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 "compiler/compilerOracle.hpp"

    28 #include "memory/resourceArea.hpp"

    29 #include "runtime/arguments.hpp"

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

    31 #include "runtime/safepointVerifiers.hpp"

    32 #include "runtime/tieredThresholdPolicy.hpp"

    33 #include "code/scopeDesc.hpp"

    34 #include "oops/method.inline.hpp"

    35 #if INCLUDE_JVMCI

    36 #include "jvmci/jvmciRuntime.hpp"

    37 #endif

    38 

    39 #ifdef TIERED

    40 

    41 template<CompLevel level>

    42 bool TieredThresholdPolicy::call_predicate_helper(int i, int b, double scale, Method* method) {

    43   double threshold_scaling;

    44   if (CompilerOracle::has_option_value(method, "CompileThresholdScaling", threshold_scaling)) {

    45     scale *= threshold_scaling;

    46   }

    47   switch(level) {

    48   case CompLevel_aot:

    49     return (i >= Tier3AOTInvocationThreshold * scale) ||

    50            (i >= Tier3AOTMinInvocationThreshold * scale && i + b >= Tier3AOTCompileThreshold * scale);

    51   case CompLevel_none:

    52   case CompLevel_limited_profile:

    53     return (i >= Tier3InvocationThreshold * scale) ||

    54            (i >= Tier3MinInvocationThreshold * scale && i + b >= Tier3CompileThreshold * scale);

    55   case CompLevel_full_profile:

    56    return (i >= Tier4InvocationThreshold * scale) ||

    57           (i >= Tier4MinInvocationThreshold * scale && i + b >= Tier4CompileThreshold * scale);

    58   }

    59   return true;

    60 }

    61 

    62 template<CompLevel level>

    63 bool TieredThresholdPolicy::loop_predicate_helper(int i, int b, double scale, Method* method) {

    64   double threshold_scaling;

    65   if (CompilerOracle::has_option_value(method, "CompileThresholdScaling", threshold_scaling)) {

    66     scale *= threshold_scaling;

    67   }

    68   switch(level) {

    69   case CompLevel_aot:

    70     return b >= Tier3AOTBackEdgeThreshold * scale;

    71   case CompLevel_none:

    72   case CompLevel_limited_profile:

    73     return b >= Tier3BackEdgeThreshold * scale;

    74   case CompLevel_full_profile:

    75     return b >= Tier4BackEdgeThreshold * scale;

    76   }

    77   return true;

    78 }

    79 

    80 // Simple methods are as good being compiled with C1 as C2.

    81 // Determine if a given method is such a case.

    82 bool TieredThresholdPolicy::is_trivial(Method* method) {

    83   if (method->is_accessor() ||

    84       method->is_constant_getter()) {

    85     return true;

    86   }

    87 #if INCLUDE_JVMCI

    88   if (UseJVMCICompiler) {

    89     AbstractCompiler* comp = CompileBroker::compiler(CompLevel_full_optimization);

    90     if (TieredCompilation && comp != NULL && comp->is_trivial(method)) {

    91       return true;

    92     }

    93   }

    94 #endif

    95   if (method->has_loops() || method->code_size() >= 15) {

    96     return false;

    97   }

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

    99   if (mdo != NULL && !mdo->would_profile() &&

   100       (method->code_size() < 5  || (mdo->num_blocks() < 4))) {

   101     return true;

   102   }

   103   return false;

   104 }

   105 

   106 CompLevel TieredThresholdPolicy::comp_level(Method* method) {

   107   CompiledMethod *nm = method->code();

   108   if (nm != NULL && nm->is_in_use()) {

   109     return (CompLevel)nm->comp_level();

   110   }

   111   return CompLevel_none;

   112 }

   113 

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

   115   int invocation_count = mh->invocation_count();

   116   int backedge_count = mh->backedge_count();

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

   118   int mdo_invocations = 0, mdo_backedges = 0;

