/*

 * Copyright (c) 2000, 2019, 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.

 *

 */

#include "precompiled.hpp"

#include "classfile/classLoaderDataGraph.inline.hpp"

#include "code/compiledIC.hpp"

#include "code/nmethod.hpp"

#include "code/scopeDesc.hpp"

#include "interpreter/interpreter.hpp"

#include "memory/resourceArea.hpp"

#include "oops/methodData.hpp"

#include "oops/method.inline.hpp"

#include "oops/oop.inline.hpp"

#include "prims/nativeLookup.hpp"

#include "runtime/frame.hpp"

#include "runtime/handles.inline.hpp"

#include "runtime/stubRoutines.hpp"

#include "runtime/thread.hpp"

#include "runtime/vframe.hpp"

#include "runtime/vmOperations.hpp"

#include "utilities/events.hpp"

#include "utilities/globalDefinitions.hpp"

#ifdef COMPILER1

#include "c1/c1_Compiler.hpp"

#endif

#ifdef COMPILER2

#include "opto/c2compiler.hpp"

#endif

CompilationPolicy* CompilationPolicy::_policy;

// Determine compilation policy based on command line argument

void compilationPolicy_init() {

  #ifdef TIERED

  if (TieredCompilation) {

    CompilationPolicy::set_policy(new TieredThresholdPolicy());

  } else {

    CompilationPolicy::set_policy(new SimpleCompPolicy());

  }

  #else

  CompilationPolicy::set_policy(new SimpleCompPolicy());

  #endif

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

}

// 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(const methodHandle& m, int comp_level) {

  // Don't allow Xcomp to cause compiles in replay mode

  if (ReplayCompiles) return false;

  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

}

void CompilationPolicy::compile_if_required(const methodHandle& selected_method, TRAPS) {

  if (must_be_compiled(selected_method)) {

    // This path is unusual, mostly used by the '-Xcomp' stress test mode.

    // Note: with several active threads, the must_be_compiled may be true

    //       while can_be_compiled is false; remove assert

    // assert(CompilationPolicy::can_be_compiled(selected_method), "cannot compile");

    if (!THREAD->can_call_java() || THREAD->is_Compiler_thread()) {

      // don't force compilation, resolve was on behalf of compiler

      return;

    }

    if (selected_method->method_holder()->is_not_initialized()) {

      // 'is_not_initialized' means not only '!is_initialized', but also that

      // initialization has not been started yet ('!being_initialized')

      // Do not force compilation of methods in uninitialized classes.

      // Note that doing this would throw an assert later,

      // in CompileBroker::compile_method.

      // We sometimes use the link resolver to do reflective lookups

      // even before classes are initialized.

      return;

    }

    CompileBroker::compile_method(selected_method, InvocationEntryBci,

        CompilationPolicy::policy()->initial_compile_level(),

        methodHandle(), 0, CompileTask::Reason_MustBeCompiled, CHECK);

  }

}

// Returns true if m is allowed to be compiled

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

  // allow any levels for WhiteBox

  assert(WhiteBoxAPI || comp_level == CompLevel_all || is_compile(comp_level), "illegal compilation 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) {

    if (TieredCompilation) {

      // enough to be compilable at any level for tiered

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

    } else {

      // must be compilable at available level for non-tiered

      return !m->is_not_compilable(CompLevel_highest_tier);

    }

  } else if (is_compile(comp_level)) {

    return !m->is_not_compilable(comp_level);

  }

  return false;

}

// Returns true if m is allowed to be osr compiled

bool CompilationPolicy::can_be_osr_compiled(const methodHandle& m, int comp_level) {

  bool result = false;

  if (comp_level == CompLevel_all) {

    if (TieredCompilation) {

      // enough to be osr compilable at any level for tiered

      result = !m->is_not_osr_compilable(CompLevel_simple) || !m->is_not_osr_compilable(CompLevel_full_optimization);

    } else {

      // must be osr compilable at available level for non-tiered

      result = !m->is_not_osr_compilable(CompLevel_highest_tier);

    }

  } else if (is_compile(comp_level)) {

    result = !m->is_not_osr_compilable(comp_level);

  }

  return (result && can_be_compiled(m, comp_level));

}

bool CompilationPolicy::is_compilation_enabled() {

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

  return CompileBroker::should_compile_new_jobs();

}

CompileTask* CompilationPolicy::select_task_helper(CompileQueue* compile_queue) {

  // Remove unloaded methods from the queue

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

    CompileTask* next = task->next();

    if (task->is_unloaded()) {

      compile_queue->remove_and_mark_stale(task);

    }

    task = next;

  }

#if INCLUDE_JVMCI

  if (UseJVMCICompiler && !BackgroundCompilation) {

    /*

     * In blocking compilation mode, the CompileBroker will make

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

     * compilations should be scheduled after all blocking compilations

     * to service non-compiler related compilations sooner and reduce the

     * chance of such compilations timing out.

