm->is_osr_method()) {

           // This is an osr method, just make it not entrant and recompile later if needed

           make_not_entrant = true;

         } else {

           if (next_level != CompLevel_full_optimization) {

             // next_level is not full opt, so we need to recompile the

             // enclosing method without the inlinee

             cur_level = CompLevel_none;

             make_not_entrant = true;

           }

         }

         if (make_not_entrant) {

           if (PrintTieredEvents) {

             int osr_bci = nm->is_osr_method() ? nm->osr_entry_bci() : InvocationEntryBci;

             print_event(MAKE_NOT_ENTRANT, mh(), mh(), osr_bci, level);

           }

           nm->make_not_entrant();

         }

       }

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

         // Fix up next_level if necessary to avoid deopts

         if (next_level == CompLevel_limited_profile && max_osr_level == CompLevel_full_profile) {

           next_level = CompLevel_full_profile;

         }

         if (cur_level != next_level) {

           compile(mh, InvocationEntryBci, next_level, thread);

         }

       }

     } else {

       cur_level = comp_level(imh());

       next_level = call_event(imh(), cur_level);

       if (!CompileBroker::compilation_is_in_queue(imh, bci) && next_level != cur_level) {

         compile(imh, InvocationEntryBci, next_level, thread);

       }

     }

   }

 }

 #endif // TIERED