/*

 * Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved.

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

 *

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

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

 * published by the Free Software Foundation.

 *

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

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

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

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

 * accompanied this code).

 *

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

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

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

 *

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

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

 * questions.

 *

 */

CompilationPolicy* CompilationPolicy::_policy;

elapsedTimer       CompilationPolicy::_accumulated_time;

bool               CompilationPolicy::_in_vm_startup;

// Determine compilation policy based on command line argument

void compilationPolicy_init() {

  CompilationPolicy::set_in_vm_startup(DelayCompilationDuringStartup);

  switch(CompilationPolicyChoice) {

  case 0:

    CompilationPolicy::set_policy(new SimpleCompPolicy());

    break;

  case 1:

#ifdef COMPILER2

    CompilationPolicy::set_policy(new StackWalkCompPolicy());

#else

    Unimplemented();

#endif

    break;

  case 2:

#ifdef TIERED

    CompilationPolicy::set_policy(new SimpleThresholdPolicy());

#else

    Unimplemented();

#endif

    break;

  default:

    fatal("CompilationPolicyChoice must be in the range: [0-2]");

  }

  CompilationPolicy::policy()->initialize();

}

void CompilationPolicy::completed_vm_startup() {

  if (TraceCompilationPolicy) {

    tty->print("CompilationPolicy: completed vm startup.\n");

  }

  _in_vm_startup = false;

}

// Returns true if m must be compiled before executing it

// This is intended to force compiles for methods (usually for

// debugging) that would otherwise be interpreted for some reason.

bool CompilationPolicy::must_be_compiled(methodHandle m, int comp_level) {

  if (m->has_compiled_code()) return false;       // already compiled

  if (!can_be_compiled(m, comp_level)) return false;

  return !UseInterpreter ||                                              // must compile all methods

         (UseCompiler && AlwaysCompileLoopMethods && m->has_loops() && CompileBroker::should_compile_new_jobs()); // eagerly compile loop methods

}

// Returns true if m is allowed to be compiled

bool CompilationPolicy::can_be_compiled(methodHandle m, int comp_level) {

  if (m->is_abstract()) return false;

  if (DontCompileHugeMethods && m->code_size() > HugeMethodLimit) return false;

  // Math intrinsics should never be compiled as this can lead to

  // monotonicity problems because the interpreter will prefer the

  // compiled code to the intrinsic version.  This can't happen in

  // production because the invocation counter can't be incremented

  // but we shouldn't expose the system to this problem in testing

  // modes.

  if (!AbstractInterpreter::can_be_compiled(m)) {

    return false;

  }

  if (comp_level == CompLevel_all) {

    return !m->is_not_compilable(CompLevel_simple) && !m->is_not_compilable(CompLevel_full_optimization);

  } else {

    return !m->is_not_compilable(comp_level);

  }

}

bool CompilationPolicy::is_compilation_enabled() {

  // NOTE: CompileBroker::should_compile_new_jobs() checks for UseCompiler

  return !delay_compilation_during_startup() && CompileBroker::should_compile_new_jobs();

}

#ifndef PRODUCT

void CompilationPolicy::print_time() {

  tty->print_cr ("Accumulated compilationPolicy times:");

  tty->print_cr ("---------------------------");

  tty->print_cr ("  Total: %3.3f sec.", _accumulated_time.seconds());

}

void NonTieredCompPolicy::trace_osr_completion(nmethod* osr_nm) {

  if (TraceOnStackReplacement) {

    if (osr_nm == NULL) tty->print_cr("compilation failed");

    else tty->print_cr("nmethod " INTPTR_FORMAT, osr_nm);

  }

}

#endif // !PRODUCT

void NonTieredCompPolicy::initialize() {

  // Setup the compiler thread numbers

  if (CICompilerCountPerCPU) {

    // Example: if CICompilerCountPerCPU is true, then we get

    // max(log2(8)-1,1) = 2 compiler threads on an 8-way machine.

    // May help big-app startup time.

    _compiler_count = MAX2(log2_intptr(os::active_processor_count())-1,1);

  } else {

    _compiler_count = CICompilerCount;

  }

}

// Note: this policy is used ONLY if TieredCompilation is off.

// compiler_count() behaves the following way:

// - with TIERED build (with both COMPILER1 and COMPILER2 defined) it should return

//   zero for the c1 compilation levels, hence the particular ordering of the

//   statements.

// - the same should happen when COMPILER2 is defined and COMPILER1 is not

//   (server build without TIERED defined).

