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->comp_level() == CompLevel_full_profile && TieredStopAtLevel > CompLevel_full_profile
270 && is_method_profiled(max_method)) {
271 max_task->set_comp_level(CompLevel_limited_profile);
272 if (PrintTieredEvents) {
273 print_event(UPDATE_IN_QUEUE, max_method, max_method, max_task->osr_bci(), (CompLevel)max_task->comp_level());
274 }
275 }
276
277 return max_task;
278 }
279
280 void SimpleThresholdPolicy::reprofile(ScopeDesc* trap_scope, bool is_osr) {
281 for (ScopeDesc* sd = trap_scope;; sd = sd->sender()) {
282 if (PrintTieredEvents) {
283 methodHandle mh(sd->method());
284 print_event(REPROFILE, mh, mh, InvocationEntryBci, CompLevel_none);
285 }
286 MethodData* mdo = sd->method()->method_data();
287 if (mdo != NULL) {
288 mdo->reset_start_counters();
289 }
290 if (sd->is_top()) break;
291 }
292 }
293
294 nmethod* SimpleThresholdPolicy::event(const methodHandle& method, const methodHandle& inlinee,
295 int branch_bci, int bci, CompLevel comp_level, CompiledMethod* nm, JavaThread* thread) {
296 if (comp_level == CompLevel_none &&
297 JvmtiExport::can_post_interpreter_events() &&
298 thread->is_interp_only_mode()) {
299 return NULL;
300 }
301 if (CompileTheWorld || ReplayCompiles) {
302 // Don't trigger other compiles in testing mode
303 return NULL;
304 }
305
306 handle_counter_overflow(method());
307 if (method() != inlinee()) {
308 handle_counter_overflow(inlinee());
309 }
310
311 if (PrintTieredEvents) {
312 print_event(bci == InvocationEntryBci ? CALL : LOOP, method, inlinee, bci, comp_level);
313 }
314
315 if (bci == InvocationEntryBci) {
316 method_invocation_event(method, inlinee, comp_level, nm, thread);
317 } else {
318 // method == inlinee if the event originated in the main method
319 method_back_branch_event(method, inlinee, bci, comp_level, nm, thread);
320 // Check if event led to a higher level OSR compilation
321 nmethod* osr_nm = inlinee->lookup_osr_nmethod_for(bci, comp_level, false);
322 if (osr_nm != NULL && osr_nm->comp_level() > comp_level) {
323 // Perform OSR with new nmethod
324 return osr_nm;
325 }
326 }
327 return NULL;
328 }
329
330 // Check if the method can be compiled, change level if necessary
331 void SimpleThresholdPolicy::compile(const methodHandle& mh, int bci, CompLevel level, JavaThread* thread) {
332 assert(level <= TieredStopAtLevel, "Invalid compilation level");
333 if (level == CompLevel_none) {
334 return;
335 }
336 if (level == CompLevel_aot) {
337 if (mh->has_aot_code()) {
338 if (PrintTieredEvents) {
339 print_event(COMPILE, mh, mh, bci, level);
340 }
341 MutexLocker ml(Compile_lock);
342 NoSafepointVerifier nsv;
343 if (mh->has_aot_code() && mh->code() != mh->aot_code()) {
344 mh->aot_code()->make_entrant();
345 if (mh->has_compiled_code()) {
346 mh->code()->make_not_entrant();
347 }
348 Method::set_code(mh, mh->aot_code());
349 }
350 }
351 return;
352 }
353
354 // Check if the method can be compiled. If it cannot be compiled with C1, continue profiling
355 // in the interpreter and then compile with C2 (the transition function will request that,
356 // see common() ). If the method cannot be compiled with C2 but still can with C1, compile it with
357 // pure C1.
