1/*
2 * Copyright (c) 2010, 2019, 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/safepoint.hpp"
32#include "runtime/safepointVerifiers.hpp"
33#include "runtime/tieredThresholdPolicy.hpp"
34#include "code/scopeDesc.hpp"
35#include "oops/method.inline.hpp"
36#if INCLUDE_JVMCI
37#include "jvmci/jvmci.hpp"
38#endif
39
40#ifdef TIERED
41
42#include "c1/c1_Compiler.hpp"
43#include "opto/c2compiler.hpp"
44
45template<CompLevel level>
46bool TieredThresholdPolicy::call_predicate_helper(int i, int b, double scale, Method* method) {
47 double threshold_scaling;
48 if (CompilerOracle::has_option_value(method, "CompileThresholdScaling", threshold_scaling)) {
49 scale *= threshold_scaling;
50 }
51 switch(level) {
52 case CompLevel_aot:
53 return (i >= Tier3AOTInvocationThreshold * scale) ||
54 (i >= Tier3AOTMinInvocationThreshold * scale && i + b >= Tier3AOTCompileThreshold * scale);
55 case CompLevel_none:
56 case CompLevel_limited_profile:
57 return (i >= Tier3InvocationThreshold * scale) ||
58 (i >= Tier3MinInvocationThreshold * scale && i + b >= Tier3CompileThreshold * scale);
59 case CompLevel_full_profile:
60 return (i >= Tier4InvocationThreshold * scale) ||
61 (i >= Tier4MinInvocationThreshold * scale && i + b >= Tier4CompileThreshold * scale);
62 }
63 return true;
64}
65
66template<CompLevel level>
67bool TieredThresholdPolicy::loop_predicate_helper(int i, int b, double scale, Method* method) {
68 double threshold_scaling;
69 if (CompilerOracle::has_option_value(method, "CompileThresholdScaling", threshold_scaling)) {
70 scale *= threshold_scaling;
71 }
72 switch(level) {
73 case CompLevel_aot:
74 return b >= Tier3AOTBackEdgeThreshold * scale;
75 case CompLevel_none:
76 case CompLevel_limited_profile:
77 return b >= Tier3BackEdgeThreshold * scale;
78 case CompLevel_full_profile:
79 return b >= Tier4BackEdgeThreshold * scale;
80 }
81 return true;
82}
83
84// Simple methods are as good being compiled with C1 as C2.
85// Determine if a given method is such a case.
86bool TieredThresholdPolicy::is_trivial(Method* method) {
87 if (method->is_accessor() ||
88 method->is_constant_getter()) {
89 return true;
90 }
91 return false;
92}
93
94bool TieredThresholdPolicy::should_compile_at_level_simple(Method* method) {
95 if (TieredThresholdPolicy::is_trivial(method)) {
96 return true;
97 }
98#if INCLUDE_JVMCI
99 if (UseJVMCICompiler) {
100 AbstractCompiler* comp = CompileBroker::compiler(CompLevel_full_optimization);
101 if (comp != NULL && comp->is_jvmci() && ((JVMCICompiler*) comp)->force_comp_at_level_simple(method)) {
102 return true;
103 }
104 }
105#endif
106 return false;
107}
108
109CompLevel TieredThresholdPolicy::comp_level(Method* method) {
110 CompiledMethod *nm = method->code();
111 if (nm != NULL && nm->is_in_use()) {
112 return (CompLevel)nm->comp_level();
113 }
114 return CompLevel_none;
115}
116
117void TieredThresholdPolicy::print_counters(const char* prefix, const methodHandle& mh) {
118 int invocation_count = mh->invocation_count();
119 int backedge_count = mh->backedge_count();
120 MethodData* mdh = mh->method_data();
121 int mdo_invocations = 0, mdo_backedges = 0;
122 int mdo_invocations_start = 0, mdo_backedges_start = 0;
123 if (mdh != NULL) {
124 mdo_invocations = mdh->invocation_count();
125 mdo_backedges = mdh->backedge_count();
126 mdo_invocations_start = mdh->invocation_count_start();
127 mdo_backedges_start = mdh->backedge_count_start();
128 }
129 tty->print(" %stotal=%d,%d %smdo=%d(%d),%d(%d)", prefix,
130 invocation_count, backedge_count, prefix,
131 mdo_invocations, mdo_invocations_start,
132 mdo_backedges, mdo_backedges_start);
133 tty->print(" %smax levels=%d,%d", prefix,
134 mh->highest_comp_level(), mh->highest_osr_comp_level());
135}
136
137// Print an event.