   119   int mdo_invocations_start = 0, mdo_backedges_start = 0;

   120   if (mdh != NULL) {

   121     mdo_invocations = mdh->invocation_count();

   122     mdo_backedges = mdh->backedge_count();

   123     mdo_invocations_start = mdh->invocation_count_start();

   124     mdo_backedges_start = mdh->backedge_count_start();

   125   }

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

   127       invocation_count, backedge_count, prefix,

   128       mdo_invocations, mdo_invocations_start,

   129       mdo_backedges, mdo_backedges_start);

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

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

   132 }

   133 

   134 // Print an event.

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

   136                                         int bci, CompLevel level) {

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

   138 

   139   ttyLocker tty_lock;

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

   141 

   142   switch(type) {

   143   case CALL:

   144     tty->print("call");

   145     break;

   146   case LOOP:

   147     tty->print("loop");

   148     break;

   149   case COMPILE:

   150     tty->print("compile");

   151     break;

   152   case REMOVE_FROM_QUEUE:

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

   154     break;

   155   case UPDATE_IN_QUEUE:

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

   157     break;

   158   case REPROFILE:

   159     tty->print("reprofile");

   160     break;

   161   case MAKE_NOT_ENTRANT:

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

   163     break;

   164   default:

   165     tty->print("unknown");

   166   }

   167 

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

   169 

   170   ResourceMark rm;

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

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

   173   if (inlinee_event) {

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

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

   176   }

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

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

   179                                       CompileBroker::queue_size(CompLevel_full_optimization));

   180 

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

   182 

   183   if (type != COMPILE) {

   184     print_counters("", mh);

   185     if (inlinee_event) {

   186       print_counters("inlinee ", imh);

   187     }

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

   189     bool need_comma = false;

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

   191       tty->print("c1");

   192       need_comma = true;

   193     }

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

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

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

   197       need_comma = true;

   198     }

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

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

   201       tty->print("c2");

   202       need_comma = true;

   203     }

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

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

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

   207     }

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

   209     if (mh->queued_for_compilation()) {

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

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

   212   }

   213   tty->print_cr("]");

   214 }

   215 

   216 void TieredThresholdPolicy::initialize() {

   217   int count = CICompilerCount;

   218 #ifdef _LP64

   219   // Turn on ergonomic compiler count selection

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

   221     FLAG_SET_DEFAULT(CICompilerCountPerCPU, true);

   222   }

   223   if (CICompilerCountPerCPU) {

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

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

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

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

   228     FLAG_SET_ERGO(intx, CICompilerCount, count);

   229   }

   230 #else

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

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

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

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

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

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

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

   238   if (FLAG_IS_DEFAULT(CICompilerCount)) {

   239     count = 3;

   240     FLAG_SET_ERGO(intx, CICompilerCount, count);

   241   }

   242 #endif

   243 

   244   if (TieredStopAtLevel < CompLevel_full_optimization) {

   245     // No C2 compiler thread required

   246     set_c1_count(count);

   247   } else {

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

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

   250   }

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

   252 

   253   // Some inlining tuning

   254 #ifdef X86

   255   if (FLAG_IS_DEFAULT(InlineSmallCode)) {

   256     FLAG_SET_DEFAULT(InlineSmallCode, 2000);

   257   }

   258 #endif

   259 

   260 #if defined SPARC || defined AARCH64

   261   if (FLAG_IS_DEFAULT(InlineSmallCode)) {

   262     FLAG_SET_DEFAULT(InlineSmallCode, 2500);

   263   }

   264 #endif

   265 

   266   set_increase_threshold_at_ratio();

   267   set_start_time(os::javaTimeMillis());

   268 }

   269 

   270 void TieredThresholdPolicy::set_carry_if_necessary(InvocationCounter *counter) {

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

   272     counter->set_carry_flag();