358 if (!can_be_compiled(mh, level)) {
359 if (level == CompLevel_full_optimization && can_be_compiled(mh, CompLevel_simple)) {
360 compile(mh, bci, CompLevel_simple, thread);
361 }
362 return;
363 }
364 if (bci != InvocationEntryBci && mh->is_not_osr_compilable(level)) {
365 return;
366 }
367 if (!CompileBroker::compilation_is_in_queue(mh)) {
368 if (PrintTieredEvents) {
369 print_event(COMPILE, mh, mh, bci, level);
370 }
371 submit_compile(mh, bci, level, thread);
372 }
373 }
374
375 // Update the rate and submit compile
376 void SimpleThresholdPolicy::submit_compile(const methodHandle& mh, int bci, CompLevel level, JavaThread* thread) {
377 int hot_count = (bci == InvocationEntryBci) ? mh->invocation_count() : mh->backedge_count();
378 update_rate(os::javaTimeMillis(), mh());
379 CompileBroker::compile_method(mh, bci, level, mh, hot_count, CompileTask::Reason_Tiered, thread);
380 }
381
382 // Print an event.
383 void SimpleThresholdPolicy::print_specific(EventType type, const methodHandle& mh, const methodHandle& imh,
384 int bci, CompLevel level) {
385 tty->print(" rate=");
386 if (mh->prev_time() == 0) tty->print("n/a");
387 else tty->print("%f", mh->rate());
388
389 tty->print(" k=%.2lf,%.2lf", threshold_scale(CompLevel_full_profile, Tier3LoadFeedback),
390 threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback));
391
392 }
393
394 // update_rate() is called from select_task() while holding a compile queue lock.
395 void SimpleThresholdPolicy::update_rate(jlong t, Method* m) {
396 // Skip update if counters are absent.
397 // Can't allocate them since we are holding compile queue lock.
398 if (m->method_counters() == NULL) return;
399
400 if (is_old(m)) {
401 // We don't remove old methods from the queue,
402 // so we can just zero the rate.
403 m->set_rate(0);
404 return;
405 }
406
407 // We don't update the rate if we've just came out of a safepoint.
408 // delta_s is the time since last safepoint in milliseconds.
409 jlong delta_s = t - SafepointSynchronize::end_of_last_safepoint();
410 jlong delta_t = t - (m->prev_time() != 0 ? m->prev_time() : start_time()); // milliseconds since the last measurement
411 // How many events were there since the last time?
412 int event_count = m->invocation_count() + m->backedge_count();
413 int delta_e = event_count - m->prev_event_count();
414
415 // We should be running for at least 1ms.
416 if (delta_s >= TieredRateUpdateMinTime) {
417 // And we must've taken the previous point at least 1ms before.
418 if (delta_t >= TieredRateUpdateMinTime && delta_e > 0) {
419 m->set_prev_time(t);
420 m->set_prev_event_count(event_count);
421 m->set_rate((float)delta_e / (float)delta_t); // Rate is events per millisecond
422 } else {
423 if (delta_t > TieredRateUpdateMaxTime && delta_e == 0) {
424 // If nothing happened for 25ms, zero the rate. Don't modify prev values.
425 m->set_rate(0);
426 }
427 }
428 }
429 }
430
431 // Check if this method has been stale from a given number of milliseconds.
432 // See select_task().
433 bool SimpleThresholdPolicy::is_stale(jlong t, jlong timeout, Method* m) {
434 jlong delta_s = t - SafepointSynchronize::end_of_last_safepoint();
435 jlong delta_t = t - m->prev_time();
436 if (delta_t > timeout && delta_s > timeout) {
437 int event_count = m->invocation_count() + m->backedge_count();
438 int delta_e = event_count - m->prev_event_count();
439 // Return true if there were no events.
440 return delta_e == 0;
441 }
442 return false;
443 }
444
445 // We don't remove old methods from the compile queue even if they have
446 // very low activity. See select_task().
