src/optimizing-compile-dispatcher.cc - v8/v8 - Git at Google

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 #include "src/optimizing-compile-dispatcher.h"

 #include "src/base/atomicops.h"
 #include "src/full-codegen/full-codegen.h"
 #include "src/isolate.h"
 #include "src/v8.h"

 namespace v8 {
 namespace internal {

 namespace {

 void DisposeOptimizedCompileJob(OptimizedCompileJob* job,
                                 bool restore_function_code) {
   // The recompile job is allocated in the CompilationInfo's zone.
   CompilationInfo* info = job->info();
   if (restore_function_code) {
     if (info->is_osr()) {
       if (!job->IsWaitingForInstall()) {
         // Remove stack check that guards OSR entry on original code.
         Handle<Code> code = info->unoptimized_code();
         uint32_t offset = code->TranslateAstIdToPcOffset(info->osr_ast_id());
         BackEdgeTable::RemoveStackCheck(code, offset);
       }
     } else {
       Handle<JSFunction> function = info->closure();
       function->ReplaceCode(function->shared()->code());
     }
   }
   delete info;
 }

 }  // namespace


 class OptimizingCompileDispatcher::CompileTask : public v8::Task {
  public:
   explicit CompileTask(Isolate* isolate) : isolate_(isolate) {
     OptimizingCompileDispatcher* dispatcher =
         isolate_->optimizing_compile_dispatcher();
     base::LockGuard<base::Mutex> lock_guard(&dispatcher->ref_count_mutex_);
     ++dispatcher->ref_count_;
   }

   virtual ~CompileTask() {}

  private:
   // v8::Task overrides.
   void Run() override {
     DisallowHeapAllocation no_allocation;
     DisallowHandleAllocation no_handles;
     DisallowHandleDereference no_deref;

     OptimizingCompileDispatcher* dispatcher =
         isolate_->optimizing_compile_dispatcher();
     {
       TimerEventScope<TimerEventRecompileConcurrent> timer(isolate_);

       if (dispatcher->recompilation_delay_ != 0) {
         base::OS::Sleep(base::TimeDelta::FromMilliseconds(
             dispatcher->recompilation_delay_));
       }

       dispatcher->CompileNext(dispatcher->NextInput(true));
     }
     {
       base::LockGuard<base::Mutex> lock_guard(&dispatcher->ref_count_mutex_);
       if (--dispatcher->ref_count_ == 0) {
         dispatcher->ref_count_zero_.NotifyOne();
       }
     }
   }

   Isolate* isolate_;

   DISALLOW_COPY_AND_ASSIGN(CompileTask);
 };


 OptimizingCompileDispatcher::~OptimizingCompileDispatcher() {
 #ifdef DEBUG
   {
     base::LockGuard<base::Mutex> lock_guard(&ref_count_mutex_);
     DCHECK_EQ(0, ref_count_);
   }
 #endif
   DCHECK_EQ(0, input_queue_length_);
   DeleteArray(input_queue_);
   if (FLAG_concurrent_osr) {
 #ifdef DEBUG
     for (int i = 0; i < osr_buffer_capacity_; i++) {
       CHECK_NULL(osr_buffer_[i]);
     }
 #endif
     DeleteArray(osr_buffer_);
   }
 }


 OptimizedCompileJob* OptimizingCompileDispatcher::NextInput(
     bool check_if_flushing) {
   base::LockGuard<base::Mutex> access_input_queue_(&input_queue_mutex_);
   if (input_queue_length_ == 0) return NULL;
   OptimizedCompileJob* job = input_queue_[InputQueueIndex(0)];
   DCHECK_NOT_NULL(job);
   input_queue_shift_ = InputQueueIndex(1);
   input_queue_length_--;
   if (check_if_flushing) {
     if (static_cast<ModeFlag>(base::Acquire_Load(&mode_)) == FLUSH) {
       if (!job->info()->is_osr()) {
         AllowHandleDereference allow_handle_dereference;
         DisposeOptimizedCompileJob(job, true);
       }
       return NULL;
     }
   }
   return job;
 }


 void OptimizingCompileDispatcher::CompileNext(OptimizedCompileJob* job) {
   if (!job) return;

   // The function may have already been optimized by OSR.  Simply continue.
   OptimizedCompileJob::Status status = job->OptimizeGraph();
   USE(status);  // Prevent an unused-variable error in release mode.
   DCHECK(status != OptimizedCompileJob::FAILED);