138void TieredThresholdPolicy::print_event(EventType type, const methodHandle& mh, const methodHandle& imh,
139 int bci, CompLevel level) {
140 bool inlinee_event = mh() != imh();
141
142 ttyLocker tty_lock;
143 tty->print("%lf: [", os::elapsedTime());
144
145 switch(type) {
146 case CALL:
147 tty->print("call");
148 break;
149 case LOOP:
150 tty->print("loop");
151 break;
152 case COMPILE:
153 tty->print("compile");
154 break;
155 case REMOVE_FROM_QUEUE:
156 tty->print("remove-from-queue");
157 break;
158 case UPDATE_IN_QUEUE:
159 tty->print("update-in-queue");
160 break;
161 case REPROFILE:
162 tty->print("reprofile");
163 break;
164 case MAKE_NOT_ENTRANT:
165 tty->print("make-not-entrant");
166 break;
167 default:
168 tty->print("unknown");
169 }
170
171 tty->print(" level=%d ", level);
172
173 ResourceMark rm;
174 char *method_name = mh->name_and_sig_as_C_string();
175 tty->print("[%s", method_name);
176 if (inlinee_event) {
177 char *inlinee_name = imh->name_and_sig_as_C_string();
178 tty->print(" [%s]] ", inlinee_name);
179 }
180 else tty->print("] ");
181 tty->print("@%d queues=%d,%d", bci, CompileBroker::queue_size(CompLevel_full_profile),
182 CompileBroker::queue_size(CompLevel_full_optimization));
183
184 print_specific(type, mh, imh, bci, level);
185
186 if (type != COMPILE) {
187 print_counters("", mh);
188 if (inlinee_event) {
189 print_counters("inlinee ", imh);
190 }
191 tty->print(" compilable=");
192 bool need_comma = false;
193 if (!mh->is_not_compilable(CompLevel_full_profile)) {
194 tty->print("c1");
195 need_comma = true;
196 }
197 if (!mh->is_not_osr_compilable(CompLevel_full_profile)) {
198 if (need_comma) tty->print(",");
199 tty->print("c1-osr");
200 need_comma = true;
201 }
202 if (!mh->is_not_compilable(CompLevel_full_optimization)) {
203 if (need_comma) tty->print(",");
204 tty->print("c2");
205 need_comma = true;
206 }
207 if (!mh->is_not_osr_compilable(CompLevel_full_optimization)) {
208 if (need_comma) tty->print(",");
209 tty->print("c2-osr");
210 }
211 tty->print(" status=");
212 if (mh->queued_for_compilation()) {
213 tty->print("in-queue");
214 } else tty->print("idle");
215 }
216 tty->print_cr("]");
217}
218
219void TieredThresholdPolicy::initialize() {
220 int count = CICompilerCount;
221 bool c1_only = TieredStopAtLevel < CompLevel_full_optimization;
222#ifdef _LP64
223 // Turn on ergonomic compiler count selection
224 if (FLAG_IS_DEFAULT(CICompilerCountPerCPU) && FLAG_IS_DEFAULT(CICompilerCount)) {
225 FLAG_SET_DEFAULT(CICompilerCountPerCPU, true);
226 }
227 if (CICompilerCountPerCPU) {
228 // Simple log n seems to grow too slowly for tiered, try something faster: log n * log log n
229 int log_cpu = log2_int(os::active_processor_count());
230 int loglog_cpu = log2_int(MAX2(log_cpu, 1));
231 count = MAX2(log_cpu * loglog_cpu * 3 / 2, 2);
232 // Make sure there is enough space in the code cache to hold all the compiler buffers
233 size_t c1_size = Compiler::code_buffer_size();
234 size_t c2_size = C2Compiler::initial_code_buffer_size();
235 size_t buffer_size = c1_only ? c1_size : (c1_size/3 + 2*c2_size/3);
236 int max_count = (ReservedCodeCacheSize - (CodeCacheMinimumUseSpace DEBUG_ONLY(* 3))) / (int)buffer_size;
237 if (count > max_count) {
238 // Lower the compiler count such that all buffers fit into the code cache
239 count = MAX2(max_count, c1_only ? 1 : 2);
240 }
241 FLAG_SET_ERGO(CICompilerCount, count);
242 }
243#else
244 // On 32-bit systems, the number of compiler threads is limited to 3.
245 // On these systems, the virtual address space available to the JVM
246 // is usually limited to 2-4 GB (the exact value depends on the platform).
247 // As the compilers (especially C2) can consume a large amount of
248 // memory, scaling the number of compiler threads with the number of
249 // available cores can result in the exhaustion of the address space
250 /// available to the VM and thus cause the VM to crash.
251 if (FLAG_IS_DEFAULT(CICompilerCount)) {
252 count = 3;
253 FLAG_SET_ERGO(CICompilerCount, count);
254 }
255#endif
256
257 if (c1_only) {
258 // No C2 compiler thread required
259 set_c1_count(count);
260 } else {
261 set_c1_count(MAX2(count / 3, 1));
262 set_c2_count(MAX2(count - c1_count(), 1));
263 }
264 assert(count == c1_count() + c2_count(), "inconsistent compiler thread count");
265
266 // Some inlining tuning
267#ifdef X86
268 if (FLAG_IS_DEFAULT(InlineSmallCode)) {
269 FLAG_SET_DEFAULT(InlineSmallCode, 2000);
270 }
271#endif
272
273#if defined SPARC || defined AARCH64
274 if (FLAG_IS_DEFAULT(InlineSmallCode)) {
275 FLAG_SET_DEFAULT(InlineSmallCode, 2500);
276 }
277#endif
278
279 set_increase_threshold_at_ratio();
280 set_start_time(os::javaTimeMillis());
281}
282
283void TieredThresholdPolicy::set_carry_if_necessary(InvocationCounter *counter) {
284 if (!counter->carry() && counter->count() > InvocationCounter::count_limit / 2) {
285 counter->set_carry_flag();
286 }
287}
288
289// Set carry flags on the counters if necessary
290void TieredThresholdPolicy::handle_counter_overflow(Method* method) {
291 MethodCounters *mcs = method->method_counters();
292 if (mcs != NULL) {
293 set_carry_if_necessary(mcs->invocation_counter());
294 set_carry_if_necessary(mcs->backedge_counter());
295 }
296 MethodData* mdo = method->method_data();
297 if (mdo != NULL) {
298 set_carry_if_necessary(mdo->invocation_counter());
299 set_carry_if_necessary(mdo->backedge_counter());
300 }
301}
302
303// Called with the queue locked and with at least one element
304CompileTask* TieredThresholdPolicy::select_task(CompileQueue* compile_queue) {
305 CompileTask *max_blocking_task = NULL;
306 CompileTask *max_task = NULL;
307 Method* max_method = NULL;
308 jlong t = os::javaTimeMillis();
309 // Iterate through the queue and find a method with a maximum rate.