447 bool SimpleThresholdPolicy::is_old(Method* method) {
448 return method->invocation_count() > 50000 || method->backedge_count() > 500000;
449 }
450
451 double SimpleThresholdPolicy::weight(Method* method) {
452 return (double)(method->rate() + 1) *
453 (method->invocation_count() + 1) * (method->backedge_count() + 1);
454 }
455
456 // Apply heuristics and return true if x should be compiled before y
457 bool SimpleThresholdPolicy::compare_methods(Method* x, Method* y) {
458 if (x->highest_comp_level() > y->highest_comp_level()) {
459 // recompilation after deopt
460 return true;
461 } else
462 if (x->highest_comp_level() == y->highest_comp_level()) {
463 if (weight(x) > weight(y)) {
464 return true;
465 }
466 }
467 return false;
468 }
469
470 // Is method profiled enough?
471 bool SimpleThresholdPolicy::is_method_profiled(Method* method) {
472 MethodData* mdo = method->method_data();
473 if (mdo != NULL) {
474 int i = mdo->invocation_count_delta();
475 int b = mdo->backedge_count_delta();
476 return call_predicate_helper<CompLevel_full_profile>(i, b, 1, method);
477 }
478 return false;
479 }
480
481 double SimpleThresholdPolicy::threshold_scale(CompLevel level, int feedback_k) {
482 double queue_size = CompileBroker::queue_size(level);
483 int comp_count = compiler_count(level);
484 double k = queue_size / (feedback_k * comp_count) + 1;
485
486 // Increase C1 compile threshold when the code cache is filled more
487 // than specified by IncreaseFirstTierCompileThresholdAt percentage.
488 // The main intention is to keep enough free space for C2 compiled code
489 // to achieve peak performance if the code cache is under stress.
490 if ((TieredStopAtLevel == CompLevel_full_optimization) && (level != CompLevel_full_optimization)) {
491 double current_reverse_free_ratio = CodeCache::reverse_free_ratio(CodeCache::get_code_blob_type(level));
492 if (current_reverse_free_ratio > _increase_threshold_at_ratio) {
493 k *= exp(current_reverse_free_ratio - _increase_threshold_at_ratio);
494 }
495 }
496 return k;
497 }
498
499 // Call and loop predicates determine whether a transition to a higher
500 // compilation level should be performed (pointers to predicate functions
501 // are passed to common()).
502 // Tier?LoadFeedback is basically a coefficient that determines of
503 // how many methods per compiler thread can be in the queue before
504 // the threshold values double.
505 bool SimpleThresholdPolicy::loop_predicate(int i, int b, CompLevel cur_level, Method* method) {
506 switch(cur_level) {
507 case CompLevel_aot: {
508 double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback);
509 return loop_predicate_helper<CompLevel_aot>(i, b, k, method);
510 }
511 case CompLevel_none:
512 case CompLevel_limited_profile: {
513 double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback);
514 return loop_predicate_helper<CompLevel_none>(i, b, k, method);
515 }
516 case CompLevel_full_profile: {
517 double k = threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback);
518 return loop_predicate_helper<CompLevel_full_profile>(i, b, k, method);
519 }
520 default:
521 return true;
522 }
523 }
524
525 bool SimpleThresholdPolicy::call_predicate(int i, int b, CompLevel cur_level, Method* method) {
526 switch(cur_level) {
527 case CompLevel_aot: {
528 double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback);
529 return call_predicate_helper<CompLevel_aot>(i, b, k, method);
530 }
531 case CompLevel_none:
532 case CompLevel_limited_profile: {
533 double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback);
534 return call_predicate_helper<CompLevel_none>(i, b, k, method);
535 }
536 case CompLevel_full_profile: {
537 double k = threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback);
538 return call_predicate_helper<CompLevel_full_profile>(i, b, k, method);
539 }
540 default:
541 return true;
542 }
543 }
544
545 // Determine is a method is mature.
546 bool SimpleThresholdPolicy::is_mature(Method* method) {
547 if (is_trivial(method)) return true;
548 MethodData* mdo = method->method_data();
549 if (mdo != NULL) {
550 int i = mdo->invocation_count();
551 int b = mdo->backedge_count();
552 double k = ProfileMaturityPercentage / 100.0;
553 return call_predicate_helper<CompLevel_full_profile>(i, b, k, method) ||
554 loop_predicate_helper<CompLevel_full_profile>(i, b, k, method);
555 }
556 return false;
557 }
558
559 // If a method is old enough and is still in the interpreter we would want to
560 // start profiling without waiting for the compiled method to arrive.
