1 /*

     2  * Copyright (c) 2010, 2018, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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

    21  * questions.

    22  *

    23  */

    24 

    25 #include "precompiled.hpp"

    26 #include "compiler/compileBroker.hpp"

    27 #include "memory/resourceArea.hpp"

    28 #include "runtime/arguments.hpp"

    29 #include "runtime/handles.inline.hpp"

    30 #include "runtime/safepointVerifiers.hpp"

    31 #include "runtime/simpleThresholdPolicy.hpp"

    32 #include "runtime/simpleThresholdPolicy.inline.hpp"

    33 #include "code/scopeDesc.hpp"

    34 #if INCLUDE_JVMCI

    35 #include "jvmci/jvmciRuntime.hpp"

    36 #endif

    37 

    38 #ifdef TIERED

    39 

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

    41   int invocation_count = mh->invocation_count();

    42   int backedge_count = mh->backedge_count();

    43   MethodData* mdh = mh->method_data();

    44   int mdo_invocations = 0, mdo_backedges = 0;

    45   int mdo_invocations_start = 0, mdo_backedges_start = 0;

    46   if (mdh != NULL) {

    47     mdo_invocations = mdh->invocation_count();

    48     mdo_backedges = mdh->backedge_count();

    49     mdo_invocations_start = mdh->invocation_count_start();

    50     mdo_backedges_start = mdh->backedge_count_start();

    51   }

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

    53       invocation_count, backedge_count, prefix,

    54       mdo_invocations, mdo_invocations_start,

    55       mdo_backedges, mdo_backedges_start);

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

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

    58 }

    59 

    60 // Print an event.

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

    62                                         int bci, CompLevel level) {

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

    64 

    65   ttyLocker tty_lock;

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

    67 

    68   switch(type) {

    69   case CALL:

    70     tty->print("call");

    71     break;

    72   case LOOP:

    73     tty->print("loop");

    74     break;

    75   case COMPILE:

    76     tty->print("compile");

    77     break;

    78   case REMOVE_FROM_QUEUE:

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

    80     break;

    81   case UPDATE_IN_QUEUE:

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

    83     break;

    84   case REPROFILE:

    85     tty->print("reprofile");

    86     break;

    87   case MAKE_NOT_ENTRANT:

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

    89     break;

    90   default:

    91     tty->print("unknown");

    92   }

    93 

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

    95 

    96   ResourceMark rm;

    97   char *method_name = mh->name_and_sig_as_C_string();

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

    99   if (inlinee_event) {

   100     char *inlinee_name = imh->name_and_sig_as_C_string();

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

   102   }

   103   else tty->print("] ");

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

   105                                       CompileBroker::queue_size(CompLevel_full_optimization));

   106 

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

   108 

   109   if (type != COMPILE) {

   110     print_counters("", mh);

   111     if (inlinee_event) {

   112       print_counters("inlinee ", imh);

   113     }

   114     tty->print(" compilable=");

   115     bool need_comma = false;

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

   117       tty->print("c1");

   118       need_comma = true;

   119     }

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

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

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

   123       need_comma = true;

   124     }

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

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

   127       tty->print("c2");

   128       need_comma = true;

   129     }

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

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

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

   133     }

   134     tty->print(" status=");

   135     if (mh->queued_for_compilation()) {

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

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

   138   }

   139   tty->print_cr("]");

   140 }

   141 

   142 void SimpleThresholdPolicy::initialize() {

   143   int count = CICompilerCount;

   144 #ifdef _LP64

   145   // Turn on ergonomic compiler count selection

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

   147     FLAG_SET_DEFAULT(CICompilerCountPerCPU, true);

   148   }

   149   if (CICompilerCountPerCPU) {

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

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

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

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

   154     FLAG_SET_ERGO(intx, CICompilerCount, count);

   155   }

   156 #else

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

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

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

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

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

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

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

   164   if (FLAG_IS_DEFAULT(CICompilerCount)) {

   165     count = 3;

