Reland "Remove support for thread-based recompilation"

src/optimizing-compile-dispatcher.cc

 // 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-compiler-thread.h"
+#include "src/optimizing-compile-dispatcher.h"
 
 #include "src/v8.h"
 
 #include "src/base/atomicops.h"
 #include "src/full-codegen.h"
 #include "src/hydrogen.h"
 #include "src/isolate.h"
-#include "src/v8threads.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 OptimizingCompilerThread::CompileTask : public v8::Task {
+class OptimizingCompileDispatcher::CompileTask : public v8::Task {
  public:
   explicit CompileTask(Isolate* isolate) : isolate_(isolate) {
-    OptimizingCompilerThread* thread = isolate_->optimizing_compiler_thread();
-    base::LockGuard<base::Mutex> lock_guard(&thread->ref_count_mutex_);
-    ++thread->ref_count_;
+    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;
 
-    OptimizingCompilerThread* thread = isolate_->optimizing_compiler_thread();
+    OptimizingCompileDispatcher* dispatcher =
+        isolate_->optimizing_compile_dispatcher();
     {
       TimerEventScope<TimerEventRecompileConcurrent> timer(isolate_);
 
-      if (thread->recompilation_delay_ != 0) {
-        base::OS::Sleep(thread->recompilation_delay_);
+      if (dispatcher->recompilation_delay_ != 0) {
+        base::OS::Sleep(dispatcher->recompilation_delay_);
       }
 
-      thread->CompileNext(thread->NextInput(true));
+      dispatcher->CompileNext(dispatcher->NextInput(true));
     }
     {
-      base::LockGuard<base::Mutex> lock_guard(&thread->ref_count_mutex_);
-      if (--thread->ref_count_ == 0) {
-        thread->ref_count_zero_.NotifyOne();
+      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);
 };
 
 
-OptimizingCompilerThread::~OptimizingCompilerThread() {
+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_);
   }
 }
 
 
-void OptimizingCompilerThread::Run() {
-#ifdef DEBUG
-  { base::LockGuard<base::Mutex> lock_guard(&thread_id_mutex_);
-    thread_id_ = ThreadId::Current().ToInteger();
-  }
-#endif
-  DisallowHeapAllocation no_allocation;
-  DisallowHandleAllocation no_handles;
-  DisallowHandleDereference no_deref;
-
-  if (job_based_recompilation_) {
-    return;
-  }
-
-  base::ElapsedTimer total_timer;
-  if (tracing_enabled_) total_timer.Start();
-
-  while (true) {
-    input_queue_semaphore_.Wait();
-    TimerEventScope<TimerEventRecompileConcurrent> timer(isolate_);
-
-    if (recompilation_delay_ != 0) {
-      base::OS::Sleep(recompilation_delay_);
-    }
-
-    switch (static_cast<StopFlag>(base::Acquire_Load(&stop_thread_))) {
-      case CONTINUE:
-        break;
-      case STOP:
-        if (tracing_enabled_) {
-          time_spent_total_ = total_timer.Elapsed();
-        }
-        stop_semaphore_.Signal();
-        return;
-      case FLUSH:
-        // The main thread is blocked, waiting for the stop semaphore.
-        { AllowHandleDereference allow_handle_dereference;
-          FlushInputQueue(true);
-        }
-        base::Release_Store(&stop_thread_,
-                            static_cast<base::AtomicWord>(CONTINUE));
-        stop_semaphore_.Signal();
-        // Return to start of consumer loop.
-        continue;
-    }
-
-    base::ElapsedTimer compiling_timer;
-    if (tracing_enabled_) compiling_timer.Start();
-
-    CompileNext(NextInput());
-
-    if (tracing_enabled_) {
-      time_spent_compiling_ += compiling_timer.Elapsed();
-    }
-  }
-}
-
-
-OptimizedCompileJob* OptimizingCompilerThread::NextInput(
+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<StopFlag>(base::Acquire_Load(&stop_thread_)) != CONTINUE) {
+    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 OptimizingCompilerThread::CompileNext(OptimizedCompileJob* 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.
+  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.
-  if (job_based_recompilation_) output_queue_mutex_.Lock();
-  output_queue_.Enqueue(job);
-  if (job_based_recompilation_) output_queue_mutex_.Unlock();
+  base::LockGuard<base::Mutex> access_output_queue_(&output_queue_mutex_);
+  output_queue_.push(job);
   isolate_->stack_guard()->RequestInstallCode();
 }
 