310 for (CompileTask* task = compile_queue->first(); task != NULL;) {
311 CompileTask* next_task = task->next();
312 Method* method = task->method();
313 // If a method was unloaded or has been stale for some time, remove it from the queue.
314 // Blocking tasks and tasks submitted from whitebox API don't become stale
315 if (task->is_unloaded() || (task->can_become_stale() && is_stale(t, TieredCompileTaskTimeout, method) && !is_old(method))) {
316 if (!task->is_unloaded()) {
317 if (PrintTieredEvents) {
318 print_event(REMOVE_FROM_QUEUE, method, method, task->osr_bci(), (CompLevel) task->comp_level());
319 }
320 method->clear_queued_for_compilation();
321 }
322 compile_queue->remove_and_mark_stale(task);
323 task = next_task;
324 continue;
325 }
326 update_rate(t, method);
327 if (max_task == NULL || compare_methods(method, max_method)) {
328 // Select a method with the highest rate
329 max_task = task;
330 max_method = method;
331 }
332
333 if (task->is_blocking()) {
334 if (max_blocking_task == NULL || compare_methods(method, max_blocking_task->method())) {
335 max_blocking_task = task;
336 }
337 }
338
339 task = next_task;
340 }
341
342 if (max_blocking_task != NULL) {
343 // In blocking compilation mode, the CompileBroker will make
344 // compilations submitted by a JVMCI compiler thread non-blocking. These
345 // compilations should be scheduled after all blocking compilations
346 // to service non-compiler related compilations sooner and reduce the
347 // chance of such compilations timing out.
348 max_task = max_blocking_task;
349 max_method = max_task->method();
350 }
351
352 if (max_task != NULL && max_task->comp_level() == CompLevel_full_profile &&
353 TieredStopAtLevel > CompLevel_full_profile &&
354 max_method != NULL && is_method_profiled(max_method)) {
355 max_task->set_comp_level(CompLevel_limited_profile);
356
357 if (CompileBroker::compilation_is_complete(max_method, max_task->osr_bci(), CompLevel_limited_profile)) {
358 if (PrintTieredEvents) {
359 print_event(REMOVE_FROM_QUEUE, max_method, max_method, max_task->osr_bci(), (CompLevel)max_task->comp_level());
360 }
361 compile_queue->remove_and_mark_stale(max_task);
362 max_method->clear_queued_for_compilation();
363 return NULL;
364 }
365
366 if (PrintTieredEvents) {
367 print_event(UPDATE_IN_QUEUE, max_method, max_method, max_task->osr_bci(), (CompLevel)max_task->comp_level());
368 }
369 }
370
371 return max_task;
372}
373
374void TieredThresholdPolicy::reprofile(ScopeDesc* trap_scope, bool is_osr) {
375 for (ScopeDesc* sd = trap_scope;; sd = sd->sender()) {
376 if (PrintTieredEvents) {
377 methodHandle mh(sd->method());
378 print_event(REPROFILE, mh, mh, InvocationEntryBci, CompLevel_none);
379 }
380 MethodData* mdo = sd->method()->method_data();
381 if (mdo != NULL) {
382 mdo->reset_start_counters();
383 }
384 if (sd->is_top()) break;
385 }
386}
387
388nmethod* TieredThresholdPolicy::event(const methodHandle& method, const methodHandle& inlinee,
389 int branch_bci, int bci, CompLevel comp_level, CompiledMethod* nm, JavaThread* thread) {
390 if (comp_level == CompLevel_none &&
391 JvmtiExport::can_post_interpreter_events() &&
392 thread->is_interp_only_mode()) {
393 return NULL;
394 }
395 if (ReplayCompiles) {
396 // Don't trigger other compiles in testing mode
397 return NULL;
398 }
399
400 handle_counter_overflow(method());
401 if (method() != inlinee()) {
402 handle_counter_overflow(inlinee());
403 }
404
405 if (PrintTieredEvents) {
406 print_event(bci == InvocationEntryBci ? CALL : LOOP, method, inlinee, bci, comp_level);
407 }
408
409 if (bci == InvocationEntryBci) {
410 method_invocation_event(method, inlinee, comp_level, nm, thread);
411 } else {
412 // method == inlinee if the event originated in the main method
413 method_back_branch_event(method, inlinee, bci, comp_level, nm, thread);
414 // Check if event led to a higher level OSR compilation
415 CompLevel expected_comp_level = comp_level;
416 if (inlinee->is_not_osr_compilable(expected_comp_level)) {
417 // It's not possble to reach the expected level so fall back to simple.