   // The function may have already been optimized by OSR.  Simply continue.
   // Use a mutex to make sure that functions marked for install
   // are always also queued.
   base::LockGuard<base::Mutex> access_output_queue_(&output_queue_mutex_);
   output_queue_.push(job);
   isolate_->stack_guard()->RequestInstallCode();
 }


 void OptimizingCompileDispatcher::FlushOutputQueue(bool restore_function_code) {
   for (;;) {
     OptimizedCompileJob* job = NULL;
     {
       base::LockGuard<base::Mutex> access_output_queue_(&output_queue_mutex_);
       if (output_queue_.empty()) return;
       job = output_queue_.front();
       output_queue_.pop();
     }

     // OSR jobs are dealt with separately.
     if (!job->info()->is_osr()) {
       DisposeOptimizedCompileJob(job, restore_function_code);
     }
   }
 }


 void OptimizingCompileDispatcher::FlushOsrBuffer(bool restore_function_code) {
   for (int i = 0; i < osr_buffer_capacity_; i++) {
     if (osr_buffer_[i] != NULL) {
       DisposeOptimizedCompileJob(osr_buffer_[i], restore_function_code);
       osr_buffer_[i] = NULL;
     }
   }
 }


 void OptimizingCompileDispatcher::Flush() {
   base::Release_Store(&mode_, static_cast<base::AtomicWord>(FLUSH));
   if (FLAG_block_concurrent_recompilation) Unblock();
   {
     base::LockGuard<base::Mutex> lock_guard(&ref_count_mutex_);
     while (ref_count_ > 0) ref_count_zero_.Wait(&ref_count_mutex_);
     base::Release_Store(&mode_, static_cast<base::AtomicWord>(COMPILE));
   }
   FlushOutputQueue(true);
   if (FLAG_concurrent_osr) FlushOsrBuffer(true);
   if (FLAG_trace_concurrent_recompilation) {
     PrintF("  ** Flushed concurrent recompilation queues.\n");
   }
 }


 void OptimizingCompileDispatcher::Stop() {
   base::Release_Store(&mode_, static_cast<base::AtomicWord>(FLUSH));
   if (FLAG_block_concurrent_recompilation) Unblock();
   {
     base::LockGuard<base::Mutex> lock_guard(&ref_count_mutex_);
     while (ref_count_ > 0) ref_count_zero_.Wait(&ref_count_mutex_);
     base::Release_Store(&mode_, static_cast<base::AtomicWord>(COMPILE));
   }

   if (recompilation_delay_ != 0) {
     // At this point the optimizing compiler thread's event loop has stopped.
     // There is no need for a mutex when reading input_queue_length_.
     while (input_queue_length_ > 0) CompileNext(NextInput());
     InstallOptimizedFunctions();
   } else {
     FlushOutputQueue(false);
   }

   if (FLAG_concurrent_osr) FlushOsrBuffer(false);

   if ((FLAG_trace_osr || FLAG_trace_concurrent_recompilation) &&
       FLAG_concurrent_osr) {
     PrintF("[COSR hit rate %d / %d]\n", osr_hits_, osr_attempts_);
   }
 }


 void OptimizingCompileDispatcher::InstallOptimizedFunctions() {
   HandleScope handle_scope(isolate_);

   for (;;) {
     OptimizedCompileJob* job = NULL;
     {
       base::LockGuard<base::Mutex> access_output_queue_(&output_queue_mutex_);
       if (output_queue_.empty()) return;
       job = output_queue_.front();
       output_queue_.pop();
     }
     CompilationInfo* info = job->info();
     Handle<JSFunction> function(*info->closure());
     if (info->is_osr()) {
       if (FLAG_trace_osr) {
         PrintF("[COSR - ");
         function->ShortPrint();
         PrintF(" is ready for install and entry at AST id %d]\n",
                info->osr_ast_id().ToInt());
       }
       job->WaitForInstall();
       // Remove stack check that guards OSR entry on original code.
       Handle<Code> code = info->unoptimized_code();
       uint32_t offset = code->TranslateAstIdToPcOffset(info->osr_ast_id());
       BackEdgeTable::RemoveStackCheck(code, offset);
     } else {
       if (function->IsOptimized()) {
         if (FLAG_trace_concurrent_recompilation) {
           PrintF("  ** Aborting compilation for ");
           function->ShortPrint();
           PrintF(" as it has already been optimized.\n");
         }
         DisposeOptimizedCompileJob(job, false);
       } else {
         Handle<Code> code = Compiler::GetConcurrentlyOptimizedCode(job);
         function->ReplaceCode(code.is_null() ? function->shared()->code()
                                              : *code);
       }
     }
   }
 }


