Mercurial > jdk8-mips64-public > hotspot / file revision

 /*

  * Copyright (c) 2000, 2013, 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 "code/compiledIC.hpp"

 #include "code/nmethod.hpp"

 #include "code/scopeDesc.hpp"

 #include "compiler/compilerOracle.hpp"

 #include "interpreter/interpreter.hpp"

 #include "oops/methodData.hpp"

 #include "oops/method.hpp"

 #include "oops/oop.inline.hpp"

 #include "prims/nativeLookup.hpp"

 #include "runtime/advancedThresholdPolicy.hpp"

 #include "runtime/compilationPolicy.hpp"

 #include "runtime/frame.hpp"

 #include "runtime/handles.inline.hpp"

 #include "runtime/rframe.hpp"

 #include "runtime/simpleThresholdPolicy.hpp"

 #include "runtime/stubRoutines.hpp"

 #include "runtime/thread.hpp"

 #include "runtime/timer.hpp"

 #include "runtime/vframe.hpp"

 #include "runtime/vm_operations.hpp"

 #include "utilities/events.hpp"

 #include "utilities/globalDefinitions.hpp"

 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;

   case 3:

 #ifdef TIERED

     CompilationPolicy::set_policy(new AdvancedThresholdPolicy());

 #else

     Unimplemented();

 #endif

     break;

   default:

     fatal("CompilationPolicyChoice must be in the range: [0-3]");

   }

   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) {

   // 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

 }

 // 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 if (is_compile(comp_level)) {

     return !m->is_not_compilable(comp_level);

   }

   return false;

 }

 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).

   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 NonTieredCompPolicy::reset_counter_for_back_branch_event(methodHandle m) {

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

   // 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

 //

 // 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(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");

   int nclasses = SystemDictionary::number_of_classes();

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

                                         CounterHalfLifeTime);

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

     Klass* k = SystemDictionary::try_get_next_class();

     if (k != NULL && k->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;

   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 complation of this method.

 void NonTieredCompPolicy::delay_compilation(Method* method) {

   MethodCounters* mcs = method->method_counters();

   if (mcs != NULL) {

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

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

   }

 }

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

   return compile_queue->first();

 }

 bool NonTieredCompPolicy::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* NonTieredCompPolicy::event(methodHandle method, methodHandle inlinee, int branch_bci,

                                     int bci, CompLevel comp_level, nmethod* 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 (CompileTheWorld || 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 NonTieredCompPolicy::trace_frequency_counter_overflow(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;

     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) {

         MethodData* 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, JavaThread* thread) {

   const int comp_level = CompLevel_highest_tier;

   const 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 ) {

       CompileBroker::compile_method(m, InvocationEntryBci, comp_level, m, hot_count, comment, thread);

     }

   }

 }

 void SimpleCompPolicy::method_back_branch_event(methodHandle m, int bci, JavaThread* thread) {

   const int comp_level = CompLevel_highest_tier;

   const int hot_count = m->backedge_count();

   const char* comment = "backedge_count";

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

     CompileBroker::compile_method(m, bci, comp_level, m, hot_count, comment, thread);

     NOT_PRODUCT(trace_osr_completion(m->lookup_osr_nmethod_for(bci, comp_level, 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, JavaThread* thread) {

   const int comp_level = CompLevel_highest_tier;

   const 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);

     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, comp_level,

                                     m, hot_count, comment, thread);

     }

   }

 }

 void StackWalkCompPolicy::method_back_branch_event(methodHandle m, int bci, JavaThread* thread) {

   const int comp_level = CompLevel_highest_tier;

   const int hot_count = m->backedge_count();

   const char* comment = "backedge_count";

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

     CompileBroker::compile_method(m, bci, comp_level, m, hot_count, comment, thread);

     NOT_PRODUCT(trace_osr_completion(m->lookup_osr_nmethod_for(bci, comp_level, 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";

       break;

     }

     if (next_m->is_not_compilable()) { // Did fail to compile this before/

       msg = "caller not compilable";

       break;

     }

     if (next->num() > MaxRecompilationSearchLength) {

       // don't go up too high when searching for recompilees

       msg = "don't go up any further: > MaxRecompilationSearchLength";

       break;

     }

     if (next->distance() > MaxInterpretedSearchLength) {

       // don't go up too high when searching for recompilees

       msg = "don't go up any further: next > MaxInterpretedSearchLength";

       break;

     }

     // Compiled frame above already decided not to inline;

     // do not recompile him.

     if (next->is_compiled()) {

       msg = "not going up into optimized code";

       break;

     }

     // Interpreted frame above us was already compiled.  Do not force

     // a recompile, although if the frame above us runs long enough an

     // OSR might still happen.

     if( current->is_interpreted() && next_m->has_compiled_code() ) {

       msg = "not going up -- already compiled caller";

       break;

     }

     // Compute how frequent this call site is.  We have current method 'm'.