// - if only COMPILER1 is defined (client build), zero should be returned for

//   the c2 level.

// - if neither is defined - always return zero.

int NonTieredCompPolicy::compiler_count(CompLevel comp_level) {

  assert(!TieredCompilation, "This policy should not be used with TieredCompilation");

#ifdef COMPILER2

  if (is_c2_compile(comp_level)) {

    return _compiler_count;

  } else {

    return 0;

  }

#endif

#ifdef COMPILER1

  if (is_c1_compile(comp_level)) {

    return _compiler_count;

  } else {

    return 0;

  }

#endif

  return 0;

}

void NonTieredCompPolicy::reset_counter_for_invocation_event(methodHandle m) {

  // Make sure invocation and backedge counter doesn't overflow again right away

  // as would be the case for native methods.

  // BUT also make sure the method doesn't look like it was never executed.

  // Set carry bit and reduce counter's value to min(count, CompileThreshold/2).

  m->invocation_counter()->set_carry();

  m->backedge_counter()->set_carry();

  assert(!m->was_never_executed(), "don't reset to 0 -- could be mistaken for never-executed");

}

void NonTieredCompPolicy::reset_counter_for_back_branch_event(methodHandle m) {

  // Delay next back-branch event but pump up invocation counter to triger

  // whole method compilation.

  InvocationCounter* i = m->invocation_counter();

  InvocationCounter* b = m->backedge_counter();

  // Don't set invocation_counter's value too low otherwise the method will

  // look like immature (ic < ~5300) which prevents the inlining based on

  // the type profiling.

  i->set(i->state(), CompileThreshold);

  // Don't reset counter too low - it is used to check if OSR method is ready.

  b->set(b->state(), CompileThreshold / 2);

}

//

// CounterDecay

//

// Interates through invocation counters and decrements them. This

// is done at each safepoint.

//

class CounterDecay : public AllStatic {

  static jlong _last_timestamp;

  static void do_method(methodOop m) {

    m->invocation_counter()->decay();

  }

public:

  static void decay();

  static bool is_decay_needed() {

    return (os::javaTimeMillis() - _last_timestamp) > CounterDecayMinIntervalLength;

  }

};

jlong CounterDecay::_last_timestamp = 0;

void CounterDecay::decay() {

  _last_timestamp = os::javaTimeMillis();

  // This operation is going to be performed only at the end of a safepoint

  // and hence GC's will not be going on, all Java mutators are suspended

  // at this point and hence SystemDictionary_lock is also not needed.

  assert(SafepointSynchronize::is_at_safepoint(), "can only be executed at a safepoint");

  int nclasses = SystemDictionary::number_of_classes();

  double classes_per_tick = nclasses * (CounterDecayMinIntervalLength * 1e-3 /

                                        CounterHalfLifeTime);

  for (int i = 0; i < classes_per_tick; i++) {

    klassOop k = SystemDictionary::try_get_next_class();

    if (k != NULL && k->klass_part()->oop_is_instance()) {

      instanceKlass::cast(k)->methods_do(do_method);

    }

  }

}

// Called at the end of the safepoint

void NonTieredCompPolicy::do_safepoint_work() {

  if(UseCounterDecay && CounterDecay::is_decay_needed()) {

    CounterDecay::decay();

  }

}

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

  ScopeDesc* sd = trap_scope;

  for (; !sd->is_top(); sd = sd->sender()) {

    // Reset ICs of inlined methods, since they can trigger compilations also.

    sd->method()->invocation_counter()->reset();

  }

  InvocationCounter* c = sd->method()->invocation_counter();

  if (is_osr) {

    // It was an OSR method, so bump the count higher.

    c->set(c->state(), CompileThreshold);

  } else {

    c->reset();

  }

  sd->method()->backedge_counter()->reset();

}

// This method can be called by any component of the runtime to notify the policy

// that it's recommended to delay the complation of this method.

void NonTieredCompPolicy::delay_compilation(methodOop method) {

  method->invocation_counter()->decay();

  method->backedge_counter()->decay();

}

void NonTieredCompPolicy::disable_compilation(methodOop method) {

  method->invocation_counter()->set_state(InvocationCounter::wait_for_nothing);

  method->backedge_counter()->set_state(InvocationCounter::wait_for_nothing);

}

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

  return compile_queue->first();