561 // We also take the load on compilers into the account.
562 bool SimpleThresholdPolicy::should_create_mdo(Method* method, CompLevel cur_level) {
563 if (cur_level == CompLevel_none &&
564 CompileBroker::queue_size(CompLevel_full_optimization) <=
565 Tier3DelayOn * compiler_count(CompLevel_full_optimization)) {
566 int i = method->invocation_count();
567 int b = method->backedge_count();
568 double k = Tier0ProfilingStartPercentage / 100.0;
569 return call_predicate_helper<CompLevel_none>(i, b, k, method) || loop_predicate_helper<CompLevel_none>(i, b, k, method);
570 }
571 return false;
572 }
573
574 // Inlining control: if we're compiling a profiled method with C1 and the callee
575 // is known to have OSRed in a C2 version, don't inline it.
576 bool SimpleThresholdPolicy::should_not_inline(ciEnv* env, ciMethod* callee) {
577 CompLevel comp_level = (CompLevel)env->comp_level();
578 if (comp_level == CompLevel_full_profile ||
579 comp_level == CompLevel_limited_profile) {
580 return callee->highest_osr_comp_level() == CompLevel_full_optimization;
581 }
582 return false;
583 }
584
585 // Create MDO if necessary.
586 void SimpleThresholdPolicy::create_mdo(const methodHandle& mh, JavaThread* THREAD) {
587 if (mh->is_native() ||
588 mh->is_abstract() ||
589 mh->is_accessor() ||
590 mh->is_constant_getter()) {
591 return;
592 }
593 if (mh->method_data() == NULL) {
594 Method::build_interpreter_method_data(mh, CHECK_AND_CLEAR);
595 }
596 }
597
598
599 /*
600 * Method states:
601 * 0 - interpreter (CompLevel_none)
602 * 1 - pure C1 (CompLevel_simple)
603 * 2 - C1 with invocation and backedge counting (CompLevel_limited_profile)
604 * 3 - C1 with full profiling (CompLevel_full_profile)
605 * 4 - C2 (CompLevel_full_optimization)
606 *
607 * Common state transition patterns:
608 * a. 0 -> 3 -> 4.
609 * The most common path. But note that even in this straightforward case
610 * profiling can start at level 0 and finish at level 3.
611 *
612 * b. 0 -> 2 -> 3 -> 4.
613 * This case occurs when the load on C2 is deemed too high. So, instead of transitioning
614 * into state 3 directly and over-profiling while a method is in the C2 queue we transition to
615 * level 2 and wait until the load on C2 decreases. This path is disabled for OSRs.
616 *
617 * c. 0 -> (3->2) -> 4.
618 * In this case we enqueue a method for compilation at level 3, but the C1 queue is long enough
619 * to enable the profiling to fully occur at level 0. In this case we change the compilation level
620 * of the method to 2 while the request is still in-queue, because it'll allow it to run much faster
621 * without full profiling while c2 is compiling.
622 *
623 * d. 0 -> 3 -> 1 or 0 -> 2 -> 1.
624 * After a method was once compiled with C1 it can be identified as trivial and be compiled to
625 * level 1. These transition can also occur if a method can't be compiled with C2 but can with C1.
626 *
627 * e. 0 -> 4.
628 * This can happen if a method fails C1 compilation (it will still be profiled in the interpreter)
629 * or because of a deopt that didn't require reprofiling (compilation won't happen in this case because
630 * the compiled version already exists).
631 *
632 * Note that since state 0 can be reached from any other state via deoptimization different loops
633 * are possible.
634 *
635 */
636
637 // Common transition function. Given a predicate determines if a method should transition to another level.
