[stubs] Port KeyedStoreIC_Megamorphic stub to Turbofan

src/objects.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/objects.h"
 
 #include <cmath>
 #include <iomanip>
 #include <memory>
 #include <sstream>
@@ skipping 15919 matching lines @@
       }
       site->SetElementsKind(to_kind);
       site->dependent_code()->DeoptimizeDependentCodeGroup(
           isolate, DependentCode::kAllocationSiteTransitionChangedGroup);
       result = true;
     }
   }
   return result;
 }
 
+AllocationSiteMode AllocationSite::GetMode(ElementsKind from, ElementsKind to) {
+  if (IsFastSmiElementsKind(from) &&
+      IsMoreGeneralElementsKindTransition(from, to)) {
+    return TRACK_ALLOCATION_SITE;
+  }
+
+  return DONT_TRACK_ALLOCATION_SITE;
+}
 
 const char* AllocationSite::PretenureDecisionName(PretenureDecision decision) {
   switch (decision) {
     case kUndecided: return "undecided";
     case kDontTenure: return "don't tenure";
     case kMaybeTenure: return "maybe tenure";
     case kTenure: return "tenure";
     case kZombie: return "zombie";
     default: UNREACHABLE();
   }
@@ skipping 4381 matching lines @@
     // Check if the accessor uses a cached property.
     if (!fti->cached_property_name()->IsTheHole(isolate)) {
       return handle(Name::cast(fti->cached_property_name()));
     }
   }
   return MaybeHandle<Name>();
 }
 
 }  // namespace internal
 }  // namespace v8