   273   }

   274 }

   275 

   276 // Set carry flags on the counters if necessary

   277 void TieredThresholdPolicy::handle_counter_overflow(Method* method) {

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

   279   if (mcs != NULL) {

   280     set_carry_if_necessary(mcs->invocation_counter());

   281     set_carry_if_necessary(mcs->backedge_counter());

   282   }

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

   284   if (mdo != NULL) {

   285     set_carry_if_necessary(mdo->invocation_counter());

   286     set_carry_if_necessary(mdo->backedge_counter());

   287   }

   288 }

   289 

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

   291 CompileTask* TieredThresholdPolicy::select_task(CompileQueue* compile_queue) {

   292   CompileTask *max_blocking_task = NULL;

   293   CompileTask *max_task = NULL;

   294   Method* max_method = NULL;

   295   jlong t = os::javaTimeMillis();

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

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

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

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

   300     update_rate(t, method);

   301     if (max_task == NULL) {

   302       max_task = task;

   303       max_method = method;

   304     } else {

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

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

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

   308         if (PrintTieredEvents) {

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

   310         }

   311         compile_queue->remove_and_mark_stale(task);

   312         method->clear_queued_for_compilation();

   313         task = next_task;

   314         continue;

   315       }

   316 

   317       // Select a method with a higher rate

   318       if (compare_methods(method, max_method)) {

   319         max_task = task;

   320         max_method = method;

   321       }

   322     }

   323 

   324     if (task->is_blocking()) {

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

   326         max_blocking_task = task;

   327       }

   328     }

   329 

   330     task = next_task;

   331   }

   332 

   333   if (max_blocking_task != NULL) {

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

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

   336     // compilations should be scheduled after all blocking compilations

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

   338     // chance of such compilations timing out.

   339     max_task = max_blocking_task;

   340     max_method = max_task->method();

   341   }

   342 

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

   344       TieredStopAtLevel > CompLevel_full_profile &&

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

   346     max_task->set_comp_level(CompLevel_limited_profile);

   347     if (PrintTieredEvents) {

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

   349     }

   350   }

   351 

   352   return max_task;

   353 }

   354 

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

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

   357     if (PrintTieredEvents) {

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

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

   360     }

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

   362     if (mdo != NULL) {

   363       mdo->reset_start_counters();

   364     }

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

   366   }

   367 }

   368 

   369 nmethod* TieredThresholdPolicy::event(const methodHandle& method, const methodHandle& inlinee,

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

   371   if (comp_level == CompLevel_none &&

   372       JvmtiExport::can_post_interpreter_events() &&

   373       thread->is_interp_only_mode()) {

   374     return NULL;

   375   }

   376   if (CompileTheWorld || ReplayCompiles) {

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

   378     return NULL;

   379   }

   380 

   381   handle_counter_overflow(method());

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

   383     handle_counter_overflow(inlinee());

   384   }

   385 

   386   if (PrintTieredEvents) {

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

   388   }

   389 

   390   if (bci == InvocationEntryBci) {

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

   392   } else {

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

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

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

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

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

   398       // Perform OSR with new nmethod

   399       return osr_nm;

   400     }

   401   }

   402   return NULL;

   403 }

   404 

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

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

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

   408   if (level == CompLevel_none) {

   409     return;

   410   }

   411   if (level == CompLevel_aot) {

   412     if (mh->has_aot_code()) {

   413       if (PrintTieredEvents) {

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

   415       }

   416       MutexLocker ml(Compile_lock);

   417       NoSafepointVerifier nsv;

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

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

   420         if (mh->has_compiled_code()) {

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

   422         }

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

   424       }

   425     }

   426     return;

   427   }

   428 

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

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

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

   432   // pure C1.

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

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

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

   436     }

   437     return;

   438   }

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

   440     return;

   441   }

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

   443     if (PrintTieredEvents) {

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

   445     }

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

   447   }

   448 }

   449 

   450 // Update the rate and submit compile

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

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

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

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

   455 }

   456 

   457 // Print an event.