     */

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

      if (task->is_blocking()) {

        return task;

      }

    }

  }

#endif

  return compile_queue->first();

}

#ifndef PRODUCT

void SimpleCompPolicy::trace_osr_completion(nmethod* osr_nm) {

  if (TraceOnStackReplacement) {

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

    else tty->print_cr("nmethod " INTPTR_FORMAT, p2i(osr_nm));

  }

}

#endif // !PRODUCT

void SimpleCompPolicy::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_int(os::active_processor_count())-1,1);

    // Make sure there is enough space in the code cache to hold all the compiler buffers

    size_t buffer_size = 1;

#ifdef COMPILER1

    buffer_size = is_client_compilation_mode_vm() ? Compiler::code_buffer_size() : buffer_size;

#endif

#ifdef COMPILER2

    buffer_size = is_server_compilation_mode_vm() ? C2Compiler::initial_code_buffer_size() : buffer_size;

#endif

    int max_count = (ReservedCodeCacheSize - (CodeCacheMinimumUseSpace DEBUG_ONLY(* 3))) / (int)buffer_size;

    if (_compiler_count > max_count) {

      // Lower the compiler count such that all buffers fit into the code cache

      _compiler_count = MAX2(max_count, 1);

    }

    FLAG_SET_ERGO(CICompilerCount, _compiler_count);

  } 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 in server compilation mode runs

//   and c2 compilation levels in client compilation mode runs.

// - with COMPILER2 not defined it should return zero for c2 compilation levels.

// - with COMPILER1 not defined it should return zero for c1 compilation levels.

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

int SimpleCompPolicy::compiler_count(CompLevel comp_level) {

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

  if (COMPILER2_PRESENT(is_server_compilation_mode_vm() && is_c2_compile(comp_level) ||)

      is_client_compilation_mode_vm() && is_c1_compile(comp_level)) {

    return _compiler_count;

  }

  return 0;

}

void SimpleCompPolicy::reset_counter_for_invocation_event(const 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).

  MethodCounters* mcs = m->method_counters();

  assert(mcs != NULL, "MethodCounters cannot be NULL for profiling");

  mcs->invocation_counter()->set_carry();

  mcs->backedge_counter()->set_carry();

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

}

void SimpleCompPolicy::reset_counter_for_back_branch_event(const methodHandle& m) {

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

  // whole method compilation.

  MethodCounters* mcs = m->method_counters();

  assert(mcs != NULL, "MethodCounters cannot be NULL for profiling");

  InvocationCounter* i = mcs->invocation_counter();

  InvocationCounter* b = mcs->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

//

// Iterates through invocation counters and decrements them. This

// is done at each safepoint.

//

class CounterDecay : public AllStatic {

  static jlong _last_timestamp;

  static void do_method(Method* m) {

    MethodCounters* mcs = m->method_counters();

    if (mcs != NULL) {

      mcs->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");

  size_t nclasses = ClassLoaderDataGraph::num_instance_classes();

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

                                        CounterHalfLifeTime);

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

    InstanceKlass* k = ClassLoaderDataGraph::try_get_next_class();

    if (k != NULL) {

      k->methods_do(do_method);

    }

  }

}

// Called at the end of the safepoint

void SimpleCompPolicy::do_safepoint_work() {

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

    CounterDecay::decay();

  }

}

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

  ScopeDesc* sd = trap_scope;

  MethodCounters* mcs;

  InvocationCounter* c;

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

    mcs = sd->method()->method_counters();

    if (mcs != NULL) {

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

      mcs->invocation_counter()->reset();

    }

  }

  mcs = sd->method()->method_counters();

  if (mcs != NULL) {

    c = mcs->invocation_counter();

    if (is_osr) {

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

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

    } else {

      c->reset();

    }

    mcs->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 compilation of this method.

void SimpleCompPolicy::delay_compilation(Method* method) {

  MethodCounters* mcs = method->method_counters();

  if (mcs != NULL) {

    mcs->invocation_counter()->decay();

    mcs->backedge_counter()->decay();

  }

}

void SimpleCompPolicy::disable_compilation(Method* method) {

  MethodCounters* mcs = method->method_counters();

  if (mcs != NULL) {

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

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

  }

}

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

  return select_task_helper(compile_queue);

}

bool SimpleCompPolicy::is_mature(Method* method) {

  MethodData* 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* SimpleCompPolicy::event(const methodHandle& method, const methodHandle& inlinee, int branch_bci,

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

  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() && 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 (ReplayCompiles) {

    // Don't trigger other compiles in testing mode

    if (bci == InvocationEntryBci) {

      reset_counter_for_invocation_event(method);

    } else {

      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, thread);

    } 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, thread);

      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 SimpleCompPolicy::trace_frequency_counter_overflow(const methodHandle& m, int branch_bci, int bci) {

  if (TraceInvocationCounterOverflow) {

    MethodCounters* mcs = m->method_counters();

    assert(mcs != NULL, "MethodCounters cannot be NULL for profiling");

    InvocationCounter* ic = mcs->invocation_counter();

    InvocationCounter* bc = mcs->backedge_counter();

    ResourceMark rm;

    if (bci == InvocationEntryBci) {

      tty->print("comp-policy cntr ovfl @ %d in entry of ", bci);

    } else {

      tty->print("comp-policy cntr ovfl @ %d in loop of ", bci);

    }

    m->print_value();

    tty->cr();

    ic->print();

    bc->print();

    if (ProfileInterpreter) {

      if (bci != InvocationEntryBci) {

        MethodData* mdo = m->method_data();

        if (mdo != NULL) {

          ProfileData *pd = mdo->bci_to_data(branch_bci);

          if (pd == NULL) {

            tty->print_cr("back branch count = N/A (missing ProfileData)");

          } else {

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

          }

        }

      }

    }

  }

}

void SimpleCompPolicy::trace_osr_request(const 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

void SimpleCompPolicy::method_invocation_event(const methodHandle& m, JavaThread* thread) {

  const int comp_level = CompLevel_highest_tier;

  const int hot_count = m->invocation_count();

  reset_counter_for_invocation_event(m);

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

    CompiledMethod* nm = m->code();