   166     FLAG_SET_ERGO(intx, CICompilerCount, count);

   167   }

   168 #endif

   169 

   170   if (TieredStopAtLevel < CompLevel_full_optimization) {

   171     // No C2 compiler thread required

   172     set_c1_count(count);

   173   } else {

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

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

   176   }

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

   178 

   179   // Some inlining tuning

   180 #ifdef X86

   181   if (FLAG_IS_DEFAULT(InlineSmallCode)) {

   182     FLAG_SET_DEFAULT(InlineSmallCode, 2000);

   183   }

   184 #endif

   185 

   186 #if defined SPARC || defined AARCH64

   187   if (FLAG_IS_DEFAULT(InlineSmallCode)) {

   188     FLAG_SET_DEFAULT(InlineSmallCode, 2500);

   189   }

   190 #endif

   191 

   192   set_increase_threshold_at_ratio();

   193   set_start_time(os::javaTimeMillis());

   194 }

   195 

   196 void SimpleThresholdPolicy::set_carry_if_necessary(InvocationCounter *counter) {

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

   198     counter->set_carry_flag();

   199   }

   200 }

   201 

   202 // Set carry flags on the counters if necessary

   203 void SimpleThresholdPolicy::handle_counter_overflow(Method* method) {

   204   MethodCounters *mcs = method->method_counters();

   205   if (mcs != NULL) {

   206     set_carry_if_necessary(mcs->invocation_counter());

   207     set_carry_if_necessary(mcs->backedge_counter());

   208   }

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

   210   if (mdo != NULL) {

   211     set_carry_if_necessary(mdo->invocation_counter());

   212     set_carry_if_necessary(mdo->backedge_counter());

   213   }

   214 }

   215 

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

   217 CompileTask* SimpleThresholdPolicy::select_task(CompileQueue* compile_queue) {

   218   CompileTask *max_blocking_task = NULL;

   219   CompileTask *max_task = NULL;

   220   Method* max_method = NULL;

   221   jlong t = os::javaTimeMillis();

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

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

   224     CompileTask* next_task = task->next();

   225     Method* method = task->method();

   226     update_rate(t, method);

   227     if (max_task == NULL) {

   228       max_task = task;

   229       max_method = method;

   230     } else {

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

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

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

   234         if (PrintTieredEvents) {

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

   236         }

   237         compile_queue->remove_and_mark_stale(task);

   238         method->clear_queued_for_compilation();

   239         task = next_task;

   240         continue;

   241       }

   242 

   243       // Select a method with a higher rate

   244       if (compare_methods(method, max_method)) {

   245         max_task = task;

   246         max_method = method;

   247       }

   248     }

   249 

   250     if (task->is_blocking()) {

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

   252         max_blocking_task = task;

   253       }

   254     }

   255 

   256     task = next_task;

   257   }

   258 

   259   if (max_blocking_task != NULL) {

   260     // In blocking compilation mode, the CompileBroker will make

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

   262     // compilations should be scheduled after all blocking compilations

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

   264     // chance of such compilations timing out.

   265     max_task = max_blocking_task;

   266     max_method = max_task->method();

   267   }

   268 

   269   if (max_task != NULL && max_task->comp_level() == CompLevel_full_profile &&

   270       TieredStopAtLevel > CompLevel_full_profile &&

   271       max_method != NULL && is_method_profiled(max_method)) {

   272     max_task->set_comp_level(CompLevel_limited_profile);

   273     if (PrintTieredEvents) {

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

   275     }

   276   }

   277 

   278   return max_task;

   279 }

   280 

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

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

   283     if (PrintTieredEvents) {

   284       methodHandle mh(sd->method());

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

   286     }

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

   288     if (mdo != NULL) {

   289       mdo->reset_start_counters();

   290     }

   291     if (sd->is_top()) break;

   292   }

   293 }

   294 

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

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

   297   if (comp_level == CompLevel_none &&

   298       JvmtiExport::can_post_interpreter_events() &&

   299       thread->is_interp_only_mode()) {

   300     return NULL;

   301   }

   302   if (CompileTheWorld || ReplayCompiles) {

   303     // Don't trigger other compiles in testing mode

   304     return NULL;