 
-void OptimizingCompilerThread::FlushInputQueue(bool restore_function_code) {
-  OptimizedCompileJob* job;
-  while ((job = NextInput())) {
-    DCHECK(!job_based_recompilation_);
-    // This should not block, since we have one signal on the input queue
-    // semaphore corresponding to each element in the input queue.
-    input_queue_semaphore_.Wait();
+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 OptimizingCompilerThread::FlushOutputQueue(bool restore_function_code) {
-  OptimizedCompileJob* job;
-  while (output_queue_.Dequeue(&job)) {
-    // OSR jobs are dealt with separately.
-    if (!job->info()->is_osr()) {
-      DisposeOptimizedCompileJob(job, restore_function_code);
     }
   }
 }
 
 
-void OptimizingCompilerThread::FlushOsrBuffer(bool 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 OptimizingCompilerThread::Flush() {
-  DCHECK(!IsOptimizerThread());
-  base::Release_Store(&stop_thread_, static_cast<base::AtomicWord>(FLUSH));
+void OptimizingCompileDispatcher::Flush() {
+  base::Release_Store(&mode_, static_cast<base::AtomicWord>(FLUSH));
   if (FLAG_block_concurrent_recompilation) Unblock();
-  if (!job_based_recompilation_) {
-    input_queue_semaphore_.Signal();
-    stop_semaphore_.Wait();
-  } else {
+  {
     base::LockGuard<base::Mutex> lock_guard(&ref_count_mutex_);
     while (ref_count_ > 0) ref_count_zero_.Wait(&ref_count_mutex_);
-    base::Release_Store(&stop_thread_, static_cast<base::AtomicWord>(CONTINUE));
+    base::Release_Store(&mode_, static_cast<base::AtomicWord>(COMPILE));
   }
   FlushOutputQueue(true);
   if (FLAG_concurrent_osr) FlushOsrBuffer(true);
-  if (tracing_enabled_) {
+  if (FLAG_trace_concurrent_recompilation) {
     PrintF("  ** Flushed concurrent recompilation queues.\n");
   }
 }
 
 
-void OptimizingCompilerThread::Stop() {
-  DCHECK(!IsOptimizerThread());
-  base::Release_Store(&stop_thread_, static_cast<base::AtomicWord>(STOP));
+void OptimizingCompileDispatcher::Stop() {
+  base::Release_Store(&mode_, static_cast<base::AtomicWord>(FLUSH));
   if (FLAG_block_concurrent_recompilation) Unblock();
-  if (!job_based_recompilation_) {
-    input_queue_semaphore_.Signal();
-    stop_semaphore_.Wait();
-  } else {
+  {
     base::LockGuard<base::Mutex> lock_guard(&ref_count_mutex_);
     while (ref_count_ > 0) ref_count_zero_.Wait(&ref_count_mutex_);
-    base::Release_Store(&stop_thread_, static_cast<base::AtomicWord>(CONTINUE));
+    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 {
-    FlushInputQueue(false);
     FlushOutputQueue(false);
   }
 
   if (FLAG_concurrent_osr) FlushOsrBuffer(false);
 
-  if (tracing_enabled_) {
-    double percentage = time_spent_compiling_.PercentOf(time_spent_total_);
-    if (job_based_recompilation_) percentage = 100.0;
-    PrintF("  ** Compiler thread did %.2f%% useful work\n", percentage);
-  }
-
-  if ((FLAG_trace_osr || tracing_enabled_) && FLAG_concurrent_osr) {
+  if ((FLAG_trace_osr || FLAG_trace_concurrent_recompilation) &&
+      FLAG_concurrent_osr) {
     PrintF("[COSR hit rate %d / %d]\n", osr_hits_, osr_attempts_);
   }
-
-  Join();
 }
 