   458 void TieredThresholdPolicy::print_specific(EventType type, const methodHandle& mh, const methodHandle& imh,

   459                                              int bci, CompLevel level) {

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

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

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

   463 

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

   465                                threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback));

   466 

   467 }

   468 

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

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

   471   // Skip update if counters are absent.

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

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

   474 

   475   if (is_old(m)) {

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

   477     // so we can just zero the rate.

   478     m->set_rate(0);

   479     return;

   480   }

   481 

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

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

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

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

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

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

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

   489 

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

   491   if (delta_s >= TieredRateUpdateMinTime) {

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

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

   494       m->set_prev_time(t);

   495       m->set_prev_event_count(event_count);

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

   497     } else {

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

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

   500         m->set_rate(0);

   501       }

   502     }

   503   }

   504 }

   505 

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

   507 // See select_task().

   508 bool TieredThresholdPolicy::is_stale(jlong t, jlong timeout, Method* m) {

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

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

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

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

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

   514     // Return true if there were no events.

   515     return delta_e == 0;

   516   }

   517   return false;

   518 }

   519 

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

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

   522 bool TieredThresholdPolicy::is_old(Method* method) {

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

   524 }

   525 

   526 double TieredThresholdPolicy::weight(Method* method) {

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

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

   529 }

   530 

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

   532 bool TieredThresholdPolicy::compare_methods(Method* x, Method* y) {

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

   534     // recompilation after deopt

   535     return true;

   536   } else

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

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

   539         return true;

   540       }

   541     }

   542   return false;

   543 }

   544 

   545 // Is method profiled enough?

   546 bool TieredThresholdPolicy::is_method_profiled(Method* method) {

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

   548   if (mdo != NULL) {

   549     int i = mdo->invocation_count_delta();

   550     int b = mdo->backedge_count_delta();

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

   552   }

   553   return false;

   554 }

   555 

   556 double TieredThresholdPolicy::threshold_scale(CompLevel level, int feedback_k) {

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

   558   int comp_count = compiler_count(level);

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

   560 

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

   562   // than specified by IncreaseFirstTierCompileThresholdAt percentage.

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

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

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

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

   567     if (current_reverse_free_ratio > _increase_threshold_at_ratio) {

   568       k *= exp(current_reverse_free_ratio - _increase_threshold_at_ratio);

   569     }

   570   }

   571   return k;

   572 }

   573 

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

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

   576 // are passed to common()).

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

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

   579 // the threshold values double.

   580 bool TieredThresholdPolicy::loop_predicate(int i, int b, CompLevel cur_level, Method* method) {

   581   switch(cur_level) {

   582   case CompLevel_aot: {

   583     double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback);

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

   585   }

   586   case CompLevel_none:

   587   case CompLevel_limited_profile: {

   588     double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback);

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

   590   }

   591   case CompLevel_full_profile: {

   592     double k = threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback);

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

   594   }

   595   default:

   596     return true;

   597   }

   598 }

   599 

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

   601   switch(cur_level) {

   602   case CompLevel_aot: {

   603     double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback);

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

   605   }

   606   case CompLevel_none:

   607   case CompLevel_limited_profile: {

   608     double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback);

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

   610   }

   611   case CompLevel_full_profile: {

   612     double k = threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback);

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

   614   }

   615   default:

   616     return true;

   617   }

   618 }

   619 

   620 // Determine is a method is mature.