   305   }

   306 

   307   handle_counter_overflow(method());

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

   309     handle_counter_overflow(inlinee());

   310   }

   311 

   312   if (PrintTieredEvents) {

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

   314   }

   315 

   316   if (bci == InvocationEntryBci) {

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

   318   } else {

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

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

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

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

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

   324       // Perform OSR with new nmethod

   325       return osr_nm;

   326     }

   327   }

   328   return NULL;

   329 }

   330 

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

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

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

   334   if (level == CompLevel_none) {

   335     return;

   336   }

   337   if (level == CompLevel_aot) {

   338     if (mh->has_aot_code()) {

   339       if (PrintTieredEvents) {

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

   341       }

   342       MutexLocker ml(Compile_lock);

   343       NoSafepointVerifier nsv;

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

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

   346         if (mh->has_compiled_code()) {

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

   348         }

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

   350       }

   351     }

   352     return;

   353   }

   354 

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

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

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

   358   // pure C1.

   359   if (!can_be_compiled(mh, level)) {

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

   361         compile(mh, bci, CompLevel_simple, thread);

   362     }

   363     return;

   364   }

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

   366     return;

   367   }

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

   369     if (PrintTieredEvents) {

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

   371     }

   372     submit_compile(mh, bci, level, thread);

   373   }

   374 }

   375 

   376 // Update the rate and submit compile

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

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

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

   380   CompileBroker::compile_method(mh, bci, level, mh, hot_count, CompileTask::Reason_Tiered, thread);

   381 }

   382 

   383 // Print an event.

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

   385                                              int bci, CompLevel level) {

   386   tty->print(" rate=");

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

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

   389 

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

   391                                threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback));

   392 

   393 }

   394 

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

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

   397   // Skip update if counters are absent.

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

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

   400 

   401   if (is_old(m)) {

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

   403     // so we can just zero the rate.

   404     m->set_rate(0);

   405     return;

   406   }

   407 

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

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

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

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

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

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

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

   415 

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

   417   if (delta_s >= TieredRateUpdateMinTime) {

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

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

   420       m->set_prev_time(t);

   421       m->set_prev_event_count(event_count);

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

   423     } else {

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

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

   426         m->set_rate(0);

   427       }

   428     }

   429   }

   430 }

   431 

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

   433 // See select_task().

   434 bool SimpleThresholdPolicy::is_stale(jlong t, jlong timeout, Method* m) {

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

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

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

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

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

   440     // Return true if there were no events.

   441     return delta_e == 0;

   442   }

   443   return false;

   444 }

   445 

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

   447 // very low activity. See select_task().

   448 bool SimpleThresholdPolicy::is_old(Method* method) {

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

   450 }

   451 

   452 double SimpleThresholdPolicy::weight(Method* method) {

   453   return (double)(method->rate() + 1) *

   454     (method->invocation_count() + 1) * (method->backedge_count() + 1);

   455 }

   456 

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

   458 bool SimpleThresholdPolicy::compare_methods(Method* x, Method* y) {

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

   460     // recompilation after deopt

   461     return true;

   462   } else

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

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

   465         return true;

   466       }

   467     }

   468   return false;

   469 }

   470 

   471 // Is method profiled enough?

   472 bool SimpleThresholdPolicy::is_method_profiled(Method* method) {

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

   474   if (mdo != NULL) {

   475     int i = mdo->invocation_count_delta();

   476     int b = mdo->backedge_count_delta();

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

   478   }

   479   return false;

   480 }

   481 

   482 double SimpleThresholdPolicy::threshold_scale(CompLevel level, int feedback_k) {

   483   double queue_size = CompileBroker::queue_size(level);

   484   int comp_count = compiler_count(level);

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

   486 

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

   488   // than specified by IncreaseFirstTierCompileThresholdAt percentage.

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

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

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

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

   493     if (current_reverse_free_ratio > _increase_threshold_at_ratio) {

   494       k *= exp(current_reverse_free_ratio - _increase_threshold_at_ratio);

   495     }

   496   }

   497   return k;

   498 }

   499 

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

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

   502 // are passed to common()).