 void OptimizingCompileDispatcher::QueueForOptimization(
     OptimizedCompileJob* job) {
   DCHECK(IsQueueAvailable());
   CompilationInfo* info = job->info();
   if (info->is_osr()) {
     osr_attempts_++;
     AddToOsrBuffer(job);
     // Add job to the front of the input queue.
     base::LockGuard<base::Mutex> access_input_queue(&input_queue_mutex_);
     DCHECK_LT(input_queue_length_, input_queue_capacity_);
     // Move shift_ back by one.
     input_queue_shift_ = InputQueueIndex(input_queue_capacity_ - 1);
     input_queue_[InputQueueIndex(0)] = job;
     input_queue_length_++;
   } else {
     // Add job to the back of the input queue.
     base::LockGuard<base::Mutex> access_input_queue(&input_queue_mutex_);
     DCHECK_LT(input_queue_length_, input_queue_capacity_);
     input_queue_[InputQueueIndex(input_queue_length_)] = job;
     input_queue_length_++;
   }
   if (FLAG_block_concurrent_recompilation) {
     blocked_jobs_++;
   } else {
     V8::GetCurrentPlatform()->CallOnBackgroundThread(
         new CompileTask(isolate_), v8::Platform::kShortRunningTask);
   }
 }


 void OptimizingCompileDispatcher::Unblock() {
   while (blocked_jobs_ > 0) {
     V8::GetCurrentPlatform()->CallOnBackgroundThread(
         new CompileTask(isolate_), v8::Platform::kShortRunningTask);
     blocked_jobs_--;
   }
 }


 OptimizedCompileJob* OptimizingCompileDispatcher::FindReadyOSRCandidate(
     Handle<JSFunction> function, BailoutId osr_ast_id) {
   for (int i = 0; i < osr_buffer_capacity_; i++) {
     OptimizedCompileJob* current = osr_buffer_[i];
     if (current != NULL && current->IsWaitingForInstall() &&
         current->info()->HasSameOsrEntry(function, osr_ast_id)) {
       osr_hits_++;
       osr_buffer_[i] = NULL;
       return current;
     }
   }
   return NULL;
 }


 bool OptimizingCompileDispatcher::IsQueuedForOSR(Handle<JSFunction> function,
                                                  BailoutId osr_ast_id) {
   for (int i = 0; i < osr_buffer_capacity_; i++) {
     OptimizedCompileJob* current = osr_buffer_[i];
     if (current != NULL &&
         current->info()->HasSameOsrEntry(function, osr_ast_id)) {
       return !current->IsWaitingForInstall();
     }
   }
   return false;
 }


 bool OptimizingCompileDispatcher::IsQueuedForOSR(JSFunction* function) {
   for (int i = 0; i < osr_buffer_capacity_; i++) {
     OptimizedCompileJob* current = osr_buffer_[i];
     if (current != NULL && *current->info()->closure() == function) {
       return !current->IsWaitingForInstall();
     }
   }
   return false;
 }


 void OptimizingCompileDispatcher::AddToOsrBuffer(OptimizedCompileJob* job) {
   // Find the next slot that is empty or has a stale job.
   OptimizedCompileJob* stale = NULL;
   while (true) {
     stale = osr_buffer_[osr_buffer_cursor_];
     if (stale == NULL || stale->IsWaitingForInstall()) break;
     osr_buffer_cursor_ = (osr_buffer_cursor_ + 1) % osr_buffer_capacity_;
   }

   // Add to found slot and dispose the evicted job.
   if (stale != NULL) {
     DCHECK(stale->IsWaitingForInstall());
     CompilationInfo* info = stale->info();
     if (FLAG_trace_osr) {
       PrintF("[COSR - Discarded ");
       info->closure()->PrintName();
       PrintF(", AST id %d]\n", info->osr_ast_id().ToInt());
     }
     DisposeOptimizedCompileJob(stale, false);
   }
   osr_buffer_[osr_buffer_cursor_] = job;
   osr_buffer_cursor_ = (osr_buffer_cursor_ + 1) % osr_buffer_capacity_;
 }
 }  // namespace internal
 }  // namespace v8
	// Copyright 2012 the V8 project authors. All rights reserved.
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	#include "src/optimizing-compile-dispatcher.h"