   621 bool TieredThresholdPolicy::is_mature(Method* method) {

   622   if (is_trivial(method)) return true;

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

   624   if (mdo != NULL) {

   625     int i = mdo->invocation_count();

   626     int b = mdo->backedge_count();

   627     double k = ProfileMaturityPercentage / 100.0;

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

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

   630   }

   631   return false;

   632 }

   633 

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

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

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

   637 bool TieredThresholdPolicy::should_create_mdo(Method* method, CompLevel cur_level) {

   638   if (cur_level == CompLevel_none &&

   639       CompileBroker::queue_size(CompLevel_full_optimization) <=

   640       Tier3DelayOn * compiler_count(CompLevel_full_optimization)) {

   641     int i = method->invocation_count();

   642     int b = method->backedge_count();

   643     double k = Tier0ProfilingStartPercentage / 100.0;

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

   645   }

   646   return false;

   647 }

   648 

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

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

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

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

   653   if (comp_level == CompLevel_full_profile ||

   654       comp_level == CompLevel_limited_profile) {

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

   656   }

   657   return false;

   658 }

   659 

   660 // Create MDO if necessary.

   661 void TieredThresholdPolicy::create_mdo(const methodHandle& mh, JavaThread* THREAD) {

   662   if (mh->is_native() ||

   663       mh->is_abstract() ||

   664       mh->is_accessor() ||

   665       mh->is_constant_getter()) {

   666     return;

   667   }

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

   669     Method::build_interpreter_method_data(mh, CHECK_AND_CLEAR);

   670   }

   671 }

   672 

   673 

   674 /*

   675  * Method states:

   676  *   0 - interpreter (CompLevel_none)

   677  *   1 - pure C1 (CompLevel_simple)

   678  *   2 - C1 with invocation and backedge counting (CompLevel_limited_profile)

   679  *   3 - C1 with full profiling (CompLevel_full_profile)

   680  *   4 - C2 (CompLevel_full_optimization)

   681  *

   682  * Common state transition patterns:

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

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

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

   686  *

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

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

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

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

   691  *

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

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

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

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

   696  *    without full profiling while c2 is compiling.

   697  *

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

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

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

   701  *

   702  * e. 0 -> 4.

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

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

   705  *    the compiled version already exists).

   706  *

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

   708  * are possible.

   709  *

   710  */

   711 

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

   713 CompLevel TieredThresholdPolicy::common(Predicate p, Method* method, CompLevel cur_level, bool disable_feedback) {

   714   CompLevel next_level = cur_level;

   715   int i = method->invocation_count();

   716   int b = method->backedge_count();

   717 

   718   if (is_trivial(method)) {

   719     next_level = CompLevel_simple;

   720   } else {

   721     switch(cur_level) {

   722       default: break;

   723       case CompLevel_aot: {

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

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

   726         next_level = CompLevel_full_optimization;

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

   728                                Tier3DelayOff * compiler_count(CompLevel_full_optimization) &&

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

   730         next_level = CompLevel_full_profile;

   731       }

   732     }

   733     break;

   734     case CompLevel_none:

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

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

   737         next_level = CompLevel_full_optimization;

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

   739 #if INCLUDE_JVMCI

   740         if (EnableJVMCI && UseJVMCICompiler) {

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

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

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

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

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

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

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

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

   749           next_level = CompLevel_full_profile;

   750         } else

   751 #endif

   752         {

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

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

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

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

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

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

   759           // when the load on C2 goes down.

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

   761               Tier3DelayOn * compiler_count(CompLevel_full_optimization)) {

   762             next_level = CompLevel_limited_profile;

   763           } else {

   764             next_level = CompLevel_full_profile;

   765           }

   766         }

   767       }

   768       break;

   769     case CompLevel_limited_profile:

   770       if (is_method_profiled(method)) {

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

   772         next_level = CompLevel_full_optimization;

   773       } else {

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

   775         if (mdo != NULL) {

   776           if (mdo->would_profile()) {

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

   778                                      Tier3DelayOff * compiler_count(CompLevel_full_optimization) &&

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

   780               next_level = CompLevel_full_profile;

   781             }

   782           } else {

   783             next_level = CompLevel_full_optimization;

   784           }

   785         } else {

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

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

   788                                    Tier3DelayOff * compiler_count(CompLevel_full_optimization) &&

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

   790             next_level = CompLevel_full_profile;