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

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

   505 // the threshold values double.

   506 bool SimpleThresholdPolicy::loop_predicate(int i, int b, CompLevel cur_level, Method* method) {

   507   switch(cur_level) {

   508   case CompLevel_aot: {

   509     double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback);

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

   511   }

   512   case CompLevel_none:

   513   case CompLevel_limited_profile: {

   514     double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback);

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

   516   }

   517   case CompLevel_full_profile: {

   518     double k = threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback);

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

   520   }

   521   default:

   522     return true;

   523   }

   524 }

   525 

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

   527   switch(cur_level) {

   528   case CompLevel_aot: {

   529     double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback);

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

   531   }

   532   case CompLevel_none:

   533   case CompLevel_limited_profile: {

   534     double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback);

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

   536   }

   537   case CompLevel_full_profile: {

   538     double k = threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback);

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

   540   }

   541   default:

   542     return true;

   543   }

   544 }

   545 

   546 // Determine is a method is mature.

   547 bool SimpleThresholdPolicy::is_mature(Method* method) {

   548   if (is_trivial(method)) return true;

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

   550   if (mdo != NULL) {

   551     int i = mdo->invocation_count();

   552     int b = mdo->backedge_count();

   553     double k = ProfileMaturityPercentage / 100.0;

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

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

   556   }

   557   return false;

   558 }

   559 

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

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

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

   563 bool SimpleThresholdPolicy::should_create_mdo(Method* method, CompLevel cur_level) {

   564   if (cur_level == CompLevel_none &&

   565       CompileBroker::queue_size(CompLevel_full_optimization) <=

   566       Tier3DelayOn * compiler_count(CompLevel_full_optimization)) {

   567     int i = method->invocation_count();

   568     int b = method->backedge_count();

   569     double k = Tier0ProfilingStartPercentage / 100.0;

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

   571   }

   572   return false;

   573 }

   574 

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

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

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

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

   579   if (comp_level == CompLevel_full_profile ||

   580       comp_level == CompLevel_limited_profile) {

   581     return callee->highest_osr_comp_level() == CompLevel_full_optimization;

   582   }

   583   return false;

   584 }

   585 

   586 // Create MDO if necessary.

   587 void SimpleThresholdPolicy::create_mdo(const methodHandle& mh, JavaThread* THREAD) {

   588   if (mh->is_native() ||

   589       mh->is_abstract() ||

   590       mh->is_accessor() ||

   591       mh->is_constant_getter()) {

   592     return;

   593   }

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

   595     Method::build_interpreter_method_data(mh, CHECK_AND_CLEAR);

   596   }

   597 }

   598 

   599 

   600 /*

   601  * Method states:

   602  *   0 - interpreter (CompLevel_none)

   603  *   1 - pure C1 (CompLevel_simple)

   604  *   2 - C1 with invocation and backedge counting (CompLevel_limited_profile)

   605  *   3 - C1 with full profiling (CompLevel_full_profile)

   606  *   4 - C2 (CompLevel_full_optimization)

   607  *

   608  * Common state transition patterns:

   609  * a. 0 -> 3 -> 4.

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

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

   612  *

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

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

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

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

   617  *

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

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

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

   621  *    of the method to 2 while the request is still in-queue, because it'll allow it to run much faster

   622  *    without full profiling while c2 is compiling.

   623  *

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

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

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

   627  *

   628  * e. 0 -> 4.

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

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

   631  *    the compiled version already exists).

   632  *

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

   634  * are possible.