638 CompLevel SimpleThresholdPolicy::common(Predicate p, Method* method, CompLevel cur_level, bool disable_feedback) {
639 CompLevel next_level = cur_level;
640 int i = method->invocation_count();
641 int b = method->backedge_count();
642
643 if (is_trivial(method)) {
644 next_level = CompLevel_simple;
645 } else {
646 switch(cur_level) {
647 default: break;
648 case CompLevel_aot: {
649 // If we were at full profile level, would we switch to full opt?
650 if (common(p, method, CompLevel_full_profile, disable_feedback) == CompLevel_full_optimization) {
651 next_level = CompLevel_full_optimization;
652 } else if (disable_feedback || (CompileBroker::queue_size(CompLevel_full_optimization) <=
653 Tier3DelayOff * compiler_count(CompLevel_full_optimization) &&
654 (this->*p)(i, b, cur_level, method))) {
655 next_level = CompLevel_full_profile;
656 }
657 }
658 break;
659 case CompLevel_none:
660 // If we were at full profile level, would we switch to full opt?
661 if (common(p, method, CompLevel_full_profile, disable_feedback) == CompLevel_full_optimization) {
662 next_level = CompLevel_full_optimization;
663 } else if ((this->*p)(i, b, cur_level, method)) {
664 #if INCLUDE_JVMCI
665 if (EnableJVMCI && UseJVMCICompiler) {
666 // Since JVMCI takes a while to warm up, its queue inevitably backs up during
667 // early VM execution. As of 2014-06-13, JVMCI's inliner assumes that the root
668 // compilation method and all potential inlinees have mature profiles (which
669 // includes type profiling). If it sees immature profiles, JVMCI's inliner
670 // can perform pathologically bad (e.g., causing OutOfMemoryErrors due to
671 // exploring/inlining too many graphs). Since a rewrite of the inliner is
672 // in progress, we simply disable the dialing back heuristic for now and will
673 // revisit this decision once the new inliner is completed.
674 next_level = CompLevel_full_profile;
675 } else
676 #endif
677 {
678 // C1-generated fully profiled code is about 30% slower than the limited profile
679 // code that has only invocation and backedge counters. The observation is that
680 // if C2 queue is large enough we can spend too much time in the fully profiled code
681 // while waiting for C2 to pick the method from the queue. To alleviate this problem
682 // we introduce a feedback on the C2 queue size. If the C2 queue is sufficiently long
683 // we choose to compile a limited profiled version and then recompile with full profiling
684 // when the load on C2 goes down.
685 if (!disable_feedback && CompileBroker::queue_size(CompLevel_full_optimization) >
686 Tier3DelayOn * compiler_count(CompLevel_full_optimization)) {
687 next_level = CompLevel_limited_profile;
688 } else {
689 next_level = CompLevel_full_profile;
690 }
691 }
692 }
693 break;
694 case CompLevel_limited_profile:
695 if (is_method_profiled(method)) {
696 // Special case: we got here because this method was fully profiled in the interpreter.
697 next_level = CompLevel_full_optimization;
698 } else {
699 MethodData* mdo = method->method_data();
700 if (mdo != NULL) {
701 if (mdo->would_profile()) {
702 if (disable_feedback || (CompileBroker::queue_size(CompLevel_full_optimization) <=
703 Tier3DelayOff * compiler_count(CompLevel_full_optimization) &&
704 (this->*p)(i, b, cur_level, method))) {
705 next_level = CompLevel_full_profile;
706 }
707 } else {
708 next_level = CompLevel_full_optimization;
709 }
710 } else {
711 // If there is no MDO we need to profile
712 if (disable_feedback || (CompileBroker::queue_size(CompLevel_full_optimization) <=
713 Tier3DelayOff * compiler_count(CompLevel_full_optimization) &&
714 (this->*p)(i, b, cur_level, method))) {
715 next_level = CompLevel_full_profile;
716 }
717 }
718 }
719 break;
720 case CompLevel_full_profile:
721 {
722 MethodData* mdo = method->method_data();
723 if (mdo != NULL) {
724 if (mdo->would_profile()) {
725 int mdo_i = mdo->invocation_count_delta();
726 int mdo_b = mdo->backedge_count_delta();
727 if ((this->*p)(mdo_i, mdo_b, cur_level, method)) {
728 next_level = CompLevel_full_optimization;
729 }
730 } else {
731 next_level = CompLevel_full_optimization;
732 }
733 }
734 }
735 break;
736 }
737 }
738 return MIN2(next_level, (CompLevel)TieredStopAtLevel);
739 }
740
741 // Determine if a method should be compiled with a normal entry point at a different level.
