Reland of r19102: Check elimination improvement: propagation of state through phis is supported, Che

src/hydrogen-instructions.h

Index: src/hydrogen-instructions.h
diff --git a/src/hydrogen-instructions.h b/src/hydrogen-instructions.h
index b1dc88aaa0c2ee7863c4b37e9763b6a3d509e764..9073ac36ca9983aa3e51550cb137b882370a511d 100644
--- a/src/hydrogen-instructions.h
+++ b/src/hydrogen-instructions.h
@@ -2651,10 +2651,10 @@ class HCheckMaps V8_FINAL : public HTemplateInstruction<2> {
  public:
   static HCheckMaps* New(Zone* zone, HValue* context, HValue* value,
                          Handle<Map> map, CompilationInfo* info,
-                         HValue *typecheck = NULL);
+                         HValue* typecheck = NULL);
   static HCheckMaps* New(Zone* zone, HValue* context,
                          HValue* value, SmallMapList* maps,
-                         HValue *typecheck = NULL) {
+                         HValue* typecheck = NULL) {
     HCheckMaps* check_map = new(zone) HCheckMaps(value, zone, typecheck);
     for (int i = 0; i < maps->length(); i++) {
       check_map->Add(maps->at(i), zone);
@@ -2673,10 +2673,18 @@ class HCheckMaps V8_FINAL : public HTemplateInstruction<2> {
   virtual void PrintDataTo(StringStream* stream) V8_OVERRIDE;
 
   HValue* value() { return OperandAt(0); }
+  HValue* typecheck() { return OperandAt(1); }
 
   Unique<Map> first_map() const { return map_set_.at(0); }
   UniqueSet<Map> map_set() const { return map_set_; }
 
+  void set_map_set(UniqueSet<Map>* maps, Zone *zone) {
+    map_set_.Clear();
+    for (int i = 0; i < maps->size(); i++) {
+      map_set_.Add(maps->at(i), zone);
+    }
+  }
+
   bool has_migration_target() const {
     return has_migration_target_;
   }