418 expected_comp_level = CompLevel_simple;
419 }
420 nmethod* osr_nm = inlinee->lookup_osr_nmethod_for(bci, expected_comp_level, false);
421 assert(osr_nm == NULL || osr_nm->comp_level() >= expected_comp_level, "lookup_osr_nmethod_for is broken");
422 if (osr_nm != NULL) {
423 // Perform OSR with new nmethod
424 return osr_nm;
425 }
426 }
427 return NULL;
428}
429
430// Check if the method can be compiled, change level if necessary
431void TieredThresholdPolicy::compile(const methodHandle& mh, int bci, CompLevel level, JavaThread* thread) {
432 assert(level <= TieredStopAtLevel, "Invalid compilation level");
433 if (level == CompLevel_none) {
434 return;
435 }
436 if (level == CompLevel_aot) {
437 if (mh->has_aot_code()) {
438 if (PrintTieredEvents) {
439 print_event(COMPILE, mh, mh, bci, level);
440 }
441 MutexLocker ml(Compile_lock);
442 NoSafepointVerifier nsv;
443 if (mh->has_aot_code() && mh->code() != mh->aot_code()) {
444 mh->aot_code()->make_entrant();
445 if (mh->has_compiled_code()) {
446 mh->code()->make_not_entrant();
447 }
448 Method::set_code(mh, mh->aot_code());
449 }
450 }
451 return;
452 }
453
454 // Check if the method can be compiled. If it cannot be compiled with C1, continue profiling
455 // in the interpreter and then compile with C2 (the transition function will request that,
456 // see common() ). If the method cannot be compiled with C2 but still can with C1, compile it with
457 // pure C1.
458 if ((bci == InvocationEntryBci && !can_be_compiled(mh, level))) {
459 if (level == CompLevel_full_optimization && can_be_compiled(mh, CompLevel_simple)) {
460 compile(mh, bci, CompLevel_simple, thread);
461 }
462 return;
463 }
464 if ((bci != InvocationEntryBci && !can_be_osr_compiled(mh, level))) {
465 if (level == CompLevel_full_optimization && can_be_osr_compiled(mh, CompLevel_simple)) {
466 nmethod* osr_nm = mh->lookup_osr_nmethod_for(bci, CompLevel_simple, false);
467 if (osr_nm != NULL && osr_nm->comp_level() > CompLevel_simple) {
468 // Invalidate the existing OSR nmethod so that a compile at CompLevel_simple is permitted.
469 osr_nm->make_not_entrant();
470 }
471 compile(mh, bci, CompLevel_simple, thread);
472 }
473 return;
474 }
475 if (bci != InvocationEntryBci && mh->is_not_osr_compilable(level)) {
476 return;
477 }
478 if (!CompileBroker::compilation_is_in_queue(mh)) {
479 if (PrintTieredEvents) {
480 print_event(COMPILE, mh, mh, bci, level);
481 }
482 submit_compile(mh, bci, level, thread);
483 }
484}
485
486// Update the rate and submit compile
487void TieredThresholdPolicy::submit_compile(const methodHandle& mh, int bci, CompLevel level, JavaThread* thread) {
488 int hot_count = (bci == InvocationEntryBci) ? mh->invocation_count() : mh->backedge_count();
489 update_rate(os::javaTimeMillis(), mh());
490 CompileBroker::compile_method(mh, bci, level, mh, hot_count, CompileTask::Reason_Tiered, thread);
491}
492
493// Print an event.
494void TieredThresholdPolicy::print_specific(EventType type, const methodHandle& mh, const methodHandle& imh,
495 int bci, CompLevel level) {
496 tty->print(" rate=");
497 if (mh->prev_time() == 0) tty->print("n/a");
498 else tty->print("%f", mh->rate());
499
500 tty->print(" k=%.2lf,%.2lf", threshold_scale(CompLevel_full_profile, Tier3LoadFeedback),
501 threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback));
502
503}
504
505// update_rate() is called from select_task() while holding a compile queue lock.
506void TieredThresholdPolicy::update_rate(jlong t, Method* m) {
507 // Skip update if counters are absent.
508 // Can't allocate them since we are holding compile queue lock.
509 if (m->method_counters() == NULL) return;
510
511 if (is_old(m)) {
512 // We don't remove old methods from the queue,
513 // so we can just zero the rate.
514 m->set_rate(0);
515 return;
516 }
517
518 // We don't update the rate if we've just came out of a safepoint.
519 // delta_s is the time since last safepoint in milliseconds.
520 jlong delta_s = t - SafepointTracing::end_of_last_safepoint_epoch_ms();
521 jlong delta_t = t - (m->prev_time() != 0 ? m->prev_time() : start_time()); // milliseconds since the last measurement
522 // How many events were there since the last time?
523 int event_count = m->invocation_count() + m->backedge_count();
524 int delta_e = event_count - m->prev_event_count();
525
526 // We should be running for at least 1ms.