   635  *

   636  */

   637 

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

   639 CompLevel SimpleThresholdPolicy::common(Predicate p, Method* method, CompLevel cur_level, bool disable_feedback) {

   640   CompLevel next_level = cur_level;

   641   int i = method->invocation_count();

   642   int b = method->backedge_count();

   643 

   644   if (is_trivial(method)) {

   645     next_level = CompLevel_simple;

   646   } else {

   647     switch(cur_level) {

   648       default: break;

   649       case CompLevel_aot: {

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

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

   652         next_level = CompLevel_full_optimization;

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

   654                                Tier3DelayOff * compiler_count(CompLevel_full_optimization) &&

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

   656         next_level = CompLevel_full_profile;

   657       }

   658     }

   659     break;

   660     case CompLevel_none:

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

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

   663         next_level = CompLevel_full_optimization;

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

   665 #if INCLUDE_JVMCI

   666         if (EnableJVMCI && UseJVMCICompiler) {

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

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

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

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

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

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

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

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

   675           next_level = CompLevel_full_profile;

   676         } else

   677 #endif

   678         {

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

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

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

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

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

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

   685           // when the load on C2 goes down.

   686           if (!disable_feedback && CompileBroker::queue_size(CompLevel_full_optimization) >

   687               Tier3DelayOn * compiler_count(CompLevel_full_optimization)) {

   688             next_level = CompLevel_limited_profile;

   689           } else {

   690             next_level = CompLevel_full_profile;

   691           }

   692         }

   693       }

   694       break;

   695     case CompLevel_limited_profile:

   696       if (is_method_profiled(method)) {

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

   698         next_level = CompLevel_full_optimization;

   699       } else {

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

   701         if (mdo != NULL) {

   702           if (mdo->would_profile()) {

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

   704                                      Tier3DelayOff * compiler_count(CompLevel_full_optimization) &&

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

   706               next_level = CompLevel_full_profile;

   707             }

   708           } else {

   709             next_level = CompLevel_full_optimization;

   710           }

   711         } else {

   712           // If there is no MDO we need to profile

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

   714                                    Tier3DelayOff * compiler_count(CompLevel_full_optimization) &&

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

   716             next_level = CompLevel_full_profile;

   717           }

   718         }

   719       }

   720       break;

   721     case CompLevel_full_profile:

   722       {

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

   724         if (mdo != NULL) {

   725           if (mdo->would_profile()) {

   726             int mdo_i = mdo->invocation_count_delta();

   727             int mdo_b = mdo->backedge_count_delta();

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

   729               next_level = CompLevel_full_optimization;

   730             }

   731           } else {

   732             next_level = CompLevel_full_optimization;

   733           }

   734         }

   735       }

   736       break;

   737     }

   738   }

   739   return MIN2(next_level, (CompLevel)TieredStopAtLevel);

   740 }

   741 

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

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

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

   745                              common(&SimpleThresholdPolicy::loop_predicate, method, cur_level, true));

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

   747 

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

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

   750   // invocation of the method.

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

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

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

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

   755       next_level = CompLevel_full_optimization;

   756     }

   757   } else {

   758     next_level = MAX2(osr_level, next_level);

   759   }

   760 #if INCLUDE_JVMCI

   761   if (UseJVMCICompiler) {

   762     next_level = JVMCIRuntime::adjust_comp_level(method, false, next_level, thread);

   763   }

   764 #endif

   765   return next_level;

   766 }

   767 

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

   769 CompLevel SimpleThresholdPolicy::loop_event(Method* method, CompLevel cur_level, JavaThread* thread) {

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

   771   if (cur_level == CompLevel_none) {

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

   773     // for the transition.

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

   775     if (osr_level > CompLevel_none) {

   776       return osr_level;

   777     }

   778   }

   779 #if INCLUDE_JVMCI

   780   if (UseJVMCICompiler) {

   781     next_level = JVMCIRuntime::adjust_comp_level(method, true, next_level, thread);

   782   }

   783 #endif

   784   return next_level;

   785 }

   786 

   787 bool SimpleThresholdPolicy::maybe_switch_to_aot(const methodHandle& mh, CompLevel cur_level, CompLevel next_level, JavaThread* thread) {

   788   if (UseAOT && !delay_compilation_during_startup()) {

   789     if (cur_level == CompLevel_full_profile || cur_level == CompLevel_none) {

   790       // If the current level is full profile or interpreter and we're switching to any other level,

   791       // activate the AOT code back first so that we won't waste time overprofiling.

