Introduce SynchronizedScope to allow heap access from compiler thread.

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
index eae1f608f9cb27a3e2841466ef65b012724dabf1..0d5a103fb01afee0df4fdd1a0f35abbffa8b591a 100644
--- a/src/optimizing-compiler-thread.h
+++ b/src/optimizing-compiler-thread.h
@@ -29,6 +29,7 @@
 #define V8_OPTIMIZING_COMPILER_THREAD_H_
 
 #include "atomicops.h"
+#include "assert-scope.h"
 #include "flags.h"
 #include "list.h"
 #include "platform.h"
@@ -39,6 +40,7 @@
 namespace v8 {
 namespace internal {
 
+class CompilationInfo;
 class HOptimizedGraphBuilder;
 class OptimizedCompileJob;
 class SharedFunctionInfo;
@@ -53,6 +55,8 @@ class OptimizingCompilerThread : public Thread {
       isolate_(isolate),
       stop_semaphore_(0),
       input_queue_semaphore_(0),
+      main_thread_semaphore_(0),
+      compiler_thread_semaphore_(0),
       input_queue_capacity_(FLAG_concurrent_recompilation_queue_length),
       input_queue_length_(0),
       input_queue_shift_(0),
@@ -61,7 +65,7 @@ class OptimizingCompilerThread : public Thread {
       osr_hits_(0),
       osr_attempts_(0),
       blocked_jobs_(0) {
-    NoBarrier_Store(&stop_thread_, static_cast<AtomicWord>(CONTINUE));
+    NoBarrier_Store(&loop_switch_, static_cast<AtomicWord>(CONTINUE));
     input_queue_ = NewArray<OptimizedCompileJob*>(input_queue_capacity_);
     if (FLAG_concurrent_osr) {
       // Allocate and mark OSR buffer slots as empty.
@@ -85,7 +89,7 @@ class OptimizingCompilerThread : public Thread {
   bool IsQueuedForOSR(JSFunction* function);
 
   inline bool IsQueueAvailable() {
-    LockGuard<Mutex> access_input_queue(&input_queue_mutex_);
+    LockGuard<Mutex> access_input_queue(&mutex_);
     return input_queue_length_ < input_queue_capacity_;
   }
 
@@ -105,12 +109,37 @@ class OptimizingCompilerThread : public Thread {
   bool IsOptimizerThread();
 #endif
 
+  void PauseMainThread();
+  void ContinueMainThread();
+  void YieldToCompilerThread();
+
+  // Use this scope during the optimization phase to synchronize with
+  // the main thread in order to access the heap.
+  class SynchronizedScope {
+   public:
+    explicit SynchronizedScope(CompilationInfo* info);
+    ~SynchronizedScope();
+
+   private:
+    CompilationInfo* info_;
+    AllowHandleAllocation allow_handle_allocation_;
+    AllowHandleDereference allow_handle_dereference_;
+    AllowHeapAllocation allow_heap_allocation_;
+  };
+
  private:
-  enum StopFlag { CONTINUE, STOP, FLUSH };
+  enum LoopSwitch { CONTINUE, STOP, FLUSH };
+  enum FlushMode { DO_NOT_RESTORE_FUNCTION_CODE, RESTORE_FUNCTION_CODE };
+
+  inline void SetSwitchAndInterceptInterrupt(LoopSwitch loop_switch);
+  inline void PrepareInterruption(LoopSwitch loop_switch);
+  inline void DisposeOptimizedCompileJob(OptimizedCompileJob* job,
+                                         FlushMode mode);
+
+  void FlushInputQueue(FlushMode mode);
+  void FlushOutputQueue(FlushMode mode);
+  void FlushOsrBuffer(FlushMode mode);
 
-  void FlushInputQueue(bool restore_function_code);
-  void FlushOutputQueue(bool restore_function_code);
-  void FlushOsrBuffer(bool restore_function_code);
   void CompileNext();
   OptimizedCompileJob* NextInput();
 
@@ -133,13 +162,15 @@ class OptimizingCompilerThread : public Thread {
   Isolate* isolate_;
   Semaphore stop_semaphore_;
   Semaphore input_queue_semaphore_;
+  Semaphore main_thread_semaphore_;
+  Semaphore compiler_thread_semaphore_;
+  Mutex mutex_;
 
   // Circular queue of incoming recompilation tasks (including OSR).
   OptimizedCompileJob** input_queue_;
   int input_queue_capacity_;
   int input_queue_length_;
   int input_queue_shift_;
-  Mutex input_queue_mutex_;
 
   // Queue of recompilation tasks ready to be installed (excluding OSR).
   UnboundQueue<OptimizedCompileJob*> output_queue_;
@@ -149,7 +180,7 @@ class OptimizingCompilerThread : public Thread {
   int osr_buffer_capacity_;
   int osr_buffer_cursor_;
 
-  volatile AtomicWord stop_thread_;
+  volatile AtomicWord loop_switch_;
   TimeDelta time_spent_compiling_;
   TimeDelta time_spent_total_;