Revert of Reland "Remove support for thread-based recompilation"

src/optimizing-compiler-thread.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/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 {
+ 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_;
+  }
+
+  virtual ~CompileTask() {}
+
+ private:
+  // v8::Task overrides.
+  void Run() OVERRIDE {
+    DisallowHeapAllocation no_allocation;
+    DisallowHandleAllocation no_handles;
+    DisallowHandleDereference no_deref;
+
+    OptimizingCompilerThread* thread = isolate_->optimizing_compiler_thread();
+    {
+      TimerEventScope<TimerEventRecompileConcurrent> timer(isolate_);
+
+      if (thread->recompilation_delay_ != 0) {
+        base::OS::Sleep(thread->recompilation_delay_);
+      }
+
+      thread->CompileNext(thread->NextInput(true));
+    }
+    {
+      base::LockGuard<base::Mutex> lock_guard(&thread->ref_count_mutex_);
+      if (--thread->ref_count_ == 0) {
+        thread->ref_count_zero_.NotifyOne();
+      }
+    }
+  }
+
+  Isolate* isolate_;
+
+  DISALLOW_COPY_AND_ASSIGN(CompileTask);
+};
+
+
+OptimizingCompilerThread::~OptimizingCompilerThread() {
+#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(
+    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 (!job->info()->is_osr()) {
+        AllowHandleDereference allow_handle_dereference;
+        DisposeOptimizedCompileJob(job, true);
+      }
+      return NULL;
+    }
+  }
+  return job;
+}
+
+
+void OptimizingCompilerThread::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.
+  if (job_based_recompilation_) output_queue_mutex_.Lock();
+  output_queue_.Enqueue(job);
+  if (job_based_recompilation_) output_queue_mutex_.Unlock();
+  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();
+    // 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) {
+  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));
+  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));
+  }
+  FlushOutputQueue(true);
+  if (FLAG_concurrent_osr) FlushOsrBuffer(true);
+  if (tracing_enabled_) {
+    PrintF("  ** Flushed concurrent recompilation queues.\n");
+  }
+}
+
+
+void OptimizingCompilerThread::Stop() {
+  DCHECK(!IsOptimizerThread());
+  base::Release_Store(&stop_thread_, static_cast<base::AtomicWord>(STOP));
+  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));
+  }
+
+  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) {
+    PrintF("[COSR hit rate %d / %d]\n", osr_hits_, osr_attempts_);
+  }
+
+  Join();
+}
+
+
+void OptimizingCompilerThread::InstallOptimizedFunctions() {
+  DCHECK(!IsOptimizerThread());
+  HandleScope handle_scope(isolate_);
+
+  OptimizedCompileJob* job;
+  while (output_queue_.Dequeue(&job)) {
+    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_) {
+          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 OptimizingCompilerThread::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_) {
+    V8::GetCurrentPlatform()->CallOnBackgroundThread(
+        new CompileTask(isolate_), v8::Platform::kShortRunningTask);
+  } else {
+    input_queue_semaphore_.Signal();
+  }
+}
+
+
+void OptimizingCompilerThread::Unblock() {
+  DCHECK(!IsOptimizerThread());
+  while (blocked_jobs_ > 0) {
+    if (job_based_recompilation_) {
+      V8::GetCurrentPlatform()->CallOnBackgroundThread(
+          new CompileTask(isolate_), v8::Platform::kShortRunningTask);
+    } else {
+      input_queue_semaphore_.Signal();
+    }
+    blocked_jobs_--;
+  }
+}
+
+
+OptimizedCompileJob* OptimizingCompilerThread::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() &&
+        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());
+  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());
+  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());
+  // 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