527 if (delta_s >= TieredRateUpdateMinTime) {
528 // And we must've taken the previous point at least 1ms before.
529 if (delta_t >= TieredRateUpdateMinTime && delta_e > 0) {
530 m->set_prev_time(t);
531 m->set_prev_event_count(event_count);
532 m->set_rate((float)delta_e / (float)delta_t); // Rate is events per millisecond
533 } else {
534 if (delta_t > TieredRateUpdateMaxTime && delta_e == 0) {
535 // If nothing happened for 25ms, zero the rate. Don't modify prev values.
536 m->set_rate(0);
537 }
538 }
539 }
540}
541
542// Check if this method has been stale for a given number of milliseconds.
543// See select_task().
544bool TieredThresholdPolicy::is_stale(jlong t, jlong timeout, Method* m) {
545 jlong delta_s = t - SafepointTracing::end_of_last_safepoint_epoch_ms();
546 jlong delta_t = t - m->prev_time();
547 if (delta_t > timeout && delta_s > timeout) {
548 int event_count = m->invocation_count() + m->backedge_count();
549 int delta_e = event_count - m->prev_event_count();
550 // Return true if there were no events.
551 return delta_e == 0;
552 }
553 return false;
554}
555
556// We don't remove old methods from the compile queue even if they have
557// very low activity. See select_task().
558bool TieredThresholdPolicy::is_old(Method* method) {
559 return method->invocation_count() > 50000 || method->backedge_count() > 500000;
560}
561
562double TieredThresholdPolicy::weight(Method* method) {
563 return (double)(method->rate() + 1) *
564 (method->invocation_count() + 1) * (method->backedge_count() + 1);
565}
566
567// Apply heuristics and return true if x should be compiled before y
568bool TieredThresholdPolicy::compare_methods(Method* x, Method* y) {
569 if (x->highest_comp_level() > y->highest_comp_level()) {
570 // recompilation after deopt
571 return true;
572 } else
573 if (x->highest_comp_level() == y->highest_comp_level()) {
574 if (weight(x) > weight(y)) {
575 return true;
576 }
577 }
578 return false;
579}
580
581// Is method profiled enough?
582bool TieredThresholdPolicy::is_method_profiled(Method* method) {
583 MethodData* mdo = method->method_data();
584 if (mdo != NULL) {
585 int i = mdo->invocation_count_delta();
586 int b = mdo->backedge_count_delta();
587 return call_predicate_helper<CompLevel_full_profile>(i, b, 1, method);
588 }
589 return false;
590}
591
592double TieredThresholdPolicy::threshold_scale(CompLevel level, int feedback_k) {
593 double queue_size = CompileBroker::queue_size(level);
594 int comp_count = compiler_count(level);
595 double k = queue_size / (feedback_k * comp_count) + 1;
596
597 // Increase C1 compile threshold when the code cache is filled more
598 // than specified by IncreaseFirstTierCompileThresholdAt percentage.
599 // The main intention is to keep enough free space for C2 compiled code
600 // to achieve peak performance if the code cache is under stress.
601 if ((TieredStopAtLevel == CompLevel_full_optimization) && (level != CompLevel_full_optimization)) {
602 double current_reverse_free_ratio = CodeCache::reverse_free_ratio(CodeCache::get_code_blob_type(level));
603 if (current_reverse_free_ratio > _increase_threshold_at_ratio) {
604 k *= exp(current_reverse_free_ratio - _increase_threshold_at_ratio);
605 }
606 }
607 return k;
608}
609
610// Call and loop predicates determine whether a transition to a higher
611// compilation level should be performed (pointers to predicate functions
612// are passed to common()).
613// Tier?LoadFeedback is basically a coefficient that determines of
614// how many methods per compiler thread can be in the queue before
615// the threshold values double.
616bool TieredThresholdPolicy::loop_predicate(int i, int b, CompLevel cur_level, Method* method) {
617 switch(cur_level) {
618 case CompLevel_aot: {
619 double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback);
620 return loop_predicate_helper<CompLevel_aot>(i, b, k, method);
621 }
622 case CompLevel_none:
623 case CompLevel_limited_profile: {
624 double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback);
625 return loop_predicate_helper<CompLevel_none>(i, b, k, method);
626 }
627 case CompLevel_full_profile: {
628 double k = threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback);
629 return loop_predicate_helper<CompLevel_full_profile>(i, b, k, method);
630 }
631 default:
632 return true;
633 }
634}
635
636bool TieredThresholdPolicy::call_predicate(int i, int b, CompLevel cur_level, Method* method) {
637 switch(cur_level) {
638 case CompLevel_aot: {
639 double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback);
640 return call_predicate_helper<CompLevel_aot>(i, b, k, method);
641 }
642 case CompLevel_none:
643 case CompLevel_limited_profile: {
644 double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback);
645 return call_predicate_helper<CompLevel_none>(i, b, k, method);
646 }
647 case CompLevel_full_profile: {
648 double k = threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback);
649 return call_predicate_helper<CompLevel_full_profile>(i, b, k, method);
650 }
651 default:
652 return true;
653 }
654}
655
656// Determine is a method is mature.