     // We know next method 'next_m' is interpreted.  Find the call site and

     // check the various invocation counts.

     int invcnt = 0;             // Caller counts

     if (ProfileInterpreter) {

       invcnt = next_m->interpreter_invocation_count();

     }

     int cnt = 0;                // Call site counts

     if (ProfileInterpreter && next_m->method_data() != NULL) {

       ResourceMark rm;

       int bci = next->top_vframe()->bci();

       ProfileData* data = next_m->method_data()->bci_to_data(bci);

       if (data != NULL && data->is_CounterData())

         cnt = data->as_CounterData()->count();

     }

     // Caller counts / call-site counts; i.e. is this call site

     // a hot call site for method next_m?

     int freq = (invcnt) ? cnt/invcnt : cnt;

     // Check size and frequency limits

     if ((msg = shouldInline(m, freq, cnt)) != NULL) {

       break;

     }

     // Check inlining negative tests

     if ((msg = shouldNotInline(m)) != NULL) {

       break;

     }

     // If the caller method is too big or something then we do not want to

     // compile it just to inline a method

     if (!can_be_compiled(next_m)) {

       msg = "caller cannot be compiled";

       break;

     }

     if( next_m->name() == vmSymbols::class_initializer_name() ) {

       msg = "do not compile class initializer (OSR ok)";

       break;

     }

     if (TraceCompilationPolicy && Verbose) {

       tty->print("\n\t     check caller: ");

       next_m->print_short_name(tty);

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

     }

     current = next;

   }

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

   if (TraceCompilationPolicy && msg) tty->print("(%s)\n", msg);

   return current;

 }

 RFrame* StackWalkCompPolicy::senderOf(RFrame* rf, GrowableArray<RFrame*>* stack) {

   RFrame* sender = rf->caller();

   if (sender && sender->num() == stack->length()) stack->push(sender);

   return sender;

 }

 const char* StackWalkCompPolicy::shouldInline(methodHandle m, float freq, int cnt) {

   // Allows targeted inlining

   // positive filter: should send be inlined?  returns NULL (--> yes)

   // or rejection msg

   int max_size = MaxInlineSize;

   int cost = m->code_size();

   // Check for too many throws (and not too huge)

   if (m->interpreter_throwout_count() > InlineThrowCount && cost < InlineThrowMaxSize ) {

     return NULL;

   }

   // bump the max size if the call is frequent

   if ((freq >= InlineFrequencyRatio) || (cnt >= InlineFrequencyCount)) {

     if (TraceFrequencyInlining) {

       tty->print("(Inlined frequent method)\n");

       m->print();

     }

     max_size = FreqInlineSize;

   }

   if (cost > max_size) {

     return (_msg = "too big");

   }

   return NULL;

 }

 const char* StackWalkCompPolicy::shouldNotInline(methodHandle m) {

   // negative filter: should send NOT be inlined?  returns NULL (--> inline) or rejection msg

   if (m->is_abstract()) return (_msg = "abstract method");

   // note: we allow ik->is_abstract()

   if (!m->method_holder()->is_initialized()) return (_msg = "method holder not initialized");

   if (m->is_native()) return (_msg = "native method");

   nmethod* m_code = m->code();

   if (m_code != NULL && m_code->code_size() > InlineSmallCode)

     return (_msg = "already compiled into a big method");

   // use frequency-based objections only for non-trivial methods

   if (m->code_size() <= MaxTrivialSize) return NULL;

   if (UseInterpreter) {     // don't use counts with -Xcomp

     if ((m->code() == NULL) && m->was_never_executed()) return (_msg = "never executed");

     if (!m->was_executed_more_than(MIN2(MinInliningThreshold, CompileThreshold >> 1))) return (_msg = "executed < MinInliningThreshold times");

   }

   if (Method::has_unloaded_classes_in_signature(m, JavaThread::current())) return (_msg = "unloaded signature classes");

   return NULL;

 }

 #endif // COMPILER2