}

bool NonTieredCompPolicy::is_mature(methodOop method) {

  methodDataOop mdo = method->method_data();

  assert(mdo != NULL, "Should be");

  uint current = mdo->mileage_of(method);

  uint initial = mdo->creation_mileage();

  if (current < initial)

    return true;  // some sort of overflow

  uint target;

  if (ProfileMaturityPercentage <= 0)

    target = (uint) -ProfileMaturityPercentage;  // absolute value

  else

    target = (uint)( (ProfileMaturityPercentage * CompileThreshold) / 100 );

  return (current >= initial + target);

}

nmethod* NonTieredCompPolicy::event(methodHandle method, methodHandle inlinee, int branch_bci, int bci, CompLevel comp_level, TRAPS) {

  assert(comp_level == CompLevel_none, "This should be only called from the interpreter");

  NOT_PRODUCT(trace_frequency_counter_overflow(method, branch_bci, bci));

  if (JvmtiExport::can_post_interpreter_events()) {

    assert(THREAD->is_Java_thread(), "Wrong type of thread");

    if (((JavaThread*)THREAD)->is_interp_only_mode()) {

      // If certain JVMTI events (e.g. frame pop event) are requested then the

      // thread is forced to remain in interpreted code. This is

      // implemented partly by a check in the run_compiled_code

      // section of the interpreter whether we should skip running

      // compiled code, and partly by skipping OSR compiles for

      // interpreted-only threads.

      if (bci != InvocationEntryBci) {

        reset_counter_for_back_branch_event(method);

        return NULL;

      }

    }

  }

  if (bci == InvocationEntryBci) {

    // when code cache is full, compilation gets switched off, UseCompiler

    // is set to false

    if (!method->has_compiled_code() && UseCompiler) {

      method_invocation_event(method, CHECK_NULL);

    } else {

      // Force counter overflow on method entry, even if no compilation

      // happened.  (The method_invocation_event call does this also.)

      reset_counter_for_invocation_event(method);

    }

    // compilation at an invocation overflow no longer goes and retries test for

    // compiled method. We always run the loser of the race as interpreted.

    // so return NULL

    return NULL;

  } else {

    // counter overflow in a loop => try to do on-stack-replacement

    nmethod* osr_nm = method->lookup_osr_nmethod_for(bci, CompLevel_highest_tier, true);

    NOT_PRODUCT(trace_osr_request(method, osr_nm, bci));

    // when code cache is full, we should not compile any more...

    if (osr_nm == NULL && UseCompiler) {

      method_back_branch_event(method, bci, CHECK_NULL);

      osr_nm = method->lookup_osr_nmethod_for(bci, CompLevel_highest_tier, true);

    }

    if (osr_nm == NULL) {

      reset_counter_for_back_branch_event(method);

      return NULL;

    }

    return osr_nm;

  }

  return NULL;

}

#ifndef PRODUCT

void NonTieredCompPolicy::trace_frequency_counter_overflow(methodHandle m, int branch_bci, int bci) {

  if (TraceInvocationCounterOverflow) {

    InvocationCounter* ic = m->invocation_counter();

    InvocationCounter* bc = m->backedge_counter();

    ResourceMark rm;

    const char* msg =

      bci == InvocationEntryBci

      ? "comp-policy cntr ovfl @ %d in entry of "

      : "comp-policy cntr ovfl @ %d in loop of ";

    tty->print(msg, bci);

    m->print_value();

    tty->cr();

    ic->print();

    bc->print();

    if (ProfileInterpreter) {

      if (bci != InvocationEntryBci) {

        methodDataOop mdo = m->method_data();

        if (mdo != NULL) {

          int count = mdo->bci_to_data(branch_bci)->as_JumpData()->taken();

          tty->print_cr("back branch count = %d", count);

        }

      }

    }

  }

}

void NonTieredCompPolicy::trace_osr_request(methodHandle method, nmethod* osr, int bci) {

  if (TraceOnStackReplacement) {

    ResourceMark rm;

    tty->print(osr != NULL ? "Reused OSR entry for " : "Requesting OSR entry for ");

    method->print_short_name(tty);

    tty->print_cr(" at bci %d", bci);

  }

}

#endif // !PRODUCT

// SimpleCompPolicy - compile current method

void SimpleCompPolicy::method_invocation_event( methodHandle m, TRAPS) {

  assert(UseCompiler || CompileTheWorld, "UseCompiler should be set by now.");

  int hot_count = m->invocation_count();

  reset_counter_for_invocation_event(m);

  const char* comment = "count";

  if (is_compilation_enabled() && can_be_compiled(m)) {

    nmethod* nm = m->code();

    if (nm == NULL ) {

      const char* comment = "count";