657bool TieredThresholdPolicy::is_mature(Method* method) {
658 if (should_compile_at_level_simple(method)) return true;
659 MethodData* mdo = method->method_data();
660 if (mdo != NULL) {
661 int i = mdo->invocation_count();
662 int b = mdo->backedge_count();
663 double k = ProfileMaturityPercentage / 100.0;
664 return call_predicate_helper<CompLevel_full_profile>(i, b, k, method) ||
665 loop_predicate_helper<CompLevel_full_profile>(i, b, k, method);
666 }
667 return false;
668}
669
670// If a method is old enough and is still in the interpreter we would want to
671// start profiling without waiting for the compiled method to arrive.
672// We also take the load on compilers into the account.
673bool TieredThresholdPolicy::should_create_mdo(Method* method, CompLevel cur_level) {
674 if (cur_level == CompLevel_none &&
675 CompileBroker::queue_size(CompLevel_full_optimization) <=
676 Tier3DelayOn * compiler_count(CompLevel_full_optimization)) {
677 int i = method->invocation_count();
678 int b = method->backedge_count();
679 double k = Tier0ProfilingStartPercentage / 100.0;
680 return call_predicate_helper<CompLevel_none>(i, b, k, method) || loop_predicate_helper<CompLevel_none>(i, b, k, method);
681 }
682 return false;
683}
684
685// Inlining control: if we're compiling a profiled method with C1 and the callee
686// is known to have OSRed in a C2 version, don't inline it.
687bool TieredThresholdPolicy::should_not_inline(ciEnv* env, ciMethod* callee) {
688 CompLevel comp_level = (CompLevel)env->comp_level();
689 if (comp_level == CompLevel_full_profile ||
690 comp_level == CompLevel_limited_profile) {
691 return callee->highest_osr_comp_level() == CompLevel_full_optimization;
692 }
693 return false;
694}
695
696// Create MDO if necessary.
697void TieredThresholdPolicy::create_mdo(const methodHandle& mh, JavaThread* THREAD) {
698 if (mh->is_native() ||
699 mh->is_abstract() ||
700 mh->is_accessor() ||
701 mh->is_constant_getter()) {
702 return;
703 }
704 if (mh->method_data() == NULL) {
705 Method::build_interpreter_method_data(mh, CHECK_AND_CLEAR);
706 }
707}
708
709
710/*
711 * Method states:
712 * 0 - interpreter (CompLevel_none)
713 * 1 - pure C1 (CompLevel_simple)
714 * 2 - C1 with invocation and backedge counting (CompLevel_limited_profile)
715 * 3 - C1 with full profiling (CompLevel_full_profile)
716 * 4 - C2 (CompLevel_full_optimization)
717 *
718 * Common state transition patterns:
719 * a. 0 -> 3 -> 4.
720 * The most common path. But note that even in this straightforward case
721 * profiling can start at level 0 and finish at level 3.
722 *
723 * b. 0 -> 2 -> 3 -> 4.
724 * This case occurs when the load on C2 is deemed too high. So, instead of transitioning
725 * into state 3 directly and over-profiling while a method is in the C2 queue we transition to
726 * level 2 and wait until the load on C2 decreases. This path is disabled for OSRs.
727 *
728 * c. 0 -> (3->2) -> 4.
729 * In this case we enqueue a method for compilation at level 3, but the C1 queue is long enough
730 * to enable the profiling to fully occur at level 0. In this case we change the compilation level
731 * of the method to 2 while the request is still in-queue, because it'll allow it to run much faster
732 * without full profiling while c2 is compiling.
733 *
734 * d. 0 -> 3 -> 1 or 0 -> 2 -> 1.
735 * After a method was once compiled with C1 it can be identified as trivial and be compiled to
736 * level 1. These transition can also occur if a method can't be compiled with C2 but can with C1.
737 *
738 * e. 0 -> 4.
739 * This can happen if a method fails C1 compilation (it will still be profiled in the interpreter)
740 * or because of a deopt that didn't require reprofiling (compilation won't happen in this case because
741 * the compiled version already exists).
742 *
743 * Note that since state 0 can be reached from any other state via deoptimization different loops
744 * are possible.
745 *
746 */
747
748// Common transition function. Given a predicate determines if a method should transition to another level.
749CompLevel TieredThresholdPolicy::common(Predicate p, Method* method, CompLevel cur_level, bool disable_feedback) {
750 CompLevel next_level = cur_level;
751 int i = method->invocation_count();
752 int b = method->backedge_count();
753
754 if (should_compile_at_level_simple(method)) {
755 next_level = CompLevel_simple;
756 } else {
757 switch(cur_level) {
758 default: break;
759 case CompLevel_aot: {
760 // If we were at full profile level, would we switch to full opt?
761 if (common(p, method, CompLevel_full_profile, disable_feedback) == CompLevel_full_optimization) {
762 next_level = CompLevel_full_optimization;
763 } else if (disable_feedback || (CompileBroker::queue_size(CompLevel_full_optimization) <=
764 Tier3DelayOff * compiler_count(CompLevel_full_optimization) &&
765 (this->*p)(i, b, cur_level, method))) {
766 next_level = CompLevel_full_profile;
767 }
768 }
769 break;
770 case CompLevel_none:
771 // If we were at full profile level, would we switch to full opt?
