Revert "Fix compilation with C++11." and "Allocation site support for monomorphic StringAdds in Bin…

src/hydrogen-instructions.h

Index: src/hydrogen-instructions.h
diff --git a/src/hydrogen-instructions.h b/src/hydrogen-instructions.h
index a32a418606a058f5368a29d0ca0782a2400136e6..086f9a1a4cea430882d2b3b8d74938ce23581386 100644
--- a/src/hydrogen-instructions.h
+++ b/src/hydrogen-instructions.h
@@ -6992,55 +6992,45 @@ class HStringAdd V8_FINAL : public HBinaryOperation {
                            HValue* context,
                            HValue* left,
                            HValue* right,
-                           PretenureFlag pretenure_flag = NOT_TENURED,
-                           StringAddFlags flags = STRING_ADD_CHECK_BOTH,
-                           Handle<AllocationSite> allocation_site =
-                               Handle<AllocationSite>::null());
+                           StringAddFlags flags = STRING_ADD_CHECK_NONE);
 
   StringAddFlags flags() const { return flags_; }
-  PretenureFlag pretenure_flag() const { return pretenure_flag_; }
 
   virtual Representation RequiredInputRepresentation(int index) V8_OVERRIDE {
     return Representation::Tagged();
   }
 
-  virtual void PrintDataTo(StringStream* stream) V8_OVERRIDE;
-
   DECLARE_CONCRETE_INSTRUCTION(StringAdd)
 
  protected:
-  virtual bool DataEquals(HValue* other) V8_OVERRIDE {
-    return flags_ == HStringAdd::cast(other)->flags_ &&
-        pretenure_flag_ == HStringAdd::cast(other)->pretenure_flag_;
-  }
+  virtual bool DataEquals(HValue* other) V8_OVERRIDE { return true; }
 
  private:
-  HStringAdd(HValue* context,
-             HValue* left,
-             HValue* right,
-             PretenureFlag pretenure_flag,
-             StringAddFlags flags,
-             Handle<AllocationSite> allocation_site)
-      : HBinaryOperation(context, left, right, HType::String()),
-        flags_(flags), pretenure_flag_(pretenure_flag) {
+  HStringAdd(HValue* context, HValue* left, HValue* right, StringAddFlags flags)
+      : HBinaryOperation(context, left, right, HType::String()), flags_(flags) {
     set_representation(Representation::Tagged());
-    SetFlag(kUseGVN);
-    SetGVNFlag(kDependsOnMaps);
-    SetGVNFlag(kChangesNewSpacePromotion);
-    if (FLAG_trace_pretenuring) {
-      PrintF("HStringAdd with AllocationSite %p %s\n",
-             allocation_site.is_null()
-                 ? static_cast<void*>(NULL)
-                 : static_cast<void*>(*allocation_site),
-             pretenure_flag == TENURED ? "tenured" : "not tenured");
+    if (MightHaveSideEffects()) {
+      SetAllSideEffects();
+    } else {
+      SetFlag(kUseGVN);
+      SetGVNFlag(kDependsOnMaps);
+      SetGVNFlag(kChangesNewSpacePromotion);
     }
   }
 
+  bool MightHaveSideEffects() const {
+    return flags_ != STRING_ADD_CHECK_NONE &&
+      (left()->ToStringCanBeObserved() || right()->ToStringCanBeObserved());
+  }
+
   // No side-effects except possible allocation:
-  virtual bool IsDeletable() const V8_OVERRIDE { return true; }
+  // NOTE: this instruction does not call ToString() on its inputs, when flags_
+  // is set to STRING_ADD_CHECK_NONE.
+  virtual bool IsDeletable() const V8_OVERRIDE {
+    return !MightHaveSideEffects();
+  }
 
   const StringAddFlags flags_;
-  const PretenureFlag pretenure_flag_;
 };