   791           }

   792         }

   793       }

   794       break;

   795     case CompLevel_full_profile:

   796       {

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

   798         if (mdo != NULL) {

   799           if (mdo->would_profile()) {

   800             int mdo_i = mdo->invocation_count_delta();

   801             int mdo_b = mdo->backedge_count_delta();

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

   803               next_level = CompLevel_full_optimization;

   804             }

   805           } else {

   806             next_level = CompLevel_full_optimization;

   807           }

   808         }

   809       }

   810       break;

   811     }

   812   }

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

   814 }

   815 

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

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

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

   819                              common(&TieredThresholdPolicy::loop_predicate, method, cur_level, true));

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

   821 

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

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

   824   // invocation of the method.

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

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

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

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

   829       next_level = CompLevel_full_optimization;

   830     }

   831   } else {

   832     next_level = MAX2(osr_level, next_level);

   833   }

   834 #if INCLUDE_JVMCI

   835   if (UseJVMCICompiler) {

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

   837   }

   838 #endif

   839   return next_level;

   840 }

   841 

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

   843 CompLevel TieredThresholdPolicy::loop_event(Method* method, CompLevel cur_level, JavaThread* thread) {

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

   845   if (cur_level == CompLevel_none) {

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

   847     // for the transition.

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

   849     if (osr_level > CompLevel_none) {

   850       return osr_level;

   851     }

   852   }

   853 #if INCLUDE_JVMCI

   854   if (UseJVMCICompiler) {

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

   856   }

   857 #endif

   858   return next_level;

   859 }

   860 

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

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

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

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

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

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

   867       // Fall through for JIT compilation.

   868     }

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

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

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

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

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

   874       return true;

   875     }

   876   }

   877   return false;

   878 }

   879 

   880 

   881 // Handle the invocation event.

   882 void TieredThresholdPolicy::method_invocation_event(const methodHandle& mh, const methodHandle& imh,

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

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

   885     create_mdo(mh, thread);

   886   }

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

   888   if (next_level != level) {

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

   890       // No JITting necessary

   891       return;

   892     }

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

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

   895     }

   896   }

   897 }

   898 

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

   900 // with a regular entry from here.

   901 void TieredThresholdPolicy::method_back_branch_event(const methodHandle& mh, const methodHandle& imh,

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

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

   904     create_mdo(mh, thread);

   905   }

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

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

   908     create_mdo(imh, thread);

   909   }

   910 

   911   if (is_compilation_enabled()) {

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

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

   914     // At the very least compile the OSR version

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

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

   917     }

   918 

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

   920     // enough calls.

   921     CompLevel cur_level, next_level;

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

   923       if (level == CompLevel_aot) {

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

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

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

   927         }

   928       } else {

   929         // Current loop event level is not AOT

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

   931         cur_level = comp_level(mh());

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

   933 

   934         if (max_osr_level == CompLevel_full_optimization) {

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

   936           bool make_not_entrant = false;

   937           if (nm->is_osr_method()) {

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

   939             make_not_entrant = true;

   940           } else {

   941             if (next_level != CompLevel_full_optimization) {

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

   943               // enclosing method without the inlinee

   944               cur_level = CompLevel_none;

   945               make_not_entrant = true;

   946             }

   947           }

   948           if (make_not_entrant) {

   949             if (PrintTieredEvents) {

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

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

   952             }

   953             nm->make_not_entrant();

   954           }

   955         }

   956         // Fix up next_level if necessary to avoid deopts

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

   958           next_level = CompLevel_full_profile;

   959         }

   960         if (cur_level != next_level) {

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

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

   963           }

   964         }

   965       }

   966     } else {

   967       cur_level = comp_level(mh());

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

   969       if (next_level != cur_level) {

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

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

   972         }

   973       }

   974     }

   975   }

   976 }

   977 

   978 #endif