	#include "src/base/atomicops.h"
	#include "src/full-codegen/full-codegen.h"
	#include "src/isolate.h"
	#include "src/v8.h"

	namespace v8 {
	namespace internal {

	namespace {

	void DisposeOptimizedCompileJob(OptimizedCompileJob* job,
	bool restore_function_code) {
	// The recompile job is allocated in the CompilationInfo's zone.
	CompilationInfo* info = job->info();
	if (restore_function_code) {
	if (info->is_osr()) {
	if (!job->IsWaitingForInstall()) {
	// Remove stack check that guards OSR entry on original code.
	Handle<Code> code = info->unoptimized_code();
	uint32_t offset = code->TranslateAstIdToPcOffset(info->osr_ast_id());
	BackEdgeTable::RemoveStackCheck(code, offset);
	}
	} else {
	Handle<JSFunction> function = info->closure();
	function->ReplaceCode(function->shared()->code());
	}
	}
	delete info;
	}

	} // namespace


	class OptimizingCompileDispatcher::CompileTask : public v8::Task {
	public:
	explicit CompileTask(Isolate* isolate) : isolate_(isolate) {
	OptimizingCompileDispatcher* dispatcher =
	isolate_->optimizing_compile_dispatcher();
	base::LockGuard<base::Mutex> lock_guard(&dispatcher->ref_count_mutex_);
	++dispatcher->ref_count_;
	}

	virtual ~CompileTask() {}

	private:
	// v8::Task overrides.
	void Run() override {
	DisallowHeapAllocation no_allocation;
	DisallowHandleAllocation no_handles;
	DisallowHandleDereference no_deref;

	OptimizingCompileDispatcher* dispatcher =
	isolate_->optimizing_compile_dispatcher();
	{
	TimerEventScope<TimerEventRecompileConcurrent> timer(isolate_);

	if (dispatcher->recompilation_delay_ != 0) {
	base::OS::Sleep(base::TimeDelta::FromMilliseconds(
	dispatcher->recompilation_delay_));
	}

	dispatcher->CompileNext(dispatcher->NextInput(true));
	}
	{
	base::LockGuard<base::Mutex> lock_guard(&dispatcher->ref_count_mutex_);
	if (--dispatcher->ref_count_ == 0) {
	dispatcher->ref_count_zero_.NotifyOne();
	}
	}
	}

	Isolate* isolate_;

	DISALLOW_COPY_AND_ASSIGN(CompileTask);
	};


	OptimizingCompileDispatcher::~OptimizingCompileDispatcher() {
	#ifdef DEBUG
	{
	base::LockGuard<base::Mutex> lock_guard(&ref_count_mutex_);
	DCHECK_EQ(0, ref_count_);
	}
	#endif
	DCHECK_EQ(0, input_queue_length_);
	DeleteArray(input_queue_);
	if (FLAG_concurrent_osr) {
	#ifdef DEBUG
	for (int i = 0; i < osr_buffer_capacity_; i++) {
	CHECK_NULL(osr_buffer_[i]);
	}
	#endif
	DeleteArray(osr_buffer_);
	}
	}


	OptimizedCompileJob* OptimizingCompileDispatcher::NextInput(
	bool check_if_flushing) {
	base::LockGuard<base::Mutex> access_input_queue_(&input_queue_mutex_);
	if (input_queue_length_ == 0) return NULL;
	OptimizedCompileJob* job = input_queue_[InputQueueIndex(0)];
	DCHECK_NOT_NULL(job);
	input_queue_shift_ = InputQueueIndex(1);
	input_queue_length_--;
	if (check_if_flushing) {
	if (static_cast<ModeFlag>(base::Acquire_Load(&mode_)) == FLUSH) {
	if (!job->info()->is_osr()) {
	AllowHandleDereference allow_handle_dereference;
	DisposeOptimizedCompileJob(job, true);
	}
	return NULL;
	}
	}
	return job;
	}


	void OptimizingCompileDispatcher::CompileNext(OptimizedCompileJob* job) {
	if (!job) return;

	// The function may have already been optimized by OSR. Simply continue.
	OptimizedCompileJob::Status status = job->OptimizeGraph();
	USE(status); // Prevent an unused-variable error in release mode.
	DCHECK(status != OptimizedCompileJob::FAILED);

