[platform] Implement a worker pool

src/libplatform/task-queue.h

Index: src/libplatform/task-queue.h
diff --git a/src/hydrogen-minus-zero.h b/src/libplatform/task-queue.h
similarity index 68%
copy from src/hydrogen-minus-zero.h
copy to src/libplatform/task-queue.h
index d23ec1196b3419cdc06e20aa3e12688979306009..a3182d35311febb984922a8c38ad0730441806d8 100644
--- a/src/hydrogen-minus-zero.h
+++ b/src/libplatform/task-queue.h
@@ -25,32 +25,47 @@
 // (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_HYDROGEN_MINUS_ZERO_H_
-#define V8_HYDROGEN_MINUS_ZERO_H_
+#ifndef V8_LIBPLATFORM_TASK_QUEUE_H_
+#define V8_LIBPLATFORM_TASK_QUEUE_H_
 
-#include "hydrogen.h"
+#include <queue>
+
+// TODO(jochen): We should have our own version of globals.h.
+#include "../globals.h"
+#include "../platform/mutex.h"
+#include "../platform/semaphore.h"
 
 namespace v8 {
-namespace internal {
 
+class Task;
 
-class HComputeMinusZeroChecksPhase : public HPhase {
+namespace internal {
+
+class TaskQueue {
  public:
-  explicit HComputeMinusZeroChecksPhase(HGraph* graph)
-      : HPhase("H_Compute minus zero checks", graph),
-        visited_(graph->GetMaximumValueID(), zone()) { }
+  TaskQueue();
+  ~TaskQueue();
 
-  void Run();
+  // Appends a task to the queue. The queue takes ownership of |task|.
+  void Append(Task* task);
 
- private:
-  void PropagateMinusZeroChecks(HValue* value);
+  // Returns the next task to process. Blocks if no task is available. Returns
+  // NULL if the queue is terminated.
+  Task* GetNext();
 
-  BitVector visited_;
+  // Terminate the queue.
+  void Terminate();
 
-  DISALLOW_COPY_AND_ASSIGN(HComputeMinusZeroChecksPhase);
-};
+ private:
+  Mutex lock_;
+  Semaphore process_queue_semaphore_;
+  std::queue<Task*> task_queue_;
+  bool terminated_;
 
+  DISALLOW_COPY_AND_ASSIGN(TaskQueue);
+};
 
 } }  // namespace v8::internal
 
-#endif  // V8_HYDROGEN_MINUS_ZERO_H_
+
+#endif  // V8_LIBPLATFORM_TASK_QUEUE_H_