742 CompLevel SimpleThresholdPolicy::call_event(Method* method, CompLevel cur_level, JavaThread * thread) {
743 CompLevel osr_level = MIN2((CompLevel) method->highest_osr_comp_level(),
744 common(&SimpleThresholdPolicy::loop_predicate, method, cur_level, true));
745 CompLevel next_level = common(&SimpleThresholdPolicy::call_predicate, method, cur_level);
746
747 // If OSR method level is greater than the regular method level, the levels should be
748 // equalized by raising the regular method level in order to avoid OSRs during each
749 // invocation of the method.
750 if (osr_level == CompLevel_full_optimization && cur_level == CompLevel_full_profile) {
751 MethodData* mdo = method->method_data();
752 guarantee(mdo != NULL, "MDO should not be NULL");
753 if (mdo->invocation_count() >= 1) {
754 next_level = CompLevel_full_optimization;
755 }
756 } else {
757 next_level = MAX2(osr_level, next_level);
758 }
759 #if INCLUDE_JVMCI
760 if (UseJVMCICompiler) {
761 next_level = JVMCIRuntime::adjust_comp_level(method, false, next_level, thread);
762 }
763 #endif
764 return next_level;
765 }
766
767 // Determine if we should do an OSR compilation of a given method.
768 CompLevel SimpleThresholdPolicy::loop_event(Method* method, CompLevel cur_level, JavaThread* thread) {
769 CompLevel next_level = common(&SimpleThresholdPolicy::loop_predicate, method, cur_level, true);
770 if (cur_level == CompLevel_none) {
771 // If there is a live OSR method that means that we deopted to the interpreter
772 // for the transition.
773 CompLevel osr_level = MIN2((CompLevel)method->highest_osr_comp_level(), next_level);
774 if (osr_level > CompLevel_none) {
775 return osr_level;
776 }
777 }
778 #if INCLUDE_JVMCI
779 if (UseJVMCICompiler) {
780 next_level = JVMCIRuntime::adjust_comp_level(method, true, next_level, thread);
781 }
782 #endif
783 return next_level;
784 }
785
786 bool SimpleThresholdPolicy::maybe_switch_to_aot(const methodHandle& mh, CompLevel cur_level, CompLevel next_level, JavaThread* thread) {
787 if (UseAOT && !delay_compilation_during_startup()) {
788 if (cur_level == CompLevel_full_profile || cur_level == CompLevel_none) {
789 // If the current level is full profile or interpreter and we're switching to any other level,
790 // activate the AOT code back first so that we won't waste time overprofiling.
791 compile(mh, InvocationEntryBci, CompLevel_aot, thread);
792 // Fall through for JIT compilation.
793 }
794 if (next_level == CompLevel_limited_profile && cur_level != CompLevel_aot && mh->has_aot_code()) {
795 // If the next level is limited profile, use the aot code (if there is any),
796 // since it's essentially the same thing.
797 compile(mh, InvocationEntryBci, CompLevel_aot, thread);
798 // Not need to JIT, we're done.
799 return true;
800 }
801 }
802 return false;
803 }
804
805
806 // Handle the invocation event.