	// The function may have already been optimized by OSR. Simply continue.
	// Use a mutex to make sure that functions marked for install
	// are always also queued.
	base::LockGuard<base::Mutex> access_output_queue_(&output_queue_mutex_);
	output_queue_.push(job);
	isolate_->stack_guard()->RequestInstallCode();
	}


	void OptimizingCompileDispatcher::FlushOutputQueue(bool restore_function_code) {
	for (;;) {
	OptimizedCompileJob* job = NULL;
	{
	base::LockGuard<base::Mutex> access_output_queue_(&output_queue_mutex_);
	if (output_queue_.empty()) return;
	job = output_queue_.front();
	output_queue_.pop();
	}

	// OSR jobs are dealt with separately.
	if (!job->info()->is_osr()) {
	DisposeOptimizedCompileJob(job, restore_function_code);
	}
	}
	}


	void OptimizingCompileDispatcher::FlushOsrBuffer(bool restore_function_code) {
	for (int i = 0; i < osr_buffer_capacity_; i++) {
	if (osr_buffer_[i] != NULL) {
	DisposeOptimizedCompileJob(osr_buffer_[i], restore_function_code);
	osr_buffer_[i] = NULL;
	}
	}
	}


	void OptimizingCompileDispatcher::Flush() {
	base::Release_Store(&mode_, static_cast<base::AtomicWord>(FLUSH));
	if (FLAG_block_concurrent_recompilation) Unblock();
	{
	base::LockGuard<base::Mutex> lock_guard(&ref_count_mutex_);
	while (ref_count_ > 0) ref_count_zero_.Wait(&ref_count_mutex_);
	base::Release_Store(&mode_, static_cast<base::AtomicWord>(COMPILE));
	}
	FlushOutputQueue(true);
	if (FLAG_concurrent_osr) FlushOsrBuffer(true);
	if (FLAG_trace_concurrent_recompilation) {
	PrintF(" ** Flushed concurrent recompilation queues.\n");
	}
	}


	void OptimizingCompileDispatcher::Stop() {
	base::Release_Store(&mode_, static_cast<base::AtomicWord>(FLUSH));
	if (FLAG_block_concurrent_recompilation) Unblock();
	{
	base::LockGuard<base::Mutex> lock_guard(&ref_count_mutex_);
	while (ref_count_ > 0) ref_count_zero_.Wait(&ref_count_mutex_);
	base::Release_Store(&mode_, static_cast<base::AtomicWord>(COMPILE));
	}

	if (recompilation_delay_ != 0) {
	// At this point the optimizing compiler thread's event loop has stopped.
	// There is no need for a mutex when reading input_queue_length_.
	while (input_queue_length_ > 0) CompileNext(NextInput());
	InstallOptimizedFunctions();
	} else {
	FlushOutputQueue(false);
	}

	if (FLAG_concurrent_osr) FlushOsrBuffer(false);

	if ((FLAG_trace_osr \|\| FLAG_trace_concurrent_recompilation) &&
	FLAG_concurrent_osr) {
	PrintF("[COSR hit rate %d / %d]\n", osr_hits_, osr_attempts_);
	}
	}


	void OptimizingCompileDispatcher::InstallOptimizedFunctions() {
	HandleScope handle_scope(isolate_);

	for (;;) {
	OptimizedCompileJob* job = NULL;
	{
	base::LockGuard<base::Mutex> access_output_queue_(&output_queue_mutex_);
	if (output_queue_.empty()) return;
	job = output_queue_.front();
	output_queue_.pop();
	}
	CompilationInfo* info = job->info();
	Handle<JSFunction> function(*info->closure());
	if (info->is_osr()) {
	if (FLAG_trace_osr) {
	PrintF("[COSR - ");
	function->ShortPrint();
	PrintF(" is ready for install and entry at AST id %d]\n",
	info->osr_ast_id().ToInt());
	}
	job->WaitForInstall();
	// Remove stack check that guards OSR entry on original code.
	Handle<Code> code = info->unoptimized_code();
	uint32_t offset = code->TranslateAstIdToPcOffset(info->osr_ast_id());
	BackEdgeTable::RemoveStackCheck(code, offset);
	} else {
	if (function->IsOptimized()) {
	if (FLAG_trace_concurrent_recompilation) {
	PrintF(" ** Aborting compilation for ");
	function->ShortPrint();
	PrintF(" as it has already been optimized.\n");
	}
	DisposeOptimizedCompileJob(job, false);
	} else {
	Handle<Code> code = Compiler::GetConcurrentlyOptimizedCode(job);
	function->ReplaceCode(code.is_null() ? function->shared()->code()
	: *code);
	}
	}
	}
	}


