Optimize functions on a second 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
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+// Copyright 2012 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#ifndef V8_OPTIMIZING_COMPILER_THREAD_H_
+#define V8_OPTIMIZING_COMPILER_THREAD_H_
+
+#include "atomicops.h"
+#include "platform.h"
+#include "flags.h"
+#include "unbound-queue.h"
+
+namespace v8 {
+namespace internal {
+
+class HGraphBuilder;
+class OptimizingCompiler;
+
+class OptimizingCompilerThread : public Thread {
+ public:
+  explicit OptimizingCompilerThread(Isolate *isolate) :
+      Thread("OptimizingCompilerThread"),
+      isolate_(isolate),
+      stop_semaphore_(OS::CreateSemaphore(0)),
+      input_queue_semaphore_(OS::CreateSemaphore(0)) {
+    NoBarrier_Store(&stop_thread_, static_cast<AtomicWord>(false));
+    NoBarrier_Store(&queue_length_, static_cast<AtomicWord>(0));
+  }
+
+  void Run();
+  void Stop();
+  void QueueForOptimization(OptimizingCompiler* optimizing_compiler);
+  void InstallOptimizedFunctions();
+
+  inline bool IsQueueAvailable() {
+    // We don't need a barrier since we have a data dependency right
+    // after.
+    Atomic32 current_length = NoBarrier_Load(&queue_length_);
+
+    // This can be queried only from the execution thread.
+    ASSERT(!IsOptimizerThread());
+    // Since only the execution thread increments queue_length_ and
+    // only one thread can run inside an Isolate at one time, a direct
+    // doesn't introduce a race -- queue_length_ may decreased in
+    // meantime, but not increased.
+    return (current_length < FLAG_parallel_recompilation_queue_length);
+  }
+
+#ifdef DEBUG
+  bool IsOptimizerThread();
+#endif
+
+  ~OptimizingCompilerThread() {
+    delete input_queue_semaphore_;
+    delete stop_semaphore_;
+  }
+
+ private:
+  Isolate* isolate_;
+  Semaphore* stop_semaphore_;
+  Semaphore* input_queue_semaphore_;
+  UnboundQueue<OptimizingCompiler*> input_queue_;
+  UnboundQueue<OptimizingCompiler*> output_queue_;
+  volatile AtomicWord stop_thread_;
+  volatile Atomic32 queue_length_;
+
+#ifdef DEBUG
+  int thread_id_;
+#endif
+};
+
+} }  // namespace v8::internal
+
+#endif  // V8_OPTIMIZING_COMPILER_THREAD_H_