807 void SimpleThresholdPolicy::method_invocation_event(const methodHandle& mh, const methodHandle& imh,
808 CompLevel level, CompiledMethod* nm, JavaThread* thread) {
809 if (should_create_mdo(mh(), level)) {
810 create_mdo(mh, thread);
811 }
812 CompLevel next_level = call_event(mh(), level, thread);
813 if (next_level != level) {
814 if (maybe_switch_to_aot(mh, level, next_level, thread)) {
815 // No JITting necessary
816 return;
817 }
818 if (is_compilation_enabled() && !CompileBroker::compilation_is_in_queue(mh)) {
819 compile(mh, InvocationEntryBci, next_level, thread);
820 }
821 }
822 }
823
824 // Handle the back branch event. Notice that we can compile the method
825 // with a regular entry from here.
826 void SimpleThresholdPolicy::method_back_branch_event(const methodHandle& mh, const methodHandle& imh,
827 int bci, CompLevel level, CompiledMethod* nm, JavaThread* thread) {
828 if (should_create_mdo(mh(), level)) {
829 create_mdo(mh, thread);
830 }
831 // Check if MDO should be created for the inlined method
832 if (should_create_mdo(imh(), level)) {
833 create_mdo(imh, thread);
834 }
835
836 if (is_compilation_enabled()) {
837 CompLevel next_osr_level = loop_event(imh(), level, thread);
838 CompLevel max_osr_level = (CompLevel)imh->highest_osr_comp_level();
839 // At the very least compile the OSR version
840 if (!CompileBroker::compilation_is_in_queue(imh) && (next_osr_level != level)) {
841 compile(imh, bci, next_osr_level, thread);
842 }
843
844 // Use loop event as an opportunity to also check if there's been
845 // enough calls.
846 CompLevel cur_level, next_level;
847 if (mh() != imh()) { // If there is an enclosing method
848 if (level == CompLevel_aot) {
849 // Recompile the enclosing method to prevent infinite OSRs. Stay at AOT level while it's compiling.
850 if (max_osr_level != CompLevel_none && !CompileBroker::compilation_is_in_queue(mh)) {
851 compile(mh, InvocationEntryBci, MIN2((CompLevel)TieredStopAtLevel, CompLevel_full_profile), thread);
852 }
853 } else {
854 // Current loop event level is not AOT
855 guarantee(nm != NULL, "Should have nmethod here");
856 cur_level = comp_level(mh());
857 next_level = call_event(mh(), cur_level, thread);
858
859 if (max_osr_level == CompLevel_full_optimization) {
860 // The inlinee OSRed to full opt, we need to modify the enclosing method to avoid deopts
861 bool make_not_entrant = false;
862 if (nm->is_osr_method()) {
863 // This is an osr method, just make it not entrant and recompile later if needed
864 make_not_entrant = true;
865 } else {
866 if (next_level != CompLevel_full_optimization) {
867 // next_level is not full opt, so we need to recompile the
868 // enclosing method without the inlinee
869 cur_level = CompLevel_none;
870 make_not_entrant = true;
871 }
872 }
873 if (make_not_entrant) {
874 if (PrintTieredEvents) {
875 int osr_bci = nm->is_osr_method() ? nm->osr_entry_bci() : InvocationEntryBci;
876 print_event(MAKE_NOT_ENTRANT, mh(), mh(), osr_bci, level);
877 }
878 nm->make_not_entrant();
879 }
880 }
881 // Fix up next_level if necessary to avoid deopts
882 if (next_level == CompLevel_limited_profile && max_osr_level == CompLevel_full_profile) {
883 next_level = CompLevel_full_profile;
884 }
885 if (cur_level != next_level) {
886 if (!maybe_switch_to_aot(mh, cur_level, next_level, thread) && !CompileBroker::compilation_is_in_queue(mh)) {
887 compile(mh, InvocationEntryBci, next_level, thread);
888 }
889 }
890 }
891 } else {
892 cur_level = comp_level(mh());
893 next_level = call_event(mh(), cur_level, thread);
894 if (next_level != cur_level) {
895 if (!maybe_switch_to_aot(mh, cur_level, next_level, thread) && !CompileBroker::compilation_is_in_queue(mh)) {
896 compile(mh, InvocationEntryBci, next_level, thread);
897 }
898 }
899 }
900 }
901 }
902
903 #endif