      CompileBroker::compile_method(m, InvocationEntryBci, CompLevel_highest_tier,

                                    m, hot_count, comment, CHECK);

    }

  }

}

void SimpleCompPolicy::method_back_branch_event(methodHandle m, int bci, TRAPS) {

  assert(UseCompiler || CompileTheWorld, "UseCompiler should be set by now.");

  int hot_count = m->backedge_count();

  const char* comment = "backedge_count";

  if (is_compilation_enabled() && !m->is_not_osr_compilable() && can_be_compiled(m)) {

    CompileBroker::compile_method(m, bci, CompLevel_highest_tier,

                                  m, hot_count, comment, CHECK);

    NOT_PRODUCT(trace_osr_completion(m->lookup_osr_nmethod_for(bci, CompLevel_highest_tier, true));)

  }

}

// StackWalkCompPolicy - walk up stack to find a suitable method to compile

#ifdef COMPILER2

const char* StackWalkCompPolicy::_msg = NULL;

// Consider m for compilation

void StackWalkCompPolicy::method_invocation_event(methodHandle m, TRAPS) {

  assert(UseCompiler || CompileTheWorld, "UseCompiler should be set by now.");

  int hot_count = m->invocation_count();

  reset_counter_for_invocation_event(m);

  const char* comment = "count";

  if (is_compilation_enabled() && m->code() == NULL && can_be_compiled(m)) {

    ResourceMark rm(THREAD);

    JavaThread *thread = (JavaThread*)THREAD;

    frame       fr     = thread->last_frame();

    assert(fr.is_interpreted_frame(), "must be interpreted");

    assert(fr.interpreter_frame_method() == m(), "bad method");

    if (TraceCompilationPolicy) {

      tty->print("method invocation trigger: ");

      m->print_short_name(tty);

      tty->print(" ( interpreted " INTPTR_FORMAT ", size=%d ) ", (address)m(), m->code_size());

    }

    RegisterMap reg_map(thread, false);

    javaVFrame* triggerVF = thread->last_java_vframe(&reg_map);

    // triggerVF is the frame that triggered its counter

    RFrame* first = new InterpretedRFrame(triggerVF->fr(), thread, m);

    if (first->top_method()->code() != NULL) {

      // called obsolete method/nmethod -- no need to recompile

      if (TraceCompilationPolicy) tty->print_cr(" --> " INTPTR_FORMAT, first->top_method()->code());

    } else {

      if (TimeCompilationPolicy) accumulated_time()->start();

      GrowableArray<RFrame*>* stack = new GrowableArray<RFrame*>(50);

      stack->push(first);

      RFrame* top = findTopInlinableFrame(stack);

      if (TimeCompilationPolicy) accumulated_time()->stop();

      assert(top != NULL, "findTopInlinableFrame returned null");

      if (TraceCompilationPolicy) top->print();

      CompileBroker::compile_method(top->top_method(), InvocationEntryBci, CompLevel_highest_tier,

                                    m, hot_count, comment, CHECK);

    }

  }

}

void StackWalkCompPolicy::method_back_branch_event(methodHandle m, int bci, TRAPS) {

  assert(UseCompiler || CompileTheWorld, "UseCompiler should be set by now.");

  int hot_count = m->backedge_count();

  const char* comment = "backedge_count";

  if (is_compilation_enabled() && !m->is_not_osr_compilable() && can_be_compiled(m)) {

    CompileBroker::compile_method(m, bci, CompLevel_highest_tier, m, hot_count, comment, CHECK);

    NOT_PRODUCT(trace_osr_completion(m->lookup_osr_nmethod_for(bci, CompLevel_highest_tier, true));)

  }

}

RFrame* StackWalkCompPolicy::findTopInlinableFrame(GrowableArray<RFrame*>* stack) {

  // go up the stack until finding a frame that (probably) won't be inlined

  // into its caller

  RFrame* current = stack->at(0); // current choice for stopping

  assert( current && !current->is_compiled(), "" );

  const char* msg = NULL;

  while (1) {

    // before going up the stack further, check if doing so would get us into

    // compiled code

    RFrame* next = senderOf(current, stack);

    if( !next )               // No next frame up the stack?

      break;                  // Then compile with current frame

    methodHandle m = current->top_method();

    methodHandle next_m = next->top_method();

    if (TraceCompilationPolicy && Verbose) {

      tty->print("[caller: ");

      next_m->print_short_name(tty);

      tty->print("] ");

    }

    if( !Inline ) {           // Inlining turned off

      msg = "Inlining turned off";