772 if (common(p, method, CompLevel_full_profile, disable_feedback) == CompLevel_full_optimization) {
773 next_level = CompLevel_full_optimization;
774 } else if ((this->*p)(i, b, cur_level, method)) {
775#if INCLUDE_JVMCI
776 if (EnableJVMCI && UseJVMCICompiler) {
777 // Since JVMCI takes a while to warm up, its queue inevitably backs up during
778 // early VM execution. As of 2014-06-13, JVMCI's inliner assumes that the root
779 // compilation method and all potential inlinees have mature profiles (which
780 // includes type profiling). If it sees immature profiles, JVMCI's inliner
781 // can perform pathologically bad (e.g., causing OutOfMemoryErrors due to
782 // exploring/inlining too many graphs). Since a rewrite of the inliner is
783 // in progress, we simply disable the dialing back heuristic for now and will
784 // revisit this decision once the new inliner is completed.
785 next_level = CompLevel_full_profile;
786 } else
787#endif
788 {
789 // C1-generated fully profiled code is about 30% slower than the limited profile
790 // code that has only invocation and backedge counters. The observation is that
791 // if C2 queue is large enough we can spend too much time in the fully profiled code
792 // while waiting for C2 to pick the method from the queue. To alleviate this problem
793 // we introduce a feedback on the C2 queue size. If the C2 queue is sufficiently long
794 // we choose to compile a limited profiled version and then recompile with full profiling
795 // when the load on C2 goes down.
796 if (!disable_feedback && CompileBroker::queue_size(CompLevel_full_optimization) >
797 Tier3DelayOn * compiler_count(CompLevel_full_optimization)) {
798 next_level = CompLevel_limited_profile;
799 } else {
800 next_level = CompLevel_full_profile;
801 }
802 }
803 }
804 break;
805 case CompLevel_limited_profile:
806 if (is_method_profiled(method)) {
807 // Special case: we got here because this method was fully profiled in the interpreter.
808 next_level = CompLevel_full_optimization;
809 } else {
810 MethodData* mdo = method->method_data();
811 if (mdo != NULL) {
812 if (mdo->would_profile()) {
813 if (disable_feedback || (CompileBroker::queue_size(CompLevel_full_optimization) <=
814 Tier3DelayOff * compiler_count(CompLevel_full_optimization) &&
815 (this->*p)(i, b, cur_level, method))) {
816 next_level = CompLevel_full_profile;
817 }
818 } else {
819 next_level = CompLevel_full_optimization;
820 }
821 } else {
822 // If there is no MDO we need to profile
823 if (disable_feedback || (CompileBroker::queue_size(CompLevel_full_optimization) <=
824 Tier3DelayOff * compiler_count(CompLevel_full_optimization) &&
825 (this->*p)(i, b, cur_level, method))) {
826 next_level = CompLevel_full_profile;
827 }
828 }
829 }
830 break;
831 case CompLevel_full_profile:
832 {
833 MethodData* mdo = method->method_data();
834 if (mdo != NULL) {
835 if (mdo->would_profile()) {
836 int mdo_i = mdo->invocation_count_delta();
837 int mdo_b = mdo->backedge_count_delta();
838 if ((this->*p)(mdo_i, mdo_b, cur_level, method)) {
839 next_level = CompLevel_full_optimization;
840 }
841 } else {
842 next_level = CompLevel_full_optimization;
843 }
844 }
845 }
846 break;
847 }
848 }
849 return MIN2(next_level, (CompLevel)TieredStopAtLevel);
850}
851
852// Determine if a method should be compiled with a normal entry point at a different level.
853CompLevel TieredThresholdPolicy::call_event(Method* method, CompLevel cur_level, JavaThread * thread) {
854 CompLevel osr_level = MIN2((CompLevel) method->highest_osr_comp_level(),
855 common(&TieredThresholdPolicy::loop_predicate, method, cur_level, true));
856 CompLevel next_level = common(&TieredThresholdPolicy::call_predicate, method, cur_level);
857
858 // If OSR method level is greater than the regular method level, the levels should be
859 // equalized by raising the regular method level in order to avoid OSRs during each
860 // invocation of the method.
861 if (osr_level == CompLevel_full_optimization && cur_level == CompLevel_full_profile) {
862 MethodData* mdo = method->method_data();
863 guarantee(mdo != NULL, "MDO should not be NULL");
864 if (mdo->invocation_count() >= 1) {
865 next_level = CompLevel_full_optimization;
866 }
867 } else {
868 next_level = MAX2(osr_level, next_level);
869 }
870 return next_level;
871}
872
873// Determine if we should do an OSR compilation of a given method.
874CompLevel TieredThresholdPolicy::loop_event(Method* method, CompLevel cur_level, JavaThread* thread) {
875 CompLevel next_level = common(&TieredThresholdPolicy::loop_predicate, method, cur_level, true);
876 if (cur_level == CompLevel_none) {
877 // If there is a live OSR method that means that we deopted to the interpreter
878 // for the transition.