	void OptimizingCompileDispatcher::QueueForOptimization(
	OptimizedCompileJob* job) {
	DCHECK(IsQueueAvailable());
	CompilationInfo* info = job->info();
	if (info->is_osr()) {
	osr_attempts_++;
	AddToOsrBuffer(job);
	// Add job to the front of the input queue.
	base::LockGuard<base::Mutex> access_input_queue(&input_queue_mutex_);
	DCHECK_LT(input_queue_length_, input_queue_capacity_);
	// Move shift_ back by one.
	input_queue_shift_ = InputQueueIndex(input_queue_capacity_ - 1);
	input_queue_[InputQueueIndex(0)] = job;
	input_queue_length_++;
	} else {
	// Add job to the back of the input queue.
	base::LockGuard<base::Mutex> access_input_queue(&input_queue_mutex_);
	DCHECK_LT(input_queue_length_, input_queue_capacity_);
	input_queue_[InputQueueIndex(input_queue_length_)] = job;
	input_queue_length_++;
	}
	if (FLAG_block_concurrent_recompilation) {
	blocked_jobs_++;
	} else {
	V8::GetCurrentPlatform()->CallOnBackgroundThread(
	new CompileTask(isolate_), v8::Platform::kShortRunningTask);
	}
	}


	void OptimizingCompileDispatcher::Unblock() {
	while (blocked_jobs_ > 0) {
	V8::GetCurrentPlatform()->CallOnBackgroundThread(
	new CompileTask(isolate_), v8::Platform::kShortRunningTask);
	blocked_jobs_--;
	}
	}


	OptimizedCompileJob* OptimizingCompileDispatcher::FindReadyOSRCandidate(
	Handle<JSFunction> function, BailoutId osr_ast_id) {
	for (int i = 0; i < osr_buffer_capacity_; i++) {
	OptimizedCompileJob* current = osr_buffer_[i];
	if (current != NULL && current->IsWaitingForInstall() &&
	current->info()->HasSameOsrEntry(function, osr_ast_id)) {
	osr_hits_++;
	osr_buffer_[i] = NULL;
	return current;
	}
	}
	return NULL;
	}


	bool OptimizingCompileDispatcher::IsQueuedForOSR(Handle<JSFunction> function,
	BailoutId osr_ast_id) {
	for (int i = 0; i < osr_buffer_capacity_; i++) {
	OptimizedCompileJob* current = osr_buffer_[i];
	if (current != NULL &&
	current->info()->HasSameOsrEntry(function, osr_ast_id)) {
	return !current->IsWaitingForInstall();
	}
	}
	return false;
	}


	bool OptimizingCompileDispatcher::IsQueuedForOSR(JSFunction* function) {
	for (int i = 0; i < osr_buffer_capacity_; i++) {
	OptimizedCompileJob* current = osr_buffer_[i];
	if (current != NULL && *current->info()->closure() == function) {
	return !current->IsWaitingForInstall();
	}
	}
	return false;
	}


	void OptimizingCompileDispatcher::AddToOsrBuffer(OptimizedCompileJob* job) {
	// Find the next slot that is empty or has a stale job.
	OptimizedCompileJob* stale = NULL;
	while (true) {
	stale = osr_buffer_[osr_buffer_cursor_];
	if (stale == NULL \|\| stale->IsWaitingForInstall()) break;
	osr_buffer_cursor_ = (osr_buffer_cursor_ + 1) % osr_buffer_capacity_;
	}

	// Add to found slot and dispose the evicted job.
	if (stale != NULL) {
	DCHECK(stale->IsWaitingForInstall());
	CompilationInfo* info = stale->info();
	if (FLAG_trace_osr) {
	PrintF("[COSR - Discarded ");
	info->closure()->PrintName();
	PrintF(", AST id %d]\n", info->osr_ast_id().ToInt());
	}
	DisposeOptimizedCompileJob(stale, false);
	}
	osr_buffer_[osr_buffer_cursor_] = job;
	osr_buffer_cursor_ = (osr_buffer_cursor_ + 1) % osr_buffer_capacity_;
	}
	} // namespace internal
	} // namespace v8