Refactor Hydrogen GVN into an HPhase and use the phase zone.

src/hydrogen-gvn.h

Index: src/hydrogen-gvn.h
diff --git a/src/hydrogen-gvn.h b/src/hydrogen-gvn.h
index 2d6075e7157a8d558a8d9f496e1e7c6b9e648c8d..819ead341c54333f85cfc1bea6f18e21168880de 100644
--- a/src/hydrogen-gvn.h
+++ b/src/hydrogen-gvn.h
@@ -76,14 +76,25 @@ class SparseSet {
 };
 
 
-class HGlobalValueNumberer BASE_EMBEDDED {
+// Perform common subexpression elimination and loop-invariant code motion.
+class HGlobalValueNumberingPhase : public HPhase {
  public:
-  HGlobalValueNumberer(HGraph* graph, CompilationInfo* info);
+  HGlobalValueNumberingPhase(HGraph* graph, Zone* zone);

[danno, 2013/06/25 15:20:54]

Why do you need to pass the zone in? Shouldn't you be able to get it from
graph()->info()->phase_zone()?

[Benedikt Meurer, 2013/06/27 08:20:04]

Done. Using the HPhase zone.

+
+  void Run() {
+    bool removed_side_effects = Analyze();
+    // Trigger a second analysis pass to further eliminate duplicate values that
+    // could only be discovered by removing side-effect-generating instructions
+    // during the first pass.
+    if (FLAG_smi_only_arrays && removed_side_effects) {
+      removed_side_effects = Analyze();
+      ASSERT(!removed_side_effects);
+    }
+  }
 
+ private:
   // Returns true if values with side effects are removed.
   bool Analyze();
-
- private:
   GVNFlagSet CollectSideEffectsOnPathsToDominatedBlock(
       HBasicBlock* dominator,
       HBasicBlock* dominated);
@@ -98,17 +109,10 @@ class HGlobalValueNumberer BASE_EMBEDDED {
   bool AllowCodeMotion();
   bool ShouldMove(HInstruction* instr, HBasicBlock* loop_header);
 
-  HGraph* graph() { return graph_; }
-  CompilationInfo* info() { return info_; }
-  Zone* phase_zone() const { return info_->phase_zone(); }
+  CompilationInfo* info() { return graph()->info(); }
 
-  HGraph* graph_;
-  CompilationInfo* info_;
   bool removed_side_effects_;
 
-  Zone* phase_zone_;
-  ZoneScope phase_zone_scope_;
-
   // A map of block IDs to their side effects.
   ZoneList<GVNFlagSet> block_side_effects_;
 
@@ -118,6 +122,8 @@ class HGlobalValueNumberer BASE_EMBEDDED {
   // Used when collecting side effects on paths from dominator to
   // dominated.
   SparseSet visited_on_paths_;
+
+  DISALLOW_COPY_AND_ASSIGN(HGlobalValueNumberingPhase);
 };