Turn dead code elimination into a proper HPhase.

src/hydrogen-dce.h

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-#ifndef V8_HYDROGEN_ESCAPE_ANALYSIS_H_
-#define V8_HYDROGEN_ESCAPE_ANALYSIS_H_
+#ifndef V8_HYDROGEN_DCE_H_
+#define V8_HYDROGEN_DCE_H_
 
-#include "allocation.h"
 #include "hydrogen.h"
 
 namespace v8 {
 namespace internal {
 
 
-class HEscapeAnalysisPhase : public HPhase {
+class HDeadCodeEliminationPhase : public HPhase {
  public:
-  explicit HEscapeAnalysisPhase(HGraph* graph)
-      : HPhase("H_Escape analysis", graph), captured_(0, zone()) { }
+  explicit HDeadCodeEliminationPhase(HGraph* graph)
+      : HPhase("H_Dead code elimination", graph),
+        worklist_(graph->blocks()->length(), zone()) { }
 
   void Run() {
-    CollectCapturedValues();
+    MarkLiveInstructions();
+    RemoveDeadInstructions();
   }
 
  private:
-  void CollectCapturedValues();
-  void CollectIfNoEscapingUses(HInstruction* instr);
+  void MarkLive(HValue* ref, HValue* instr);
+  void MarkLiveInstructions();
+  void RemoveDeadInstructions();
 
-  ZoneList<HValue*> captured_;
+  ZoneList<HValue*> worklist_;

[Dmitry Lomov (no reviews), 2013/07/05 19:06:20]

It looks like the uses of worklist_ inside MarkLiveInstructions and
RemoveDeadInstructions are completely independent, and they both assert that
they start with empty worklist.
Let's not introduce the state where there is no state - keep worklist local to
each function and pass it to MarkLive. Maybe even better, make MarkList return
boolean and keep addition to worklist local to MarkLiveInstructions.

[Benedikt Meurer, 2013/07/06 07:30:42]

Done.

 };
 
 
 } }  // namespace v8::internal
 
-#endif  // V8_HYDROGEN_ESCAPE_ANALYSIS_H_
+#endif  // V8_HYDROGEN_DCE_H_