   792       compile(mh, InvocationEntryBci, CompLevel_aot, thread);

   793       // Fall through for JIT compilation.

   794     }

   795     if (next_level == CompLevel_limited_profile && cur_level != CompLevel_aot && mh->has_aot_code()) {

   796       // If the next level is limited profile, use the aot code (if there is any),

   797       // since it's essentially the same thing.

   798       compile(mh, InvocationEntryBci, CompLevel_aot, thread);

   799       // Not need to JIT, we're done.

   800       return true;

   801     }

   802   }

   803   return false;

   804 }

   805 

   806 

   807 // Handle the invocation event.

   808 void SimpleThresholdPolicy::method_invocation_event(const methodHandle& mh, const methodHandle& imh,

   809                                                       CompLevel level, CompiledMethod* nm, JavaThread* thread) {

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

   811     create_mdo(mh, thread);

   812   }

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

   814   if (next_level != level) {

   815     if (maybe_switch_to_aot(mh, level, next_level, thread)) {

   816       // No JITting necessary

   817       return;

   818     }

   819     if (is_compilation_enabled() && !CompileBroker::compilation_is_in_queue(mh)) {

   820       compile(mh, InvocationEntryBci, next_level, thread);

   821     }

   822   }

   823 }

   824 

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

   826 // with a regular entry from here.

   827 void SimpleThresholdPolicy::method_back_branch_event(const methodHandle& mh, const methodHandle& imh,

   828                                                      int bci, CompLevel level, CompiledMethod* nm, JavaThread* thread) {

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

   830     create_mdo(mh, thread);

   831   }

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

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

   834     create_mdo(imh, thread);

   835   }

   836 

   837   if (is_compilation_enabled()) {

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

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

   840     // At the very least compile the OSR version

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

   842       compile(imh, bci, next_osr_level, thread);

   843     }

   844 

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

   846     // enough calls.

   847     CompLevel cur_level, next_level;

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

   849       if (level == CompLevel_aot) {

   850         // Recompile the enclosing method to prevent infinite OSRs. Stay at AOT level while it's compiling.

   851         if (max_osr_level != CompLevel_none && !CompileBroker::compilation_is_in_queue(mh)) {

   852           compile(mh, InvocationEntryBci, MIN2((CompLevel)TieredStopAtLevel, CompLevel_full_profile), thread);

   853         }

   854       } else {

   855         // Current loop event level is not AOT

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

   857         cur_level = comp_level(mh());

   858         next_level = call_event(mh(), cur_level, thread);

   859 

   860         if (max_osr_level == CompLevel_full_optimization) {

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

   862           bool make_not_entrant = false;

   863           if (nm->is_osr_method()) {

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

   865             make_not_entrant = true;

   866           } else {

   867             if (next_level != CompLevel_full_optimization) {

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

   869               // enclosing method without the inlinee

   870               cur_level = CompLevel_none;

   871               make_not_entrant = true;

   872             }

   873           }

   874           if (make_not_entrant) {

   875             if (PrintTieredEvents) {

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

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

   878             }

   879             nm->make_not_entrant();

   880           }

   881         }

   882         // Fix up next_level if necessary to avoid deopts

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

   884           next_level = CompLevel_full_profile;

   885         }

   886         if (cur_level != next_level) {

   887           if (!maybe_switch_to_aot(mh, cur_level, next_level, thread) && !CompileBroker::compilation_is_in_queue(mh)) {

   888             compile(mh, InvocationEntryBci, next_level, thread);

   889           }

   890         }

   891       }

   892     } else {

   893       cur_level = comp_level(mh());

   894       next_level = call_event(mh(), cur_level, thread);

   895       if (next_level != cur_level) {

   896         if (!maybe_switch_to_aot(mh, cur_level, next_level, thread) && !CompileBroker::compilation_is_in_queue(mh)) {

   897           compile(mh, InvocationEntryBci, next_level, thread);

   898         }

   899       }

   900     }

   901   }

   902 }

   903 

   904 #endif