 
-void OptimizingCompilerThread::InstallOptimizedFunctions() {
-  DCHECK(!IsOptimizerThread());
+void OptimizingCompileDispatcher::InstallOptimizedFunctions() {
   HandleScope handle_scope(isolate_);
 
-  OptimizedCompileJob* job;
-  while (output_queue_.Dequeue(&job)) {
+  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 (tracing_enabled_) {
+        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);
+        function->ReplaceCode(code.is_null() ? function->shared()->code()
+                                             : *code);
       }
     }
   }
 }
 
 
-void OptimizingCompilerThread::QueueForOptimization(OptimizedCompileJob* job) {
+void OptimizingCompileDispatcher::QueueForOptimization(
+    OptimizedCompileJob* job) {
   DCHECK(IsQueueAvailable());
-  DCHECK(!IsOptimizerThread());
   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 if (job_based_recompilation_) {
+  } else {
     V8::GetCurrentPlatform()->CallOnBackgroundThread(
         new CompileTask(isolate_), v8::Platform::kShortRunningTask);
-  } else {
-    input_queue_semaphore_.Signal();
   }
 }
 
 
-void OptimizingCompilerThread::Unblock() {
-  DCHECK(!IsOptimizerThread());
+void OptimizingCompileDispatcher::Unblock() {
   while (blocked_jobs_ > 0) {
-    if (job_based_recompilation_) {
-      V8::GetCurrentPlatform()->CallOnBackgroundThread(
-          new CompileTask(isolate_), v8::Platform::kShortRunningTask);
-    } else {
-      input_queue_semaphore_.Signal();
-    }
+    V8::GetCurrentPlatform()->CallOnBackgroundThread(
+        new CompileTask(isolate_), v8::Platform::kShortRunningTask);
     blocked_jobs_--;
   }
 }
 
 
-OptimizedCompileJob* OptimizingCompilerThread::FindReadyOSRCandidate(
+OptimizedCompileJob* OptimizingCompileDispatcher::FindReadyOSRCandidate(
     Handle<JSFunction> function, BailoutId osr_ast_id) {
-  DCHECK(!IsOptimizerThread());
   for (int i = 0; i < osr_buffer_capacity_; i++) {
     OptimizedCompileJob* current = osr_buffer_[i];
-    if (current != NULL &&
-        current->IsWaitingForInstall() &&
+    if (current != NULL && current->IsWaitingForInstall() &&
         current->info()->HasSameOsrEntry(function, osr_ast_id)) {
       osr_hits_++;
       osr_buffer_[i] = NULL;
       return current;
     }
   }
   return NULL;
 }
 
 
-bool OptimizingCompilerThread::IsQueuedForOSR(Handle<JSFunction> function,
-                                              BailoutId osr_ast_id) {
-  DCHECK(!IsOptimizerThread());
+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 OptimizingCompilerThread::IsQueuedForOSR(JSFunction* function) {
-  DCHECK(!IsOptimizerThread());
+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 OptimizingCompilerThread::AddToOsrBuffer(OptimizedCompileJob* job) {
-  DCHECK(!IsOptimizerThread());
+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_;
 }
-
-
-#ifdef DEBUG
-bool OptimizingCompilerThread::IsOptimizerThread(Isolate* isolate) {
-  return isolate->concurrent_recompilation_enabled() &&
-         isolate->optimizing_compiler_thread()->IsOptimizerThread();
 }
-
-
-bool OptimizingCompilerThread::IsOptimizerThread() {
-  base::LockGuard<base::Mutex> lock_guard(&thread_id_mutex_);
-  return ThreadId::Current().ToInteger() == thread_id_;
-}
-#endif
-
-
-} }  // namespace v8::internal
+}  // namespace v8::internal