879 CompLevel osr_level = MIN2((CompLevel)method->highest_osr_comp_level(), next_level);
880 if (osr_level > CompLevel_none) {
881 return osr_level;
882 }
883 }
884 return next_level;
885}
886
887bool TieredThresholdPolicy::maybe_switch_to_aot(const methodHandle& mh, CompLevel cur_level, CompLevel next_level, JavaThread* thread) {
888 if (UseAOT) {
889 if (cur_level == CompLevel_full_profile || cur_level == CompLevel_none) {
890 // If the current level is full profile or interpreter and we're switching to any other level,
891 // activate the AOT code back first so that we won't waste time overprofiling.
892 compile(mh, InvocationEntryBci, CompLevel_aot, thread);
893 // Fall through for JIT compilation.
894 }
895 if (next_level == CompLevel_limited_profile && cur_level != CompLevel_aot && mh->has_aot_code()) {
896 // If the next level is limited profile, use the aot code (if there is any),
897 // since it's essentially the same thing.
898 compile(mh, InvocationEntryBci, CompLevel_aot, thread);
899 // Not need to JIT, we're done.
900 return true;
901 }
902 }
903 return false;
904}
905
906
907// Handle the invocation event.
908void TieredThresholdPolicy::method_invocation_event(const methodHandle& mh, const methodHandle& imh,
909 CompLevel level, CompiledMethod* nm, JavaThread* thread) {
910 if (should_create_mdo(mh(), level)) {
911 create_mdo(mh, thread);
912 }
913 CompLevel next_level = call_event(mh(), level, thread);
914 if (next_level != level) {
915 if (maybe_switch_to_aot(mh, level, next_level, thread)) {
916 // No JITting necessary
917 return;
918 }
919 if (is_compilation_enabled() && !CompileBroker::compilation_is_in_queue(mh)) {
920 compile(mh, InvocationEntryBci, next_level, thread);
921 }
922 }
923}
924
925// Handle the back branch event. Notice that we can compile the method
926// with a regular entry from here.
927void TieredThresholdPolicy::method_back_branch_event(const methodHandle& mh, const methodHandle& imh,
928 int bci, CompLevel level, CompiledMethod* nm, JavaThread* thread) {
929 if (should_create_mdo(mh(), level)) {
930 create_mdo(mh, thread);
931 }
932 // Check if MDO should be created for the inlined method
933 if (should_create_mdo(imh(), level)) {
934 create_mdo(imh, thread);
935 }
936
937 if (is_compilation_enabled()) {
938 CompLevel next_osr_level = loop_event(imh(), level, thread);
939 CompLevel max_osr_level = (CompLevel)imh->highest_osr_comp_level();
940 // At the very least compile the OSR version
941 if (!CompileBroker::compilation_is_in_queue(imh) && (next_osr_level != level)) {
942 compile(imh, bci, next_osr_level, thread);
943 }
944
945 // Use loop event as an opportunity to also check if there's been
946 // enough calls.
947 CompLevel cur_level, next_level;
948 if (mh() != imh()) { // If there is an enclosing method
949 if (level == CompLevel_aot) {
950 // Recompile the enclosing method to prevent infinite OSRs. Stay at AOT level while it's compiling.
951 if (max_osr_level != CompLevel_none && !CompileBroker::compilation_is_in_queue(mh)) {
952 compile(mh, InvocationEntryBci, MIN2((CompLevel)TieredStopAtLevel, CompLevel_full_profile), thread);
953 }
954 } else {
955 // Current loop event level is not AOT
956 guarantee(nm != NULL, "Should have nmethod here");
957 cur_level = comp_level(mh());
958 next_level = call_event(mh(), cur_level, thread);
959
960 if (max_osr_level == CompLevel_full_optimization) {
961 // The inlinee OSRed to full opt, we need to modify the enclosing method to avoid deopts
962 bool make_not_entrant = false;
963 if (nm->is_osr_method()) {
964 // This is an osr method, just make it not entrant and recompile later if needed
965 make_not_entrant = true;
966 } else {
967 if (next_level != CompLevel_full_optimization) {
968 // next_level is not full opt, so we need to recompile the
969 // enclosing method without the inlinee
970 cur_level = CompLevel_none;
971 make_not_entrant = true;
972 }
973 }
974 if (make_not_entrant) {
975 if (PrintTieredEvents) {
976 int osr_bci = nm->is_osr_method() ? nm->osr_entry_bci() : InvocationEntryBci;
977 print_event(MAKE_NOT_ENTRANT, mh(), mh(), osr_bci, level);
978 }
979 nm->make_not_entrant();
980 }
981 }
982 // Fix up next_level if necessary to avoid deopts
983 if (next_level == CompLevel_limited_profile && max_osr_level == CompLevel_full_profile) {
984 next_level = CompLevel_full_profile;
985 }
986 if (cur_level != next_level) {
987 if (!maybe_switch_to_aot(mh, cur_level, next_level, thread) && !CompileBroker::compilation_is_in_queue(mh)) {
988 compile(mh, InvocationEntryBci, next_level, thread);
989 }
990 }
991 }
992 } else {
993 cur_level = comp_level(mh());
994 next_level = call_event(mh(), cur_level, thread);
995 if (next_level != cur_level) {
996 if (!maybe_switch_to_aot(mh, cur_level, next_level, thread) && !CompileBroker::compilation_is_in_queue(mh)) {
997 compile(mh, InvocationEntryBci, next_level, thread);
998 }
999 }
1000 }
1001 }
1002}
1003
1004#endif
1005