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

src/optimizing-compiler-thread.h

Index: src/optimizing-compiler-thread.h
diff --git a/src/optimizing-compiler-thread.h b/src/optimizing-compiler-thread.h
new file mode 100644
index 0000000000000000000000000000000000000000..7d60d9bf74556317754537296059a29f6336757d
--- /dev/null
+++ b/src/optimizing-compiler-thread.h
@@ -0,0 +1,166 @@
+// 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.
+
+#ifndef V8_OPTIMIZING_COMPILER_THREAD_H_
+#define V8_OPTIMIZING_COMPILER_THREAD_H_
+
+#include "src/base/atomicops.h"
+#include "src/base/platform/condition-variable.h"
+#include "src/base/platform/mutex.h"
+#include "src/base/platform/platform.h"
+#include "src/base/platform/time.h"
+#include "src/flags.h"
+#include "src/list.h"
+#include "src/unbound-queue-inl.h"
+
+namespace v8 {
+namespace internal {
+
+class HOptimizedGraphBuilder;
+class OptimizedCompileJob;
+class SharedFunctionInfo;
+
+class OptimizingCompilerThread : public base::Thread {
+ public:
+  explicit OptimizingCompilerThread(Isolate* isolate)
+      : Thread(Options("OptimizingCompilerThread")),
+#ifdef DEBUG
+        thread_id_(0),
+#endif
+        isolate_(isolate),
+        stop_semaphore_(0),
+        input_queue_semaphore_(0),
+        input_queue_capacity_(FLAG_concurrent_recompilation_queue_length),
+        input_queue_length_(0),
+        input_queue_shift_(0),
+        osr_buffer_capacity_(FLAG_concurrent_recompilation_queue_length + 4),
+        osr_buffer_cursor_(0),
+        osr_hits_(0),
+        osr_attempts_(0),
+        blocked_jobs_(0),
+        ref_count_(0),
+        tracing_enabled_(FLAG_trace_concurrent_recompilation),
+        job_based_recompilation_(FLAG_job_based_recompilation),
+        recompilation_delay_(FLAG_concurrent_recompilation_delay) {
+    base::NoBarrier_Store(&stop_thread_,
+                          static_cast<base::AtomicWord>(CONTINUE));
+    input_queue_ = NewArray<OptimizedCompileJob*>(input_queue_capacity_);
+    if (FLAG_concurrent_osr) {
+      // Allocate and mark OSR buffer slots as empty.
+      osr_buffer_ = NewArray<OptimizedCompileJob*>(osr_buffer_capacity_);
+      for (int i = 0; i < osr_buffer_capacity_; i++) osr_buffer_[i] = NULL;
+    }
+  }
+
+  ~OptimizingCompilerThread();
+
+  void Run();
+  void Stop();
+  void Flush();
+  void QueueForOptimization(OptimizedCompileJob* optimizing_compiler);
+  void Unblock();
+  void InstallOptimizedFunctions();
+  OptimizedCompileJob* FindReadyOSRCandidate(Handle<JSFunction> function,
+                                             BailoutId osr_ast_id);
+  bool IsQueuedForOSR(Handle<JSFunction> function, BailoutId osr_ast_id);
+
+  bool IsQueuedForOSR(JSFunction* function);
+
+  inline bool IsQueueAvailable() {
+    base::LockGuard<base::Mutex> access_input_queue(&input_queue_mutex_);
+    return input_queue_length_ < input_queue_capacity_;
+  }
+
+  inline void AgeBufferedOsrJobs() {
+    // Advance cursor of the cyclic buffer to next empty slot or stale OSR job.
+    // Dispose said OSR job in the latter case.  Calling this on every GC
+    // should make sure that we do not hold onto stale jobs indefinitely.
+    AddToOsrBuffer(NULL);
+  }
+
+  static bool Enabled(int max_available) {
+    return (FLAG_concurrent_recompilation && max_available > 1);
+  }
+
+#ifdef DEBUG
+  static bool IsOptimizerThread(Isolate* isolate);
+  bool IsOptimizerThread();
+#endif
+
+ private:
+  class CompileTask;
+
+  enum StopFlag { CONTINUE, STOP, FLUSH };
+
+  void FlushInputQueue(bool restore_function_code);
+  void FlushOutputQueue(bool restore_function_code);
+  void FlushOsrBuffer(bool restore_function_code);
+  void CompileNext(OptimizedCompileJob* job);
+  OptimizedCompileJob* NextInput(bool check_if_flushing = false);
+
+  // Add a recompilation task for OSR to the cyclic buffer, awaiting OSR entry.
+  // Tasks evicted from the cyclic buffer are discarded.
+  void AddToOsrBuffer(OptimizedCompileJob* compiler);
+
+  inline int InputQueueIndex(int i) {
+    int result = (i + input_queue_shift_) % input_queue_capacity_;
+    DCHECK_LE(0, result);
+    DCHECK_LT(result, input_queue_capacity_);
+    return result;
+  }
+
+#ifdef DEBUG
+  int thread_id_;
+  base::Mutex thread_id_mutex_;
+#endif
+
+  Isolate* isolate_;
+  base::Semaphore stop_semaphore_;
+  base::Semaphore input_queue_semaphore_;
+
+  // Circular queue of incoming recompilation tasks (including OSR).
+  OptimizedCompileJob** input_queue_;
+  int input_queue_capacity_;
+  int input_queue_length_;
+  int input_queue_shift_;
+  base::Mutex input_queue_mutex_;
+
+  // Queue of recompilation tasks ready to be installed (excluding OSR).
+  UnboundQueue<OptimizedCompileJob*> output_queue_;
+  // Used for job based recompilation which has multiple producers on
+  // different threads.
+  base::Mutex output_queue_mutex_;
+
+  // Cyclic buffer of recompilation tasks for OSR.
+  OptimizedCompileJob** osr_buffer_;
+  int osr_buffer_capacity_;
+  int osr_buffer_cursor_;
+
+  volatile base::AtomicWord stop_thread_;
+  base::TimeDelta time_spent_compiling_;
+  base::TimeDelta time_spent_total_;
+
+  int osr_hits_;
+  int osr_attempts_;
+
+  int blocked_jobs_;
+
+  int ref_count_;
+  base::Mutex ref_count_mutex_;
+  base::ConditionVariable ref_count_zero_;
+
+  // Copies of FLAG_trace_concurrent_recompilation,
+  // FLAG_concurrent_recompilation_delay and
+  // FLAG_job_based_recompilation that will be used from the background thread.
+  //
+  // Since flags might get modified while the background thread is running, it
+  // is not safe to access them directly.
+  bool tracing_enabled_;
+  bool job_based_recompilation_;
+  int recompilation_delay_;
+};
+
+} }  // namespace v8::internal
+
+#endif  // V8_OPTIMIZING_COMPILER_THREAD_H_